Results from Banding Glaucous-Winged Gulls: In the Northern Gulf of Georgia, B.C., from 1922 to 1949

Pearse, Theed

doi:10.2307/4510974

Cited by 2 publications

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“…Figure 3 shows the numbers of birds found belong- but Pearse (1963) found only 57% of 100 band recoveries of Glaucous-winged Gulls were in their first year, which is much closer to our figures.…”

Section: Resultssupporting

confidence: 86%

“…The dispersal pattern of small numbers of Glaucous-winged Gulls (Larus glaucescens) banded as chicks in British Columbia have been reported previously. Pearse (1923Pearse ( , 1963 found that birds of all age classes wintered in the vicinity of their nesting colony, although a few first-year gulls moved up to 2080 km. Sprot (1937) reported that most immature gulls remained within 96 km of their natal colony, but because of small samples he could provide no insight into adult dispersal.…”

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confidence: 99%

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Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia

Butler,

Verbeek,

Foottit

1980

The Canadian Field-Naturalist

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Recoveries of 1002 Glaucous-winged Gulls (Larus glaucescens) banded as chicks in 11 breeding colonies in British Columbia from 1963 to 1977 were analyzed. First-year (0-1 yr old) gulls died mainly between September and November; second-year gulls (1-2 yr old) showed a similar but less pronounced trend; but relatively more adults (4+ yr old) died during the late summer. Mortality rate estimates of first year gulls were between 57.9% (based on percent of bands recovered) and 59.2% (based on life table data). Glaucous-winged Gulls mostly dispersed in a southerly direction from the breeding colonies. Although individual first-year gulls dispersed farther (up to 2050 km) than older age classes, the mean dispersal distance between age classes showed little difference.

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Section: Resultssupporting

confidence: 86%

mentioning

confidence: 99%

Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia

Butler,

Verbeek,

Foottit

1980

The Canadian Field-Naturalist

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“…This area includes all present-day colonies larger than 10s of pairs within the region, but excludes the more westerly colonies where diet is likely to have been influenced by the offshore marine conditions of the Pacific Ocean. Banding and telemetry data show that most glaucous-winged gulls breeding in the Salish Sea remain in or near the area year-round and that dispersal from natal to breeding sites is local (Pearse 1963;Butler et al, 1980;Reid, 1988;J. Elliott, unpublished data), and thus these birds primarily represent a single oceanographic region.…”

Section: Study Areamentioning

confidence: 99%

Changing gull diet in a changing world: A 150‐year stable isotope (δ¹³C,δ¹⁵N) record from feathers collected in the Pacific Northwest of North America

Blight

Hobson

Kyser

et al. 2014

Global Change Biology

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The world's oceans have undergone significant ecological changes following European colonial expansion and associated industrialization. Seabirds are useful indicators of marine food web structure and can be used to track multidecadal environmental change, potentially reflecting long-term human impacts. We used stable isotope (δ(13)C, δ(15)N) analysis of feathers from glaucous-winged gulls (Larus glaucescens) in a heavily disturbed region of the northeast Pacific to ask whether diets of this generalist forager changed in response to shifts in food availability over 150 years, and whether any detected change might explain long-term trends in gull abundance. Sampled feathers came from birds collected between 1860 and 2009 at nesting colonies in the Salish Sea, a transboundary marine system adjacent to Washington, USA and British Columbia, Canada. To determine whether temporal trends in stable isotope ratios might simply reflect changes to baseline environmental values, we also analysed muscle tissue from forage fishes collected in the same region over a multidecadal timeframe. Values of δ(13)C and δ(15)N declined since 1860 in both subadult and adult gulls (δ(13)C, ~ 2-6‰; δ(15)N, ~4-5‰), indicating that their diet has become less marine over time, and that birds now feed at a lower trophic level than previously. Conversely, forage fish δ(13)C and δ(15)N values showed no trends, supporting our conclusion that gull feather values were indicative of declines in marine food availability rather than of baseline environmental change. Gradual declines in feather isotope values are consistent with trends predicted had gulls consumed less fish over time, but were equivocal with respect to whether gulls had switched to a more garbage-based diet, or one comprising marine invertebrates. Nevertheless, our results suggest a long-term decrease in diet quality linked to declining fish abundance or other anthropogenic influences, and may help to explain regional population declines in this species and other piscivores.

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Results from Banding Glaucous-Winged Gulls: In the Northern Gulf of Georgia, B.C., from 1922 to 1949

Cited by 2 publications

References 0 publications

Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia

Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia

Changing gull diet in a changing world: A 150‐year stable isotope (δ¹³C,δ¹⁵N) record from feathers collected in the Pacific Northwest of North America

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Results from Banding Glaucous-Winged Gulls: In the Northern Gulf of Georgia, B.C., from 1922 to 1949

Cited by 2 publications

References 0 publications

Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia

Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia

Changing gull diet in a changing world: A 150‐year stable isotope (δ13C,δ15N) record from feathers collected in the Pacific Northwest of North America

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Changing gull diet in a changing world: A 150‐year stable isotope (δ¹³C,δ¹⁵N) record from feathers collected in the Pacific Northwest of North America