habitat use by harlequin ducks (histrionicus histrionicus...
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Habitat Use by Harlequin Ducks (Histrionicus
histrionicus) during Brood-rearing in the Rocky
Mountains of Alberta
Beth MacCALLUM1, Chiarastella FEDER2, Barry GODSALVE3, Marion I.
PAIBOMESAI4, and Allison PATTERSON5 1Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1, Canada. Email: [email protected] 2Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1, Canada.
Present address: 5712-57 St. Close, Rocky Mountain House, AB, T4T 1H8. Canada. Email: [email protected] 3Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1, Canada. Email: [email protected] 4Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1, Canada. Email: [email protected] 5Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1, Canada.
Present address: EDI Environmental Dynamics Inc., 301 George St, Prince George, BC V2L 3M6, Canada. Email:
Abstract
Prefledging waterfowl are vulnerable to an array of mortality agents and are often spatially restricted. Factors affecting
habitat use by brood-rearing harlequin duck (Histrionicus histrionicus) females at the home range scale were
investigated in the east slope of Alberta’s Rocky Mountains. Generalized linear models were used to assess the effect
of environmental parameters on harlequin duck brood presence (n = 38) and brood absence (n = 38). A set of models
were built a priori and subsequently ranked by Akaike Information Criterion (AICc). Models relating to foraging
conditions indicated the probability of an area being used for brood-rearing increased with total invertebrate biomass.
Correspondence: Beth MacCallum, Bighorn Wildlife Technologies Ltd., 176 Moberly Drive, Hinton, AB, T7V 1Z1,
Canada. Email: [email protected]
CWBM 2016: Volume 5, Number 2
Original Research
ISSN: 1929–3100
Models relating to predator avoidance indicated the probability of brood use was high when percentage of channel
overhang was close to 0, and declined with increasing overhang, shrub coverage in the 1st m, bank relief and more
exposed bank. When models were combined, results suggested that predator avoidance had more support than
foraging conditions. Comparisons between brood-rearing areas and spring foraging areas indicated that brood use
areas had lower bank relief, less exposed bank, and higher invertebrate biomass than areas used for foraging in spring.
Comparisons of brood-rearing areas to nesting areas indicated that brood-rearing areas had less channel overhang and
less shrub cover in the 1st m than nesting areas. We conclude that harlequin duck females select habitat for brood-
rearing based on the ability to detect predators and the presence of habitat features that allow ducklings to avoid
predators. At the home range scale, invertebrate biomass was important but not as important as predator avoidance
features.
Key Words: Alberta, Brood-rearing, Habitat, Harlequin Duck, Histrionicus histrionicus.
INTRODUCTION
Habitat selection plays an important role in a species life
history because it can affect an individual's ability to forage,
survive and reproduce (Jones 2001). This is especially
evident for migratory duck species that make use of a range
of habitats throughout their breeding cycle (Wallen 1987;
Heath 2001). Quality of brood-rearing habitat can affect
growth rate and final body size of developing waterfowl.
Habitat selection by waterfowl during brood-rearing may be
affected by food quality and density, availability of loafing
areas that enhance the ability of the female to detect
predators, and other factors that facilitate predator avoidance
or secure a stable food supply (Sedinger 1992; Mainguy et
al. 2006). The choice of brood-rearing habitat by waterfowl
is presumably an optimization of costs and benefits among
different components including food availability
(Gardarsson and Einarsson 1994; McCollin 1998) and
predator avoidance (Martin 1993; Heath 2001).
The harlequin duck (Histrionicus histrionicus) is a small
sea duck with a circumpolar distribution. In western North
America, the harlequin duck winters on the Pacific coast and
breeds on interior freshwater streams. In Alberta, breeding
range is restricted to high elevation streams of the Rocky
Mountains and foothills located in the southwest portion of
the province. Harlequin duck females bear the cost of
incubation and brood-rearing alone, as males return to
coastal molting and wintering grounds shortly after
incubation begins (Bengtson 1972). Thus, habitat selection
during brood-rearing must ensure adequate nutrition for the
female and ducklings to meet their physiological needs, as
well as provide concealment and safety from predators.
Observations of harlequin duck females leading recently
hatched young to discrete areas within the breeding stream
(Robertson and Goudie 1999; MacCallum et al. 2006) and of
harlequin duck broods remaining in relatively confined areas
for extended periods (Kuchel 1977; Machmer 2001) suggest
that habitat requirements during the brood-rearing period are
more constrained than during the rest of the breeding cycle.
Spatial separation of nesting and brood-rearing habitat has
been documented for harlequin ducks in the Maligne
watersheds of Alberta (Hunt and Ydenberg 2000) and for
other waterfowl species (Grand et al. 1997; Mainguy et al.
2006).
