bird island biodiversity action plan · plant species and introduced weedy species. the island also...

2014

EAC – Ecological Evaluation Pty Ltd

June 2014

Bird Island Biodiversity Action Plan

Document Information Client Adelaide & Mt Lofty Ranges Natural

Resources Management Board

Issue Date 12/9/2014

Version 2.3

Author Tim Milne

Title Director

Signature Verified by Sarah Telfer

Title Director

Signature

Document History Version Issue Date

1.0 20/6/2014

2.0 4/7/2014

2.1 21/7/14

2.2 24/7/14

2.3 12/9/14

EAC – Ecological Evaluation Pty Ltd have prepared this report for the sole purposes of the Client for the specific purpose only for which it is supplied. We accept no liability for any direct or consequential loss arising from the transmission of this information to third parties. This report is current at the date of writing only and EAC – Ecological Evaluation Pty Ltd will not be responsible for informing of any future changes in circumstances which may affect the accuracy of the information contained in this report. EAC – Ecological Evaluation Pty Ltd does not offer or hold itself out as offering any advice relating to legal or regulatory implications. Certain assumptions have been made in the preparation of this report. We have assumed that all information and documents provided to us by the Client or as a result of a specific request or enquiry were complete, accurate and up-to-date. Where we have obtained information from a government register or database, we have assumed that the information is accurate. Where an assumption has been made, we have not made any independent investigations with respect to the matters the subject of that assumption. We are not aware of any reason why any of the assumptions are incorrect.

EAC- Ecological Evaluation Pty Ltd 5/26 Hack St Mount Barker, South Australia 5251 Telephone: (08) 8185 3225 [email protected]

E c o l o g i c a l E v a l u a t i o n

mailto:[email protected]

Contents Executive Summary............................................................................................................................... 4

1. INTRODUCTION ............................................................................................................................. 1

2. STUDY AREA .................................................................................................................................. 2

2.1 Current land management .................................................................................................... 3

2.2 Brief History of Bird Island .................................................................................................... 3

2.3 Biodiversity significance ........................................................................................................ 9

3. AIM AND OBJECTIVES OF THE PLAN ............................................................................................ 10

4. ENVIRONMENTAL ASSETS ........................................................................................................... 10

4.1 Landform and soils .............................................................................................................. 10

4.2 Native vegetation communities .......................................................................................... 10

4.2.1 Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland .................... 10

4.2.2 Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia

marina ssp. marina ..................................................................................................................... 13

4.2.3 Atriplex cinerea / Nitraria billardierei Open Shrubland ............................................... 14

4.2.4 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland .................... 16

4.3 Significant Flora Species ...................................................................................................... 17

4.4 Native Fauna ....................................................................................................................... 18

4.4.1 Birds ............................................................................................................................ 18

4.4.2 Reptiles and Frogs ....................................................................................................... 20

4.4.3 Mammals .................................................................................................................... 20

4.4.4 Fish .............................................................................................................................. 20

4.4.5 Intertidal Invertebrates ............................................................................................... 21

5. THREATS (MANAGEMENT ISSUES) .............................................................................................. 21

5.1 Predation of birds and their nests by pest animals ............................................................. 21

5.2 Recreational activities ......................................................................................................... 22

5.3 Invasive weeds .................................................................................................................... 23

5.4 Over-proliferation of Silver Gulls ......................................................................................... 24

5.6 Marine pollution ................................................................................................................. 24

5.6 Lack of cadastral status ....................................................................................................... 26

5.7 Dredge spoil deposition from dredging of the Outer Harbor Channel ................................ 26

5.8 Climate change.................................................................................................................... 26

6. MANAGEMENT OBJECTIVES AND ACTIONS ................................................................................ 27

6.1 Biodiversity management objectives .................................................................................. 27

6.2 Biodiversity management actions ....................................................................................... 27

6.2.1 Managing pest animals ................................................................................................... 27

6.2.2 Managing recreational impacts ....................................................................................... 27

6.2.3 Managing weeds ............................................................................................................. 29

6.2.3.1 Samphire Shrubland Communities .............................................................................. 30

6.2.3.2 Atriplex cinerea / Nitraria billardierei Open Shrubland ............................................... 30

6.2.3.3 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland .................... 30

6.2.4 Rubbish/debris removal .................................................................................................. 30

6.2.5 Dredge spoil deposition from dredging of the Outer Harbor Channel ............................ 30

6.2.6 Maintaining open habitat areas ...................................................................................... 31

6.2.7 Revegetation ................................................................................................................... 31

7. COMMUNITY INVOLVEMENT ...................................................................................................... 32

8. MONITORING .............................................................................................................................. 33

8.1 Monitoring Pest Animals ..................................................................................................... 33

8.2 Monitoring of Native Vegetation Extent and Condition ...................................................... 33

8.3 Monitoring Seabird and Wader Populations ....................................................................... 33

8.4 Plan implementation – progress reporting ......................................................................... 34

9. BIODIVERSITY ACTION PLAN ....................................................................................................... 35

Appendix 1: BushRAT monitoring data ............................................................................................... 39

Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland ....................................... 41

Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina ssp.

marina ............................................................................................................................................ 43

Atriplex cinerea / Nitraria billardierei Open Shrubland ................................................................... 45

Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland ........................................ 48

Appendix 2: Notes on birds in the Outer Harbor Area (adapted from Telfer 2013) ............................ 51

Appendix 3: Weed control methods ................................................................................................... 66

Appendix 4: Works record sheets ....................................................................................................... 74

Executive Summary Bird Island (also known as Section Banks) is situated at the northern end of the Outer Harbor

breakwater. It is an exposed artificial island made of coarse shell-grit, clay and sand that extends for

approximately 1600m. It has been created by a combination of anthropogenic and natural

processes.

Bird Island provides significant habitat values for many bird species, including seabirds and waders of

state, national and international conservation significance. Ten native bird species have been

observed to breed on the island, with another three species considered to possibly breed there. Of

this total of 13 native breeding species, three are considered to be Rare at a state level - Kelp Gull,

Pied Oystercatcher and Sooty Oystercatcher, and the fourth species, the Fairy Tern, is Endangered at

State level and Vulnerable at a national level. The tidal flats around Bird Island are rich in

invertebrates, adding to the value for the area for seabirds.

The vegetation of the island is composed of both native and introduced weed species. The

vegetation varies from areas dominated by introduced species, to areas where native species

predominate. Time series photography indicates that samphire and mangrove vegetation has

colonised the eastern side of the Island in the last ten years.

The Island, and particularly its significant vagrant, resident and breeding bird species, is exposed to a

number of threats. Key threats include:

the impact of introduced pests, such as black rats and foxes;

unmanaged human visitation, particularly when associated with uncontrolled pet dogs

invasive weeds

overproliferation of native Silver Gulls and their impacts on other bird species

marine pollution

possible future dredging and spoil deposition

loss of open habitat areas favorable for nesting for some bird species

A series of management actions are proposed to maintain or improve the biodiversity values on the

Island. These include:

controlling pest animals

managing recreational impacts

restricting access of pet dogs

treating priority weeds, whilst recognising the roosting values provided by some species

replacing weedy shrub species with native shrubs

monitoring growth of vegetation with removal (if required) to ensure some open habitat

areas remain

removing rubbish and debris

increasing community awareness of the significance of Bird Island

A Biodiversity Action Plan table has been developed which summarises the actions required,

provides specific targets, and links to an ongoing monitoring program that can document success.

1. INTRODUCTION

Bird Island (also known as the Northern Breakwater/Revetment or Section Banks) is situated at the

northern end of the Outer Harbor breakwater. It is an exposed artificial island made of coarse shell-

grit, clay and sand that extends for approximately 1600m. It has been colonised by indigenous local

plant species and introduced weedy species. The island also forms a significant roost and feeding

site for both migratory and non-migratory shorebirds, and is a breeding rookery for seabirds,

including Australian Pelican and the endangered Fairy Tern. As such, it has high inherent biodiversity

values, and provides habitat for bird species of national and international significance.

The intent of this project is to develop a Biodiversity Action Plan which documents the significant

biodiversity assets of the Island, threats to these assets, and develops practical and pragmatic

actions to ameliorate these threats. An ongoing monitoring program to evaluate success of

proposed actions will also be devised.

