hidden risk: mercury in terrestrial ecosystems of the northeast

8/3/2019 HIDDEN RISK: MERCURY IN TERRESTRIAL ECOSYSTEMS OF THE NORTHEAST

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Editor: Deborah McKew

Color Illustrations: Shearon Murphy

B&W Illustrations: Iain Stenhouse

Photography:Je Nadler Nature Photography, www.jnphoto.net; Garth McElroy Avian Photography,www.eatheredotos.com; Merlin D. Tuttle, Bat Conservation International, www.batcon.org;

Philip Myers, Animal Diversity Web, http://animaldiversity.org; GreenStock @ iStock.com; aniszewski @ iStock.com; orchidpoet @ iStock.com; other iStock images

Printing:J.S. McCarthy

To order reports or request more information, contact:

Biodiversity Research Institute652 Main Street, Gorham, Maine 04038

Phone: (207) 839-7600 Fax: (207) 839-7655www.briloon.org/hiddenrisk

Hidden Risk mm f mj fg f f k b B R I

p w T N C.

About Bovrty Rarch Ittut

Biodiversity Research Institute, headquartered in Gorham, Maine, is anon-prot ecological research group whose mission is to assess emergingthreats to wildlie and ecosystems through collaborative research, and touse scientic ndings to advance environmental awareness and inormdecision makers.

For general inormation, visit: www.briloon.org

For inormation about the Center or Mercury Studies, visit:www.briloon.org/hgcenter

About Th Natur CorvacyThe mission o The Nature Conservancy is to conserve the lands andwaters upon which all lie depends. The Conservancy accomplishesits mission through a collaborative approach that links the dedicatedeorts o a diverse sta, including over 500 scientists located across theU.S. and in over 30 countries around the world with many partners,including individuals, academic institutions, non-prot organizations,governments, and corporations.

For general inormation, visit: www.nature.org

FSC Mixed Sources

Cover Stock 55%Text Stock 50%


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Suggested Citation for This Report

Evers, D.C., A.K. Jackson, T.H. Tear and C.E. Osborne. 2012. Hidden Risk: Mercury in TerrestrialEcosystems o the Northeast. Biodiversity Research Institute. Gorham, Maine. 33 pages.

All data collected can be found in:

Osborne, C., D. Evers, M. Duron, N. Schoch, D. Yates, O. Lane, D. Buck, I. Johnson, and J.Franklin. 2011. Mercury Contamination Within Terrestrial Ecosystems in New England andMid-Atlantic States: Proles o Soil, Invertebrates, Songbirds, and Bats. BRI Report 2011-09.

Submitted to The Nature Conservancy.

Ba c g ro u

Executive Summary ............................................................................................................................................ 2

Mercury: Local, Regional, and Global Concerns ......................................................................................... 3

Impact o Mercury on People ........................................................................................................................... 4

Impact o Mercury on Wildlie ........................................................................................................................ 5

M rcu ry T rr t r a l Eco y t m o t h N o rt h a tWhy Do Species Vary in Mercury Levels? ...................................................................................................... 6

Why Do Habitats Vary in Mercury Levels?.................................................................................................... 7

How Do We Assess Mercury Exposure? ......................................................................................................... 8

Mercury in Songbirds and Bats o the Northeast ....................................................................................... 9

I ca t o r S p c o r t h N o rt h a tTarget Indicators or Mercury in the Northeast ........................................................................................ 10Louisiana Waterthrush: Forested Rivers and Creeks ...............................................................................12

Wood Thrush: Upland Deciduous Forests .................................................................................................14

Bicknells Thrush: High Elevation Forests .................................................................................................16

Rusty Blackbird: Bogs and Beaver Ponds .................................................................................................... 18

Saltmarsh Sparrow: Estuaries ........................................................................................................................20

Little Brown Bat: Unrestricted Ecosystems ................................................................................................22

F u t u r D r ct o Management Recommendations ..................................................................................................................24

Neotropical Connections ................................................................................................................................26

Neotropical Case Study: Northern Waterthrush ...................................................................................... 27

Interaction o Environmental Stressors ......................................................................................................28

National and International Mercury Monitoring ....................................................................................29

Using Science to Inorm Mercury Policy ....................................................................................................30

Literature Cited .................................................................................................................................................. 32

Acknowledgements ........................................................................................................................................... 33

Tabl o Cott


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Mercury is a pollutant that iscause or concern at local, regional,and global scales. While areaso high contamination (knownas biological mercury hotspots)may occur near mercury-emittingsources, oten they do not.Because mercury released intothe atmosphere can circle theworld beore being deposited,habitats located ar rom pointsources o mercury can still be omajor concern to wildlie health.Although great strides have beenmade to reduce mercury releasedinto the air and water rom humanactivities, this report illustratesthat high levels o mercury persist

in many wildlie species distributedacross many habitat types.

Excutv Summary

Figure 1: I ee ye, eehe hve ee e e ee k he vy euy he eve, uywh veve, uh . Th e eeh he e we k, he e we ; he e we , he e weue u he euy he we. Uuey, he e uh ee h wee eze y ew ye .

Why Care about Invertivores?

s ec t- eating s pec ies ar e integ r alm ponents of healthy ec os ys tem s ,th r oles r ang ing f r om s eeds per s er s to ins ec t c ontr ol ler see pag e 5).

W h a t I s a n I n v e rt i v or

Often r efer r ed to as ins ec t eatethe s ong bir ds and bats des c r ibethis r epor t ar e m or e ac c ur ately

inver tivor es bec aus e they eat a wvar iety of inver t ebr ate s pec ies ss pider s , s nai ls , and wor m s , inaddit ion to ins ec ts .

The human health eects omercury contamination are well

documented; adverse eectsinclude impacts on cardiovascularhealth, IQ, workplace productivity,and motor control. Similarly,mercury negatively aectswildlie populations by hinderingbehavior and reproduction. Pastinvestigations have emphasizedadverse impacts to sh-eatingwildlie, such as common loons,bald eagles, and river otters. Inthis report, we synthesize currentresearch and document elevated

mercury concentrations in a newgroup o animalsterrestrialinvertivoresthat until now haslargely been ignored in mercuryinvestigations. We show thatmercury concentrations in thisanimal group are signicantenough to cause physiologicaland reproductive harm, creatinga major paradigm shit inecotoxicological research,

assessment, monitoring,management, and policy.

Major g clu:

At-risk habitats and associatedindicator species are identiedbased on the species level oconservation concern, relativeabundance, and ability to buildup mercury in their bodies.

Current environmentalmercury loads have theability to signicantly reducereproductive success in severalsongbird species o conservationconcern in the northeasternU.S. including the saltmarshsparrow and rusty blackbird.

Bats also build up signicantbody burdens o mercury;individuals rom multiple speciesrom all 10 areas sampled exceededthe subclinical threshold orchanges to neurochemistry.

Mercury loading in songbirdsis not only restricted duringthe breeding season; somespecies, such as the northernwaterthrush, build up high levelso mercury during migrationand in tropical wintering areas.

Standardized monitoring ofenvironmental mercury loads isneeded to measure how changesin mercury emissions are relatedto new U.S. EPA regulations;we suggest that terrestrialinvertivores are importantindicators or assessing shortand long-term changes.

Despite rising global mercuryemissions, there are actions thatboth managers and policy makerscan take to limit uture ecosystemdegradation. Through greaterunderstanding o both the extento wildlie exposure and harmulimpacts to ecosystem health,it is now clear that increasedconservation eorts are necessaryto reduce this neurotoxin in

our environment or the beneto wildlie and people.

0

10

20

30

40

50

60

1980s 1990s 2000s 2010s

Invertivore species(mammals and birds)

Fish-eating species(mammals and birds)


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Mrcury: Local, Rgoal, a Global Cocr

Mercury is a naturally occurringheavy metal ound within theEarths crust. Used in many

industrial processes, mercuryis emitted into the atmospherethrough a variety o anthropogenicsources. While some source types,such as waste incinerators, havereduced their mercury emissions95% between 1990 and 2005, utilitycoal boilers continue to emit morethan 50 tons o mercury each year[1]. In December 2011, the U.S.Environmental Protection Agency(EPA) nalized a rule called theMercury and Air Toxics Standards

(MATS) that requires all electricgenerating plants to upgradeto advanced pollution controlequipment by 2016 [2].

Local Cocr. Researchers have shown that mercury levels in soil are higher inareas close to power plants, with the areas downwind o the power plant usuallyreceiving higher inputs [3]. Combining this inux o mercury into an ecosystemwith certain ecological actors, such as precipitation or soil acidication, can leadto a biological mercury hotspot, where we see elevated mercury levels in a relativelydistinct geographic area. Areas o high contamination are oten related to localenvironmental conditions that have an ability (via a process called methylation)to convert mercury into its most toxic orm. For example, wetland habitats areprime areas where this process occurs, and are thereore highlighted in this report.

