Avian cholera emergence in arctic-nesting northern Common Eiders: Using community-based, participatory surveillance to delineate disease outbreak patterns and predict transmission risk

Emerging infectious diseases are a growing concern in wildlife conservation. Documenting outbreak patterns and determining the ecological drivers of transmission risk are fundamental to predicting disease spread and assessing potential impacts on population viability. However, evaluating disease in wildlife populations requires expansive surveillance networks that often do not exist in remote and developing areas. Here, we describe the results of a community-based research initiative conducted in collaboration with indigenous harvesters, the Inuit, in response to a new series of Avian Cholera outbreaks affecting Common Eiders (Somateria mollissima) and other comingling species in the Canadian Arctic. Avian Cholera is a virulent disease of birds caused by the bacterium Pasteurella multocida. Common Eiders are a valuable subsistence resource for Inuit, who hunt the birds for meat and visit breeding colonies during the summer to collect eggs and feather down for use in clothing and blankets. We compiled the observations of harvesters about the growing epidemic and with their assistance undertook field investigation of 131 colonies distributed over >1200 km of coastline in the affected region. Thirteen locations were identified where Avian Cholera outbreaks have occurred since 2004. Mortality rates ranged from 1% to 43% of the local breeding population at these locations. Using a species-habitat model (Maxent), we determined that the distribution of outbreak events has not been random within the study area and that colony size, vegetation cover, and a measure of host crowding in shared wetlands were significantly correlated to outbreak risk. In addition, outbrea

Age and breeding stage-related variation in the survival and harvest of temperate-breeding Canada Geese in Ontario

The abundance of Canada geese (Branta canadensis) nesting in temperate regions of North America has increased dramatically during the past half century. Numbers have reached nuisance levels in many areas and supplementary hunting seasons, which are timed to occur before and after traditional waterfowl hunting periods, are widely employed to limit population growth. We evaluated how changes in hunting regulations have affected population growth, the seasonal age distribution of harvest, and survival rates of temperate-breeding Canada geese banded in Ontario. We found that although the number of geese harvested in the province has increased, population growth has not abated. Annual survival rates (S̄) of locally nesting adults (i.e., after-hatch-year geese captured in brood flocks) have declined in association with harvest liberalization (pre-liberalization: S̄ = 0.78 ± 0.06 SE; post-liberalization: S̄ = 0.74 ± 0.04 SE) and we estimated negative process correlation between hunter recovery rates and survival rates within this group (ρ = - 0.24), which is indicative of an additive effect of harvest mortality on total mortality. However, peak harvest has advanced into early September, which is a time when large numbers of molt migrant individuals are present in northern portions of the population's range. Molt migrant flocks are comprised primarily of subadults and adult geese that failed to hatch eggs (i.e., non-reproductive individuals), many of which are unaffiliated with the local breeding population. We found that hunter recovery rates of non-reproductive geese were greater and survival rates were less than those of locally nesting adults; however, process correlation between recovery and survival rates was weakly positive (ρ = 0.09), which indicates that harvest mortality is at least partially compensatory within non-reproductive cohorts. We conclude that current harvest levels are insufficient to halt population growth and that the influence of hunting, relative to its potential, is diminished by a disproportionate take of individuals of low reproductive value during the early hunting season

Longer ice-free seasons increase the risk of nest depredation by polar bears for colonial breeding birds in the Canadian Arctic

Northern polar regions have warmed more than other parts of the globe potentiallyamplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands. In this study, we examined polar bears' use of an ancillary prey resource, eggs of colonial nesting birds, in relation to diminishing sea ice coverage in a low latitude region of the Canadian Arctic. Long-term monitoring reveals that bear incursions onto common eider (Somateria mollissima) and thick-billed murre (Uria lomvia) nesting colonies have increased greater than sevenfold since the 1980s and that there is an inverse correlation between ice season length and bear presence. In surveys encompassing more than 1000 km of coastline during years of record low ice coverage (2010-2012), we encountered bears or bear sign on 34% of eider colonies and estimated greater egg loss as a consequence of depredation by bears than by more customary nest predators, such as foxes and gulls. Our findings demonstrate how changes in abiotic conditions caused by climate change have altered predator-prey dynamics and are leading to cascading ecological impacts in Arctic ecosystems

Injecting epidemiology into population viability analysis: Avian cholera transmission dynamics at an arctic seabird colony