The Biodiversity Action Plan includes:

mapping of different vegetation associations

inventory of plant species present

inventory of actual and potential habitat for native species, with a focus on species of conservation significance at state, national and international level

mapping pest plant distribution and density

prioritising weeds for control

an assessment of the presence of pest animals

identification of priority issues relating to human activity/usage

identification of actions necessary to improve the conservation, management and protection of the Island

baseline monitoring and a description of an ongoing monitoring methodology to measure success of management actions

The Bird Island Biodiversity Action Plan is intended to align with, and contribute to, the objectives of

the following strategies and plans:

The Adelaide and Mount Lofty Ranges Natural Resources Management Plan (2013) which

outlines the Adelaide and Mt Lofty Ranges NRM Board's investment priorities over a three-

year period. This includes the establishment of long-term goals and clearly defined targets.

The Metropolitan Adelaide and Northern Coastal Action Plan 2009. The goal of this Plan is to

understand and facilitate the conservation, protection and maintenance of the region’s

natural coastal resources and to establish conservation priorities for places and areas within

the Region. The Plan includes a regional recommendation on Conserving Valuable Areas,

with an objective: To raise the conservation status and management investment in selected

significant areas within the region. A specific action is identified: To facilitate management of

the Section Banks through clarification of its status.

The Regional Recovery Plan for Threatened Species and Ecological Communities of Adelaide

and the Mount Lofty Ranges 2009-2014.

Adelaide Dolphin Sanctuary Management Plan Objectives

Wildlife Conservation Plan for Migratory Shorebirds (2006)

Proposal for the Adelaide International Bird Sanctuary. Surveys indicate the importance of

the island as a roost site for migratory shorebirds and adjacent tidal flats of Section Bank

have high species richness of shorebird food species.

2. STUDY AREA Bird Island is located in the Port River, approximately 15km northwest of Adelaide. It is at the

northern end of the Northern Revetment mound (a rock breakwater) about 700 m offshore from

Outer Harbor. This Biodiversity Action Plan also incorporates the area known as the Northern

Revetment, which is the northernmost section of the north Outer Harbor breakwater (Figure 2.0).

Figure 2.0: Bird Island Study Area

2.1 Current land management The Island and the surrounding seabed and intertidal area are owned freehold by the Minister for

Transport and Infrastructure by virtue of the Harbors and Navigation Act 1993. The southern portion

of this island is under the long term control of Flinders Ports by way of a Port Operating Agreement

that expires in 2100. The northern portion of the island is not covered by the Port Operating

Agreement and management responsibility is with the Minister for Transport and Infrastructure.

2.2 Brief History of Bird Island Outer Harbor was constructed in the early 1900s and opened to shipping in 19081. The northern

breakwater, consisting of jarrah piles and huge stone blocks, was completed in 19132, although was

increased in height by two metres in 19623. Bird Island was created from sediment dredged from

the Port River and deposited to the north of the northern revetment in about 19764. At that time the

Section Bank was separated from the northern revetment by about 160 m, but the two are now

joined.

Cooe (2008)5 noted “The loss of extensive areas of seagrass along the Adelaide metropolitan coast

has caused the mobilisation of exposed sediment. Resuspended sediment moves northwards and is

deposited on sand banks (such as Section Bank [Bird Island]) off Outer Harbor and the northern

beaches”. As such Bird Island is slowly growing to the north-east as this sediment accumulates.

Vincent (1988) noted the Island was only 900m long in 1987, but its current length is approximately

1.6 km from the northern revetment to the north east, with a vegetated width of up to 200 metres.

This near doubling in length of Section Banks in the last 30 years has resulted both from channel

dredging and dumping, as well as accumulation of sediments driven north along the coast by wave

energy and the northerly littoral or longshore current.

Bird Island has been colonised by coastal plants, particularly Nitre-bush Nitraria billardierei and

Coast Saltbush Atriplex cinerea on higher ground, with Australian seablite Suaeda australis and

samphire Sarcocornia quinqueflora (and seedling mangroves Avicennia marina) on finer sediments

on the eastern side6.

Figures 2.2.1 to 2.2.5 show the historical changes that have occurred to the site from the late 1960’s

1 Ritter, R. (2005). Triumph, Tragedy and Port Adelaide. Hyde Park Press. 2 Ritter, R. (2005). Triumph, Tragedy and Port Adelaide. Hyde Park Press. 3 Vincent, D. 1988. Nesting of the Kelp Gull and other new breeding records from Outer Harbor. South Australian Ornithologist 30: 122-24. 4 Ritter, R. (2005). Triumph, Tragedy and Port Adelaide. Hyde Park Press. 5 Cooe. 2008. Marine and Coastal Environment and Potential Impact Assessment. Report prepared for Walker Corporation. 6 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008.

Figure 2.2.1: Aerial photography 9/1/1969. There is some sand accumulation at the end of the

breakwater, but Bird Island does not exist in its current location. The northern revetment does

not exist.

Figure 2.2.2: Aerial photography 19/3/1979. There appears to have been deposition of

materials to create a wall from the northern end of the breakwater. There appears to be

some vegetation present. Nitre Bush (Nitraria billardieri) was planted around this time (Greg

Johnston pers. comm.).

Figure 2.2.3: Aerial photography 28/9/1989. The wall of deposited material appears to have

been washed away. Bird Island is isolated from the northern breakwater. Vegetation is

evident.

Figure 2.2.4: Aerial photography 6/10/1999. The northern revetment has been created which

joins Bird Island to the northern breakwater. The Island is increasing in size to the north, with

vegetation developing in this newly formed area.

Figure 2.2.5: Aerial photography 24/1/2005. There is continued development of vegetation on

the northern end of Bird Island, as well as expansion north eastwards.

Figure 2.2.6: Aerial photography 2013. Note samphire vegetation developing on the eastern

side (brown-red in colour) and continued expansion north eastwards.

2.3 Biodiversity significance Populations of shorebirds (also known as ‘waders’) appear to be declining throughout the world.

Section Banks / Bird Island has been identified as a significant area for several shorebird species and

also supports regular breeding populations of 4 resident shorebirds as well as several waterbird and

tern species7. It is one of seven priority habitats on the eastern Gulf St Vincent with one or more

species in internationally or nationally significant numbers7. Carpenter (2008) noted: “The Section

Bank and adjoining revetment have significant value as a habitat for waterbirds, particularly:

1. as a nesting site for ground nesting colonial species (Australian Pelicans, Black-faced Cormorants,

Australian White Ibis, Royal Spoonbill, Fairy, Crested and Caspian Terns), and;

2. as a safe high tide roost for migratory and non-migratory waders. Its value as a roost reflects the

productivity of the adjacent tidal flats of Barker Inlet as a feeding habitat for these birds. Numbers

of migratory waders are greatest in summer, although significant numbers (mostly immature birds)

may remain over winter. Numbers of non-migratory waders fluctuate according to conditions

elsewhere, particularly inland floods. “

The large open mudflats on Section Bank provide some protection from raptors, contributing to

favourable habitat conditions for shorebirds8. Based on invertebrate surveys, Section Bank also has

some of the most species-rich tidal flats in the northern region. About 90 taxa found in total, being

highest on Section Bank and in particular zones of single sites. Molluscs, Annelida and Crustacea

accounted for the majority of the species9.

In addition, Johnston and Wiebkin10 note the northern revetment at Outer Harbor has “the largest

breeding colony of the endemic Black-faced cormorant, with up to 6000 nests recorded during the

winter breeding season”. The nesting colonies for Black-faced Cormorant, Royal Spoonbill, Fairy

Tern and Australian Pelican are significant at State level11.

Purnell et al (2013) recommend “The significant refuge habitat on Section Banks should be secured

and optimised by increasing pest control and reducing recreational visitation12.”