In the McLeod watershed of Alberta, segregation in the
spatial distribution of harlequin ducks during the breeding
season has been documented (MacCallum et al. 2006). In
early spring, during pre-incubation, harlequin pairs forage
downstream of nest locations and brood-rearing areas. Nests
are generally found in small tributary streams positioned
high in the watershed upstream of brood-rearing areas. After
hatching, hens move their broods to areas that are
intermediate in elevation between the pre-incubation and
incubation use areas. Similar behavior has been recorded for
harlequin ducks in other systems (Robertson and Goudie
1999).
In Alberta, the harlequin duck is designated as a Species of
Special Concern because it has narrow breeding
requirements, a relatively small population size and is
sensitive to disturbance during breeding (Alberta
Endangered Species Conservation Committee 2000).
Harlequin ducks breeding in the McLeod River watershed of
Alberta appear to restrict their distribution to specific areas
within the McLeod River and Whitehorse Creek during the
brood-rearing period. A better understanding of habitat
requirements during the different life stages of the breeding
season would enhance our ability to design harlequin duck
stream surveys, conduct stream restoration activities, and
develop area specific conservation plans. The objective of
this study was to identify which habitat characteristics
female harlequin ducks select for brood-rearing.
Predictions
We formulated 3 a priori predictions related to how female
harlequins select brood-rearing habitat.
33 MacCALLUM et al.
Prediction 1. If brood-rearing habitat is driven by prey
availability, then brood-rearing areas should provide higher
prey abundance, biomass, and/or biomass quality than brood
non-rearing areas.
Prediction 2. If brood-rearing habitat is driven by predation
risk, then brood-rearing areas should have more channel and
bank vegetation to provide concealment, have more islands
or loafing areas, and/or greater visibility up and down stream.
Prediction 3. Females should select habitats that optimize
food quality and availability, predation avoidance and
suitable river characteristics for ducklings (Rodway et al.
2000; Heath 2001).
STUDY AREA
The McLeod River originates in the front range of the
Canadian Rocky Mountains and flows approximately 360
km northeast into the Athabasca River. Harlequin ducks
occupy the headwaters of the McLeod River above 1,320 m
elevation, including Whitehorse, Prospect, Unnamed, Harris
and Thornton Creeks (Figure 1). Vegetation associated with
the McLeod River consists of valley bottom willow (Salix
spp.) and dwarf birch (Betula glandulosa) shrub
communities, lodgepole pine (Pinus contorta) and
Engelmann spruce (Picea engelmannii)-subalpine fir (Abies
lasiocarpa) forests, and scattered grasslands on steep, south-
facing aspects (Strong 1992). The most common predators
of harlequin duck adults, juveniles, ducklings and eggs in the
McLeod watershed include: mink (Neovison vison), marten
(Martes americana), coyote (Canis latrans), osprey
(Pandion haliaetus), northern goshawk (Accipiter gentilis),
red-tailed hawk (Buteo jamaicensis), golden eagle (Aquila
chrysaetos), and great-horned owl (Bubo virginianus).
METHODS
Stream Surveys
The linear habitat of breeding harlequin ducks requires
survey methods not typical for most waterfowl (Heath et al.
2006). Breeding pair and brood counts were conducted on
the McLeod River and its tributaries annually from 1996 to
2005 using in-stream walking surveys, a method with similar
assumptions as the line transect technique (British Columbia
Ministry of Environment, Lands and Parks 1998). Breeding
pair surveys occurred in late May, and brood surveys
occurred in late July and again in late August. Observers
equipped with binoculars and spotting scopes walked
upstream in the water or immediately adjacent the water.
Observers stopped at each corner to scan the upstream view
before proceeding. All birds were classified to sex and age;
positions were recorded using GPS and marked on an air
photo. Surveys of the river and major tributaries were
completed in 3 to 4 consecutive days. To understand
breeding chronology and distribution within the watershed,
repetitive surveys throughout the entire breeding season
were completed in the first 2 years of survey: 8 surveys in
1996 and 6 in 1997.
Data Collection
The presence/absence of broods were used to divide the
study area into brood use and non-use areas. Brood use areas
were used by the hen for all phases of brood-rearing whereas
brood non-use areas never had broods. These non-use
reaches were located upstream and downstream of the brood-
rearing reaches and were used exclusively by adults for other
activities.
We divided the study area into stream reaches using the
classification of Duhaime (2003); 74 stream reaches were
classified as brood use areas and 107 were classified as brood
non-use areas. From the above we randomly selected 38
brood use and 38 brood non-use stream reaches for sampling.
Of the 38 brood non-use stream reaches, 17 were located
upstream of the brood use areas in the headwaters of the
McLeod River above Thornton Creek, and in Unnamed
Creek, Harris Creek and Prospect Creek, and 21 were located
downstream of the brood use areas below the confluence of
the McLeod River and Whitehorse Creek. Brood use areas
were located in the McLeod River between the confluence
with Whitehorse Creek and Thornton Creek, and in
Whitehorse Creek from the mouth to Harlequin Creek
(Figure 1). The centroid of the stream reaches was used as
the sample site; mean reach length was 317 m. Brood
observations and stream reaches were mapped using
MapInfo v.8.