Rgoal Cocr. Because the availability o mercury depends on bothatmospheric deposition and habitat type, certain regions can be at higher riskto mercury contamination than others. For example, researchers have oundhigh mercury levels across taxa ( ish, birds, mammals) in the Great Lakesregion [4]. A similar synthesis was completed in the northeastern U.S. andeastern Canada; a third synthesis is currently being planned or the westernU.S., Canada, and Mexico (www.briloon.org/mercuryconnections).

Global Cocr. When mercury is released into the atmosphere, some settlesinto the surrounding area but some can move great distances on the prevail-ing wind patterns beore settling back to earth. Because o this, we must look atmercury concerns on a global scale as well, and remember that mercury is truly apollutant without borders [5].

Figure 2: Mj ue U.S. e U.S. EPA vee(1990 2005). E e u wee hve ee eue y ve 95%, whe uy ee he e [1].

Why Ar W Stll Cocr about Mrcury?

Although great strides have already been made in reducing mercury emissions rom incinerators, and the MATSrule will likely have the same eect on coal-red power plants, it is important to continue to monitor the eecto mercury at local, regional, and global scales.

How o Mrcury Etr th Evromt?

0

50

100

150

200

250

300

1990 2005

MercuryEmissions(tons/

year)

Utility coal boilers

Medical waste incinerators

Municipal waste combustors

Industrial boilers

Other


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P o p l a r x p o t o m rcu ry a l l l t a g

Mercury is a potent neurotoxin with wide ranging implications orhuman health and wellness. With more than 3,700 sh consumptionadvisories in the United States, mercury is a risk or many people, not justthose who subsist on sh [6].

The impact o mercury in the U.S. has both economic and health eects

(see box at let).

Impact o Mrcury o Popl

Wh y Car e abou t th e Effe ct o f M e r c u r y o n H u m a n s ?

The U.S. EPA Mercur y andAir Toxics Standards (MATS)

rule [2] is est imated toimprove the health o U.S.

c it izens at a sav ings o

$ 3 7 - 9 0 b i l l i o n

The MATS rule wil lpr eve nt up to:

11,000premature deaths

2,800cases o chronic bronchitis

4,500heart attacks

130,000asthma attacks

5,700hospital and emergency room

visits

3,200,000restricted activity days

I exee e, euy exue ue e MDee, whee evee e u he he wh ue hh u euy.

F u t u r Wo r : Bra S c c Br g

MeHgMeHg

MeHg

MeHg

Meuy exue ue hee ke eveee ee (uh wk eeh) [9]

Meuy exue he huhu e, ue e, ue,ey [10], IQ [11]

Hh euy eve u e h ee e ee k he k [7] vu ee [8]

Mhe e, ueuy, he ehuh he e

Mjy ey ke ehyeuy(MeH) ue h u

A d u l t s

Pregnant WomenC h i l d r e n

Che e

exe euyu evee


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Why Do Spc Vary Mrcury Lvl?

Wildlie vary in their mercuryexposure based primarily onwhat they eat. Mercury increases

as it moves up the ood web, aprocess called biomagnication.Organisms that eed at hightrophic levels generally havehigher mercury levels than thosethat eed at lower trophic levels.

Abiotic (non-living)

Atmospheric DepositionMercury released into the air can beincorporated directly into primary

producers, such as tree leaves.Soil and Lea Litterare thesites o primary mercurymethylation by bacteria.

Biotic (living)

Invertebrates such as pill bugsand millipedes consume lea littercontaminated with mercury.

Spiders eat other spiders and

insects, adding 1-2 trophic levels.With each link in a ood web,mercury biomagnication increases,meaning that spiders generallyhave higher mercury contentthan plant-eating insects [27].

Wood thrushes, blackbirds, andsparrows orage on the ground, eatinginvertebrates rom the lea litter.

Bats accumulate mercury roma diverse prey base, includingying insects and spiders.

Vireos and warblers orage in treecanopies and consume predatoryinsects and spiders, makingthem a top-level predator. Leaf Litter

Pill Bug

Wood Thr

Vireo

Spider

Bat

M rcu ry t h F o o W b


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Elemental mercury released intothe ecosystem cannot readily beincorporated into the ood web

without rst being methylated ormade available to living organisms.The process o methylationoccurs with the help o bacteriaound primarily in wet areas.This causes large variation inthe amount o mercury ound inwildlie based on habitat type.

For example, atmosphericdeposition o mercury can besimilar in two adjacent habitatsan upland meadow and a wet bog.

I little mercury in the meadowis made available by methylation,then wildlie living in that habitatwould be relatively protectedrom mercury toxicity. The wethabitat o the bog, however,could allow or high rates omethylation, which would bereected in high mercury levelsin the organisms that live there.

Why Do Habtat Vary Mrcury Lvl?

Mercury concentrations insongbirds rom Dome Is land, LaGeorge, NY, rank among the higin the state and the region[28]

Researchers have discoveredthat is land spiders have highemercury concentrations thanspiders col lected rom orestedareas directly adjacent to LakeGeorge, prompting more researinto the mechanism behind thisdi erence [29].

L o n g I s l a n d S a l t m a r s h

At Pine Neck Preserve andNorth Cinder Is land, LongIsland, saltmarsh sparrowsexhibit e levated blood mercuryconcentrations, without anyknown mercury inputs in the arResearch traced these high mer

levels down the ood web, startwith lower- level organisms suchamphipods (also known as skudwhich consume sediment organmatter and detr itus. Amphipodare then preyed upon by marshspiders which, in turn, are thepreerred prey i tems or saltmasparrows during the summerbreeding season.

The uh eu y eeh e hee ewee h ee e v e .O he w e, we w ue h hwv u ee vy euy e wh heye, hw e h vy euy e he e euy ehy .

I n te ra cti on of S pe ci e s a n d H a bi ta t

+

H a b t a t S t v t y t o M rcu ry

Dome Island

F ood W e b Re se a rchNew York, USA


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0

10

20

30

40

50

SpeciesMercuryConcentration(pp

m,ww)

n = 10

How Do W A Mrcury Expour?

The heeeh ue ue w,ee, hh, vey hh k.

H o w t o I n t e r p r e t B a r C h a r t s

Gee = Mxu eve eee(.e., h he hhe euy eve hwe u)

Bk = Avee euy eve e vu

E = S ev, e-ue vy he vee vue(.e., e e hee e eeeee vu)

R i s k Level

R e d u c t i o n i nN e s t S u c c e s s

B l o o dM e r c u r y

Lw e h 10% < 0.7

Mee ewee 10% 20% 0.7 - 1.2

Hh ewee 20% 30% 1.2 - 1.7

Vey Hh e h 30% >1.7

The data reported here were collected opportunisti-cally over 11 years across 11 states. Most o the bats andbirds were sampled as part o larger projects; the di-erent study sites are shown in the sampling locations

maps on the adjacent page. We purposeully excluded avast dataset summarizing wildlie mercury exposure oncontaminated sites to ocus exclusively on the impact oair pollution. There are many other places, such as U.S.EPA-designated Superund sites, where mercury levelsin wildlie exceed those presented here.

The inormation presented in this report is themost current and widespread data summarized todate. Despite this eort, there are limitations to theanalysis as a result o the opportunistic, rather than

comprehensive, way we currently collect mercuryinormation. These limitations are an importantreason or dramatically improving mercurymonitoring networks (see National and InternationalMercury Monitoring on page 29).

In order to calibrate what these blood levels meanin terms o the health o invertivores, we use datacollected in two studies to create eects levels orsongbirds and bats. Based on a model o mercuryeects on reproductive success in Carolina wrens,

we have developed a gradient o eects levels orsongbirds (below) [22]. For bats, we do not have datato support a range o eects, instead we must usea preliminary subclinical threshold developed orchanges to neurochemistry o little brown bats [30].

S on g bi rd Ef f e cts L e v e l s

= e ze (ue vue)

The goal o this summary is toanswer the question How badcan mercury contamination get?Given our opportunistic sampling,we can provide an answer byexamining the maximum mercurylevels detected in terrestrialinvertivores. We also present moreconventional statistics (meansand standard deviationsseebox at right). For species withlarge sample sizes, mean mercuryvalues can give insight into overallpopulation mercury loads, butthese values can be misleading orspecies with small sample sizes.

Lmtato o Opportutc Samplg

Maxmum Bloo Lvl

Mrcury Ect Lvl


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Mercury inSongbirds and Batsof the Northeast

We sampled 1,878 individual songbirds, representing 79 species, between1999 and 2010. Mercury data by species is presented in order rom lowest tohighest blood mercury concentrations, regardless o sampling location.

Figure 3: B eve ee wh euy eve h u he k eue e ue. Le hw euy eve e wh 10% (0.7), 20% (1.2 ), 30% (1.7 ) eue e ue [22].