7 Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts 8 Dittmann, S., Baggalley, S., J. Keuning and Imgraben, S. (2012). Mudflat Condition Monitoring in Gulf St Vincent. Final Report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. 9 Dittmann, S., Baggalley, S., J. Keuning and Imgraben, S. (2012). Mudflat Condition Monitoring in Gulf St Vincent. Final Report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. 10 Johnston, G. and Wiebkin, A. (2008). Birds of Gulf St Vincent. In “Natural history of Gulf St Vincent”. S. A. Shepherd, S. Bryars, I. Kirkegaard, P. Harbison and J. T. Jennings (eds). Royal Society of South Australia, Adelaide. pp. 324-338. 11 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished. 12

Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts

3. AIM AND OBJECTIVES OF THE PLAN The aim of the Biodiversity Action Plan for Bird Island is to document the significant biodiversity

assets of the Island, threats to these assets, and to develop practical and pragmatic actions to

ameliorate these threats, based on an understanding of resources available. An ongoing monitoring

program to evaluate success of proposed actions is also included.

4. ENVIRONMENTAL ASSETS

4.1 Landform and soils Bird Island has been created by two processes – deposition of silty material in the late 1970’s from

material dredged from the Outer Harbor channel, and accumulation of sediments driven north along

the coast by wave energy and the northerly littoral or longshore current. As such, the soils present

are silt, particularly in the southern and landward sides of the Island, and sands which are present on

the seaward and northern sides and overlie the silt in some places.

4.2 Native vegetation communities The vegetation of Bird Island is defined by soil types, exposure to the sea, and time since deposition.

It can be broadly categorised into coastal dune, samphire and mangrove communities. The

following section describes the vegetation types found on site, which are also shown in Figure 4.2.

Note that plant species lists are based upon a once-off visit only. A comprehensive list would require

visiting the site on multiple occasions to take into account seasonal and rainfall related variability.

Each vegetation community was also assessed using the Department for Environment Water and

Natural Resources “BushRAT” methodology, with results summarised in Appendix 1.

4.2.1 Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland

This low closed samphire shrubland occurs in the eastern, sheltered side of Bird Island (Figure 4.2).

It is essentially weed free, with a high cover of native samphire species. Identification to species

level was not possible for all samphires due to the timing of the one-off visit on which this plant

species list was based.

Table 4.2.1.1: Plant species present in the Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland

Species Name Common Name Conservation Status

Comment

AUS SA SL

Sarcocornia quinqueflora Beaded Glasswort

Suaeda australis Austral Seablite

Tecticornia sp.

Figure 4.2.1.1: Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland

Figure 4.2: Vegetation Communities of Bird Island

4.2.1: Sarcocornia sp. / Tecticornia sp. / Sueda australis low closed shrubland

4.2.2: Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina

4.2.3: Atriplex cinerea / Nitraria billardierei Open Shrubland

4.2.4: Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland

4.2.2 Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia

marina ssp. marina

This vegetation type borders much of the sheltered eastern side of Bird Island (Figure 4.2), generally

on the boundary between samphire communities of 4.1.1 and marine environments. It is essentially

weed free, with a high cover of native samphire species, and emergent young Mangroves (Avicennia

marina ssp. marina). Identification to species level was not possible for all samphires due to the

timing of the one-off visit on which this plant species list was based. The first permanent mangroves

were noted in this area in 2005 (Greg Johnston pers. obs.). Whilst not extensive at this stage,

ongoing expansion of this mangrove may be a management issue. This is because expansion may

pose a threat to shorebird habitat in Gulf St Vincent, with incursion by mangroves occurring in many

coastal areas. The expansion of mangroves can limit the availability of the open spaces that

shorebirds use for roosting and feeding. Shorebirds prefer the security of open spaces with high

visibility for the easy detection of approaching predators13.

Figure 4.2.2.1: Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina ssp. marina

13

Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts.

Table 4.2.2.1: Plant species present in the Sarcocornia sp. / Tecticornia sp. low closed shrubland with emergent Avicennia marina ssp. marina


Comment

AUS SA SL

Avicennia marina ssp. marina Mangrove


Tecticornia sp.

4.2.3 Atriplex cinerea / Nitraria billardierei Open Shrubland

This open shrubland occurs in northern, sand-based soils of Bird Island. In some parts the shrubland

is very open. Woody weeds are relatively sparse, and there is a moderate to good diversity of

native plant species.

Figure 4.2.3.1: Atriplex cinerea / Nitraria billardierei Open Shrubland

Table 4.2.3.1: Plant species present in the Atriplex cinerea / Nitraria billardierei Open Shrubland


Comment

AUS SA SL

Atriplex cinerea Grey Saltbush

Atriplex semibaccata Creeping Saltbush


Comment

AUS SA SL

Austrostipa sp. Speargrass

Carpobrotus rossii Karkalla

Enchylaena tomentosa var.

tomentosa Barrier Saltbush

Myoporum insulare Native Juniper

Nitraria billardierei Dillon Bush


Senecio pinnatifolius var.

pinnatifolius

Senecio quadridentatus Cotton Fireweed

Suaeda australis Austral Seablite

Threlkeldia diffusa Coast Bonefruit

Table 4.2.3.2: Weed species present in the Atriplex cinerea / Nitraria billardierei Open Shrubland

Species Name Common Name Cover Comment

Ammophila arenaria Marram Grass 1

Arctotheca calendula Cape Dandelion 1a

Cakile maritima ssp. maritima Beach Rocket 3

Conyza bonariensis Tall Fleabane 1

Euphorbia paralias Sea Spurge 1

Galenia pubescens var.

pubescens Galenia 1

Lycium ferocissimum African Boxthorn 1a Mostly at southern end

Mesembryanthemum

crystallinum Iceplant 1a

Solanum nigrum Black-berry Nightshade 1

Sonchus oleraceus Milk Thistle 1a

Cover Rating

not many, cover

4.2.4 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland

This shrubland is found in the southern portions of Bird Island. It is principally on silty soils, or sand

over silt. Boxthorns (Lycium ferocissimum) are prevalent, and the understorey is heavily weed

invaded by species such as Beach Rocket (Cakile maritima ssp. maritima), Galenia (Galenia

pubescens var. pubescens), Marshmallow (Malva parviflora) and Stinging Nettle (Urtica urens).

Figure 4.2.4.1: Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland

Table 4.2.4.1: Plant species present in the Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland


Comment

AUS SA SL

Atriplex cinerea Grey Saltbush

Carpobrotus rossii Karkalla

Enchylaena tomentosa var.

tomentosa Barrier Saltbush

Ficinia nodosa Knobby Club-sedge

Myoporum insulare Native Juniper


Comment

AUS SA SL



Senecio pinnatifolius var.

pinnatifolius

Table 4.2.4.2: Weed species present in the Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland

Species Name Common Name Cover Comment

Ammophila arenaria Marram Grass 1a

Arctotheca calendula Cape Dandelion 1a

Atriplex prostrata Creeping Saltbush 2

Cakile maritima ssp. maritima Beach Rocket 2

Chenopodium murale Sowbane 1a

Euphorbia paralias Sea Spurge 1a

Galenia pubescens var.

pubescens Galenia 4

Lycium ferocissimum African Boxthorn 3

Malva parviflora Marshmallow 2

Mesembryanthemum

crystallinum Iceplant 3

Oxalis pes-caprae Soursop 1

Reichardia tingitana Reichardia 1a

Urtica urens Stinging Nettle 1a

Cover Rating

not many, cover

4.4 Native Fauna

4.4.1 Birds

Bird Island provides a safe haven for numerous local and migratory bird species, due to restricted

access to the Island. Table 5, adapted from Carpenter (2008) and Johnston et al (2010), summarises

birds known from the Island, along with their conservation status and breeding and visitation status.

Ten native bird species have been observed to breed on the island, with another three species

considered to possibly breed there. Of this total of 13 native breeding species, three are considered

to be Rare at a state level - Kelp Gull, Pied Oystercatcher and Sooty Oystercatcher, and the fourth

species, the Fairy Tern, is Endangered at State level and Vulnerable at a national level. In addition to

these breeding species, a further 61 species have been noted using the island or adjoining tidal flats

and waterways as habitat, including thirteen species of state conservation significance, and the

Southern Giant-Petrel (Macronectes giganteus) which is considered to be nationally Endangered and

Vulnerable at a state level.

The tidal flats adjacent to Bird Island provide significant habitat for wading birds covered under the

‘Japan- Australia Migratory Bird Agreement’ (JAMBA) and ‘China Australia Migratory Bird

Agreement’ (CAMBA). Species covered by these agreements are noted in Table 5.