Habitat variables describing the physical characteristics of
the stream, vegetation cover, food abundance and human
disturbance were collected from all reaches between 31 July
and 24 August 2006, which corresponds to the late-chick
rearing period for harlequin ducks in this watershed.
Stream characteristics were measured within a 30-m
stream segment centered on the sample site and along a
cross-section of the stream channel established at the sample
site. Vegetation was measured in 1-m intervals along a 1 m
x 6 m quadrat located perpendicular to the stream on the right
and left banks. Benthic invertebrates were sampled at each
site with a kick net standardized by time (Sylvestre 2004).
Samples collected in the field were preserved by adding 85%
ethanol at a 1:1 ratio of ethanol to sample.
Macroinvertebrates were identified to the family level by G.
Lester of EcoAnalysts, Inc. Detailed methods for all habitat
variables are provided in Table 1.
34 MacCALLUM et al.
Data Analysis
Prior to modeling habitat selection, we used Spearman’s
correlation coefficient to identify and eliminate highly
correlated variables (|rs| ≥ 0.6, Sokal and Rolhf 1981).
Among variables with high collinearity we retained the
variable that made most sense biologically (Table 1).
We used binomial generalized linear models (GLM) with
a logit-link function to assess the effects of environmental
parameters on habitat selection during the brood-rearing
period (Crawley 2002). The response variable was the
presence (1) or the absence (0) of broods. We used an
information theoretic approach to evaluate the importance of
a suite of environmental parameters in differentiating habitat
selection during brood-rearing from the rest of the breeding
cycle. We adopted a hierarchical approach to model
development because of the large number of potential
environmental parameters. First, we examined a set of
models consisting of parameters that could be related to
foraging conditions (mean depth, gradient, % cobble
substrate, and macroinvertebrate biomass). Second, we
examined a set of models based on environmental parameters
that could be related to predator avoidance (channel
overhang, bank shrub cover, bank relief, bank exposure, and
human disturbance). Third, we combined variables with
strong support from the foraging conditions and predator
avoidance model sets to determine if harlequin duck females
were selecting brood-rearing areas that optimize both of
Figure 1. Location of streams and associated elevations sampled for harlequin duck habitat in the
McLeod River watershed, Alberta, 31 July–24 August 2006. Lines with ticks: brood non-use
downstream; solid line: brood use; dashed line: brood non-use upstream.
35 MacCALLUM et al.
these functions. For each set of models, we considered all
possible combinations of main effects and a null model.
Akaike’s Information Criterion (AICc) corrected for small
samples was used to select the best model from 3 sets of
candidate models (Burnham and Anderson 2002). Models
within ≤ 2 ΔAICc of the top model were considered to be
supported. To avoid consideration of uninformative
parameters, if the supported model(s) with the fewest
numbers of parameters (k) was nested within larger
supported models, the smaller model(s) was considered the
most parsimonious (Burnham and Anderson 2002; Arnold
2010). We also computed importance values (Σ ωi), model
averaged estimates (β), and unconditional standard errors
(SE) to evaluate the strength of evidence for each variable
within the model sets.
Finally, we compared habitat selection of brood use areas
to the brood non-use areas depending on their spatial location
within the watershed. We classified the brood non-use areas
as spring foraging if they were located downstream of brood-
rearing areas; or as nesting habitat if they were located
upstream of brood-rearing areas. We used binomial GLMs to
compare brood use areas to brood non-use spring foraging
and nesting areas. All environmental variables identified as
important to brood-rearing habitat selection in the previous
Table 1. Field measurements describing harlequin duck habitat, McLeod River and tributaries, 31 July to 24 August, 2006.
Variables used for modeling are indicated in italics.
36 MacCALLUM et al.
analysis were considered as potential predictors for the
spatial comparisons.
Analyses were performed using R 2.15.2
RESULTS
Foraging Conditions Models
Five models were less than 2 AICc units apart (Table 2);
the most parsimonious model included only invertebrate
biomass and the other models included biomass as a
predictor. Invertebrate biomass had an importance value of
0.89, which was more than twice as high as the next strongest
variable (Table 3) suggesting that the probability of an area
being used for brood-rearing increased with invertebrate
biomass (Figure 2).
Predator Avoidance Models
Among the models using variables expected to relate to
predator avoidance, 4 models were within 2 AICc units
(Table 2); however, the most parsimonious model was a
subset of the other 3 supported models. The model with the
most support included channel overhang, shrub cover in the
1st m, bank relief, and exposed bank; these 4 variables had
importance values between 0.94 and 1.00 (Table 3). Shrub
importance values of 0.32 and 0.59, respectively (Table 3).
