The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia

I examined the decline of Ancient Murrelets ( Synthliboramphus antiquus ), a small, burrow‐nesting seabird, at Langara Island. The island’s seabird colony was historically one of the largest colonies of Ancient Murrelets in British Columbia—perhaps in the world—with an estimated 200,000 nesting pair...

Full description

Bibliographic Details
Published in:Conservation Biology
Main Author: Bertram, Douglas F.
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 1995
Subjects:
Online Access:http://dx.doi.org/10.1046/j.1523-1739.1995.09040865.x
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1523-1739.1995.09040865.x
http://onlinelibrary.wiley.com/wol1/doi/10.1046/j.1523-1739.1995.09040865.x/fullpdf
id crwiley:10.1046/j.1523-1739.1995.09040865.x
record_format openpolar
spelling crwiley:10.1046/j.1523-1739.1995.09040865.x 2024-06-02T08:13:44+00:00 The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia Bertram, Douglas F. 1995 http://dx.doi.org/10.1046/j.1523-1739.1995.09040865.x https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1523-1739.1995.09040865.x http://onlinelibrary.wiley.com/wol1/doi/10.1046/j.1523-1739.1995.09040865.x/fullpdf en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Conservation Biology volume 9, issue 4, page 865-872 ISSN 0888-8892 1523-1739 journal-article 1995 crwiley https://doi.org/10.1046/j.1523-1739.1995.09040865.x 2024-05-03T12:07:17Z I examined the decline of Ancient Murrelets ( Synthliboramphus antiquus ), a small, burrow‐nesting seabird, at Langara Island. The island’s seabird colony was historically one of the largest colonies of Ancient Murrelets in British Columbia—perhaps in the world—with an estimated 200,000 nesting pairs. I reviewed historical information and compared the results of surveys from 1981 and 1988 that employed the same census protocol. The extent of the colony, a potential index of population size, declined from 101 ha in 1981 to 48 ha in 1988. Burrow density increased during the same period, however, suggesting that the colony bad consolidated. In 1988, the population estimate was 24,200 ± 4000 (S.E.) breeding pairs compared to 22,000 ± 3700 in 1981. in 1988, 29% of the burrows that were completely searched contained bones of Ancient Murrelets. Bones were most common in burrows located in abandoned areas of the colony and were least common where burrow occupancy was high. The discovery of adult Ancient Murrelets killed in their burrows by introduced rats, combined with the high proportion of burrows with bones, suggests that rats ( Rattus rattus and R. norvegicus ) have contributed significantly to the decline of the population. In addition, the presence and activities of a salmon‐fishing fleet in the 1950s and 1960s may also be linked to the decline of the Langara Ancient Murrelet population during that period because these fisheries are known to have caused heavy mortality through fatal light attraction and drowning in gill nets. The combined effects of ongoing predation by introduced rats and—to a lesser extent—previous, episodic fishery‐induced mortality are probable causes for the population decline. Article in Journal/Newspaper Rattus rattus Wiley Online Library Burrows ENVELOPE(163.650,163.650,-74.300,-74.300) Langara Island ENVELOPE(-133.021,-133.021,54.235,54.235) Conservation Biology 9 4 865 872
institution Open Polar
collection Wiley Online Library
op_collection_id crwiley
language English
description I examined the decline of Ancient Murrelets ( Synthliboramphus antiquus ), a small, burrow‐nesting seabird, at Langara Island. The island’s seabird colony was historically one of the largest colonies of Ancient Murrelets in British Columbia—perhaps in the world—with an estimated 200,000 nesting pairs. I reviewed historical information and compared the results of surveys from 1981 and 1988 that employed the same census protocol. The extent of the colony, a potential index of population size, declined from 101 ha in 1981 to 48 ha in 1988. Burrow density increased during the same period, however, suggesting that the colony bad consolidated. In 1988, the population estimate was 24,200 ± 4000 (S.E.) breeding pairs compared to 22,000 ± 3700 in 1981. in 1988, 29% of the burrows that were completely searched contained bones of Ancient Murrelets. Bones were most common in burrows located in abandoned areas of the colony and were least common where burrow occupancy was high. The discovery of adult Ancient Murrelets killed in their burrows by introduced rats, combined with the high proportion of burrows with bones, suggests that rats ( Rattus rattus and R. norvegicus ) have contributed significantly to the decline of the population. In addition, the presence and activities of a salmon‐fishing fleet in the 1950s and 1960s may also be linked to the decline of the Langara Ancient Murrelet population during that period because these fisheries are known to have caused heavy mortality through fatal light attraction and drowning in gill nets. The combined effects of ongoing predation by introduced rats and—to a lesser extent—previous, episodic fishery‐induced mortality are probable causes for the population decline.
format Article in Journal/Newspaper
author Bertram, Douglas F.
spellingShingle Bertram, Douglas F.
The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia
author_facet Bertram, Douglas F.
author_sort Bertram, Douglas F.
title The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia
title_short The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia
title_full The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia
title_fullStr The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia
title_full_unstemmed The Roles of Introduced Rats and Commercial Fishing in the Decline of Ancient Murrelets on Langara Island, British Columbia
title_sort roles of introduced rats and commercial fishing in the decline of ancient murrelets on langara island, british columbia
publisher Wiley
publishDate 1995
url http://dx.doi.org/10.1046/j.1523-1739.1995.09040865.x
https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1523-1739.1995.09040865.x
http://onlinelibrary.wiley.com/wol1/doi/10.1046/j.1523-1739.1995.09040865.x/fullpdf
long_lat ENVELOPE(163.650,163.650,-74.300,-74.300)
ENVELOPE(-133.021,-133.021,54.235,54.235)
geographic Burrows
Langara Island
geographic_facet Burrows
Langara Island
genre Rattus rattus
genre_facet Rattus rattus
op_source Conservation Biology
volume 9, issue 4, page 865-872
ISSN 0888-8892 1523-1739
op_rights http://onlinelibrary.wiley.com/termsAndConditions#vor
op_doi https://doi.org/10.1046/j.1523-1739.1995.09040865.x
container_title Conservation Biology
container_volume 9
container_issue 4
container_start_page 865
op_container_end_page 872
_version_ 1800737339522154496