Table 5: List of Birds known from Bird Island and surrounding flats (adapted from Carpenter 2008 and Johnston et al 2010

14)

COMMON NAME SCIENTIFIC NAME EPBC NPW Status in study area

Arctic Jaeger Stercorarius parasiticus Vagrant

Australasian Gannet Morus serrator Irregular non-breeding visitor

Australian Hobby Falco longipennis Regular non-breeding visitor

Australian Pelican Pelecanus conspicillatus Breeding resident

Australian White Ibis Threskiornis molucca Breeding resident

Australian Shelduck Tadorna tadornoides Irregular non-breeding visitor

Banded Stilt Cladorhynchus leucocephalus

V Irregular non-breeding visitor

Bar-tailed Godwit Limosa lapponica R Regular non-breeding visitor

Black-faced Cormorant Phalacrocorax fuscescens

Breeding resident

Black-shouldered Kite Elanus axillaris Irregular non-breeding visitor

(one bird observed in 2003)

Black-winged Stilt Himantopus himantopus Irregular non-breeding visitor

Black Swan Cygnus atratus Regular non-breeding visitor

Brown Falcon Falco berigora Irregular non-breeding visitor

(one observed in 2006)

Cape Barren Goose Cereopsis novaehollandiae R

Irregular non-breeding visitor (seen once in 2011)

Caspian Tern Sterna caspia Breeding resident

14 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished.

Crested Tern Sterna bergii Breeding resident

Chestnut Teal Anas castanea Regular non-breeding visitor

Common Greenshank Tringa nebularia Regular non-breeding visitor

*Common Starling *Sturnus vulgaris Breeding resident

Curlew Sandpiper Calidris ferruginea Regular non-breeding visitor

Double-banded Plover Charadrius bicinctus Regular non-breeding visitor

Eastern Curlew Numenius madagascariensis

V Regular non-breeding visitor

Eastern Great Egret Ardea modesta Resident (breeds nearby)

*Eurasian Skylark *Alauda arvensis Irregular non-breeding visitor

Fairy Tern Sterna nereis V E Breeds and disperses

Fluttering Shearwater Puffinus gavia Vagrant

Galah Cacatua rosiecapilla Irregular non-breeding visitor

Great Cormorant Phalacrocorax carbo Regular non-breeding visitor

Great Egret Ardea alba Regular non-breeding visitor

Grey Plover Pluvialis squatarola Regular non-breeding visitor

Grey Teal Anas gracilis Regular non-breeding visitor

Hoary-headed Grebe Poliocephalus poliocephalus

Regular non-breeding visitor

Hooded Plover Thinornis rubricollis V Vagrant

Kelp Gull Larus dominicanus R Irregular breeding resident

Little Black Cormorant Phalacrocorax sulcirostris

Regular non-breeding visitor

Little Egret Egretta garzetta R Resident (breeds nearby)

Little Grassbird Megalurus gramineus Irregular non-breeding visitor

Little Penguin Eudyptula minor Irregular non-breeding visitor

Little Pied Cormorant Phalacrocorax melanoleucos

Resident (breeds nearby)

Little Raven Corvus mellori Regular non-breeding visitor

Magpie-lark Grallina cyanoleuca Irregular non-breeding visitor

Marsh Sandpiper Tringa stagnatilis Irregular non-breeding visitor

Masked Lapwing Vanellus miles Breeding resident

Nankeen Night Heron Nycticorax caledonicus Resident (breeds nearby)

Osprey Pandion haliaetus E Irregular non-breeding visitor - observed once in 2001

Pacific Gull Larus pacificus Possible breeding resident

Pied Cormorant Phalacrocorax varius Resident (breeds nearby)

Pied Oystercatcher Haematopus longirostris R Breeding resident

Red-capped Plover Charadrius ruficapillus Breeding resident

Red-necked Avocet Revurvirostra novaehollandiae

Irregular non-breeding visitor

Red-necked Stint Calidris ruficollis Regular non-breeding visitor

Rock Parrot15 Neophema petrophila R Irregular non-breeding visitor

Royal Spoonbill Platalea regia Breeds and disperses

Ruddy Turnstone Arenaria interpres M R Vagrant. One observed in 2010.

Salvin’s Prion Pachyptila salvini Vagrant

Sharp-tailed Sandpiper Calidris acuminata Regular non-breeding visitor

15 Noted on site as part of this study 9/5/14

Short-tailed Shearwater Puffinus tenuirostris Vagrant

Silvereye Zosterops lateralis Irregular non-breeding visitor

Silver Gull Larus novaehollandiae Breeding resident

Singing Honeyeater Lichenostomus virescens Regular non-breeding visitor

Sooty Oystercatcher Haematopus fuliginosus R Possible breeding resident

Southern Giant-Petrel Macronectes giganteus E V Vagrant

Straw-necked Ibis Threskiornis spinicollis Breeding resident

Swamp Harrier Circus approximans Irregular non-breeding visitor

(observed once in 2007)

Terek Sandpiper Xenus cinereus R Irregular non-breeding visitor

Welcome Swallow Hirundo neoxena Resident (breeds nearby)

Whimbrel Numenius phaeopus R Regular non-breeding visitor

Whiskered Tern Chlidonias hybridus Regular non-breeding visitor

Whistling Kite Haliastur sphenurus Irregular non-breeding visitor

White-bellied Sea-eagle Haliaeetus leucogaster E Resident (breeds nearby)

White-faced Heron Egretta novaehollandiae Resident (breeds nearby)

White-fronted Chat Epthinaura albifrons Breeding resident

Willie Wagtail Rhipidura leucophrys Irregular non-breeding visitor

Yellow-billed Spoonbill Platalea flavipes Irregular non-breeding visitor

EPBC: Environment Protection and Biodiversity Conservation Act, NPW = Schedules of the National Parks and Wildlife Act 2008

4.4.2 Reptiles and Frogs

No reptiles were noted at the time of inspection, although it is possible that small lizards, such as the

Marbled Gecko Christinus marmoratus may have colonised the area as this species has been

observed on small offshore Islands such as Wright Island near Victor Harbor (pers. obs). Due to the

very exposed, saline nature of the environment at the site it is considered highly unlikely that frogs

will be present.

4.4.3 Mammals

There are no native terrestrial mammal present on Bird Island. Bats may possibly fly over the area,

but there are currently no suitable niches for shelter (such as tree hollows). The waters around Bird

Island provide important Dolphin habitat, which has led to the creation of the Adelaide Dolphin

Sanctuary. Introduced mammal species for management include the fox, cat, rat and domestic dog.

4.4.4 Fish

Bird Island is part of a larger ecosystem unit which includes the Port River, Barker Inlet and Torrens

Island, Mutton Cove to the west on the LeFevre Peninsula and the St Kilda Mangroves to the north.

Whilst the focus of this Management Plan is the area of Bird Island above the high tide mark, it

should be noted that the Port River estuary contains the largest area of mangrove forest, shallow

seagrasses and mudflats in Gulf St Vincent. Sheltered conditions and good light penetration create

very high levels of plant and animal production making these prime contributors to the ecology of

the gulf and major nursery habitats for juvenile species of commercial fish and crustaceans,

particularly juvenile Western King Prawns and King George Whiting16.

16 Adelaide and Mount Lofty Ranges Natural Resources Management Board, 2008.

4.4.5 Intertidal Invertebrates

Section Bank has some of the most species rich tidal flats in the northern region. About 90 taxa have

been found in total, being highest on Section Bank and in particular zones of single sites. Molluscs,

Annelida and Crustacea accounted for the majority of the species17.

5. THREATS (MANAGEMENT ISSUES) For Bird Island the management issues of particular concern in terms of biodiversity conservation

include:

Predation of nests and birds by pest animals (foxes, cats, rats);

Recreational activities disturbing nesting species and impacting on habitats;

Disturbance and impacts from domestic dogs

Weed invasion;

Over-proliferation of native Silver Gulls limiting nesting success of less abundant bird

species;

Marine pollution;

Lack of cadastral status;

Dredge spoil deposition from dredging of the Outer Harbor Channel;

Climate change

These are discussed in detail below.

