Predation rates, timing, and predator composition for Scoters (<i>Melanitta</i>spp.) in marine habitats

Anderson, Eric M.; Esler, Daniel; Boyd, W. Sean; Evenson, Joseph R.; Nysewander, David R.; Ward, David H.; Dickson, Rian D.; Uher‐Koch, Brian D.; VanStratt, Corey S.; Hupp, Jerry W.

doi:10.1139/z11-110

Cited by 10 publications

(10 citation statements)

References 33 publications

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“…that died within 14 days of release. Certainly, the environmental factors that a marked bird encounters following release are unique to the species and the release site (e.g., predators; Anderson et al ). Furthermore, conditions such as weather or predator density that are likely to influence survival may be more or less important in a particular season or year, contributing substantial intra‐ and interannual variation in effect and creating a moving target for biologists attempting to minimize mortalities associated with these factors.…”

Section: Discussionmentioning

confidence: 99%

“…Mulcahy and Esler () and Esler et al () described the immediate post‐release period (14 days) as the duration when telemetry data were most likely influenced by side effects of deployment (i.e., capture, holding, surgery). Subsequently, several telemetry studies have considered or implemented a 14‐day censoring period prior to data analysis (e.g., Hupp et al , ; Iverson et al ; Mulcahy et al ; Anderson et al ).…”

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confidence: 99%

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Factors influencing immediate post-release survival of spectacled eiders following surgical implantation of transmitters with percutaneous antennae

Sexson

Mulcahy

Spriggs³

et al. 2014

Jour. Wild. Mgmt.

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Surgically implanted transmitters are a common method for tracking animal movements. Immediately following surgical implantation, animals pass through a critical recovery phase when behaviors may deviate from normal and the likelihood of individual survival may be reduced. Therefore, data collected during this period may be censored to minimize bias introduced by surgery‐related behaviors or mortality. However, immediate post‐release mortalities negate a sampling effort and reduce the amount of data potentially collected after the censoring period. Wildlife biologists should employ methods to support an animal's survival through this period, but factors contributing to immediate post‐release survival have not been formally assessed. We evaluated factors that potentially influenced the immediate post‐release survival of 56 spectacled eiders (Somateria fischeri) marked with coelomically implanted satellite transmitters with percutaneous antennae in northern Alaska in 2010 and 2011. We modeled survival through the first 14 days following release and assessed the relative importance and effect of 15 covariates hypothesized to influence survival during this immediate post‐release period. Estimated daily survival rate increased over the duration of the immediate post‐release period; the probability of mortality was greatest within the first 5 days following release. Our top‐ranking model included the effect of 2 blood analytes, pH and hematocrit, measured prior to surgical implantation of a transmitter. We found a positive response to pH; eiders exhibiting acidemia (low pH) prior to surgery were less likely to survive the immediate post‐release period. We found a curvilinear response to hematocrit; eiders exhibiting extremely low or high pre‐surgery hematocrit were also less likely to survive the immediate post‐release period. In the interest of maximizing the survival of marked birds following release, hematological data obtained prior to surgical implantation of telemetry equipment may be useful when screening for optimal surgical candidates or informing appropriate response to mitigate potentially deleterious disorders such as acidemia. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Factors influencing immediate post-release survival of spectacled eiders following surgical implantation of transmitters with percutaneous antennae

Sexson

Mulcahy

Spriggs³

et al. 2014

Jour. Wild. Mgmt.

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“…Combined with a mobile substrate of sand or a sand-gravel mixture, these conditions result in a frequently changing benthic foraging habitat. At Dogfish Banks, there is virtually no presence of bald eagles (Haliaeetus leucocephalus), which are the most likely predator of white-winged scoters (Anderson et al 2012). Relative to other study sites, Dogfish Banks birds feed on a more diverse suite of prey (Palm et al 2012).…”

Section: Study Sitesmentioning

confidence: 99%

Baseline Corticosterone in Wintering Marine Birds: Methodological Considerations and Ecological Patterns

Palm¹,

Esler²,

Anderson³

et al. 2013

Physiological and Biochemical Zoology

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Previous studies have related levels of plasma corticosterone (CORT) of seabirds to variation in foraging conditions during the breeding period, but it is unclear whether similar relationships between foraging conditions and baseline CORT exist during other life stages. We validated methods for identifying baseline CORT of lethally sampled birds and assessed variation in baseline CORT relative to winter habitat conditions. We collected free-living white-winged scoters (Melanitta fusca) at four wintering sites during December and February. We found increasing CORT values beyond 3 min after time since flush (the duration between initial flush and death), presumably reflecting acute stress responses. Our results demonstrate that it is possible to obtain baseline CORT from lethally sampled birds if the time from initial flush until death is measured. Our study sites varied appreciably in exposure to wind and waves, predation danger, diving depths, and the fraction of preferred foods in scoter diets. Despite these habitat differences, baseline CORT did not vary across sites or winter periods. We interpret this lack of variation as evidence that birds select wintering areas where they can successfully manage site-specific costs and maintain physiological homeostasis.

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“…Constant molt survival found in this study contrasted with findings related to surf scoter winter survival, which varied between geographic location, period of winter, age and sex class, and mass (Uher‐Koch ). Lower winter scoter survival does not seem to be related to prey depletion (lower mid‐winter survival than late winter; Uher‐Koch ) but could be a potential predator response (Anderson et al ), or associated with the harsher winter conditions.…”

Section: Discussionmentioning

confidence: 98%

Survival of surf scoters and white-winged scoters during remigial molt

et al. 2014

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Quantifying sources and timing of variation in demographic rates is necessary to determine where and when constraints may exist within the annual cycle of organisms. Surf scoters (Melanitta perspicillata) and white‐winged scoters (M. fusca) undergo simultaneous remigial molt during which they are flightless for >1 month. Molt could result in reduced survival due to increased predation risk or increased energetic demands associated with regrowing flight feathers. Waterfowl survival during remigial molt varies across species, and has rarely been assessed for sea ducks. To quantify survival during remigial molt, we deployed very high frequency (VHF) transmitters on surf scoters (n = 108) and white‐winged scoters (n = 57) in southeast Alaska and the Salish Sea (British Columbia and Washington) in 2008 and 2009. After censoring mortalities potentially related to capture and handling effects, we detected no mortalities during remigial molt; thus, estimates of daily and period survival for both scoter species during molt were 1.00. We performed sensitivity analyses in which mortalities were added to the dataset to simulate potential mortality rates for the population and then estimated the probability of obtaining a dataset with 0 mortalities. We found that only at high survival rates was there a high probability of observing 0 mortalities. We conclude that remigial molt is normally a period of low mortality in the annual cycle of scoters. The molt period does not appear to be a constraint on scoter populations; therefore, other annual cycle stages should be targeted by research and management efforts to change population trajectories. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

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Predation rates, timing, and predator composition for Scoters (Melanittaspp.) in marine habitats

Cited by 10 publications

References 33 publications

Factors influencing immediate post-release survival of spectacled eiders following surgical implantation of transmitters with percutaneous antennae

Factors influencing immediate post-release survival of spectacled eiders following surgical implantation of transmitters with percutaneous antennae

Baseline Corticosterone in Wintering Marine Birds: Methodological Considerations and Ecological Patterns

Survival of surf scoters and white-winged scoters during remigial molt

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