Survival of Barrow's goldeneyes during remigial molt and fall staging

Hogan, Danica; Thompson, Jonathan E.; Esler, Daniel

doi:10.1002/jwmg.507

Cited by 9 publications

(12 citation statements)

References 52 publications

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“…spawning along the Pacific coast, which may provide potential scoter predators, such as bald eagles ( Haliaeetus leucocephalus ), with an alternative food source. We observed low rates of predation during this period of the annual cycle, consistent with other studies of molting sea ducks (Iverson and Esler , Hogan et al ). Collectively, these studies suggest that potential costs associated with the flightless molt period are likely low.…”

Section: Discussionsupporting

confidence: 92%

“…The high molting survival rates that we documented are consistent with high survival rates described for other species of sea ducks during remigial molt (Iverson and Esler , Hogan et al ). Scoter survival rates during molt were higher than those found for dabbling ducks (Bowman and Longcore , Miller et al , Fleskes et al ).…”

Section: Discussionsupporting

confidence: 91%

“…Documenting such patterns is critical for directing effective conservation (Lebreton et al ). Remigial molt survival has been found to be high for other sea duck species (Iverson and Esler , Hogan et al ). Because survival of scoters during remigial molt has never been documented, it is unknown whether they follow the same pattern or how variation in vital rates during remigial molt might affect population trajectories.…”

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confidence: 99%

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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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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%

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

et al. 2014

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“…Possible explanations for this difference in foraging behavior are that (1) the perceived risk from diurnal predators was higher on Leddy, causing birds to be more vigilant on Leddy Lake during the day and leaving less time for foraging (Evans and Day 2001); and/or (2) daily activity patterns of prey organisms differed between lakes, with Leddy Lake prey being more available at night. Survival of molting birds on both Cardinal and Leddy lakes was high (0.95; Hogan et al 2013) and avian predators were rarely observed on either lake during remigial molt (D. Hogan pers. obs.).…”

Section: Discussionmentioning

confidence: 97%

Variation in body mass and foraging effort of Barrow’s Goldeneyes (Bucephala islandica) during remigial molt

Hogan

Esler

Thompson

2013

The Auk

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Molt is a metabolically demanding process in the annual cycle of birds, particularly for species that undergo simultaneous remigial molt because nutritional and energetic costs occur during a short period. Birds that molt remiges simultaneously utilize many different body-mass and foraging strategies to meet the nutritional and energetic costs of remigial molt, and documentation of interspecific variation has contributed to understanding species-specific risks associated with molt. However, little is known about intraspecific variation in body-mass and foraging strategies among birds that molt remiges simultaneously. We documented body-mass dynamics and foraging effort of Barrow's Goldeneyes {Bucephala islándica) during simultaneous remigial molt at two important postbreeding sites, including a large, hypereuthrophic lake and a small, mesotrophic lake in Alberta, to determine whether strategies for meeting nutritional costs of remigial molt varied across sites, years, and cohorts. Average body mass of all age and sex cohorts on both lakes increased during remigial molt in both 2009 and 2010. Birds were heavier on the smaller lake, and heavier in 2010 than in 2009, and adult males were heavier than subadult males. Radiomarked adult males exhibited similar foraging effort on each lake in each year (approximately 120-140 min day"'); however, birds foraged primarily diurnally on the large lake and nocturnally on the small lake. We conclude that Barrow's Goldeneyes exhibit considerable intraspecific variation in body-mass and foraging dynamics during remigial molt across sites, years, and cohorts, which suggests that these components of molt strategy are plastic and responsive to local environmental conditions. Variation de la masse corporelle et de l'effort d'alimentation de Bucephala islándica lors de la mue des rémiges RÉSUMÉ.-La mue est un processus du cycle annuel des oiseaux qui est exigeant sur le plan métabolique, particulièrement chez les espèces qui subissent une mue simultanée des rémiges car les coûts nutritionnels et énergétiques se produisent sur une courte période. Les oiseaux dont les rémiges muent simultanément utilisent diverses stratégies de masse corporelle et alimentaires afin d'assumer les coûts nutritionnels et énergétiques de la mue des rémiges. La documentation sur la variation interspécifique a contribué à la compréhension des risques spécifiques associés à la mue. Toutefois, on en sait peu sur la variation intraspécifique de la masse corporelle et les stratégies alimentaires chez les oiseaux qui subissent une mue simultanée des rémiges. Nous avons documenté la dynamique de la masse corporelle et l'effort d'alimentation de Bucephala islándica au cours de la mue simultanée des rémiges à deux importants sites de mue postnuptiale, soit un grand lac hypereuthrophe et un petit lac mésotrophe en Alberta, afin de déterminer si les stratégies pour assumer les coûts nutritionnels de la mue des rémiges varient entre les sites, les années et les cohortes. La masse corporelle moyenne de toutes les cohort...

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“…Our survival analyses were limited to surf scoters because we detected no mortalities of white‐winged scoters during molt (Uher‐Koch et al ), and we marked only surf scoters during winter. Previous research from sea ducks has shown that mortalities from capture, handling, and radio attachment are most likely to occur within the first 14 days (Esler et al , Hogan et al ). Accordingly, our first survival analysis was restricted to the initial 14 days following attachment of radiotransmitters, with separate analyses for molt and winter periods.…”

Section: Methodsmentioning

confidence: 99%

Attaching transmitters to waterbirds using one versus two subcutaneous anchors: Retention and survival trade‐offs

et al. 2017

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A major challenge of wildlife telemetry is choosing an attachment technique that maximizes transmitter retention while minimizing negative side effects. For waterbirds, attachment of transmitters with subcutaneous anchors has been an effective and well-established technique, having been used on >40 species. This method was recently modified to include a second subcutaneous anchor, presumably increasing transmitter retention beyond that of single-anchor attachments. This putative benefit may be offset, however, by increased health risks related to additional incisions and subcutaneous protrusions. To test this potential trade-off, we attached radiotransmitters to molting and wintering surf (Melanitta perspicillata) and whitewinged scoters (M. fusca) during 2008 and 2009 in Washington State and southeast Alaska, USA, using single-(121 scoters) and double-anchor (128 scoters) attachment techniques. We estimated daily probabilities of survival and radio retention for each group, this being apparent retention for wintering scoters because we could not differentiate shed transmitters from flighted emigration. For scoters during the flightless remigial molt, we found that addition of a second anchor increased cumulative retention probability (AESE) over a 49-day period from 0.69 AE 0.11 for single-anchor to 0.88 AE 0.07 for double-anchor attachments, while having no effect on survival. However, during winter, scoters with double-anchor attachments experienced no improvement in apparent retention, while having significantly lower survival during their first 14 days following transmitter attachment; of 15 mortalities during this period, 11 had 2 subcutaneous anchors. From day 15 onward, winter survival rates were nearly identical for single-versus double-anchor attachments, indicating that adverse effects of subcutaneous anchors were mainly limited to the 14-day postattachment period. Overall, given that the survival cost of adding a second subcutaneous anchor was substantial for wintering scoters-decreasing 14-day survival by 12% for adults and 23% for juveniles-we recommend that researchers opt for single-anchor attachments under most circumstances, especially during winter when birds may be energetically challenged. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

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Survival of Barrow's goldeneyes during remigial molt and fall staging

Cited by 9 publications

References 52 publications

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

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

Variation in body mass and foraging effort of Barrow’s Goldeneyes (Bucephala islandica) during remigial molt

Attaching transmitters to waterbirds using one versus two subcutaneous anchors: Retention and survival trade‐offs

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