5.1 Predation of birds and their nests by pest animals Many waterbirds nest or roost on the ground where they are vulnerable to introduced predators.

Small numbers of foxes travel to and possible live on the Island, and large numbers of black rats

(Rattus rattus) inhabit Bird Island. The Metropolitan Adelaide and Northern Coastal Action Plan

notes that the nesting birds on the Section Bank are at risk from fox predation18. Foxes were first

noted on Bird Island in 2002/3 (Greg Johnston pers. comm.). Following these initial sightings, a

number of roosting waders ceased to roost on Bird Island (Greg Johnston pers. comm.), providing

evidence of the significant impacts of this feral species.

It is likely that more foxes will access the Section Bank as sand deposition provides a low tide link to

Torrens Island19. Foxes have been sighted crossing the mudflats and sandbanks between Torrens

and Bird Island (Greg Johnston pers. comm.). Unwanted domestic cats are regularly dumped on

Torrens Island and are a problem around the Quarantine Station and the Torrens Island Power

Station20. These cats may also access Bird Island as linkage between Bird and Torrens Island

increases. Foxes also spread weeds amongst native vegetation, increasing the risk of introducing

weeds not currently present on Bird Island. The use of poisoned baits to control foxes and cats is

17 Dittmann, S., Baggalley, S., J. Keuning and Imgraben, S. (2012). Mudflat Condition Monitoring in Gulf St Vincent. Final Report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. 18 Caton B., Fotheringham D., Krahnert E., Pearson J., Royal M. and Sandercock R. (2009). Metropolitan Adelaide and Northern Coastal Action Plan. Prepared for the Adelaide and Mount Lofty Ranges NRM Board and Department for Environment and Heritage 19

Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 20 Aaron Machado, AMWRO, pers. comm., July 2013

problematic, as domestic pets are at times let loose on Bird Island, and may ingest the poison.

However domestic dogs themselves are also a significant cause of disturbance and appear to have

resulted in nest failures of pelicans on the island.

Black Rats (Rattus rattus) feed on refuse around nesting colonies, and may also prey on the eggs of

smaller waterbirds, and so are likely to be affecting the breeding of terns on Bird Island21. Rat

populations undergo an annual flux related to the timing of bird breeding on the Island – with peak

numbers following the principal bird breeding time during winter, and with a population crash in the

summer months (Greg Johnston pers. comm.). At the time of writing there is a baiting program

underway to control Rats on the Island, with poisoned bait rodent stations being established from

the northern end of the Northern Revetment.

5.2 Recreational activities As Bird Island has increased in size and the vegetation present has become more structurally

complex, visitation rates have increased. Humans are accessing the island for a number of reasons,

including out of interest, to allow pets to get exercise and defecate, for toileting, and even as a short

cut for kayakers to carry their craft across the island and hence reach the open sea faster (J. Hayes

pers. comm.). Whilst most are day visits, camping may also occur. The collection of bird eggs from

breeding colonies (for human consumption) has impacted the black-faced cormorant colony on the

Northern Revetment Mound and pelican, ibis, gull and tern colonies on Bird Island in some years22.

Collection of intertidal invertebrates (for bait and a commercial cockle fishery on Section Bank) has

the potential to directly affect the amount of prey available to birds23. Both humans and animals

may cause incubating birds to flush from their nests, leaving them vulnerable to predation by Silver

Gulls24. Domestic dogs may also attack or maim juvenile or adult birds. Carpenter (1998) noted that

larger bird species (such as egrets and herons) typically flush from about 100 metres and smaller

species (eg plovers) from 20-50 metres. In the process of flushing, there may also be stampedes of

adults or young, and trampling of eggs and nests25. Disturbance of the adult birds when they are

departing from or returning to the colony may possibly lead to regurgitation of food carried for

chicks26.

Whilst direct impacts on birds and their nesting success are the key recreational impacts, other

impacts include:

21 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 22 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished. 23 Johnston, G., Close, D. and Carpenter, G. (2010). Birds of Section bank and the Revetment Mound at Outer Harbour, South Australia. Unpublished. 24 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 25 GBRMPA 1997, Guidelines for Managing Visitation to Seabird Breeding Islands, Prepared by WBM Oceanics

Australia and Gordon Claridge for the Great Barrier Reef Marine Park Authority and Environment Australia-

Biodiversity Group. 26 GBRMPA 1997, Guidelines for Managing Visitation to Seabird Breeding Islands, Prepared by WBM Oceanics


Biodiversity Group.

trampling or crushing vegetation when walking through dune areas;

compaction of soil which limits natural regeneration;

disturbance of soil and erosion which encourages weeds;

introduction of new weed species; and

the illegal dumping of rubbish and debris which may cause entanglement;

littering with food scraps which may attract unwanted Silver Gulls.

5.3 Invasive weeds Weeds threaten the diversity and structure of native vegetation communities, and can have

concomitant effects on native fauna. However, in sand dune systems it is important to be careful

with treatment and removal as the weeds may be playing a role in binding the sand and thus

preventing sand drift and loss. Table 5.1 lists the priority weeds for control, based upon the

Metropolitan and Northern Coastal Action Plan (MANCAP). Ongoing weed management strategies

need to address both removal of priority weed species, as well as revegetation with native species at

appropriate densities.

Table 5.1: List of Priority Weeds for control

Species Common Name 27Declared 28WONS 29MANCAP Threat Level

30Red Alert Weed Rating

*Ammophila arenaria Marram Grass 3 3

*Euphorbia paralias Sea Spurge 2 3

*Euphorbia terracina False Caper Y 2 3

*Galenia pubescens var.

pubescens

Coastal Galenia 2 -

*Lycium ferocissium African Boxthorn Y Y 2 3

*Mesembryanthemum

crystallinum

Common Iceplant 2 -

*Oxalis pes-caprae Soursob Y 2 3

Carpenter (2008) 31 also notes that more open sites are favoured for nesting by terns, whereas areas

where weedy ground cover is high favour Silver Gulls. Tree Mallow has caused significant problems

in coastal habitats in South Australia, and has blanketed bare sites favoured by nesting terns on

Section Banks32 (although note that Mallow (Malva parviflora) was the dominant plant noted in the

27

Biosecurity SA Weeds and Pest Animals. Declared plants in South Australia, October 2012 http://www.pir.sa.gov.au/biosecuritysa/nrm_biosecurity/weeds/declared_plants_in_south_australia,_october_2012 28

Australian Weeds Committee (2012), Weeds of National Significance 2012. Department of Agriculture, Fisheries and Forestry, Canberra, ACT http://www.weeds.org.au/WoNS/ 29 Caton B., Fotheringham D., Krahnert E., Pearson J., Royal M. and Sandercock R. 2009. Metropolitan Adelaide and Northern Coastal Action Plan. Prepared for the Adelaide and Mount Lofty Ranges NRM Board and Department for Environment and Heritage 30

Refer to Croft, S.J., J.A. Pedler & T.I. Milne (2005 – 2008) Bushland Condition Monitoring Manual. Nature Conservation Society of SA Inc. 31 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 32


http://www.pir.sa.gov.au/biosecuritysa/nrm_biosecurity/weeds/declared_plants_in_south_australia,_october_2012http://www.weeds.org.au/WoNS/

assessment undertaken as part of this project, not Tree Mallow (Malva arborea)). As such, weed

management needs to aim for a reduction in weed ground cover to a more natural state.

5.4 Over-proliferation of Silver Gulls Silver Gulls have increased in numbers enormously over the last half century33. Carpenter (2008)

notes:

“Silver Gulls began nesting on the Northern Revetment as early as 1955 (Cleland 1956), and about

400 birds nested there in 1970, prior to the construction of the Section Bank (Vincent 1988). Silver

Gulls began nesting at the Section Bank as soon as December 1979, when 20,000 nests were

recorded. By October 1987 over 50,000 birds were nesting over all of the vegetated parts of the

island (Vincent 1988). The Wingfield Dump provided a ready source of food for breeding gulls until

operations at the dump changed in late 2005 (G. Johnston pers. comm.). Breeding birds were then

reduced to about one third of former numbers, and only about 150 nests were attempted in 2007.

