Wintering Behavior, Physiology and Site Fidelity in a Partial Migrant, the American Dipper (<i>Cinclus mexicanus</i>)

Whitehorne, Ivy

doi:10.1675/063.033.0405

Cited by 8 publications

(10 citation statements)

References 46 publications

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“…We demonstrated that residents, all of whom attempted to breed, consistently had higher productivity than migrants [ 28 ]. We also found no difference in the physiological state of residents and migrants [ 41 ]; physiological state was assessed in the winter using size-corrected mass, hematocrit, leucocrit, total white blood cell count and heterophil to lymphocyte ratio, immunoglobulin, triglyceride and free glycerol levels, total antioxidant capacity and total oxidative status of plasma. However, we estimated that the annual apparent survival of residents was slightly, but not significantly higher, than the annual apparent survival of migrants [ 28 ].…”

Section: Discussionmentioning

confidence: 98%

“…Alternatively, we may have estimated the apparent survival of migrants and residents to be equal even though the true survival of migrants is higher than the true survival of residents because migrants have lower over-winter site fidelity and are more likely to leave the study area permanently. We have shown that over the course of a single winter the site fidelity of migrants is lower than that of residents [ 41 ]. However, we have rarely observed overwintering dippers to use more than one of our eight low elevation study sites even though they are only separated by 3–40 km.…”

Section: Discussionmentioning

confidence: 99%

“…However, we have rarely observed overwintering dippers to use more than one of our eight low elevation study sites even though they are only separated by 3–40 km. Whitehorne [ 41 ] observed 4 migrants and 2 residents (total n = 87 banded birds) at more than one site during the winter of 2006/2007, but none of these birds left their primary winter site permanently. We observed 2 migrants and 1 resident (total n = 260) at two sites during winter censuses conducted in November, January and March from 1999–2009; two birds returned to their original site of capture and one migrant changed wintering locations.…”

Section: Discussionmentioning

confidence: 99%

“…Residents in contrast occupy a multi-purpose territory year round. Male and female residents defend their territory and exclude conspecifics during the breeding season, but are less aggressive in the winter when they tolerate the presence of conspecifics in some parts of their territory [ 41 ]. We have also demonstrated that migrants and residents rarely switch migratory strategies [ 28 ], and both migrants and residents exhibit high levels of fidelity to their breeding and wintering territories [ 41 , 42 ].…”

Section: Methodsmentioning

confidence: 99%

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Do American Dippers Obtain a Survival Benefit from Altitudinal Migration?

et al. 2015

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Studies of partial migrants provide an opportunity to assess the cost and benefits of migration. Previous work has demonstrated that sedentary American dippers (residents) have higher annual productivity than altitudinal migrants that move to higher elevations to breed. Here we use a ten-year (30 period) mark-recapture dataset to evaluate whether migrants offset their lower productivity with higher survival during the migration-breeding period when they occupy different habitat, or early and late-winter periods when they coexist with residents. Mark-recapture models provide no evidence that apparent monthly survival of migrants is higher than that of residents at any time of the year. The best-supported model suggests that monthly survival is higher in the migration-breeding period than winter periods. Another well-supported model suggested that residency conferred a survival benefit, and annual apparent survival (calculated from model weighted monthly apparent survival estimates using the Delta method) of residents (0.511 ± 0.038SE) was slightly higher than that of migrants (0.487 ± 0.032). Winter survival of American dippers was influenced by environmental conditions; monthly apparent survival increased as maximum daily flow rates increased and declined as winter temperatures became colder. However, we found no evidence that environmental conditions altered differences in winter survival of residents and migrants. Since migratory American dippers have lower productivity and slightly lower survival than residents our data suggests that partial migration is likely an outcome of competition for limited nest sites at low elevations, with less competitive individuals being forced to migrate to higher elevations in order to breed.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Do American Dippers Obtain a Survival Benefit from Altitudinal Migration?

et al. 2015

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“…Although some dipper populations exhibit seasonal altitudinal migration within a watershed , these birds are year‐round residents on fast‐flowing coastal mountain streams targeted for run‐of‐river dams, and both residents and altitudinal migrants exhibit high site fidelity to breeding and wintering territories . American dippers are less territorial during the fall and winter compared with the breeding season, but they are frequently sighted in the same kilometer‐long stream reach during these seasons . With their high site fidelity and foraging behavior that is strongly tied to streamflow variation , dippers have been successfully used as indicators of local stream quality and contaminant exposure .…”

