|
Atlantic
Cooperative Wildlife
Ecology Research
Network
|
| Canadian Wildlife Service | Acadia University | Memorial University of Newfoundland | University of New Brunswick |
| Abstracts | Publications | Students | Research Associates | About Us | Contact Info | News | Listserve |
|
Bonne Bay Research Centre, Rocky Harbour, NL (MUN) 2002 Balancing
territorial defence with extra-territorial activities: Herring Gulls
nesting within a Common Eider colony We observed six pairs of uniquely marked Herring Gulls (Larus argentatus) occupying all-purpose territories within a Common Eider (Somateria mollissima) colony in Canada's Eastern Arctic. Eight-hour behavioural watches occurred daily through the incubation period. We quantified location and frequency of territorial intrusions, territorial chases and predation events. We also monitored territory attendance for each pair. We manipulated prey availability by placing eggs within focal territories. We hypothesize time allotted to territorial defence by the non-incubating member of the pair is related primarily to territory prey availability. We further hypothesize that absenteeism by the non-incubating individual leads to increased rates of intrusion and stealing of prey from its territory.
Comparative feeding ecology of
herring gulls (Larinus argentatus) and great
black-backed gulls (L. marinus) in the bay of
fundy - a progress report In 2001 and 2002 I investigated which food sources Herring Gulls (Larinus argentatus) and Great Black-backed Gulls (L. marinus) use, how much of their diet consisted of anthropogenic food, and how far they would fly from their breeding colony to obtain it. My research focus was on coastal islands with breeding colonies in the Bay of Fundy, from Saint John, New Brunswick to the Deer Island and Wolves Archipelagoes. Success in 2001 with a method using colour- and shape-coded craft foam pieces to assess the distances gulls will travel to food sources from their breeding colonies led to its continued use in 2002 and the expanded deployment of pieces to new food sources. Regurgitations were collected from adults and chicks to assess diet. Two different methods of collecting regurgitations from adult gulls were tried and will be compared. Preliminary results of adult and chick condition measurements will be presented, but much of the data analysis still lies ahead. The extent to which gulls feed on anthropogenic food sources is of interest because it may affect not only their population trends, but also those of other species of conservation interest.
Timing of breeding and optimal
resource allocation in arctic-nesting common eider: preliminary results. There is a growing body of evidence that the allocation of resources to egg production may play a major role in determining parental fitness and optimal breeding strategy in birds. The main goal of our study is to test predictions of a dynamic model of condition-dependent individual optimal lay date and clutch size. In summer 2002, we captured 117 female common eiders during the pre-laying period at the largest eider colony in the Canadian Arctic (East Bay, Southampton Island). Birds were marked with nasal tags and some with radio-transmitters (25) in order to track them during the nesting period. Preliminary results will be presented on the relationships between pre-breeding body condition, probability of nesting, lay date and clutch size. Analyses of the isotopic signatures of egg components and body tissues of 30 collected birds should allow us to investigate the source of nutrients that are invested in egg production.
Understanding the breeding biology
of Arctic Terns (Sterna Paradesaea) on Machias Seal Island (NB) and
Country Island (NS). We are comparing the breeding biology of Arctic Terns on Machias Seal Island (NB), to the colony on Country Island (NS). From preliminary analysis it seems that the population numbers for Arctic Terns on Machias Seal are not increasing compared to the Country Island colony numbers. This is supported by the productivity numbers (chicks fledge/pair), which are generally much lower on Machias Seal than on Country Island. While the two colonies are similar in many factors such as : low predation on both islands and the colonies are both mixed with Common Terns (Sterna hirundo), we will attempt to identify the factors that may be affecting productivity in the two colonies. We are using collected data from 1998 until 2003. While still in the preliminary stages, one of the factors that seem to be of significance is chick diet. Another goal of this study is to standardize data collection between managed islands.
The effect of landscape alteration
on movement behaviour of peatland dragonflies of Western Newfoundland. Currently, commercial timber harvesting is taking place in the Greater Gros Morne Ecosystem. This is greatly altering the landscape for species that use the forest as a resource. I am interested in the effects of the cutting on populations of peatland dragonflies. In particular, I am looking at 1- dragonfly movement at different scales, 2- how movement behaviour differs at different boundaries (forest vs. scrub vs. clear-cuts), and 3- if movement is a function of distance and/or habitat/matrix type. This past summer, we conducted a large-scale mark-release-recapture experiment in seven different bogs to test these three questions. I will present preliminary findings.