Silver Gulls also probably affect breeding of terns by predating eggs and young, particularly when

ready sources of other food are not available.”

As noted in Section 5.3, open nesting habitat areas need to be maintained to favour less prevalent

species (such as Fairy Terns) over Silver Gulls.

5.6 Marine pollution Carpenter (2008) provided a succinct summary of the issues with marine pollution:

“Being located at the entrance of a busy city port, there is greater potential for marine pollution to

impact on waterbirds at the Section Bank. The Port River has been used to discard various industrial

and human waste for many years. Oil spills have the potential to affect seabirds anywhere in marine

environments. High levels of heavy metals in the marine environment have also been found in South

Australia (Long et al. 1997), although their impacts on birds (especially nesting species) are

unknown. Entanglement with fishing gear is also an important issue. It is likely that many birds

would die or are preyed upon as a result of entangling with fishing-line. Copley (1996) also

considered entanglements in fishing nets a potential threat to Black-faced Cormorants, although

total mortalities are likely to be low. Ingestion of plastic debris by surface feeding seabirds may also

result in increased mortality (Copley 1996).”

Preliminary studies (Fernandes et al 200834, 201035) highlighted possible concern about the

contamination of Barker Inlet with anti-bacterial and endocrine disrupting chemicals present in

33 Johnston, G. and Wiebkin, A. (2008). Birds of Gulf St Vincent. In “Natural history of Gulf St Vincent”. S. A. Shepherd, S. Bryars, I. Kirkegaard, P. Harbison and J. T. Jennings (eds). Royal Society of South Australia, Adelaide. pp. 324-338. 34 Fernandes, M., Shareef, A., Karkkainen, M. and Kookana, R. (2008) The occurrence of endocrine disrupting chemicals and triclosan in sediments of Barker Inlet, South Australia. A report prepared for the Adelaide and Mount Lofty Ranges Natural Resources Management Board. SARDI Publication No. F2008/001026-1. South Australian Research & Development Institute (Aquatic Sciences), Adelaide, 11 pp. 35

Fernandes, M., Shareef, A., Kookana, R., Gaylard, S., Hoare, S. & Kildea, T. (2010) Estrogens, triclosan and derivatives in sediments of Barker Inlet, South Australia. A report prepared for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the South Australian Environment Protection Authority.

pharmaceuticals and personal care products. The authors note “The implications for shorebird prey

species is unclear. Very little information is available on the toxicological response of marine

organisms to these compounds. Triclosan has been identified as toxic to freshwater algae at trace

levels. The need for further research has been identified to determine the risks associated with

accumulation in Barker Inlet, particularly to photosynthetic organisms at the base of the food chain,

from phytoplankton to mangroves. These compounds also have the potential for bioaccumulation,

and to cause hormonal disruption, and the effects to the local fauna, including its resident

population of Indo-Pacific bottlenose dolphins and seasonal populations of migratory shorebirds,

requires further research in the future.”

With the increase in the size of the island and its increased significance for sea and shorebirds, there

is a need to ensure that the importance of the island is noted on oil spill response atlas. Much

rubbish/debris is washed up on Bird Island. This includes items such as fishing line, rope, plastic

drink containers, plastic bags, old shoes, hats, timber, etc. The build-up of rubbish poses a threat to

the biodiversity assets of the area by inhibiting the growth of native flora species as well as

entanglement or ingestion by birds as discussed above. An example of debris accumulation is shown

in Figure 5.4.1.

Appendix 3 includes an example Marine Debris Monitoring Strategy datasheet provided by AMWRO

who regularly undertake the systematic collection and sorting of marine and other debris.

South Australian Research and Development Institute (Aquatic Sciences), Adelaide, 20 pp. SARDI Publication No. F2010/000385-1. SARDI Research Report Series No 448. 20p..

Figure 5.3.1: Debris accumulation in seaweed on the north eastern edge of Bird Island

5.6 Lack of cadastral status Due to its recent development, Bird Island has no formal cadastral status. This has been identified as

a significant issue in the Metropolitan Adelaide and Northern Coastal Action Plan. Without formal

land tenure, ongoing responsibility for management is unclear.

5.7 Dredge spoil deposition from dredging of the Outer Harbor Channel Whilst Bird Island has been created from a combination of anthropogenic (spoil deposition) and

natural (sand accumulation) processes, any future deposition of dredge spoil as a result of dredging

the Outer Harbor Channel needs to consider the substantial biodiversity values of the Island as it

currently exists.

5.8 Climate change It is expected that the current mean sea level rise of 3mm/year in the region will accelerate over the

next 50-100 years. Bird Island is likely to be inundated, unless the rise is offset by sedimentation

and/or possible mangrove expansion.

6. MANAGEMENT OBJECTIVES AND ACTIONS

6.1 Biodiversity management objectives It is recognised that the key biodiversity asset of the Island is the habitat value it provides for

waterbirds. As such, the key biodiversity management objectives are to:

remove or reduce threats to waterbirds, especially significant nesting species

improve habitat values of remnant vegetation

6.2 Biodiversity management actions These management objectives will be achieved by the following broad actions:

managing pest animals

managing recreational impacts

managing weeds

rubbish/debris removal

managing potential dredge spoil deposition

maintaining the open nature of the habitats of the Island

revegetating appropriately

Each is discussed below.

6.2.1 Managing pest animals Implementation of a fox control program is seen as a high priority, however as discussed previously

this is problematic due to ongoing visitation to the Island by people and their domestic animals.

Control programs in Torrens Island Conservation Park may reduce numbers that traverse sand banks

to reach Bird Island. The Adelaide Pelican Research and Bird Monitoring Group is a group of

volunteers that regularly access the Island to gather data on bird species and to assist in

management. It is recommended that this group remain vigilant for the signs of foxes and when

signs are noted and reported to DEWNR so that a short term baiting program can be implemented.

This would help to minimise potential impacts on native fauna and pets that may access the island

(as there would be less risk when baits are only present for a short time) whilst still retaining

effectiveness in reducing fox numbers. Signage is also recommended (refer Section 6.2.2).

Ongoing control and monitoring of Black Rats is recommended. The optimal time for poisoning

would be in autumn/early winter, prior to the annual peak of rat numbers as noted previously. At

the time of writing there is a baiting program underway to control Rats on the Island, with poisoned

bait rodent stations being established from the northern end of the Northern Revetment across the

Island. Current rat control is being monitored, as one risk identified is that it may result in increased

silver gull numbers which themselves have potential to predate other native seabird and shorebird

eggs and chicks.

6.2.2 Managing recreational impacts To protect the nesting habitats of bird species that are important at national and international

levels, unmanaged human visitation to Bird Island needs to be minimised. The Great Barrier Reef

Marine Park Authority has produced a series of guidelines to reduce the impact of daytrip visitors to

seabird breeding islands36. These guidelines include the following actions:

establishment of activity zones located to limit the movement of visitors to the least

sensitive parts of seabird breeding islands and designation of these with fences, markers,

signs etc.;

erection of screen fences to avoid disturbance of birds;

construction of appropriate viewing facilities to reduce random access to the breeding area;

restriction of human presence to the beach so that this is not visible to the nesting birds;

restriction of daytrip visits so that people do not arrive less than two hours after sunrise and

do depart at least two hours before sunset;

brochures, videos, talks and other awareness tools to make visitors aware of the potential

for disturbance;

restriction of access to the breeding island to only those daytrip operators who are

marketing the breeding seabirds as a major attraction; and

provision of appropriate waste bins and education about the dangers of carelessly disposing

of waste such as cigarette butts.

Not all of these actions are relevant or required for Bird Island at this stage, but may be reflected

upon in the future if circumstances change. The following are the key activities recommended at

this point in time to manage recreational impacts:

Signage: It is recommended that interpretive and regulatory signage is installed to inform visitors of

the significant values present, and to keep people and their animals away from these nesting areas.

It is recommended that this signage also reflect the risk posed to domestic animals through poisoned

baits that may be laid on the Island. As such the following key points should be noted:

Bird Island forms critical habitat for native seabird and wader species

Nesting birds that are frightened from their nests may lose their young

Foxes need to be controlled using poisoned baits, as they prey on the nesting birds

At some times, poisoned baits will be laid that are toxic and may be dug up and eaten if

domestic pets are allowed to roam freely

It is recommended that signs be established at the south eastern end of the Island (adjacent the

northern revetment), the south western seaward side (adjacent the northern revetment) and at the

northern end.