Sogbr MrcuryCoctrato

Bat Mrcury Coctrato

Songbird Sampling Locations

Bat Sampling Locations

Figure 4: Fu eve ee e he hee Ue Se. Re ehw ey u heh euy exue (10 u),ve whh eehe hve hw he he euhey [30].Fuhe eeh eee k uh u he wh vee ue.

We sampled 802 individual bats, representing 13 species, between 2006and 2008.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

LouisianaWaterthrush

(n = 20)*

WoodThrush

(n = 160)*

Traill'sFlycatcher

(n = 6)*

Yellow-throatedVireo(n = 2)*

SeasideSparrow(n = 8)

Bicknell'sThrush(n = 50)*

Red-wingedBlackbird(n = 40)

EasternWood-pewee

(n = 2)*

PalmWarbler

(n = 9)

IndigoBunting

(n = 11)*

Nelson'sSparrow(n = 97)

RustyBlackbird(n = 93)

BloodHgConcentration(ppm,ww

Maximum Mean + Standard Deviation

Very High Risk

High Risk

Moderate Risk

Low Risk

* Denotes neotropical migrant species

0

20

40

60

80

100

120

Hoary Bat

(n = 6)

Seminole Bat

(n = 9) Big-earedBat

(n = 4)

Silver-haired

Bat(n = 7)

Eastern

Pipistrelle(n = 22)

Indiana Bat

(n = 12)

Eastern

Small-footedMyotis

(n = 7)

Southeastern

Myotis(n = 9)

Red Bat

(n = 38)

Little Brown

Bat(n = 441)

Evening Bat

(n = 39)

Northern

Long-earedBat

(n = 148)

Big Brown Bat

(n = 59)

FurH

gConcentration(ppm,ww)

Ma ximum Mean + Standard Deviation


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Ecosystem TypeEue

IndicatorSh S

Ecosystem TypeB BeveP

IndicatorRuy Bk

Ecosystem TypeUee

IndicatorLe Bw B

Mercury exposure depends on both speciescharacteristics (such as trophic level) and habitatcharacteristics (such as wet-dry cycles). To disentangledierences between habitat and species, we chose

an indicator songbird species to best representthe mercury risk in each ecosystem type. Because

little brown bats are ound in many dierentecosystems, we chose them as an unrestrictedecosystem indicator. On the ollowing pages, wewill describe mercury levels in these species and

explain why we see variation among them.

Targt Icator or Mrcury th Northat

Ecosystem TypeU Fe

IndicatorW Thuh

Ecosystem TypeHh EevFe

IndicatorBke Thuh

Ecosystem TypeFee Rve Ceek

IndicatorLu

Wehuh


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Ecoytm Stu

As expected, birds ound in habitats

with pronounced wet-dry cycles, suchas bogs, beaver ponds, and estuarieshave the highest blood mercuryconcentrations. Interestingly, wealso ound elevated blood levels inbirds ound in upland areas suchas deciduous and high elevationorests. In the ollowing pages, wewill explain each species habitatand ood preerences so thatyou can better understand howthey can acquire methylmercurybody burdens o concern.

For two species o high conservationconcern, the rusty blackbird and thesaltmarsh sparrow, we ound atmo-spheric deposition o mercury toreduce nesting success by an averageo 10%, which could have implicationsor already struggling populations.

Figure 6: Geh e ue. We ue 11 e V Me. B euy e h e e e hee 19 uy e. Due he u ue u ,we eey hve ee eh eh ee, u we e e e e e ewee ee e.

C NY

C CT

C RI

C MA

Suhee NH

C ME

Nhe ME

Wee ME

Whe M NH

Ak NY

Ck M NY

Wee NY

Suhe NY

Wee PA

Ee WV

Suhwee VANhwee VA

Gee M VT

DE

Figure 5: B euy e ,eee k e wh ee ee eye.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

Forested Riversand Creeks

UplandDeciduous

Forest

High ElevationForest

Bogs andBeaver Ponds

Estuaries

BloodHgConcentration(ppm,ww)

Maximum

VeryHigh Risk

High Risk

Moderate Risk

Low Risk

Mean + Standard Deviation

LouisianaWaterthrush

(n = 20)

WoodThrush

(n = 160)

BicknellsThrush

(n = 50)

RustyBlackbird

(n = 93)

SaltmarshSparrow

(n = 479)


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The Louisiana waterthrush is nota thrush at all; it belongs inhe warbler amily. However, unlikether warblers, this speciesreers to spend its time near swit

moving orested streams and smallvers. Its song, a mix o high-itched ringing sounds and metallichirps, is loud enough to be heardbove the rushing water o itsavored habitat.

distinguishing characteristic ohe Louisiana waterthrush is itsail bob; it constantly wags itsail as it orages along the groundgenus and species names both

mean tail-wagger). Some suggesthat this tail-wagging may help toamoulage the bird against the

moving waters.

Other Birds o Conservationoncern in this habitat:rothonotary war bler, yellow-hroated warbler, and hooded

warbler.

Habtat

When breeding in the eastern United States and southern Canada, theLouisiana waterthrush requires ast-owing streams or small rivers thatwind through closed-canopy, hilly, deciduous orest. This bird nests onthe ground along the riverbanksin small hollows, under allen logs,or in the exposed roots o upturned trees. Its habitat requirements aresimilar in its wintering grounds in the West Indies, Central America, and

northern South America. In areas o the Northeast with pronouncedspring runo, these types o streams have extreme wet-dry cycles, leading

to increased mercury methylation.

Fg

Foraging at the edge o owing water, this warbler eats many aquaticinvertebrates, along with higher trophic-level organisms such as spiders,

amphibians, and small sh.

Louaa Watrthruh (Parkesia motacilla)

PhotoJefNad

lerPhotography

*Potential forVery High Hg Risk onContaminated Sites

Pote n ti a l L ow H g Ri sk

*


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F or t R vr a C r I c at or

Mrcury R

Although our indings show thatthe Louisiana waterthrush is at lowrisk due to atmospheric depositiono mercury, the negative eect opoint-source mercury on aquaticecosystems is well documented

and mercury has been shown topersist in rivers more than 80miles rom its original source [31].Both habitat and dietary habitscompound to create a higherrisk o mercury exposure alongheavily contaminated rivers. Forspecies like this warbler, which acepopulation declines due to habitatloss, mercury contamination posesan added ecological burden.

0.0

0.2

0.4

0.6

0.8

1.0

Pennsylvania(n = 4)

Catskill MtnsNew York

(n = 4)

WesternNew York

(n = 3)

SouthwestVirginia

(n = 7)

SouthernNew York

(n = 2)

BloodHgCon

centration(ppm,ww)

Maximum


ec actionC u r r e n t a n d F u t u r e R i s k s

Pollution to rivers and streams,rising water temperatures, loss of

forest area due to humandevelopment, and infestation ofhemlock woolly adelgid (whichdefoliates this particular evergreen),are all reasons for concern for thisbird species.

R e c o m m e n d a t i o n s

Protecting forests and waterways onboth breeding and wintering groundsare important conservation actionsfor this species. Research should

focus on habitat use and ecology inthe tropical regions to which this birdmigrates. Also, more informationis needed on migration routes andstopover habitats.

Figure 7: Geh eee euy exue Lu wehuheWhe e ze e w h ee, u ue euyh uhe New Yk uhwe V.

Photo GreenStock rom iStock.com


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Habtat

This thrush spends its breeding season in a wide variety o deciduousand mixed orests throughout the eastern hal o the United Statesromthe Gul States to southern Canada and rom the eastern edge o theGreat Plains to the Atlantic Coast. It preers thickly orested areas witha dense understory, moist soil, and abundant lea litter (also prime siteso mercury methylation). In early all, the wood thrush migrates to thebroad-leaved orests o Central America. They oten return to the samebreeding and wintering grounds each year.

Fg

The wood thrush eeds mostly on invertebrates at ground level, oragingin lea litter, and on ruits rom shrubs (especially important duringmigration).

Woo Thruh (Hylocichla mustelina)

The wood thrush, a bird o thedeep orest, sings a hauntingnd complex array o songs thatave been described as lutelike,thereal, hollow, sometimesxhibiting an electrical quality. complicated syrinx (song box)llows this thrush to sing t wo notest once, creating the eect o aarmony with itsel; the males take

ull advantage o this talent whenourting.

n the mid-19th century, HenryDavid Thoreau, one o the earliest

nd most proound environmentalwriters, declared the abundantwood thrush an indicator o the

ealth o a orest; sightings ohe wood thrush have becomencreasingly rare over the last ourecades.

Other Birds o Conservationoncern in this habitat: cerulean

warbler, worm-eating warbler,entucky warbler, and Swainsons

warbler.

Pote n ti a lM o d e r a t e

H g Ri sk

PhotoJefNad

lerPhotography


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Mrcury R

Since the wood thrush eeds primarilyon the orest oor by moving lea litterto locate prey, the pathway o meth-ylmercury through its prey is likelyconnected with the organic soil and thelea litter. High mercury levels in soil

relate with high mercury levels in thewood thrush; in these same areas, soilcalcium levels were low, most likely dueto acid rain. For a breeding bird eedingin this habitat, this is a worrisome com-bination. Wood thrush populationsare declining signicantly across theirrange; and in New York and neighbor-ing states that decline is linked to theloss o calcium, a vital nutrient orreproduction [32].