Arctic Terns in the Gulf of Maine
and Bay of Fundy: Are the birds crossing borders? In 1999 we began a study of Arctic Terns nesting in the Gulf of Maine and the Bay of Fundy. The main goal of this project is to determine if the colonies are demographically independent or part of a regional metapopulation. There are four island colonies in the study and we have banded over 1000 adult Arctic Terns on these islands during the last four years. For the last three years we have re-sighted or re-captured as many individuals as possible on the four key islands in the study and have also looked for banded individuals on other tern colonies in the region. Currently we have two estimates of annual survival and three estimates of movement among the colonies. These estimates represent the first estimates of their kind for Arctic Terns in North America. I will discuss the evidence for a regional metapopulation and the potential implications of our results.
Review of ACWERN-UNB's research on
forest birds ACWERN's overall mandate is to investigate the effects of environmental change on wildlife populations in Atlantic Canada. To do this we need to assess what are the likely environmental changes, and design research to explore effects of those changes. The UNB node uses similar approaches to this problem in two ecosystems &endash; forested and marine. In both systems we explore large-scale patterns of distribution to identify critical environmental linkages, and investigate local (population) responses to environmental changes; where possible we try to include the full range of fitness components (i.e. density, productivity and survival). Here I review our work on birds in forest ecosystems, summarising completed and continuing work by several graduate students. Reasoning that the largest current environmental change affecting forest ecosystems in Atlantic Canada is forestry, all our projects address the effects of forestry on quantity and quality of habitat for birds. Most projects involve both landscape and stand scales, and contribute to the assessment of the relative importance of effects and responses at these scales in generally-forested versus converted landscapes.
Review of ACWERN-UNB's research on
marine birds Here I review our work on birds in marine ecosystems, summarising completed and continuing work by several graduate students. There is no marine equivalent of forestry to highlight as an overriding factor effecting environmental change, so our approach is to establish long-term measures of key demographic parameters and ecological responses of the birds we study. Our main study sites and species are Machias Seal Island (MSI) (Arctic and Common Terns, Razorbills and Atlantic Puffins) and Common Eiders in S.W. Bay of Fundy. On MSI 8 years of systematic measurement are detecting interesting changes that may (or may not!) signal significant changes in the marine system. Our Eider work, by contrast, has focused more on ecological factors likely to be affecting the population (gull predation, rockweed harvesting).
The effect of military jet
over-flights on Harlequin Ducks breeding in central Labrador Harlequin Ducks breeding at Fig River (Treatment Site) and Crooked River (Control Site) in central Labrador were studied in 2001 and 2002. I applied a Before After Control Impact (BACI) statistical design that controls for time and space to demonstrate a significant impact on behaviour of Harlequin Ducks during low-level (30-100m agl) military jet over-flights. Harlequin Ducks exposed to noise generated from military jet over-flights displayed ALERT behaviours in orders of magnitude greater than birds not exposed to aircraft. Noise levels measured in proximity to the study birds varied, and peaks > 100 dBA were common and some events attained 130-140dBA. There was a positive dose-response relationship between ALERT behaviours and generated noise levels. There was evidence of short-term habituation during sorties with successive military jet over-flights, i.e., minutes apart, whereas this pattern was not evident for intermittent jet over-flights. In an effort to determine if noise from military jet over-flights generated a physiological response in the study birds, I collected feces from rocks on days with no over-flights, and days following over-flights. These samples are being assayed for corticosterone levels, a hormone released in birds that is indicative of a physiological response to a stressor. Attempts to measure and interpret behavioural/physiological responses to body condition of Harlequin Ducks will be discussed.
Breeding in a burrow conveys
advantages for Razorbills on Machias Seal Island. Razorbills breed in a variety of nest site types. On Machias Seal Island, Razorbill nest site types were divided into three categories based on the amount of cover: burrow, crevice, and open. Other authors have shown no difference in the proportion of successful nests between nest types, but on Machias Seal Island there is a clear distinction between the proportion of successful nests in each type. Logistic regression modeling determined that of year, nest type, location on island, volume index and relative lay date, only location was left out of the final model. Nest type is a strong predictor of nest success based on its coefficient p-value, therefore, nest type is further analyzed to look at differences in relative lay date, volume index, substrate, number of walls, closest neighbours and relative temperature amplitude, among nest types.