Infectious diseases have the potential to spread rapidly and cause high mortality within populations of immunologically naïve hosts. The recent appearance of avian cholera, a highly virulent disease of birds caused by the bacterium Pasteurella multocida, at remote Arctic seabird colonies is an emerging conservation concern. Determining disease risk to population viability requires a quantitative understanding of transmission potential and the factors that regulate epidemic persistence. Estimates of the basic (R0) and real-time (Rt) reproductive number are critical in this regard - enumerating the number of secondary infections caused by each primary infection in a newly invaded host population and the decline in transmission rate as susceptible individuals are removed via mortality or immunized recovery. Here, we use data collected at a closely monitored common eider (Somateria mollissima) breeding colony located in the Canadian Arctic to examine transmission and host population dynamics. Specifically, we infer epidemic curves from daily mortality observations and use a likelihood-based procedure to estimate changes in the reproductive number over a series of annual outbreaks. These data are interpreted in relation to concurrent changes in host numbers to assess local extinction risk. Consistent with expectations for a novel pathogen invasion, case incidence increased exponentially during the initial wave of exposure (R0 = 2·5; generation time = 6·5 days ± 1·1 SD). Disease conditions gradually abated, but only after several years of smouldering infection (Rt ≈ 1). In total, 6194 eider deaths were recorded during outbreaks spanning eight consecutive breeding seasons. Breeding pair abundance declined by 56% from the pre-outbreak peak; however, a robust population of >4000 pairs remained intact upon epidemic fade-out. Overall, outbreak patterns were consistent with herd immunity acting as a mitigating factor governing in the extent and duration of mortality. Disease mortality is frequently modelled as a form of stochastic catastrophe in wildlife population assessments, whereas our approach gives shape to the functional response between transmission and host population dynamics. We conclude that increased emphasis on

Sex-specific survival of adult common eiders in Nova Scotia, Canada

Common eiders (Somateria mollissima) are large sea ducks with a circumpolar distribution and have high cultural significance to sport hunters and indigenous peoples in many countries. Their gregarious habits, including colonial breeding and forming large flocks during migration and winter, make eiders susceptible to environmental stressors during breeding and non-breeding seasons. Our objective was to assess whether low adult survivorship could be contributing to suspected local population declines in Nova Scotia, Canada. We banded molting male and breeding female common eiders along the marine coastline of Nova Scotia and recaptured them in later years. We found that from 1997 to 2011, when males and females were banded, male survival (S) was high (S = 0.92; 95% CI = 0.87–0.95), whereas female survival was approximately 10% lower (S = 0.83; 95% CI = 0.78–0.87) and at a level comparable to what has been reported in other regions of the world where eider populations are thought to be in decline. Recovery rates (f) of harvested male and female eiders were indistinguishable (f = 0.013; 95% CI = 0.010–0.016), suggesting that lower female survival is attributable to factors other than hunting. Supplementary analyses using a longer-term data set for females only (1978–2011) and including live recapture data indicated that female survival rates have not changed markedly during the past 40 years and that the emigration rate from colonies is low (∼6%). We conclude that to successfully conserve this population, sources of non-harvest female mortality should be investigated and used to develop targeted management solutions. We speculate that one of those sources of mortality is predation on females at breeding colonies, notably from eagles and mustelids. © 2016 The Wildlife Society

Multicentury perspective assessing the sustainability of the historical harvest of seaducks

Where available, census data on seabirds often do not extend beyond a few years or decades, challenging our ability to identify drivers of population change and to develop conservation policies. Here, we reconstruct long-term population dynamics of northern common eiders (Somateria mollissima borealis). We analyzed sterols together with stable nitrogen isotopes in dated pond sediment cores to show that eiders underwent broadscale population declines over the 20th century at Canadian subarctic breeding sites. Likely, a rapidly growing Greenland population, combined with relocation of Inuit to larger Arctic communities and associated increases in the availability of firearms and motors during the early to mid-20th century, generated more efficient hunting practices, which in turn reduced the number of adult eiders breeding at Canadian nesting islands. Our paleolimnological approach highlights that current and local monitoring windows for many sensitive seabird species may be inadequate for making key conservation decisions

The BaBar detector: Upgrades, operation and performance

Contains fulltext : 121729.pdf (preprint version ) (Open Access