U p la F or t I c at or

Figure 8: Geh eee euy exue w huhe.W huhe V uhe New Yk hw eeve euyeve e he he e.


Causes for the recent wood thrushdecline may include forest destruction

and fragmentation, as well as acidrain. The combination of high mercurylevels in areas with acid rain maycombine to create a 1-2 punch thatis more damaging to the populationthan either effect in isolation.However, more research is neededto better understand this complexinteraction.


Protecting large tracts of forests in

breeding areas, as well as maintaininghabitat that these birds need formigration are critical for the survivalof this species.

Wintering grounds in CentralAmerica must also be protectedto ensure the long-term success ofwood thrush populations. Furtherwork in understanding the ecologyof this species on its winteringgrounds will provide valuable clues tounderstanding population declines.

0.0

0.2

0.4

0.6

0.8

1.0

Catskill MtnsNew York(n = 13)

WestVirginia

(n = 2)

Delaware(n=19)

WesternMaine(n = 3)

CoastalNew York(n = 22)

Pennsylvania(n = 23)

WesternNew York

(n = 6)

Virginia(n=12)

SouthernNew York(n = 60)

BloodHgC

oncentration(ppm,ww)

Maximum


Photo aniszewski rom iStock.com


18/3616

HabtatThis species is extremely restricted in its habitat and range. It breeds indense areas o stunted balsam r and spruce ound at high elevationsrom the northern Gul o St. Lawrence and easternmost Nova Scotia,to the White Mountains o New Hampshire, the Green Mountains oVermont, and the Catskill Mountains o New York State. Its winteringgrounds are also restricted; this species migrates to one o only ourislands in the Greater Antilles, in the Caribbean Sea.

Fg

These birds eed primarily on insects, especially beetles and ants; they will

eat wild ruit during migration. During the breeding season, they eedon or close to the ground, but will also orage or ood in the branches otrees, sometimes y-catching rom their perches.

Bcll Thruh (Catharus bicknelli)

In 1904, John Burroughs, literar ynaturalist in the tradition ohoreau, described the song o

he Bicknells thrush as a musicalwhisper o great sweetness and

ower. However, the plaintiveall o this mid-sized thrush isarely heard by those other thanhe most intrepid bird enthusiastsnd ornithologists. Reclusive andlusive, this bird is one o the r arest

ongbirds in North America.

During breeding season, thisird preers remote, inhospitableabitats high in the mountainouserrain o the northeastern Unitedtates and southeastern Canada.he Bicknells thrush exhibitsnusual mating habits; both malesnd emales mate with multipleartners (known as polygynandrous)esulting in mixed paternity inearly every nest.

Other Birds o Conservationoncern in this habitat: blackpoll

warbler, and yellow-belliedycatcher.

Pote n ti a lM ode ra te H g

Ri sk

PhotoJefNad

lerPhotography


19/361 7

Mrcury RBased on habitat and diet alone, wewould expect Bicknells thrush tobe relatively removed rom mercuryexposure. This is not the case becausehigh elevation mountain areas are proneto increased precipitation, and thereore,increased pollution rom cloud water[33]. These conditions are ripe or theproduction o methylmercury. Highelevation species such as the Bicknells

thrush have proportionally highermercury levels than associated low-elevation mountainside neighbors, suchas other thrushes.

H g h Elvat o F or t I c at or

Figure 9: Geh eee euy exue Bke huhe. Due he u hequee, Bke huh e u heeh e ue, u he ue weeMe hw hhe euy eve h he e.

Photo Jef Nadler Photography


Recreational and commercial develop-ment (e.g., ski trails, telephone towers,

and wind turbines) in mountain forestscontribute to increased habitat frag-mentation and loss. Climate change alsoputs the Bicknells thrush at risk as itdiminishes the already narrow band ofhabitat in the birds mountain breedinggrounds. Extensive loss and degradationof primary overwintering forests maypose the greatest threat to the long-term viability of the Bicknells thrush.


Efforts are needed to continue to protector manage known and potential breedinghabitat; land management agencies canpartner with timber companies to developand implement best management practicesto maintain a t arget amount of Bicknellsthrush habitat in working forests.

It is equally important to protect,manage, and restore known and potentialwinter habitat. Working with and develop-ing strong collaborative efforts withCaribbean partners is critical to theprotection of habitat on the winteringgrounds. It is also important to identifymigratory stopover sites, routes, andpatterns.

0.0

0.2

0.4

0.6

0.8

1.0

AdirondacksNew York

(n = 5)

White MtsNew

Hampshire(n = 4)

Catskill

Mtns

New York(n = 18)

Green MtsVermont

(n = 9)

WestMai(n =

BloodHgConc

entration(ppm,ww)

Maximum



20/3618

Habtat

The vast boreal region o Canada and Alaska along with the Acadianorest o eastern Canada and New England represent the core breedinghabitat o the rusty blackbird. They select orested wetlands, muskegswamps, and beaver bogs or breeding, laying speckled blue and browneggs in nests constructed in the stunted spruce or r trees typical o thesehabitats. In early autumn the blackbird migrates to the southern U.S. orthe winter, eeding on invertebrates and grains in both wet bottomlandsand dryer uplands, such as pecan plantations.

FgThe rusty blackbird eeds preerentially on aquatic insect larvae and largeadult ying insects, taking advantage o spring emergence events whilebreeding. In winter they become opportunistic as insects become scarcer,eeding on grains and tree masts.

Ruty Blacbr (Euphagus carolinus)

Named or its rust brown winterplumage, the rusty blackbirds occasionally mistaken or itsear relative, the common grackle.

Although rusty blackbirds werence abundant enough to blackenhe ields and cloud the air dur ing

migration, today migrating andwintering locks rarely exceed a ew

ozen due to an unexplained yet

ramatic population crash.

Unlike many other North Americanlackbirds, rusty blackbirds will

orm monogomous pairs whilereeding that will oten persist the

ollowing breeding season. Theyan be aggressive while breeding,ttacking larger species, such asays, that could prey on their young.

When ood is scarce during harshwinters, these blackbirds have been

nown to attack and eat other

ongbirds.Other Birds o ConservationConcern in this habitat: olive-sidedlycatcher, bay-breasted war bler,nd Canada warbler.

Pote n ti a l Ve ry H i g h H g Ri sk

PhotoJefNad

lerPhotography


21/361 9

0.0

0.5

1.0

1.5

2.0

2.5

NorthernMaine

(n = 13)

WesternMaine(n = 2)

Vermont(n = 9)

New Hampshire(n = 69)

BloodHgCon

centration(ppm,ww)

Maximum


Mrcury RRusty blackbirds are exposed tolevels o mercury that maynegatively aect them whilebreeding in New England andMaritime Canada; concentrationso mercury or individualsbreeding in the Northeast aremore than our times that othose breeding in Alaska, with anaverage concentration o about

0.9 ppm. The high mercuryexposure is due to a diet basedon aquatic macroinvertebratesand spiders, allowing or multipleintermediate trophic levels anda high bioconcentration oaquatic mercury. Additionally,the acidic water typical o theirbreeding habitat promotes a highbioavailability o mercury oruptake [34].

Bog a Bavr P o I c at or

Figure 10: Geh eee euy exue uy k. Ruyk e ey h he ee u, u he h wee e hve hh euy eve e.


Rusty blackbird populations have declinedmore than 90% since the 1960s, with an

upper estimate of 13% decline per yeararate exceeding that of other borealbreeding birds. While several factors havebeen proposed, no consensus has beenreached to explain the population loss.Likely factors: the interaction of habitatloss due to human development; intensiveforestry; wetland draining and floodcontrol; climate change; and environmentalcontaminants, including mercury.


Although the habitat preferred by rustyblackbirds is relatively inaccessibleand somewhat inhospitable, breedingpopulations may still be in danger; morecareful monitoring, in addition to theBreeding Bird Survey, is needed to confirmthis. This species is more adaptableduring migration and in wintering areas,however, preliminary analyses ofChristmas Bird Count trends in thesoutheastern U.S. during the latter halfof the 20th century suggest that closerattention should be paid to migrating

and wintering populations, especiallyregarding potential impacts associatedwith current agricultural practices.

Photo orchidpoet rom iStock.com


22/3620

In her H y m n t o A p h r o d i t e ,the ancient Greek poet appho descr ibes wing-

whirr ing sparrows pul l ing theoddess s char iot across theky. Throughout h istory, theseommon bi rdsthe sparrowami ly i s the largest b i rd ami ly inhe wor ldhave ound the i r waynto c lass ic l i te rature rom the

Gospe ls , to Shakespeare s p lays ,o Stephen Kings thr i l l e rs .