Endogenous reserve dynamics of
Northern Common Eiders (Somateria mollissima borealis)
during the non-breeding season. In waterfowl, endogenous reserves have been shown to influence survival, recruitment, hunting vulnerability, and productivity. Despite this, there is little known about the energetics of Northern Common Eider Ducks. Our research focused on the energy reserve dynamics of a population that over-winters along coasts of southwest Greenland, migrates through Hudson Strait and breeds on Southampton Island, Nunavut. Birds were collected throughout the winter in Nuuk, Greenland and in spring in Cape Dorset, Nunavut by Inuit hunters. Male and females eiders were also trapped alive at East Bay, Southampton, Nunavut. Total lipid reserves were estimated from body mass, abdominal and femoral fat using equations derived from total carcass analyses of a sub-sample (n=92). Adult males and females had different energy reserve dynamics. The endogenous reserve levels of males were stable throughout the winter, then decreased during migration, and remained low upon arrival to the breeding grounds. Females showed greater fluctuations during the winter. Like drakes, hens also showed a decline in reserves during migration, however they substantially and quickly increased upon arrival to the breeding grounds. We suggest that, a) eiders in this population do not require large fat reserves during winter because reliable food sources exist throughout the winter; b) eiders maintain low reserves during migration to maximize flight efficiency; and c) at the beginning of the breeding season, females acquire reserves for egg production and incubation while males utilise energy reserves during mate guarding activities.
Survival of Atlantic Puffins at the Gannet Islands, Labrador 1996-2002 Ian L. Jones ACWERN Memorial University of Newfoundland Survival rate Phi is the key demographic parameter for long-lived species, so variation in survival rate is thus the major determining factor in seabird population dynamics. Accordingly we marked and resighted 776 adult Atlantic Puffins at islands GC2 and GC4 in the Gannet Islands, Labrador between 1996 and 2002. Survival analysis was performed using program MARK. The data fit MARK assumptions well, with c-hat = 3.04 . The best model indicated constant survival rate over 1996-2002 and no difference between islands, with recapture rate p varying both between islands and across years (Phi(constant) p(island x year)). The survival rate estimate for all birds (breeding and non-breeding) was 87.1% (95% confidence limits 84.2 to 89.4%) a tight estimate consistent with a stable population of a long-lived seabird. I found no evidence of a link between survival and the environmental covariate North Atlantic Oscillation (although with only seven occasions the fit would need to have been perfect in order to be detected). At least three more years of resightings are required to achieve sufficient power to rigorously test for links to oceanography.
Is the large seabird breeding colony
on Kiska Island at risk? Introductions of alien organisms, especially rats, have been the root of many ecological problems, the most notable of which occur on island flora and fauna. During World War II rats were accidentally introduced onto Kiska Island, Alaska. In 2001 and 2002 Least Auklet (Aethia pusilla) fledging and overall reproductive success at the Sirius Point colony on Kiska Island were much lower than at nearby colonies where there are no rats. Least Auklet chicks at Kiska in 2002 also showed evidence of parental neglect possibly resulting from rat disturbance and predation. Food webs will be constructed using stable isotopes to determine trophic feeding level and feeding environment of the rats on Kiska. In 2001 and 2002 rats contributed directly and possibly indirectly to the reproductive failure at the Sirius Point colony by predating adults, eggs and nestlings. The resulting near reproductive failure indicates that a population decline is virtually certain.
Eastern Canada Piping Plover (Charadrius
melodus) banding study In 1985, COSEWIC upgraded the Piping Plover to Endangered as a result of continuing population declines. In 1998, a banding project was initiated by CWS to provide insight into juvenile recruitment, adult survival and dispersal patterns. Recapture rates of plovers vary by age and province. New Brunswick, Newfoundland and Nova Scotia banding results show that recapture rates for birds banded as adults are approximately twice that of birds banded as juveniles. For Prince Edward Island, the recapture rate of banded adults is approximately five times that of birds banded as juveniles. Results to date suggest that the Nova Scotia population is discrete, while the Gulf of St Lawrence provincial populations are exchanging individuals. Wintering ground and migration sightings have been made in Florida, Georgia, South Carolina, North Carolina, Rhode Island, Maryland, New York, New Jersey and Massachusetts. The banding study will continue for two years with a focus on recaptures.
The influence of landscape matrix on
the distribution of a peatland dragonfly (Leucorrhinia
hudsonica) in western Newfoundland A landscape's matrix may comprise useable resources or unusable habitat, mortality risks, barriers to movement, or it may even facilitate movement. Matrix habitats can therefore exert a large influence on the dynamics and spatial distribution of populations, which is particularly relevant for conservation in fragmented landscapes. We examined the population spatial distribution of a peatland dragonfly, the Hudsonian Whiteface (Leucorrhinia hudsonica), in a commercially harvested forest in western Newfoundland, Canada. We used multi-scaled sampling in natural and harvested landscapes to investigate the effects of landscape structure and matrix alteration on the incidence and abundance of L. hudsonica larvae. The most important factors influencing larval distribution were matrix habitats between nearest-neighbour peatlands, and the pH of breeding pools within the peatlands. Incidence was higher in peatlands separated by scrub/ cut matrix than forest. Pool pH was significantly lower in scrub peatlands, and exerted a negative influence on larval incidence and abundance.
