Browsing by Author "Brown, Stephen C."

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    Composition and Drivers of Gut Microbial Communities in Arctic-Breeding Shorebirds
    Grond, Kirsten; Santo Domingo, Jorge W.; Lanctot, Richard B.; Jumpponen, Ari; Bentzen, Rebecca L.; Boldenow, Megan L.; Brown, Stephen C.; Casler, Bruce; Cunningham, Jenny A.; Doll, Andrew C.; Freeman, Scott; Hill, Brooke L.; Kendall, Steven J.; Kwon, Eunbi; Liebezeit, Joseph R.; Pirie-Dominix, Lisa; Rausch, Jennie; Sandercock, Brett K. (2019-10-09)
    Gut microbiota can have important effects on host health, but explanatory factors and pathways that determine gut microbial composition can differ among host lineages. In mammals, host phylogeny is one of the main drivers of gut microbiota, a result of vertical transfer of microbiota during birth. In birds, it is less clear what the drivers might be, but both phylogeny and environmental factors may play a role. We investigated host and environmental factors that underlie variation in gut microbiota composition in eight species of migratory shorebirds. We characterized bacterial communities from 375 fecal samples collected from adults of eight shorebird species captured at a network of nine breeding sites in the Arctic and sub-Arctic ecoregions of North America, by sequencing the V4 region of the bacterial 16S ribosomal RNA gene. Firmicutes (55.4%), Proteobacteria (13.8%), Fusobacteria (10.2%), and Bacteroidetes (8.1%) dominated the gut microbiota of adult shorebirds. Breeding location was the main driver of variation in gut microbiota of breeding shorebirds (R-2 = 11.6%), followed by shorebird host species (R-2 = 1.8%), and sampling year (R-2 = 0.9%), but most variation remained unexplained. Site variation resulted from differences in the core bacterial taxa, whereas rare, lowabundance bacteria drove host species variation. Our study is the first to highlight a greater importance of local environment than phylogeny as a driver of gut microbiota composition in wild, migratory birds under natural conditions.
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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.