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Browsing by Author "Lank, David B."

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    Delayed egg-laying and shortened incubation duration of Arctic-breeding shorebirds coincide with climate cooling
    Kwon, Eunbi; English, Willow B.; Weiser, Emily L.; Franks, Samantha E.; Hodkinson, David J.; Lank, David B.; Sandercock, Brett K. (Wiley, 2017)
    Biological impacts of climate change are exemplified by shifts in phenology. As the timing of breeding advances, the within-season relationships between timing of breeding and reproductive traits may change and cause long-term changes in the population mean value of reproductive traits. We investigated long-term changes in the timing of breeding and within-season patterns of clutch size, egg volume, incubation duration, and daily nest survival of three shorebird species between two decades. Based on previously known within-season patterns and assuming a warming trend, we hypothesized that the timing of clutch initiation would advance between decades and would be coupled with increases in mean clutch size, egg volume, and daily nest survival rate. We monitored 1,378 nests of western sandpipers, semipalmated sandpipers, and red-necked phalaropes at a subarctic site during 1993–1996 and 2010–2014. Sandpipers have biparental incubation, whereas phalaropes have uniparental incubation. We found an unexpected long-term cooling trend during the early part of the breeding season. Three species delayed clutch initiation by 5 days in the 2010s relative to the 1990s. Clutch size and daily nest survival showed strong within-season declines in sandpipers, but not in phalaropes. Egg volume showed strong within-season declines in one species of sandpiper, but increased in phalaropes. Despite the within-season patterns in traits and shifts in phenology, clutch size, egg volume, and daily nest survival were similar between decades. In contrast, incubation duration did not show within-season variation, but decreased by 2 days in sandpipers and increased by 2 days in phalaropes. Shorebirds demonstrated variable breeding phenology and incubation duration in relation to climate cooling, but little change in nonphenological components of traits. Our results indicate that the breeding phenology of shorebirds is closely associated with the temperature conditions on breeding ground, the effects of which can vary among reproductive traits and among sympatric species.
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    Effects of environmental conditions on reproductive effort and nest success of Arctic-breeding shorebirds
    Weiser, Emily L.; Brown, Stephen C.; Lanctot, Richard B.; Gates, H. River; Abraham, Kenneth F.; Bentzen, Rebecca L.; Bety, Joel; Boldenow, Megan L.; Brook, Rodney W.; Donnelly, Tyrone F.; English, Willow B.; Flemming, Scott A.; Franks, Samantha E.; Gilchrist, H. Grant; Giroux, Marie-Andree; Johnson, Andrew; Kendall, Steven J.; Kennedy, Lisa V.; Koloski, Laura; Kwon, Eunbi; Lamarre, Jean-Francois; Lank, David B.; Latty, Christopher J.; Lecomte, Nicolas; Liebezeit, Joseph R.; McKinnon, Laura; Nol, Erica; Perz, Johanna; Rausch, Jennie; Robards, Martin; Saalfeld, Sarah T.; Senner, Nathan R.; Smith, Paul A.; Soloviev, Mikhail; Solovyeva, Diana; Ward, David H.; Woodard, Paul F.; Sandercock, Brett K. (2018-07)
    The Arctic is experiencing rapidly warming conditions, increasing predator abundance, and diminishing population cycles of keystone species such as lemmings. However, it is still not known how many Arctic animals will respond to a changing climate with altered trophic interactions. We studied clutch size, incubation duration and nest survival of 17 taxa of Arctic-breeding shorebirds at 16 field sites over 7years. We predicted that physiological benefits of higher temperatures and earlier snowmelt would increase reproductive effort and nest survival, and we expected increasing predator abundance and decreasing abundance of alternative prey (arvicoline rodents) to have a negative effect on reproduction. Although we observed wide ranges of conditions during our study, we found no effects of covariates on reproductive traits in 12 of 17 taxa. In the remaining taxa, most relationships agreed with our predictions. Earlier snowmelt increased the probability of laying a full clutch from 0.61 to 0.91 for Western Sandpipers, and shortened incubation by 1.42days for arcticola Dunlin and 0.77days for Red Phalaropes. Higher temperatures increased the probability of a full clutch from 0.60 to 0.93 for Western Sandpipers and from 0.76 to 0.97 for Red-necked Phalaropes, and increased daily nest survival rates from 0.9634 to 0.9890 for Semipalmated Sandpipers and 0.9546 to 0.9880 for Western Sandpipers. Higher abundance of predators (foxes) reduced daily nest survival rates only in Western Sandpipers (0.9821-0.9031). In contrast to our predictions, the probability of a full clutch was lowest (0.83) for Semipalmated Sandpipers at moderate abundance of alternative prey, rather than low abundance (0.90). Our findings suggest that in the short-term, climate warming may have neutral or positive effects on the nesting cycle of most Arctic-breeding shorebirds.
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    Effects of leg flags on nest survival of four species of Arctic-breeding shorebirds
    Weiser, Emily L.; Lanctot, Richard B.; Brown, Stephen C.; Gates, H. River; Bentzen, Rebecca L.; Boldenow, Megan L.; Cunningham, Jenny A.; Doll, Andrew C.; Donnelly, Tyrone F.; English, Willow B.; Franks, Samantha E.; Grond, Kirsten; Herzog, Patrick; Hill, Brooke L.; Kendall, Steven J.; Kwon, Eunbi; Lank, David B.; Liebezeit, Joseph R.; Rausch, Jennie; Saalfeld, Sarah T.; Taylor, Audrey R.; Ward, David H.; Woodard, Paul F.; Sandercock, Brett K. (2018-09)
    Marking wild birds is an integral part of many field studies. However, if marks affect the vital rates or behavior of marked individuals, any conclusions reached by a study might be biased relative to the general population. Leg bands have rarely been found to have negative effects on birds and are frequently used to mark individuals. Leg flags, which are larger, heavier, and might produce more drag than bands, are commonly used on shorebirds and can help improve resighting rates. However, no one to date has assessed the possible effects of leg flags on the demographic performance of shorebirds. At seven sites in Arctic Alaska and western Canada, we marked individuals and monitored nest survival of four species of Arctic-breeding shorebirds, including Semipalmated Sandpipers (Calidris pusilla), Western Sandpipers (C. mauri), Red-necked Phalaropes (Phalarope lobatus), and Red Phalaropes (P. fielicarius). We used a daily nest survival model in a Bayesian framework to test for effects of leg flags, relative to birds with only bands, on daily survival rates of 1952 nests. We found no evidence of a difference in nest survival between birds with flags and those with only bands. Our results suggest, therefore, that leg flags have little effect on the nest success of Arctic-breeding sandpipers and phalaropes. Additional studies are needed, however, to evaluate the possible effects of flags on shorebirds that use other habitats and on survival rates of adults and chicks.