Parental and foraging behavior of
Thick-billed murres and Razorbills at Gannet Islands: Female and Male
roles. Murres (Uria sp.) and Razorbills (Alca torda) share a distinctive reproductive strategy, a second period of chick-rearing at sea where the male is the only care-giver. According to optimal models of energy expenditure, both sexes will minimize their parental effort in order to maximize their lifetime reproductive success. This study aims to determine the parental roles of males and females at the nest site and their underlined foraging strategies across two related species. Parental and foraging behavior of Thick-billed murres and Razorbills were studied at Gannet Islands, Labrador during 2000-2002. Continuous observations of nest attendance, feeding frequency and foraging trips were undertaken during the incubation/brooding period. Foraging activity at sea was recorded using time-depth recorders. Preliminary results suggest females tend to compensate male reduction on chick feeding and males spend more time at the nest site. Foraging strategies seem to differ between species and sexes according to parental roles and environmental constraints.
The fate of Razorbills banded as
chicks at the Gannet Islands, Labrador Razorbills are a species of concern in Atlantic Canada due to low population size relative to some other auk species and evidence of anthropogenic mortality. Accordingly, MUN-ACWERN began a chick banding program at the Gannet Islands, Labrador in 1996 to quantify recruitment, adult survival and dispersal. A total of 2,371 chicks were banded to 2002. Eight were later recovered dead, six shot in the Newfoundland murre hunt and two found dead on beaches in Massachusetts, USA. I read bands of adult birds at the Gannet Islands during June-August 2002 to look for known age birds. I resighted 53 individuals banded as chicks, including 6 two-year-olds, 19 three-year-olds, 4 four-year-olds, 8 five-year olds, and 16 six-year-olds. No two-year-olds were seen. A total of 40 birds (67%) were seen near the ledge/site where they were hatched, the remainder were seen on different islands from the banding location. This marked population will likely prove useful for demographic modeling of this interesting species.
Movement of boreal songbirds through naturally high and low forest habitats in Western Newfoundland Kristin Powell ACWERN Acadia University We observed how bird movement was influenced by resource structure and composition at the landscape scale by examining how these factors influenced the homing ability of songbirds in western Newfoundland. From June 9 to July 4, 2002, we translocated 33 paired male birds of 5 different species from their nests to sites with similar habitat characteristics up to four kilometers away. Males were captured in mist nets, banded with unique color bands, translocated by truck, and their return success and time-to-return were recorded. Habitat amount, configuration, and matrix type were determined for all study areas using GIS software and data. Preliminary data analysis shows that overall recapture values were low but results were highly species specific. The knowledge gained from these translocation experiments will help us understand the influence of natural broad-scale resource structure on songbirds and will suggest which species are or are not sensitive to variation in landscape resource structure.
Gull predation as a factor in the
evolution of plumage variation of Least Auklets (Aethia
pusilla). Least Auklet (Aethia pusilla), probably the most abundant seabird in the Bering Sea, displays an unusual amount of polymorphism in its breeding plumage. Predation pressure by Glaucous-winged Gulls (Larus glaucescens) could be a driving force behind the evolution of Least Auklet plumage polymorphism. To test whether gulls have a preference for a certain plumage type I performed an experiment in which I observed gull attack rates on manipulated models. Gulls might prefer a plumage type because it is easier to detect, provides a better meal, or because it is correlated with an auklet's ability to escape during an attack. Acceleration during take-off of captured auklets was measured from videotape using digital single frame analysis. I will discuss the potential of take-off acceleration as a cheap measure of a bird's condition.
The relationship between forest
productivity and songbird habitat quality To determine the effects of forest productivity on songbird habitat quality, bird numbers were recorded at 220 point counts within 5 forest cover types representing a gradient of timber volume. Stands with the highest timber volume supported the highest densities of yellow-rumped warblers and contained one unique species, i.e., brown creeper, in low densities. The densities of many species showed no difference between cover types, e.g., boreal chickadees, black-backed woodpeckers, or were highest in the moderate and lower volume stands, e.g., hermit thrushes. Significant yearly variation was observed in bird densities and cover type selection for many species. Future analyses will include an index of reproductive success to further evaluate the differences in bird habitat quality. Patterns of bird abundance and breeding success will be evaluated in the context of vegetation structure and insect abundance. Environmental factors influencing forest productivity will be investigated. |