The probability of brood use was high when the percentage
of channel overhang was close to 0 and declined rapidly with
increasing overhang (Figure 3). The probability of brood use
declined steadily with higher % shrub cover in the 1st m,
increasing bank relief, and more exposed bank (Figure 3).
Figure 2. Estimated relationship between invertebrate biomass (g) and the
probability of brood use, based on the model Brood ~ Biomass (Table 2). The
solid line is the estimated probability, dashed lines are the 95 % confidence
intervals, open circles are biomass values for brood use sample sites, and closed
circles are biomass values for brood non-use sample sites.
MacCALLUM et al. 37
Combined Models
We considered invertebrate biomass, channel overhang,
shrub cover in the 1st m, bank relief and exposed bank in a
3rd model set to determine if harlequin ducks in the McLeod
River select brood-rearing habitat that optimizes both
foraging conditions and predator avoidance (i.e., a tradeoff).
The full model had the lowest AICc score, 70.56; however,
the next model was only 1.02 AICc higher and included the
4 predator avoidance variables without biomass. We
considered the model with only the 4 predator avoidance
variables to have the most support because it was nested
within this larger model. Within this model set channel
overhang, shrub cover in the 1st m, bank relief and exposed
bank had importance values between 0.94 and 1.00;
invertebrate biomass had an importance value of only 0.64
(Table 3). Model averaged parameter estimates and
unconditional standard errors were similar for the parameters
Table 2. Three model sets examining the relationship between environmental brood-rearing habitat selection by harlequin
ducks: (a) models based on variables related to foraging conditions, (b) models based on variables related to predator
avoidance, and (c) models combining variables identified as important for either foraging of predator avoidance. We present
results for all models within <2 ΔAICc of the model with the lowest AICc value for each model set. Among these models we
considered the smallest model nested within larger models to have the most support; for each model set the model with the
most support is shown in italics. This table includes the number of parameters (k), Akaike’s Information Criterion corrected
for small sample sizes (AICc), ΔAICc, AICc weight (ωi), cumulative AICc weights (Σ ωi), and the log likelihood (Log-L)
for each model.
MacCALLUM et al. MacCALLUM et al. 38
in the combined model set and the estimated values from the
previous model sets (Table 3). Among the 3 model sets,
models based on variables related to predator avoidance had
more support than models based only on foraging conditions
or models combining foraging conditions and predator
avoidance.
Spatial Comparisons of Brood Use and Brood Non-Use
Areas
When brood use habitat was compared only to the brood
non-use spring foraging habitat located downstream of the
brood use areas, there was strong support for the model
including bank relief, exposed bank and invertebrate biomass
able 4a); these 3 variables had importance values of 0.92,
0.99 and 0.94, respectively (Table 5a). Bank relief and
exposed bank were lower in brood-rearing habitat than in
spring foraging habitat, while invertebrate biomass was
higher in brood-rearing habitat.
The top model for differentiating between brood-rearing
habitat and brood non-use nesting habitat located upstream
of the brood use areas included channel overhang and shrub
cover in the 1st m (Table 4b); both of these variables had
importance values of 1.00 (Table 5b). The probability of
brood use versus nesting use declined with increasing
channel overhang and increasing shrub cover in the 1st m.
Brood use areas had lower channel overhang and lower shrub
cover in the 1st m than nesting areas.
DISCUSSION
Models relating to foraging conditions indicated that the
probability of an area being used for brood-rearing increased
with total invertebrate biomass. Ducklings feed primarily on
benthic macroinvertebrates and they must grow rapidly and
fledge in a timely fashion before they can migrate long
distances to coastal wintering grounds. In our study,
Chironomids were the dominant taxa in the majority of sites.
Hunt (1998) indicated that Chironomids may be part of the
harlequin duck diet during brood-rearing.
Models relating to predator avoidance indicated that the
probability of brood use was high when the percentage of
channel overhang is close to 0 and declined rapidly with
Table 3. Importance values (Σ ωi), model averaged parameter estimates, and unconditional standard errors (SE) for all
parameters considered in the 3 model sets used to identify habitat variables that could be important in harlequin duck brood-
rearing habitat selection: (a) foraging conditions, (b) predator avoidance, and (c) combined models. Variables with strong
support are indicated in italics.
