BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES
Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. W...
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ftdatacite:10.6084/m9.figshare.c.3300569.v1 2023-05-15T14:18:11+02:00 BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES Anthony, Robert G. Estes, James A. Ricca, Mark A. A. Keith Miles Forsman, Eric D. 2016 https://dx.doi.org/10.6084/m9.figshare.c.3300569.v1 https://figshare.com/collections/BALD_EAGLES_AND_SEA_OTTERS_IN_THE_ALEUTIAN_ARCHIPELAGO_INDIRECT_EFFECTS_OF_TROPHIC_CASCADES/3300569/1 unknown Figshare https://dx.doi.org/10.1890/07-1818.1 https://dx.doi.org/10.6084/m9.figshare.c.3300569 CC-BY http://creativecommons.org/licenses/by/3.0/us CC-BY Environmental Science Ecology FOS Biological sciences Collection article 2016 ftdatacite https://doi.org/10.6084/m9.figshare.c.3300569.v1 https://doi.org/10.1890/07-1818.1 https://doi.org/10.6084/m9.figshare.c.3300569 2021-11-05T12:55:41Z Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993–1994 and 2000–2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993–1994 to 2000–2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling (Hexagammus lagocephalus), and smooth lumpsuckers (Aptocyclus ventricosus) in the eagle's diet declined with corresponding increases in Rock Ptarmigan (Lagopus mutus), Glaucous-winged Gulls (Larus glaucescens), Atka mackerel (Pleurogrammus monopterygius), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex predator to another. Article in Journal/Newspaper Archipelago Lagopus mutus rock ptarmigan Alaska Aleutian Islands DataCite Metadata Store (German National Library of Science and Technology) Atka ENVELOPE(151.789,151.789,60.835,60.835) Four Islands ENVELOPE(-108.218,-108.218,56.050,56.050) |
institution |
Open Polar |
collection |
DataCite Metadata Store (German National Library of Science and Technology) |
op_collection_id |
ftdatacite |
language |
unknown |
topic |
Environmental Science Ecology FOS Biological sciences |
spellingShingle |
Environmental Science Ecology FOS Biological sciences Anthony, Robert G. Estes, James A. Ricca, Mark A. A. Keith Miles Forsman, Eric D. BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES |
topic_facet |
Environmental Science Ecology FOS Biological sciences |
description |
Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993–1994 and 2000–2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993–1994 to 2000–2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling (Hexagammus lagocephalus), and smooth lumpsuckers (Aptocyclus ventricosus) in the eagle's diet declined with corresponding increases in Rock Ptarmigan (Lagopus mutus), Glaucous-winged Gulls (Larus glaucescens), Atka mackerel (Pleurogrammus monopterygius), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex predator to another. |
format |
Article in Journal/Newspaper |
author |
Anthony, Robert G. Estes, James A. Ricca, Mark A. A. Keith Miles Forsman, Eric D. |
author_facet |
Anthony, Robert G. Estes, James A. Ricca, Mark A. A. Keith Miles Forsman, Eric D. |
author_sort |
Anthony, Robert G. |
title |
BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES |
title_short |
BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES |
title_full |
BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES |
title_fullStr |
BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES |
title_full_unstemmed |
BALD EAGLES AND SEA OTTERS IN THE ALEUTIAN ARCHIPELAGO: INDIRECT EFFECTS OF TROPHIC CASCADES |
title_sort |
bald eagles and sea otters in the aleutian archipelago: indirect effects of trophic cascades |
publisher |
Figshare |
publishDate |
2016 |
url |
https://dx.doi.org/10.6084/m9.figshare.c.3300569.v1 https://figshare.com/collections/BALD_EAGLES_AND_SEA_OTTERS_IN_THE_ALEUTIAN_ARCHIPELAGO_INDIRECT_EFFECTS_OF_TROPHIC_CASCADES/3300569/1 |
long_lat |
ENVELOPE(151.789,151.789,60.835,60.835) ENVELOPE(-108.218,-108.218,56.050,56.050) |
geographic |
Atka Four Islands |
geographic_facet |
Atka Four Islands |
genre |
Archipelago Lagopus mutus rock ptarmigan Alaska Aleutian Islands |
genre_facet |
Archipelago Lagopus mutus rock ptarmigan Alaska Aleutian Islands |
op_relation |
https://dx.doi.org/10.1890/07-1818.1 https://dx.doi.org/10.6084/m9.figshare.c.3300569 |
op_rights |
CC-BY http://creativecommons.org/licenses/by/3.0/us |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.6084/m9.figshare.c.3300569.v1 https://doi.org/10.1890/07-1818.1 https://doi.org/10.6084/m9.figshare.c.3300569 |
_version_ |
1766289880717983744 |