Prevention of dog access: Purnell et al. 37recommend that dogs are prohibited from Section Banks

during the migration/breeding season (September – March). These recommendations could

36 GBRMPA 1997, Guidelines for Managing Visitation to Seabird Breeding Islands, Prepared by WBM Oceanics


Biodiversity Group. 37


potentially be implemented, with signage supporting these restrictions, although implementation

and enforcement of restrictions would need to be negotiated between key stakeholders.

Fencing: Fencing could also be considered as a potential management intervention – for example,

key nesting areas for Fairy Terns could be fenced such that humans and dogs could not access the

area. However, there are risks in such an approach – for example, ringlock fence established around

Hooded Plover nests has led to nest abandonment38. Natural Resources Adelaide and Mount Lofty

Ranges staff undertake beach-nesting bird management in other areas, (for Hooded Plover) with

BirdLife Australia. It is recommended that fencing is considered as an intervention only in the

following circumstances:

that Fairy Tern colonies consistently nest in the same area

that other attempts to reduce disturbance by dogs and humans are not successful

Guidelines for nest site management and appropriate dimensions for fencing can be found in

Maguire (2008) 39.

Visitor and community awareness: Signage will help raise visitor awareness, but there would be

additional benefits to raising broader community awareness. These are discussed in Section 7.

6.2.3 Managing weeds Whilst weed infestation, particularly when leading to a reduction in open nesting spaces, is

considered likely to reduce nesting opportunities for terns40, it should be recognised that:

Vegetation community 4.4.2 is on silty soils that were deposited as a result of dredging,

rather than a more natural sandy base. There is ongoing nutrient addition as a result of bird

faecal deposition. This leads to conditions more suited to the weed species that are present

than coastal native species. Even if weeds were treated/removed, ongoing infestation is

likely to occur;

To treat weeds present in winter/spring (when most appropriate for control when green)

would result in significant disturbance to nesting birds;

Some introduced species, such as boxthorn, are providing roosting values for species of birds

such as Australian White Ibis (Threskiornis molucca) and Straw-necked Ibis (Threskiornis

spinicollis). Staged removal that incorporates replacement with medium sized native shrub

species such as Atriplex cinerea and Nitraria billardierei needs to be undertaken;

As a rule of thumb, weed control activities should focus on removal of priority weeds from

the least weedy areas first41.

The following weed control strategy has been prepared with reference to these key points.

38 Maguire, G.S. (2008). A practical guide for managing beach-nesting birds in Australia. Birds Australia, Melbourne. 39 Maguire, G.S. (2008). A practical guide for managing beach-nesting birds in Australia. Birds Australia, Melbourne. 40

Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 41 Robertson, M. (2005). Stop Bushland Weeds. Nature Conservation Society of South Australia Inc.

6.2.3.1 Samphire Shrubland Communities

There are no current weed issues in the samphire shrubland communities (4.2.1 Sarcocornia sp. /

Tecticornia sp. / Sueda australis low closed shrubland and 4.2.2 Sarcocornia sp. / Tecticornia sp. low

closed shrubland with emergent Avicennia marina ssp. marina Figure 4.2). Ongoing monitoring of

this area for the presence of weeds should be undertaken, and weeds removed if detected.

6.2.3.2 Atriplex cinerea / Nitraria billardierei Open Shrubland

Weed control efforts should initially focus on the removal of Boxthorn and Galenia from the Atriplex

cinerea / Nitraria billardierei Open Shrubland in the northern sections of the Island (Figure 4.2). This

will maintain the open structure favoured by key nesting species. As these weeds are only at

relatively low levels currently, it is unlikely that their control and removal will cause sand movement

as a result of loss of stabilising roots, and native species present are in relatively high density and

thus can provide the habitat values required by roosting birds. There are also small patches of

Marram Grass on the low primary dunes on the western side of the Island. It is recommended that

this grass is removed.

6.2.3.3 Atriplex cinerea / Nitraria billardierei / Lycium ferocissimum Shrubland

The southern end of Bird Island (vegetation community 4.4.2 Figure 4.2) has the greatest issue with

weeds. It is recommended that weed control focus on priority weeds and commence in a staged

fashion, working from the north, and replacing weedy species with native plants that can bind the

soil. Any boxthorn control needs to take into consideration the roosting values of the plant.

Therefore it is recommended that after poisoning, the plant skeleton be left in place until

replacement native species are established. In this area Mallow (Malva parviflora) is prominent, and

as indicated previously has been implicated in reduction of bare sites favoured by nesting terns.

Weed control activities at all times need to consider disturbance to nesting birds at the time control

is undertaken. As such, control programs should be limited to summer months, when there is little

breeding occurring, and impacts on roosting habitat considered as discussed above.

6.2.4 Rubbish/debris removal Ongoing removal of rubbish and debris will help to minimise impacts on seabirds. The Adelaide

Pelican Research and Bird Monitoring Group regularly remove rubbish from the Island, particularly

that rubbish which poses a threat to nesting birds, such as tangled fishing lines and nets. This action

may be maintained by community groups into the future. However, these should always be

targeted clean ups by small supervised groups, who are aware of bird disturbance issues, rather

than large community clean ups, unless undertaken outside of seabird breeding and shorebird

seasons.

6.2.5 Dredge spoil deposition from dredging of the Outer Harbor Channel No dredge spoil should be put on top of the existing vegetation on the Island. Any potential future

dumping of spoil needs to be done in such a manner that the biodiversity values of the Island as

detailed in this document are not compromised. This includes consideration of disturbance to

nesting birds. Any dredging or dumping activities proposed should be timed to minimise impact to

nesting seabirds and migratory shorebirds. The tidal flats have a high biodiversity and provide a

valuable shorebird resource. Any potential dredging or removal of sand may need referral under the

Environment Protection and Biodiversity Conservation Act for potential impact to migratory

shorebirds listed under the Act.

6.2.6 Maintaining open habitat areas It is desirable to maintain significant areas of bare habitat on Bird Island. More open sites are

favoured for nesting by terns, whereas areas where weedy ground cover is high favour Silver Gulls42.

Shorebirds also prefer the security of open spaces with high visibility for the easy detection of

approaching predators43. The continued expansion of both shrub habitats and Grey Mangrove on

Bird Island may therefore have a negative impact on seabird and wader populations on the Island.

Whilst at this point in time there is no evidence that management intervention is required (aside

from those already discussed), it may be a requirement in the future to intentionally remove

vegetation (including native vegetation) to create appropriate bare areas for nesting, and retain the

required open spaces. As an example, Towra Spit Island near Sydney is a significant breeding site for

the endangered Little Tern. Areas of spinifex, Lomandra and Acacias have been removed from the

Island so there are areas of bare sand for little terns to build their nests. However, as chicks require

shelter once they begin to stray from the nest before fledging, vegetation on Towra Spit Island is

maintained in a perimeter around the cleared area44. Similar actions could be undertaken on Bird

Island if warranted. Consultation would need to be undertaken with the Native Vegetation Section,

Department for Environment, Water and Natural Resources if this clearance involved native species.

6.2.7 Revegetation Revegetation efforts should be undertaken in conjunction with weed control efforts. These efforts

should focus upon supplementing existing habitat, using appropriate species for the vegetation type

and planting at appropriate (natural) densities. The site has already demonstrated an ability for

native species to naturally colonise and regenerate, and as such, revegetation should specifically

focus on replacing structural weed species (eg Boxthorn) with native species. The revegetation

recommended is relatively limited, recognising the key biodiversity values of the Island (seabird and

wader species) may be disturbed by a broad scale revegetation program.