39 MacCALLUM et al.
increasing overhang. The probability of brood use declined
steadily with higher % shrub cover in the 1st m, increasing
bank relief, and more exposed bank. Vegetation close to
water that is too dense may prevent the sighting of a predator
(Orians and Wittenberger 1991). Other studies suggest that
vegetation cover is positively associated with harlequin
ducks because it provides cover from possible predators
(Heath 2001; Kuchel 1977; Machmer 2001). Kuchel (1977)
reported that brood-rearing females in Glacier National Park
used overhanging vegetation on vertical banks as shelter
during feeding and as escape cover. However, in the McLeod
watershed, the probability of brood presence declined with
increasing bank relief. The hen's ability to detect a terrestrial
predator may play a more important role in the survival of
the ducklings than the use of channel overhang to hide them
from predators. Brood-rearing habitat on the Salmo River,
Figure 3. Estimated relationships between channel overhang(a), shrub cover in the 1st m (b), bank relief
(c), and exposed bank (d) on the probability of brood use, based on the model: Brood ~ Overhang +
Shrub1 + Relief +Bank (Table 2). The solid line is the estimated probability, dashed lines are the 95 %
confidence intervals, open circles are biomass values for brood use sample sites, and closed circles are
biomass values for brood non-use sample sites. Estimates for each variable are calculated over the range
of observed values for that variable while holding other predictors in the model constant at their median
value.
40 MacCALLUM et
al.
Table 4. Two model sets comparing harlequin duck habitat selection depending on spatial location within the McLeod River,
AB: (a) brood-rearing habitat to spring foraging habitat and (b) brood-rearing habitat to nesting habitat. We present results
for all models within <2 ΔAICc of the model with the lowest AICc value for each model set. Among these models we
considered the smallest model nested within larger models to have the most support; for each model set the model with the
most support is shown in italics. This table includes the number of parameters (K), Akaike’s Information Criterion corrected
for small sample sizes (AICc), ΔAICc, AICc weight (ωi), cumulative AICc weights (Σ ωi), and the log likelihood (Log-L)
for each model.
Table 5. . Importance values (Σ ωi), model averaged parameter estimates, and unconditional standard errors (SE) for all
parameters considered in the 2 model sets comparing harlequin duck habitat selection depending on spatial location within
the McLeod River, AB: (a) brood-rearing habitat to spring foraging habitat and (b) brood-rearing habitat to nesting habitat.
Variables with strong support are indicated in italics.
MacCALLUM et al. 41
British Columbia had greater than 20% channel overhang
(Machmer 2001). Differences in biophysical characteristics
(i.e., bank structure) between the systems may explain this
differential use with respect to channel overhang and may be
an example of behavioural adaptation to the local
environment.
We suggest that in the McLeod system, hens rearing a
brood choose areas where the vegetation structure does not
compromise the ability to detect a predator, while providing
escape cover in case of attack. In this system, harlequin
ducks use areas with varied shrub coverage, preferring high
coverage during nesting while foraging in areas where the
shrub coverage is lower. This suggests that harlequin ducks,
at the landscape level, may prefer heterogeneous habitats as
requirements change with environmental conditions and
stage of duckling development (Heath 2001).
Models that tested whether the selection of brood-rearing
habitat optimizes both foraging conditions and predator
avoidance indicated that the models with variables relating
to predator avoidance had more support than models based
only on foraging conditions or models combining foraging
conditions and predator avoidance.
In the McLeod watershed we have observed harlequin
ducks using a variety of anti-predator strategies including but
not limited to: hiding in or under bank vegetation, stationary
behavior on shore (terrestrial responses), diving, swimming
long distances underwater, camouflage hovering in the
current (aquatic responses), and flying (aerial response).
Apparent species-specific recognition and appropriate anti-
predator strategies have been recorded for harlequin ducks
(MacCallum 2003). Once the young have hatched the female
is constrained in her ability to avoid predators by the physical
capabilities of the developing young. Young downy
ducklings are not strong swimmers and dive infrequently
until the 3rd or 4th week (Kuchel 1977). During this period,
hens use terrestrial responses and have been observed
leading the young from the water to hide under dense
vegetation when threatened.
As the young develop through the various growth stages,
they become more adept at using aquatic based escape
strategies and finally at the end of the summer are capable of
flying. Older broods are more likely to be found using a
larger portion of the stream than during the earlier growth
stages (B. MacCallum, personal observation). Ducklings that
become temporarily separated from the hen appear to be less
vigilant than the hen with ducklings. The females’ selection
of habitat may be influenced by the development of anti-
predator responses in the young.
Despite not being included in the ‘best’ model, total
invertebrate biomass was 25% higher in brood-rearing areas
compared to non-use areas, which suggests that food
availability still may be important in this system at the home
range level. Prey abundance may not be the best predictor of
food availability, as habitat characteristics (i.e., type of
aquatic vegetation, depth of benthic sediments) also
influence availability to foraging waterfowl (Sedinger 1992).