The saltmarsh sparrow, nowenet ica l l y d ist inguished romhe Nelsons sparrow, spends i tsnt i re l i e cyc le in the trans i t ionalreas between land and sea.

Dur ing the breeding season, theon-terr i tor ia l males have earned reputat ion or promiscui ty ;hey o ten breed more than onceur ing a season. These b i rds

ynchronize nest ing wi th theides , ledg ing the i r young in only ight days .

Other Bi rds o Conservat ionConcern in th is habi tat : Ne lsons

parrow, seas ide sparrow, c lapper a i l , and wi l le t .

Habtat

Salt marshes are ound along the intertidal shores o estuaries andsounds where salinity ranges rom reshwater (urther inland) to oceanlevels (coastal). These coastal marshes, subject to the ebb and ow othe tides, oten experience rapid changes in salinity and temperature,to which the birds must adapt. The saltmarsh sparrow migrates only atnight to their wintering estuaries in the southeastern United States.

Fg

Saltmarsh sparrows eed mostly on insects, spiders, amphipods, and smallsnails, supplementing this diet with seeds and wild rice. When oraging,they run in short spurts, walk, or slowly hop.

Saltmarh Sparrow (Ammodramus caudacutus)

PhotoGarthMcE

lroy

Pote n ti a l Ve ry H i g h H g Ri sk


23/362 1

0.0

1.0

2.0

3.0

4.0

CoastalConnecticut

(n = 32)

CoastalNew York

(n = 27)

CoastalRhode Island

(n = 55)

Coastal Maine(n = 220)

CoastalMassachuset

(n = 145)

BloodHgCo

ncentration(ppm,ww)

Maximum


Photo: BRI archives

E t u a r I c a t o r

Figure 11: Geh eee euy exue h w.Sh w hw ve hhe euy eve h y he he eeue, wh e euy h Mhue.

Mrcury R

Saltmarsh sparrows showed elevatedblood mercury concentrationsacross much o their breeding range,most likely due to both dietary andhabitat preerences that put them athigh risk to mercury exposure [35].Findings o elevated blood mercuryconcentrations at several sitessuggest that mercury accumulations

may be high enough in the blood osaltmarsh sparrows to cause regularnest ailure at a rate that may putlocal populations at risk. Mercury, asa neurotoxin, is especially a problemor these estuary dwellers, as it mayaect the sparrows ability to time itsnesting patterns with the tides.


Rising sea levels attributed to climatechange pose a serious threat to these birds,

which spend their entire life cycle near thewaters edges. Marsh degradation, invasivespecies such as phragmites, and loss dueto coastal development is also a continuingproblem.


The saltmarsh sparrow is an excellentindicator species for contaminants inestuaries: they are endemic to the region;spend their entire life cycle in saltmarshhabitats; and tend to eat high in the food

chain. Limiting mercury exposure is criti-cal. Salt marsh managers must identifyand reduce sources of mercury by imple-menting Best Management Practices(BMP) for storm water managementwhere it affects the saltmarsh, use vegeta-tive buffers, remove sources of mercurysuch as landfills, and support regulationsto reduce the amount of mercury enteringthe water system.

Because these birds are especially vul-nerable to rising sea levels as a result ofclimate change, it is important that landuse planners and decision-makers extendcoastal protection further inland.


24/3622

Habtat

The little brown bat is ound ina wide range o orested areasthroughout North America, romsouthern Alaska eastward through

the southern hal o Canada toNewoundland, south throughmost o the continental UnitedStates, and in higher elevationorested regions o Mexico. Theyroost in tree cavities and caves, aswell as in barns and attics.

Fg

These bats orage over both landand water, usually eeding onswarms o insects to save time andenergy in their search or ood.

Lttl Brow Bat (Myotis lucifugus)

Ancient Egyptians believed theycured illness, the Chinese viewhem as good luck, Westerners earhey are vampiresthere is no lack o

yth, legend, or olklore surroundingats. These creatures, the onlyammals that can ly, are actually

uite beneicial to people.

he little brown bat, with its glossyrownish-black ur, was once one the most common bats ound

n North America. Now, however,ecause o a ungus causinghite-nose syndrome, little brownat populations have declinedramatically and are now beingonsidered or ederal listing. Not aerritorial animal, these bats roostn large colonies, some reportedly asarge as 300,000 individuals.

he little brown bat, which grows toe about three inches long and weighsquarter o an ounce, can eat up to

,200 mosquitoes in an hour; this batan consume up to its body weightn insects in one night. The serviceo pest control provided by theseoracious eaters is valued at $22.9illion per year in the U.S. [25].

PhotoPhilipMyers,AnimalDiversityWeb

Figure 12: B u vey h wh he Nhe,k vue e . M ve ye e N L Cve e [36].

Water or Wetland

Developed

Forest

Grassland or Shrub

Pote n ti a lH i g h H g Ri sk


25/362 3

Figure 13: Me u euy e e w ee ehe he Nhe. A e ehve vu wh u e hexee he 10 ey uheh (e e). A e ve 10, eehe hve hw he ew euhey [30].

U r t r c t E c o y t m I c a t o r

Mrcury R

Bats are long-lived and have the potential to accumulate highconcentrations o mercury over time. High mercury levels maylead to a myriad o problems such as compromised immunesystems, which would make it harder to ght inections like

white-nose syndrome. The interaction o bats and windarms isan additional concern as bats approaching the blades o windturbines may suer rom pulmonary death (i.e., the burstingo capillaries). The ability o bats with elevated mercury bodyburdens to avoid wind turbines requires urther investigation.

Photo Merlin B. Tuttle, Bat Conservation International


White-nose syndrome (WNS), so namedfor the white fungus that grows on the

muzzle and wings of affected bats, isdecimating entire populations of theseanimals (nine different bat species havebeen affected). This fungus irritatesthe bat, causing it to waken more oftenduring hibernation, depleting stored fatreserves. Infected bats, emerging toosoon from hibernation dehydrated andmalnourished, freeze or starve to death;mortality rates are nearly 100% at somesites.


Northeastern bats are in danger due tomultiple threats, including WNS, habitatloss, pesticide use, mercury pollution,and wind-power development. The U.S.Fish and Wildlife Service is coordinatinga national management plan to addressWNS, but more research is needed tobetter understand other threats that batsface.

Some bat species, including the Indianabat (Myotis sodalis), are already on thefederal endangered species list anda petition has been filed to list littlebrown bats. Beyond the urgent needto understand and mitigate the effectsof WNS, bats should be protectedthrough management of forests andcave exploration, as well as by limitingpesticide use. Debunking myths througheducation will help raise public awarenessas to the value of bats.

0

5

10

15

20

25

30

35

40

West Virginia

(n = 62)

Pennsylvania

(n = 30)

Coastal

Massachusetts

(n = 14)

Northwest

Virginia

(n = 143)

Coastal

New York

(n = 15)

Southeast

New

Hampshire

(n = 5)

Central &

Western

New York

(n = 52)

Southern

New York

(n = 29)

Coastal

Maine

(n = 31)

Adirondacks

New York

(n = 60)

FurHgConcentr

ation(ppm,ww)



26/3624

Primary Indicator: w huhSecondary Indicators: eue we, w-e we,Keuky we, Sw we, A fyhe

Primary Indicator: Bke huhSecondary Indicators: k we, yew-ee fyhe

Primary Indicator: Lu wehuhSecondary Indicators: hy we, yew-he we,he we, he wehuh, C we

Birds and other wildlie living in orests are oten limited by the

amount o calcium available or uptake. Acid deposition createdrom the burning o ossil uels can intensiy the leachingo calcium rom the soil [32]. In areas that are also subjectto a high amount o mercury deposition, this can becomea dangerous combination o threats. Besides the need orcontrol o mercury emissions, orests can be managed orreducing soil acidication that will alleviate the eect omultiple environmental stressors.

Logging near orested rivers and creeks not only enhanceserosion, it also remobilizes mercury previously sequestered inthe soils [39, 40]. By restricting logging near water bodies,

direct movement o mercury into the watershed can beminimized. The contamination o streams and rivers in oneplace may have signicant ramications more than 80 milesdownstream [31].

Forest res have the ability to mobilize mercury sequesteredin the soils and vegetation o orests [37, 38]. This mercuryis then ree to enter the atmosphere or be remobilized intonearby habitats and then ingested by organisms. Fire is otennecessary or the overall health o orests, but allowing ormore requent, less severe orest res will reduce the risk olarge scale mobilization o mercury into the ecosystem.