Section: Introductionmentioning

confidence: 99%

Impact of flow diversion by run‐of‐river dams on American dipper diet and mercury exposure

Silverthorn

Bishop

Jardine

et al. 2017

Enviro Toxic and Chemistry

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Run-of-river dams produce lower greenhouse gas emissions than large hydropower projects, but there is a paucity of research on their potential ecotoxicological impacts through disruption of natural flow regimes. We used stable isotopes (δ C, δ N, δ S) to reconstruct diet and trace methylmercury in a predatory river-resident passerine, the American dipper (Cinclus mexicanus), at 7 regulated and 6 free-flowing mountain streams in coastal British Columbia, Canada. Assimilated diets were comparable among regulated and unregulated streams, dominated by benthic macroinvertebrates and resident freshwater fish, with negligible contributions from anadromous Pacific salmon. Although invertebrates at unregulated streams were isotopically similar along their gradient, dippers and invertebrates sampled below dams on regulated streams had S-depleted tissues, suggesting increased activity of sulfate-reducing bacteria and more Hg methylation below the dams. Mercury concentrations in dipper blood (417.6 ± 74.1 standard error [SE] ng/g wet wt at regulated streams, 340.7 ± 42.7 SE ng/g wet wt at unregulated streams) and feathers (1564 .6 ± 367.2 SE ng/g dry wt regulated, 1149.0 ± 152.1 SE ng/g dry wt unregulated), however, were not significantly different between stream types. Relative to other passerines across western North America, dippers in these densely forested mountain streams experienced high mercury exposure; and one recently regulated stream supported dippers with mercury concentrations of potential toxicity concern (up to 8459.5 ng/g dry wt in feathers and 1824.6 ng/g wet wt in whole blood). Elevated mercury in dippers is likely attributable to the birds' relatively high trophic position and high regional inorganic mercury deposition; however, biogeochemical conditions in reservoirs of some regulated streams may be contributing to methylmercury production. Environ Toxicol Chem 2018;37:411-426. © 2017 SETAC.

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Relationship between salmon egg subsidy and the distribution of an avian predator

Yamada

Katahira

Miura

et al. 2022

Ecology and Evolution

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As a spatial subsidy, which is the phenomenon of transferring resources from a donor system to a recipient system, anadromous salmonids contribute to the supply of marine‐derived nutrients to freshwater and terrestrial systems. Live salmon and salmon carcasses and eggs are utilized by various organisms and affect their abundance and distribution. However, the evaluation of the effect of salmon subsidies on the abundance and distribution of terrestrial animals is biased toward predators or scavengers that utilize spawning adults and carcasses, and few studies have focused on the effect of salmon eggs as a subsidy. To avoid underestimating the function of salmon subsidies, the response to the availability of salmon eggs in various systems should be investigated. Here, we investigated the abundance and feeding behavior of the brown dipper Cinclus pallasii, as a consumer of salmon eggs, based on the hypothesis that the availability of salmon eggs affects the diet composition and stream distribution of this small predator. In addition, to test whether changes in the abundance of brown dippers are determined by salmon spawning, their abundance was compared upstream and downstream of the check dams in three streams during the peak spawning period. Brown dippers used salmon eggs during the spawning season (53.7% of diet composition), and their abundance increased as the number of spawning redds increased. In contrast, this pattern was not observed upstream of the check dam. These results suggested that the abundance and stream distribution of brown dippers vary according to the variation in the spatiotemporal availability of salmon eggs.

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Wintering Behavior, Physiology and Site Fidelity in a Partial Migrant, the American Dipper (Cinclus mexicanus)

Cited by 8 publications

References 46 publications

Do American Dippers Obtain a Survival Benefit from Altitudinal Migration?

Do American Dippers Obtain a Survival Benefit from Altitudinal Migration?

Impact of flow diversion by run‐of‐river dams on American dipper diet and mercury exposure

Relationship between salmon egg subsidy and the distribution of an avian predator

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