When brood use areas were compared only to brood non-
use spring foraging areas, the model that included bank relief
(negative association), exposed bank (negative association)
and invertebrate biomass (positive association) had the
strongest support. Females with young actively avoid spring
foraging areas at lower elevations; they have been observed
leading broods upstream after having been washed
downstream by flooding (B. MacCallum, personal
observation). Habitat downstream of the brood-rearing areas
have more exposed bank, bank relief, and less shrub cover
that may provide an advantage for predators as downy
ducklings need easy access to shoreline shrub cover for
hiding especially in early stages of development. Too much
shrub cover on the bank may obscure the hens’ ability to see
predators but some shrub cover is necessary to provide
escape cover for ducklings. A number of authors (Bengtson
1972; Rodway 1998) have suggested that harlequin ducks
may be food limited on breeding streams. Spring foraging
areas located downstream of the brood-rearing areas provide
benthic forage early in spring when higher reaches may still
be ice covered; late-season invertebrate hatches in the brood-
rearing stretches high in the subalpine provide nutrition for
developing ducklings prior to migration.
When brood use areas were compared to brood non-use
nesting areas, the probability of brood use declined with
increasing channel overhang and increasing shrub cover in
the 1st m. Incubating hens usually choose nest sites with
overhead cover to conceal her nest, which is generally placed
on the ground within a few metres of the stream bank
(Bengtson 1972; Bruner 1997; Smith 2000). In the McLeod
watershed, 75% of 25 nests were found within 1.65 m of
stream banks. Overhanging vegetation may help camouflage
the hen movement into and out of the nest from avian
predators patrolling the stream as well as preventing
terrestrial predators from approaching the stream bank. Hens
are capable of flying quickly to areas more suited for
foraging and preening requirements before returning to the
nest. In choosing her nest location she needs only consider
physical characteristics that would keep her hidden.
A number of variables, which did not appear to influence
the choice of habitat during brood-rearing, may influence
harlequin duck distribution at the landscape level, e.g., %
cobbles, % riffles, loafing sites, and islands. Cobble
substrates and riffles, which are ideal locations for optimal
MacCALLUM et al. 42
prey items, were found throughout the brood use and non-
use areas with no apparent differences between the areas.
Loafing sites identified by others as important for harlequin
ducks for resting, preening and possibly vigilance (Heath
2001; Machmer 2001) were so ubiquitous in the McLeod
system that they were not included in the analyses. Islands,
which are probably important for providing refuge from
predators (Rodway 1998; Machmer 2001) were found in
only a few sites in the McLeod, and were therefore
eliminated prior to analysis. These variables did not vary
across the harlequin duck home range level. However, the
importance of particular habitat features may depend on the
scale of analysis (Orians and Wittenberger 1991) as habitat
selection may be a hierarchical process from landscape
through to nest site scales for migratory birds (Kaminski and
Weller 1992; Jones 2001; Heath and Montevecchi 2008).
Our results suggest that harlequin ducks are capable of
complex evaluation and can choose a specific location for a
particular purpose. Breeding hens are capable of using
streams with a variable structure to fulfill foraging, nesting
and brood-rearing functions. This highlights the importance
of evaluating habitat choices at different scales as the
importance of specific features may vary at the landscape
versus home range level (Kuchel 1977; Rodway 1998;
Chalfoun and Martin 2007; Heath and Montevecchi 2008).
At the landscape scale, we conclude that harlequin duck
females select brood-rearing areas based primarily on
predator avoidance features. Choice of brood-rearing habitat
with danger reducing features that are intermediate between
spring foraging and nesting habitats may reflect constraints
imposed on the hen by the development of the physical
capabilities of the ducklings and the need for the hen to detect
predators. Invertebrate biomass was important within the
home range but not as significant as the presence of a variety
of predator avoidance features.
We suggest that the best model can be useful in areas with
similar habitat characteristics to the McLeod River system,
i.e., the northern east slope of the Alberta Rocky Mountains.
The predictive power of the model may diminish when
applied to habitats that are substantially different from the
McLeod system because hens appear to be capable of
adjusting their behaviour based on local physical features
and the predator landscapes. This characteristic should be
taken into account when investigating habitat use of specific
life cycle stages during the breeding season.
ACKNOWLEDGEMENTS
This study was supported financially by Alberta
Conservation Association, Alberta Parks and Protected
Areas, Forest Resource Improvement Association of Alberta,
Teck Coal Limited, Cardinal River Operations and
Weyerhaeuser Company Ltd. In-kind contributions were
made by Bighorn Wildlife Technologies Ltd. and
Whitehorse Wildland Provincial Park. The Foothills Model
Forest provided stream reach classification for habitat
stratification. Bob Gliddon provided survey equipment.
Conor Johnson and Andrew Godsalve provided field support.
We thank Dr. Carl Schwarz for his advice to our many
questions, and Dr. Robin Leech who reviewed earlier drafts
of this paper.
LITERATURE CITED
Alberta Endangered Species Conservation Committee.
2000. Initial conservation action statement: harlequin
duck. Internal Report, Alberta Fish and Wildlife Division,
Edmonton, Alberta, Canada.
Arnold, T. W. 2010. Uninformative parameters and mode
selection using Akaike’s Information Criterion. Journal
of Wildlife Management 74: 1175 -1178.