Maagmt Rcommato

Improv r maagmt

Ruc ac poto

Rtrct loggg ar watr bo

High Elevation Forests

Upland Forests

Forested Rivers and Creeks


27/362 5

Primary Indicator: h wSecondary Indicators: Ne w, ee w, e , we

Primary Indicator: uy kSecondary Indicator: ve-e fyhe, y-ee we,C we, V , e e

Primary Indicator: e w u eeSecondary Indicator: Nh Ae ee,uy he e wh we h

Large uctuations in water levels within reservoirs can intensiythe amount o mercury methylation in an ecosystem [41,

42]. The repeated wetting and drying o water body edgesallows the bacteria that methylate mercury to thrive andincrease the amount o biologically available mercury.The most reasonable way to control this methylationis to maintain more constant water levels in these

reservoirs, particularly in late summer and early all.

Because o its prevalence in various industrial processes and waste-water treatment plants, mercury has historically been released invarying quantities into many dierent water bodies throughout

the United States. Estuaries are oten the nal destination orthis source o mercury, and the high degree o methylationin coastal wetlands allows or much o it to become availableto wildlie [35]. Although many o these point sources have

known inputs, there are many that are unknown and unex-plored. In some cases, the solution can be as easy as discovering

and cleaning up the legacy dump site. Without intensive biomoni-toring in our nations estuaries, we will not be able to determinewhere these hotspots o high mercury levels in wildlie occur.

Mercury emissions must be controlled at the source, and the

U.S. EPA has recently nalized its Mercury and Air ToxicsStandards (MATS) rule to regulate mercury emissions rompower plants in the United States [2]. Implemention othis rule is necessary or protection o ecosystem health,including areas particularly sensitive and/or close tosources that are likely biological mercury hotspots [41].

Ruc mrcury mo

Cotrol rrvor watr lvl fuctuato

Trac h or uow pot ourc

Unrestricted Ecosystems

Artificial Reservoirs

Estuaries


28/3626

MrcuryA Mgratory Thrat

Mercury is a global pollutant that has a potential to adversely aecthundreds o bird species across the western hemisphere. For migratoryspecies, this means that they can encounter mercury contamination ontheir breeding grounds, as well as along migratory routes and on theirwintering grounds. Moreover, migrating birds might be at greater risk tothe toxic eects o mercury. Mercury is stored in muscle; most birds willuse their muscle reserves to help uel their migratory ights especiallyduring stressul times when at reserves are expended. This muscle burncould potentially give birds a high dose o mercury during migration.

Migration accounts or nearly 75% o all annual mortality rates insome songbirds; the added burden o toxic mercury exposure maymake the process even more challenging. While mercury exposureduring the breeding season is well documented, contamination duringmigration and over the winter is still relatively unknown. Migration is aascinating natural process, however, its linkages across the world makesunderstanding the risks o mercury exposure all the more difcult.

Corvato ComplxtUnderstanding migratory connectivity, the strength o connectionsbetween wintering and breeding areas, has become vital to theconservation o migratory birds. When a species has strong connectivity,

traditional conservation measures may not be eective. For example,i the New England breeding population o the northern waterthrush(eatured at right) was declining and landscape managers wanted toprotect it throughout its annual lie cycle, one strategy might be topurchase wintering ground habitat and manage it or waterthrushes.I this population only wintered in the Caribbean, then it makes senseto conserve land in the Caribbean. Without this inormation well-intentioned eorts might protect land in Central America, but actuallyachieve very little in meaningul results or the breeding population.Understanding the complexities o migration is crucial to makingeective conservation decisions.

U n de rsta n di n g M i g ra ti onigration is a common lie historyrategy that maniests in a myriad

ways across species. Hawks andgles migrate during the day toke advantage o air currents,hile songbirds migrate at night avoid predators. Some songbirdecies, even those as small as

ummingbirds, will embark on 182 hour nonstop over-water lights

arrive at their destinations.

abirds migrate almost entirelyver water: Arctic terns track both

asts o the Atlantic Ocean ineir Arctic to Antarctic route,

hile albatrosses track the winds ine middle o the Southern Ocean.

here are about as many types oigration as there are migratoryecies; understanding howigration works in each speciescritical toward understandinge risks that these animals take

roughout their entire lie cycle.mall devices, called geolocators,

n be attached to a bird to records migration. Geolocators estimatee global position o the bird bylculating sunset and sunrise to

etermine latitude and longitude,abling scientists to learn more

bout the migration habits o birds small as wood thrushes [43].

B R Is T ER R A N e twork

BRI h evee he Tee Eye ReeRh Aee (TERRA) Newk he wee hehee ve u ue euy he y . Thuh wh C, heU.S., Mex, Ce Suh Ae, he CeI, we he ee ue hw euy e eehuhu he e ye.

Notropcal Cocto What I s a N e otropi ca l

M i g r a n t ?

A bir d that br eeds in the U . S .and Canada, then tr avels toCentr al or S outh A m er ic a or the Car ibbean for the winter .

While this report documents mercury concentrations in songbirdson their breeding grounds in the northeastern United States, thereis growing concern or birds that migrate to wintering grounds inCentral and South America and the Caribbean Islands. BiodiversityResearch Institute has gathered evidence that the mercury threat intropical habitats may be much greater than expected.


29/362 7

Figure 15: Dee hee he he wehuh ee (k ee) we (h ee) e wh y ue (w). Th ee ehze eue e he ew e whee BRI h ye-u euy exue, u y he e e e ey exe y (ee x h).

N e o t r o p i c a l M i g r a n t S o n g bo f C o n s e r v a t i o n C o n c e r n

Ove-e Fyhe

40-ye ee=80%

W Thuh40-ye ee=50%

Ceue We40-ye ee=70%

Bke Thuh

40-ye ee=N

Bk We

40-ye ee=809Northern Waterthrush

*Based on ranNorth American Breeding Bird Sur

Mercury levels ound in thenorthern waterthrush duringwinter, over migration, and onbreeding grounds are similar.Blood mercury concentrations areconsistently elevated throughoutthe year, demonstrating thatdietary uptake is a year-roundconcern, and despite migratorymovements this species has lesso an ability than some speciesor ridding its body o mercuryburdens during times o lowenvironmental mercury exposure.This double whammy o mercurytoxicity restricts interseasonaldepuration or release o mercury.

Notropcal Ca Stuy: Northr Watrthruh

Migrat ion:High Risk

Breeding:High Risk

Winter ing:

Very HighRisk

Figure 14: B euy e he wehuhhuhu he y ye.

0.0

0.4

0.8

1.2

1.6

2.0

Wintering

Belize

n = 26Floridan = 64

Breeding

New Englandn = 8

BloodHgConcentration(ppm,ww)


Wintering Migration Breeding

Very High Risk

High Risk

Moderate Risk

Low Risk


30/3628

Acid deposition is a well-documented environmental stressor with various negative impacts on ecosystems.

Itracto o Evromtal Stror

The interaction o environmental mercury and climate change can add additional stress to alreadythreatened species.

Although we ocus on mercury exposure and eects in this report, there are many other environmental stressorsthat can act in concert with mercury to create problems or terrestrial ecosystems.

Increased acidity in soil promotes increased methylmercuryproduction, resulting in higher mercury exposure in invertivores.

Acidic deposition leaches calcium rom the soil, resultingin the decreased availability and abundance o calcium-richinvertebrate prey that songbirds eat [32, 44]. Decreased calciumavailability or egg production combined with the neurotoxiceects o mercury can potentially lead to nest ailure.

Rising sea levels may lead to loss o coastal wetlands, habitatalterations, and potential changes in mercury cycling in wetlands.

Rising temperatures could lead to enhanced methylation o mercury

or select habitats.

Increases in precipitation in some parts o the U.S. could lead toincreases in atmospheric deposition o mercury.

Forest res, expected to increase with global warming,release stored mercury into the environment.

Changes in ood web structure that occur asspecies adapt to changes in habitat and availableood sources may alter mercury exposure.

More requent and increased storm intensitycould lead to episodes o high mercury exposure as

a result o runo.

Thawing o permarost will rapidly release thousands oyears o bound mercury (natural and anthropogenic) into theair and water.

Acid Rain

Climate Change


31/362 9

Natoal a Itratoal Mrcury Motorg

There are two goals o this report.First, to characterize the risk omercury within the terrestrialinvertivore community. Second,to oer relevant inormationor management and policyactions that can be taken toreduce the impact o mercuryon the terrestrial ecosystem.

Th Importac oMrcury Motorg

As we look to the uture, how willwe know i our management andpolicy decisions are eective? Itis critical to establish mercurymonitoring networks, bothnationally and internationally,

so quantitative assessments canbe related with regulatory eortsattempting to lower anthropogenicmercury, particularly in sensitiveecosystems, such as wetlands.

For aquatic systems, we demon-strate encouraging results romthe Great Lakes Region, wherereduction in mercury emissionshas helped decrease the amounto mercury in dierent sh spe-cies over time (see gure at right).

Figure 16:Te e h e euy e vee yye ue e he Ge Lke we e he U.S.Ge Lke e he ve O [45].

Ahuh h eee e k he qu ey e, he euy eve wy wh he e . Weue h he hh he h e e e ee ee eve e:

S e u e e h ye, ewee ee h e h.

