Nest Distribution and Productivity of Bald Eagles in Western Washington

Grubb, Teryl G.; Manuwal, David A.; Anderson, Clifford M.

doi:10.2307/3533742

Cited by 7 publications

(7 citation statements)

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“…Herein, I report on tests of two additional hypotheses involving habitat quality and food abundance. Correlations between habitat attributes and productivity have been found in some regions but not in others (Grubb 1976, McEwan and Hirth 1979, Hodges and Robards 1982. lfhabitat limits breeding, habitat characteristics should differ between active and inactive nests and between successful and unsuccessful nests.…”

Section: Introductionmentioning

confidence: 99%

Regulation of Bald Eagle Reproductive Rates in Southeast Alaska

Hansen¹

1987

Ecology

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I examined the influence of food abundance and habitat quality on reproduction of Bald Eagles (Haliaeetus leucocephalus) in the Chilkat Valley, Alaska. The proportion of active nests was greatest and the timing oflaying earliest in portions of the study area where food was most abundant. Clutch size was not related to food availability. Offspring survival was higher in breeding areas where food was experimentally provided than in control areas. Whether nests were active was also related to 2 of 11 habitat features measured at breeding areas. One habitat variable was associated with nest success. The findings suggest that variable productivity and a surplus of non breeders are the norm in the region as a result of high variability of annual food supplies and strong intraspecific competition. The results further suggest that the decline of this species in other parts of North America was at least partially due to alteration of eagle food sources and habitats by humans.

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Section: Introductionmentioning

confidence: 99%

Regulation of Bald Eagle Reproductive Rates in Southeast Alaska

Hansen¹

1987

Ecology

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“…Surveys have ranged from regional efforts covering one year (e.g., Grubb et al 1975) to statewide, multi-year projects (e.g., this study). Results of surveys usually were reported as percent of breeding areas that were occupied and nesting was successful (nesting success), number of young per occupied breeding area (productivity), and number of young per successful nesting attempt (brood size).…”

Section: Productivitymentioning

confidence: 99%

“…Timing of aerial and ground surveys initially was based on similar surveys conducted in Washington (Grubb et al 1975), then was modified slightly to fit nesting chronology in Oregon (Isaacs et al 1983). Occupancy surveys (App.…”

Section: Protocolmentioning

confidence: 99%

Coming to Terms About Describing Golden Eagle Reproduction

Steenhof¹,

Kochert

McIntyre

et al. 2017

Journal of Raptor Research

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“…The nest-site groupings obtained by K-means showed geographical clustering, with distinct groups in Vancouver, Delta, further up the Fraser Valley, Reproductive Rate. Nesting success averaged 68% for all 6 yr included in the analysis, which is slightly higher than historical values for eagles in western Washington (Grubb et al 1975) and northern California (Jenkins and Jackman 2006), although we measured success per active nest rather than per occupied nest, so these values are not completely comparable. Nesting success in the last century varied from 48% to 77% in different populations, with the lowest figures for Alaskan populations that may have been at carrying capacity (Hansen 1987, reviewed in Steidl et al 1997.…”

Section: Discussionmentioning

confidence: 80%

“…We defined an occupied territory as one with at least one adult on the nesting territory at multiple times during the length of breeding season, i.e., from territory establishment to fledging of young. We considered a nest active after there was evidence of egg-laying (i.e., incubating adult or the presence of young; Grubb et al 1975, Dykstra et al 2009. We defined nesting success as the percentage of active nests that resulted in at least one fledged young.…”

Section: Studymentioning

confidence: 99%