Bengtson, S-A. 1972. Breeding ecology of the harlequin
duck Histrionicus histrionicus (L.) in Iceland. Ornis
Scandinavica 3: 1-19.
British Columbia Ministry of Environment, Lands, and
Parks. 1998. Inventory methods for riverine birds:
harlequin duck, belted kingfisher and American dipper.
Unpublished report, Standards for components of British
Columbia’s Biodiversity No. 12, Version 2.0, Victoria,
British Columbia, Canada.
Bruner, H. J. 1997. Habitat use and productivity of
harlequin ducks in the central Cascade Range of Oregon.
MSc thesis, Oregon State University, Corvallis, Oregon,
USA.
Burnham, K. P., and D. R. Anderson. 2002. Model
selection and multimodel inference: a practical
information theoretic approach. 2nd edition. Springer-
Verlag, New York, New York, USA.
Chalfoun, A. D., and T. E. Martin. 2007. Assessments of
habitat preferences and quality depend on spatial scale
and metrics of fitness. Journal of Applied Ecology 44:
983-992.
Crawley, M. K. 2002. Statistical computing: an
introduction to data analysis using S+. John Wiley and
Sons, Chichester, West Sussex, England.
Duhaime, K. 2003. Watershed delineation and stream
classification for the Northern East Slopes Region
including the Foothills Model Forest. Facet Decision
Systems, Inc., Vancouver, British Columbia; Foothills
Model Forest, Hinton, Alberta, Canada.
MacCALLUM et al. 43
Gardarsson, A., and A. Einarsson. 1994. Responses of
breeding duck populations to changes in food supply.
Hydrobiologia 279-280: 15-27.
Grand, J. B., P. L. Flint, and P. J. Heglund. 1997. Habitat
use by nesting and brood rearing northern pintails on the
Yukon-Kuskokwim Delta, Alaska. Journal of Wildlife
Management 61: 1199-1207.
Heath, J. P. 2001. Factors influencing breeding distributions
of harlequin ducks Histrionicus histrionicus in northern
Labrador: a multi-scale approach. MSc thesis, Memorial
University of Newfoundland, St. John's, Newfoundland,
Canada.
Heath, J. P., and W. A. Montevecchi. 2008. Differential
use of similar habitat by harlequin ducks: trade-offs and
implications for identifying critical habitat. Canadian
Journal of Zoology 86: 419-426.
Heath, J. P., G. J. Robertson, and W. A. Montevecchi.
2006. Population structure of breeding harlequin ducks
and the influence of predation risk. Canadian Journal of
Zoology 84: 855-864.
Hunt, W. A. 1998. The ecology of harlequin ducks
Histrionicus histrionicus breeding in Jasper National
Park, Canada. MSc thesis, Simon Fraser University,
Burnaby, British Columbia, Canada.
Hunt, B., and R. Ydenberg. 2000. Harlequins Histrionicus
histrionicus in a Rocky Mountain watershed I:
background and general breeding. Wildfowl 51: 155-168.
Jones, J. 2001. Habitat selection studies in avian ecology: a
critical review. The Auk 118: 557-562.
Kaminski, R. M., and M. W. Weller. 1992. Breeding
habitats of nearctic waterfowl. Pages 568-589 in B. D. J.
Batt, A. D. Afton, M. G. Anderson, C. D. Ankney, D. H.
Johnson, J. A. Kadlec, and G. L. Krapu, editors. Ecology
and management of breeding waterfowl. University of
Minnesota Press, Minneapolis, Minnesota, USA.
Kuchel, C. R. 1977. Some aspects of the behavior and
ecology of harlequin ducks breeding in Glacier National
Park, Montana. MSc thesis. University of Montana,
Missoula, Montana, USA.
MacCallum, B. 2003. Osprey attack on a harlequin duck
brood. Blue Jay 61: 126.
MacCallum, B., D. Farr, C. Weik, and B. Godsalve. 2006.
The harlequin duck in Alberta's northern Rocky
Mountains and foothills, a review of breeding ecology
and conservation outlook. Bighorn Wildlife
Technologies Ltd., Hinton, Alberta; Foothills Model
Forest, Hinton, Alberta, Canada.
Machmer, M. M. 2001. Salmo River harlequin duck
inventory, monitoring and brood assessment. Columbia
Basin Fish and Wildlife Compensation Program and
Pandion Ecological Research Ltd., Nelson, British
Columbia, Canada.
Mainguy, J., G. Gauthier, J.-F. Giroux, and I. Duclos.
2006. Habitat use and behaviour of greater snow geese
during movements from nesting to brood rearing areas.
Canadian Journal of Zoology 84: 1096-1103.
Martin, T. E. 1993. Nest predation and nest sites: new
perspective on old patterns. Biosciences 43: 523-532.