B e e eh y ju wh y .

B euy e e e ue (~30 y) eyuke ehyeu y, e h h ue eve he ehyeuy he we hee ee h he e euy he y ke wh euy e (BRI uu he ).

S on gbird s an d B ats:C an d id ate s for T e rre strial Me rcu ry Mon itorin g

Walleye and Largemouth BassFillet Mercury

Year1970 1980 1990 2000 2010

Filletmercury(ppm,ww)

0.0

0.2

0.4

0.6

0.8

U.S. walleye (Great Lakes region)

U.S. largemouth bass (Great Lakes region)

Canadian largemouth bass (province of Ontario)


32/3630

The intent o this report is to present an overviewo current inormation about environmentalmercury pollution in the terrestrial ecosystemso the northeastern United States and to supportand improve ongoing and uture investments thataddress the risk o environmental mercury loads.We have summarized the most recent data relatedto songbird and bat mercury exposure, but have alsoshown that more research and better monitoring isneeded to ully understand the scope o this hiddenrisk to these and other wildlie species.

Reducing anthropogenic sources o mercury is one es-sential strategy or minimizing the impact o mercury

on people and wildlie, but to eectively inorm policydecisions at each stage o the process, scientists alsoneed more data.

We recommend a concurrent three-pronged approachor minimizing adverse impacts o mercury on wildlie:

1. Identiy the species, habitats, and regions at riskto mercury exposure

2. Address synergistic interactions o mercury withother environmental pollutants

3. Minimize wildlie exposure by reducing mercuryemissions.

Ug Scc to Iorm Mrcury Polcy

Legislation or a National Mercury Monitoring Network (MercNet)was introduced into the 112th Congress (to the Senate Public Worksand the House Energy and Commerce Committees) and will provide acomprehensive and standard way or measuring mercury in the air, water,soil, as well as in sh and wildlie. Songbirds and bats are nominated as

part o the mercury monitoring eort [1, 46].

Congress needs to pass legislation authorizing the creation o MercNet,which will allow the ederal government to scienti ically evaluate thee icacy o policy and management decisions that, in turn, will allow

or better decisions in the uture and protect past mercury abatement

investments.

Improve mercury monitoringin both aquatic and terrestrialecosystems across the UnitedStates

It is time to establish air pollution thresholds to protect and restore U.S.ecosystems. A critical loads approach to understanding air pollutionimpacts requires the assessment o multiple contaminant loadingto sensitive ecosystems above which signicant adverse impacts are

detected. This strategy is accepted as superior by the scientic andregulatory communities, and is in use in Europe, Canada, and parts othe United States, but has yet to be used to understand the interactiono mercury with other contaminants. Although critical loads allowor more rened policy decisions, their establishment requires rmcommitment and unding in order to enable the most up-to-datescientic determinations.

Congress should direct the U.S. EPA to implement critical loads or sulur andnitrogen, along with thresholds or mercury, and the U.S. EPA should use thesethresholds to assess progress under the Clean Air Act.

Develop science-based policyrecommendations or setting airpollution thresholds to protectecosystems and species

Etablh MrcNt [1]

St ar polluto thrhol or coytm [47]

1. I de n ti f y th e spe ci e s, h a bi ta ts, a n d re g i on s a t r i sk to me rcu ry e x posu re

2. Addre ss sy n e rg i st i c i n te ra cti on s of me rcu r y w i th oth e r e n v i ron me n ta l pol l u ta n ts


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U bt avalabl tchology [2]

Technological pollution control or reducing mercury pollution has beenenormously successul in the regulation o municipal and medical wasteincinerators [49] and the U.S. EPA Mercury and Air Toxics StandardsRule will provide similar reductions or power plants with a goal o 90%less mercury emissions.

Ensure implementation o this common sense solution to the largest stationarysource o airborne mercurycoal-fred power plants.

Prvt bologcal mrcury hotpot [41]

While cap and trade programs are eective in certain pollution strate-gies, like those or acid rain components, it is inappropriate or a pollut-ant like mercury. There is a growing body o evidence that local mercuryemission sources, such as rom coal-red power plants, can have signi-cant local eects on downwind ecosystems leading to the development obiological mercury hotspots [41, 50].

By avoiding mercury cap and trade systems, our expectation is to prevent newmercury hotspots rom being created across the United States and globally.

Support UNEP Mrcury Traty [51]

The United Nations Environment Programme (UNEP) intends to ratiy

a globally binding agreement on mercury in 2013. Reductions in thepurposeul use o mercury or small-scale gold mining, chlor-alkaliplants, and in manuactured products are planned, while emissionsrom ossil-uel burning and other sources are being negotiated.

The U.S. State Department and the U.S. EPA should continue their internationalleadership roles in guiding new standards or global mercury pollution as well asin helping set comprehensive and standard monitoring programs. Adding newdelegates rom other ederal agencies, such as the Department o Interior, will help

acilitate greater connections with environmental mercury studies and manage-ment in the United States.

Reduce mercury emissions romcoal-fred power plants

Avoid mercury cap and tradesystems

Regulate global mercuryemissions

3. M i n i mi ze w i l dl i f e me rcu ry e x posu re by re du ci n g me rcu ry e mi ssi on s


34/3632

1. Schmeltz et al. 2011. MercNet: a national

monitoring network to assess responses to

changing mercury emissions in the UnitedStates. Ecotoxicol 20:1713-1725.

2. U.S. EPA Mercury and Air Toxics Standards.

2011. http://www.epa.gov/mats.

3. Hatcher & Filippelli. 2011. Mercury cyclingin an urbanized watershed: the inuence o

wind distribution and regional subwatershed

geometry in central Indiana, USA. Water AirSoil Poll 219:251-261.

4. Evers et al. 2011. Mercury in the Great Lakes

region: bioaccumulation, spatiotemporal pat-

terns, ecological risks, and policy. Ecotoxicol20:1487-1499.

5. UNEP Chemicals Branch. 2008. The global

atmospheric mercury assessment: sources,emissions, and transport. UNEP-Chemicals,

Geneva.

6. U.S. EPA. 2010. Fish Advisories Listing. http://

water.epa.gov/scitech/swguidance/shshell-sh/shadvisories/advisories_index.cm.

7. Guallar et al. 2002. Mercury, sh oils, and the

risk o myocardial inarction. New Eng J Med

347:1747-1754.

8. Roman et al. 2011. Evaluation o the cardio-

vascular eects o methylmercury exposures:

current evidence supports development o adoseresponse unction or regulatory benets

analysis. Environ Health Persp 119:607-614.

9. May. 2000. Disturbing behavior: neurotoxic

eects in children. Environ Health Persp108:262-267.

10. Grandjean et al. 1999. Methylmercury expo-

sure biomarkers as indicators o neurotoxic-

ity in children aged 7 years. Am J Epidemiol150:301-305.

11. Swain et al. 2007. Socioeconomic conse-

quences o mercury use and pollution. Ambio36:46-62.

12. Evers et al. 2008. Adverse eects rom environ-

mental mercury loads on breeding common

loons. Ecotoxicol 17:69-81.

13. Facemire et al. 1995. Reproductive impair-

ment in the Florida panther: nature or nur-

ture? Environ Health Persp 103:79-86.

14. Braun et al. 2006. Elevated mercury levels ina declining population o ivory gulls in the

Canadian Arctic. Mar Pollut Bull 52: 969-987.

15. Sleeman et al. 2010. Mercury poisoning in aree-living northern river otter. J Wildlie Dis

46:1035-1039.

16. Schwarzbach et al. 2006. Eects o predation,

ooding, and contamination on reproduc-tive success o Caliornia clapper rails in San

Francisco Bay. Auk 123:45-60.

17. Hallinger et al. 2011. Mercury exposure andsurvival in ree-living tree swallows. Ecotoxicol20:39-46.

18. Hawley et al. 2009. Compromised immune

competence in ree-living tree swallows ex-

posed to mercury. Ecotoxicol 18:499-503.

19. Wada et al. 2009. Suppressed adrenocortical

responses and thyroid hormone levels in birds

near a mercury-contaminated river. EnvironSci Technol 43:6031-6038.

20. Heinz et al. 2009. Species dierences in the

sensitivity o avian embryos to methylmercury.

Arch Environ Con Tox 56:129-138.

21. Brasso et al. 2008. Eects o mercury exposure

on the reproductive success o tree swallows.

Ecotoxicol 17:133-141.

22. Jackson et al. 2011. Mercury exposure aectsthe reproductive success o a ree-living ter-

restrial songbird, the Carolina Wren. Auk

128:759-769.

23. Wenny et al. 2011. Perspectives in ornithol-ogy: the need to quantiy ecosystem services

provided by birds. Auk 128:1-14.

24. Jedlicka et al. 2011. Avian conservationpractices strengthen ecosystem services in

Caliornia vineyards. PLoS ONE 6(11):e27347.

doi:10.1371/journal.pone.0027347.