Table 6.2.7: Revegetation plant list

Scientific name Common name Notes

Atriplex cinerea Grey Saltbush Plant as replacement species for staged removal of Boxthorn

Enchylaena tomentosa var. tomentosa Barrier Saltbush


42 Carpenter, G. (2008), Birds of the Section Bank, Outer Harbor. A report prepared by G. Carpenter for Coast and Marine Branch, Department of Environment and Heritage, June 2008. 43 Purnell, C., Peter, J., Clemens, R. (2013). Shorebird Population Monitoring within Gulf St Vincent: July 2011 to June 2012 Annual Report. BirdLife Australia report for the Adelaide and Mount Lofty Ranges Natural Resources Management Board and the Department of the Environment, Water, Heritage and the Arts. 44

Department for Environment and Climate Change NSW (2008). Best practice guidelines. Managing threatened beach-nesting shorebirds. State of NSW and Department of Environment and Climate Change NSW.

7. COMMUNITY INVOLVEMENT The Adelaide Pelican Research and Bird Monitoring Group and several key individuals such as Greg

Johnston and David Close have been involved in ongoing monitoring and management of Bird Island.

Aside from this group, there is little general awareness of the importance and sensitivity of the

Island. As noted previously, visitation rates to Section Banks and Bird Island are increasing, with

increasing impact on the biodiversity of the Island. Increasing community involvement and

understanding of the Island may be an approach to improving protection from key threats such as

pet dogs being allowed to run free on the Island and disturb nesting birds. Positive impacts that may

occur through increased community involvement include:

Increased understanding of the importance of Bird Island in the local community;

Increased media opportunities to build community awareness of threats to the Island;

Reduced impacts on the Island of inappropriate recreational use (including impacts of dogs)

through:

o avoidance of the Island by community members aware of the values of the Island;

o informal enforcement of restrictions (such as no free ranging dogs on the Island) by

community members aware of the need for such restrictions;

Ongoing involvement in management and monitoring activities;

Ongoing active community involvement ensures that conservation actions become

sustainable.

However increased community involvement would need to managed to be consistent with

maintaining the conservation values of the Island, and so would need to ensure perverse outcomes,

such as increased visitation (as a result of increased awareness) that causes disturbance to nesting

and roosting birds, does not occur. As such there needs to be ongoing broad oversight of

community involvement with the Island.

The South Australian Government has made a commitment to an International Bird Sanctuary over

the Dry Creek saltfields that also extends 60km along the Gulf Saint Vincent coast from the Barker

Inlet to the south to Port Parham in the north. It is recommended that as part of the process of the

development of this Sanctuary, consideration is given to the broader context of wader and seabird

dynamics within the Gulf, and that all components of this system are considered and managed

appropriately. With regard to community involvement, there will be a suite of community

engagement opportunities, as well as tourism opportunities, related to this new International

Sanctuary. There will also be significant opportunities to build community understanding of the

importance of the seabird and wader habitat in the Gulf, including Bird Island. As such this new

Sanctuary could contribute to the management of Bird Island by:

Improving community awareness of issues relating to wader and seabird conservation;

Improving understanding of the importance of Bird Island as a safe place for birds to breed

Providing opportunities for community to be involved with conservation, whilst also

ensuring that sensitive locations, such as Bird Island, do not become overexposed to threats

from excess visitation by sympathetic users;

Providing opportunities for birdwatchers/tourists to see waders and seabirds in situ at

locations other than Bird Island;

Providing broad oversight of community involvement with the Island.

It is also recommended that the Adelaide Pelican Research and Bird Monitoring Group is consulted

and empowered in any ongoing management and decision making processes as part of ongoing

community involvement with the project.

8. MONITORING

8.1 Monitoring Pest Animals As discussed previously, it is recommended that ongoing surveillance is undertaken for the presence

of foxes, and responsive baiting undertaken if detected. Black Rats should also be monitored

through an annual baiting program in early winter, with the number of baits taken being an indicator

of the presence and number of rats present. Monitoring of Silver Gulls should be undertaken to

determine if rat control is leading to increased gull numbers. Additionally monitoring of nesting

seabirds should also be undertaken.

8.2 Monitoring of Native Vegetation Extent and Condition Baseline data has been collected as part of this report using the Department for Environment, Water

and Natural Resources “BushRAT” assessment methodology45. This technique is derived from the

Nature Conservation Society of South Australia’s ‘Bushland Condition Monitoring’ (BCM)

methodology, including a Rapid Assessment version (Croft et al, 2005), but uses an area of

vegetation of consistent condition rather than the 30m x 30m quadrats used in the BCM

methodology. Three ‘components’ of the biodiversity value of the site are measured and scored:

vegetation condition, conservation value and landscape context. For this project, only the

vegetation condition components have been scored. Example datasheets from the BushRAT method

are provided in Appendix 1.

A summary of the BushRAT method and the data collected for this project is provided in Appendix 1.

The baseline mapping of extent of vegetation types (Figure 4.2) can be used in conjunction with

weed cover estimates to track progress of weed control activities. GPS locations of site photographs

can be used for ongoing photopoint monitoring (refer Appendix 1)).

Figure 4.2, site photographs and BushRAT data can also be used as a baseline to evaluate changes to

the extent and type of vegetation on the Island. As discussed in Section 6.2.6, ongoing evaluation of

the extent of open nesting and feeding habitat needs to be undertaken to ensure optimal habitat

conditions for seabirds and waders.

8.3 Monitoring Seabird and Wader Populations Greg Johnston has conducted research into the Pelicans and other birds of Bird Island for over 15

years. This work has been carried on by the Adelaide Pelican Research and Bird Monitoring Group,

who visit the Island each week and conduct bird counts and gather observations. This group has also

begun to contribute data to shorebird counts in Gulf St Vincent through Birds South Australia and

BirdLife Australia’s Shorebirds 2020 Program, along with other volunteer contributors. The Adelaide

and Mount Lofty Ranges Natural Resources Management Board along with BirdLife Australia has

been undertaking shorebird population monitoring across Gulf St Vincent. This includes surveys of

45 DEWNR (2012) NVBMU BushRAT assessment and scoring Manual. Unpublished document, Department for Environment, Water and Natural Resources, Waite.

Bird Island by shorebird researchers. These works should be continued, to help confirm the

significance of the Bird Island area, as well as to contribute to the broader understanding of wader

and seabird populations.

8.4 Plan implementation – progress reporting Progress reporting helps with the assessment of the effort put in to management actions. Some

efforts will be more successful than others. Various factors such as weather or control technique

may affect outcomes. Example Works Record sheets are included in Appendix 4.

9. BIODIVERSITY ACTION PLAN The table below lists the biodiversity management threats/issues for Bird Island, related objectives, actions already taken to address them, and further

actions being proposed.

ISSUE/THREAT 5-Yr Objective Actions to date – what/ who Proposed actions- what/ where/how Priority (H, M, L)

Expected yr completion

Pest animals

Foxes No foxes present and new incursions treated when detected

Undertake an opportune baiting program whenever signs of foxes are detected.

H

Ongoing

Feral Cats No cats present and new incursions treated if detected

Remain vigilant for presence of cats and control with baiting program as required. Inform Cat and Dog Management Board of issues and seek targeted awareness in the Port and Torrens Island area.

H

Ongoing

Rats Rat populations treated annually to reduce impacts

72 bait stations established in June/July 2014.

Continue to treat rats using bait stations in late autumn / early winter. Monitor potential effects on seabirds, particularly increases of Silver Gulls.

H Ongoing

Recreation – Negative impacts on biodiversity (trampling, disturbance to native fauna, erosion, rubbish dumping, etc)

Recreational activities (including pet dogs) disturbing nesting

All visitors to Bird Island are not negatively impacting on native flora and fauna.

On an ad-hoc basis when inappropriate activities have been noted.

Install appropriate interpretive/regulatory signage at strategic locations to inform/educate visitors about the values of Bird Island and the risks posed to pets by baiting programs. Consider closing Island at key nesting periods. Improve knowledge and understanding of the values of Bird Island through appropriate local media. Seek to incorporate the Bird Island area into patrols by Adelaide Dolphin Sanctuary staff. Ensure that planning for visitor management of the island is incorporated into management planning for the proposed Adelaide International Bird Sanctuary

H H

2017

ISSUE/THREAT 5-Yr Objective Actions to date – what/ who Proposed actions- what/ where/how Priority (H, M, L)

Expected yr completion

Weeds

Boxthorn Eradicate from Bird Island once replacement structural plants have bee

bird island biodiversity action plan · plant species and introduced weedy species. the island also...

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