McCollin, D. 1998. Forest edges and habitat selection in
birds: A functional approach. Ecography 21: 247-260.
Orians, G. H., and J. F. Wittenberger. 1991. Spatial and
temporal scales in habitat selection. The American
Naturalist 137: 29-49.
Robertson, G. J., and I. R. Goudie. 1999. Harlequin duck
(Histrionicus histrionicus). No. 466 in A. Poole, and F.
Gill, editors. The Birds of North America. Academy of
Natural Sciences, Philadelphia, Pennsylvania; American
Ornithologists' Union, Washington, D.C., USA.
Rodway, M. S. 1998. Habitat use by harlequin ducks
breeding in Hebron Fiord, Labrador. Canadian Journal of
Zoology 76: 897-901.
Rodway, M. S., J. W. Gosse Jr., I. Fong, W. A.
Montevecchi, S. G. Gilliland, and G. C. Turner. 2000.
Abundance, habitat use, activity patterns, and foraging
behavior of harlequin ducks breeding in Hebron Fiord,
Labrador, in 1996. Canadian Wildlife Service Technical
Report Series No. 350, St. John’s, Newfoundland,
Canada.
Sedinger, J. S. 1992. Ecology of prefledging waterfowl.
Pages 109-127 in B. D. J. Batt, A. D. Afton, M. G.
Anderson, C. D. Ankney, D. H. Johnson, J. A. Kadlec,
and G. L. Krapu, editors. Ecology and management of
breeding waterfowl, University of Minnesota Press,
Minneapolis, Minnesota, USA.
Smith, C. 2000. Population dynamics and breeding ecology
of harlequin ducks in Banff National Park, Alberta, 1995-
1999. Technical report, Parks Canada, Banff National
Park, Banff, Alberta, Canada.
Sokal, R. R., and F. J. Rohlf. 1981. Biometry. 2nd edition.
W. H. Freeman and Company, New York, New York,
USA.
Strong, W. L. 1992. Ecoregions and ecodistricts of Alberta,
Vol. I. Alberta Forestry, Lands and Wildlife, Land
Information Services Division, Resource Information
Branch, Edmonton, Alberta, Canada.
Sylvestre, S. 2004. Invertebrate biomonitoring field and
laboratory manual for running water habitats, Revision.
Canadian Aquatic Biomonitoring Network, Environment
Canada, Pacific and Yukon Region, Vancouver, British
Columbia, Canada.
MacCALLUM et al. 44 45
Wallen, R. L. 1987. Habitat utilization by harlequin ducks
in Grand Teton National Park. MSc thesis, Montana
State University, Bozeman, Montana, USA.
ABOUT THE AUTHORS
Beth MacCallum completed a BSc from Queen’s
University, and a MEDes from the University of Calgary.
She works as a wildlife
biologist for Bighorn Wildlife
Technologies Ltd. in Hinton,
Alberta specializing in wildlife
inventory, impact assessment
and reclamation planning for
wildlife. She is a past president
of the Alberta Chapter of the
Wildlife Society and director of
the Northern Wild Sheep and
Goat Council.
Chiarastella Feder holds a
BSc in Natural Resources
Conservation and Management
from Pavia University, Italy,
and an MSc in Wildlife
Ecology from the Université de
Sherbrooke, Québec. Her
expertise is on bighorn sheep
which she studied at Ram
Mountain, Alberta. She has
researched red squirrel
behavior in a fragmented
landscape in northwest Italy,
has assisted in alpine ungulate
management in Dolomiti
Bellunesi National Park, Italy, and conservation and ecology
of the bold face saki monkey in the Madre de Dios system,
Peru. In Alberta, she has assisted with bighorn sheep
research at Sheep River, harlequin duck research in Hinton,
and wolf and cougar research near Nordegg. She is currently
employed as a wildlife biologist for the Government of
Alberta.
Barry Godsalve received a BSc from University of
Calgary. He specialized in
spatial analysis of wildlife
distribution in terrestrial and
aquatic habitats. Barry, now
deceased, worked with Bighorn
Wildlife Technologies in
Hinton, Alberta as a GIS
specialist and field technician.
Marion I. Paibomesai holds a
BSc in Marine Biology, and a
MSc in Integrative Biology from
the University of Guelph where
she investigated clock genes and
their genomic distributions in
three species of salmonid fishes.
Marion has worked as a research
technician at Bighorn Wildlife
Technologies Ltd. and most
recently for the Ontario Ministry
of Agriculture, Food and Rural
Affairs.
Allison Patterson received her
BSc degree from the University of Victoria, and her MSc
degree from Oregon State University. She is a wildlife
biologist at EDI Environmental Dynamics Inc in Prince
George, BC and has recently begun a PhD at McGill
University studying the non-breeding distribution and
behaviour of thick-billed murres.
Received 6 September 2016 – Accepted 13 October 2016
MacCALLUM et al. 45