25. Boyles et al. 2011. Economic importance obats. Science 332:41-42.

26. Whelan et al. 2008. Ecosystem services pro-

vided by birds. Ann NY Acad Sci 1134:25-60.

27. Cristol et al. 2008. The movement o aquaticmercury through terrestrial ood webs. Sci-

ence 320:335.

28. Evers & Duron. 2007. Assessing the availabil-ity o methylmercury in terrestrial breeding

birds o New York and Pennsylvania, 2005-

2006. Report BRI 2008-15 submitted to TheNature Conservancy and NYSERDA.

29. Buck et al. 2009. Assessing Methylmercury

Pathways or Terrestrial Invertivores: Pilot

Assessment on Dome Island, New York.Report BRI 2009-20 submitted to The Nature

Conservancy.

30. Nam et al. 2012. Elevated mercury exposure

and neurochemical alterations in little brownbats rom a site with historical mercury con-

tamination. Accepted, Ecotoxicol.

31. Jackson et al. 2011. Mercury exposure in ter-

restrial birds ar downstream o an historicalpoint source. Environ Pollut 159:3302-3308.

32. Hames et al. 2002. Adverse eects o acid

rain on the distribution o the wood thrushin North America. P Natl Acad Sci USA

99:11235-11240.

33. Rimmer et al. 2005. Mercury concentrations

in Bicknells thrush and other insectivorouspasserines in montane orests o northeastern

North America. Ecotoxicol 14:223-240.

34. Edmonds et al. 2010. Geographic and seasonalvariation in mercury exposure o the declining

Rusty Blackbird. Condor 112:789-799.

35. Lane et al. 2011. Mercury in breeding salt-

marsh sparrows. Ecotoxicol 20:1984-1991.

36. Homer et al. 2004. Development o a 2001national landcover database or the United

States. Photogrammetric Engin and Remote

Sensing pp. 829-840.

37. Kelly et al. 2006. Forest re increases mercuryaccumulation by shes via ood web restruc-

turing and increased mercury inputs. P Natl

Acad Sci-USA 103:19380-19385.

38. Biswas et al. 2007. Release o mercury rom

Rocky Mountain orest res. Global Biogeo-

chemistry Cycles 21 GB1002.

39. Porvari et al. 2003. Forestry practices increasemercury and methyl mercury output rom

boreal orest catchments. Environ Sci Technol

37:2389-2393.

40. Garcia et al. 2007. Seasonal and inter-annualvariations in methyl mercury concentrations

in zooplankton rom boreal lakes impacted by

deorestation or natural orest res. EnvironMonit Assess 131:1-11.

41. Evers et al. 2007. Biological mercury hotspots

in the northeastern United States and south-

eastern Canada. BioScience 57:29-43.

42. Sorenson et al. 2005. Relationship between

mercury accumulation in young-o-the-year

yellow perch and water-level uctuations.Environ Sci Technol 39:9237-9243.

43. Stutchbury et al. 2009. Tracking long-distance

songbird migration by using geolocators.

Science 323:896.

44. Likens et al.1996. Long-term eects o acid

rain: Response and recovery o a orest ecosys-

tem. Science 272:244-246.

45. Monson et al. 2011. Spatiotemporal trends omercury in walleye and largemouth bass rom

the Laurentian Great Lakes Region. Ecotoxicol

20:1555-1567.

46. Mason et al. 2008 Monitoring the response

to changing mercury deposition. Environ Sci

Technol. 39:14A-22A.

47. Fenn et al. 2011. Setting limits: using air pol-lution thresholds to protect and restore U.S.

ecosystems. Issues in Ecology Report Number

14:1-21.

48. Lovett et al. 2009. Eects o air pollution onecosystems and biological diversity in the

eastern United States. The Year in Ecology

and Conservation Biology, Ann NY Acad Sci1162:99-135.

49. Cain et al. 2011. Mercury policy in the Great

Lakes states: past successes and uture oppor-tunities. Ecotoxicol 20:1500-1511.

50. Driscoll et al. 2007. Mercury contamination in

orest and reshwater ecosystems in the north-

eastern United States. BioScience 57:1-12.

51. UNEP Chemicals Branch. 2011. http://www.

unep.org/hazardoussubstances/Mercury/

tabid/434/Deault.aspx.

Ltratur Ct


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Acowlgmt

We are grateul or a grant rom The Nature Conser-vancys Rodney Johnson and Katherine Ordway Stew-ardship Endowment that supported the developmento this publication as well as parts o the originalresearch. This research was the result o years o col-laborations and we would like to acknowledge thosethat oered their assistance.

Many researchers generously shared their data with us.We are deeply indebted to Dr. David Braun o Sound-Science. We thank Chris Rimmer and Kent McFar-land o the Vermont Center or Ecostudies or theirassistance with sampling Bicknells thrushes; GregShriver or providing samples rom wood thrushes inDelaware; Sam Edmonds, Nelson ODriscoll, and thenumerous researchers involved with the InternationalRusty Blackbird Working Group or sharing theirextensive sampling o rusty blackbirds; Je Loukmasrom the New York State Department o Environmen-

tal Conservation or providing invertebrate mercurydata; Gary Lovett rom the Institute or EcosystemStudies or supplying soil data; and Chad Seewagenrom the Wildlie Conservation Society or providingmultiple years o samples.

Others provided eld accommodations, logisticalsupport, and helpul expertise. We thank the SUNYCollege o Environmental Science and ForestrysAdirondack Ecological Center or providing accessto study sites and lodging or eld crews; the staat the Montezuma National Wildlie Reuge andthe Tonawanda Wildlie Management Area or site

access and permits to sample birds and bats; thesta o the Marine Nature Study Area in Hempstead,NY or logistical support and assistance in theeld; Al Hicks o the New York State Departmento Environmental Conservation and John Chengero Bat Conservation and Management or theirassistance with providing bat samples; Cara Lee atThe Nature Conservancy or helping us with eldhousing, logistics, and site access; Bruce Conneryat Acadia National Park or helping us with eldhousing, permits, and site access; Dr. Ford and staor assisting us with site selection and permissionin the Fernow Experimental Forest; Bill DeLuca

or assisting with sampling eorts, eld housing,permits, and site access in New Hampshire; the BoyScouts o America or providing access and a eldcamp at Massawepie or multiple years; the YMCAor providing housing/eld camps and site accessor multiple years; Bill Schuster at Black Rock Forestor providing site access and permission or multipleyears; Bob Mulvihill at Powdermill Avian ResearchCenter or providing permission, site selection, siteaccess, sampling assistance, samples, and an incredible

learning environment or multiple years; Mike Fowlesand site managers at the U.S. Army Corp o Engineersor providing site permits/access and enthusiasticallyassisting with Pennsylvania eld logistics; TomLeBlanc o Allegany State Park or providing siteselection recommendations, logistical support, eldhousing, and overall enthusiasm or our project;the sta at numerous National Wildlie Reugesincluding Rachel Carson NWR (ME), Wertheim NWR(NY), Parker River NWR (MA), Ninigret NWR (RI),McKinney NWR (CT); Maine Department o InlandFisheries and Wildlie; Jen Walsh at the Universityo New Hampshire or eld assistance; and HenryCaldwell o Dome Island or providing all kindso help with boats, eld housing, and permits, aswell as being a gracious host or multiple years.

We are especially grateul to the sta o Cornells Labo Ornithology, Conservation Science department,

or their support o this project. In particular, wethank James D. Lowe or all his devoted work inthe eld, banding birds and collecting soil, leaves,and bird samples, and or his assistance withpreparing the metadata; Maria Stager or her aid inbird sampling and banding; Kenneth V. Rosenbergor his departmental support; and Kevin Webb,rom Cornells Lab o Ornithology, InormationScience department, or his excellent GIS support.

Within The Nature Conservancy, we appreciate thosewho supported this work over the years including: Da-vid Higby, Peter Kareiva, Mark King, Cara Lee, Nicole

Maher, Rebecca Shirer, Brad Stratton, Troy Weldy, andAlan White.

Within Biodiversity Research Institute, this reportwould not have been possible without the eort omany BRI staers who oered data and expertise. Wethank Evan Adams or help with Neotropical Con-nections, David Buck or ood web inormation, SethDresser or help with website design, Melissa Duronor her leadership and expertise in collecting the elddata, Julie Franklin or her early eorts in coordinat-ing this large project, Ian Johnson or his patience inmaking GIS maps, Oksana Lane or collecting many o

the songbird samples, Deborah McKew or design andediting, Dr. Nina Schoch or her insight on the policyrecommendations, Dr. Iain Stenhouse or providingthe bird lie cycle gures, and Dave Yates or providingbat data.

w w w . bri l oon . org /h i dde n ri sk


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652 M i St t 195 N K R d

To learn more about the i mpacts of mercur y on wildlife and people,visit www.briloon.org/hiddenrisk

hidden risk: mercury in terrestrial ecosystems of the northeast

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