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Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines

The marbled murrelet (Brachyramphus marmoratus) is classified as a threatened species under the US Endangered Species Act in Washington, Oregon, and California USA due to population declines, loss of breeding habitat, and other factors. To date, population assessments have focused on breeding season...

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Autores principales: Pearson, Scott F., Keren, Ilai, Lance, Monique M., Raphael, Martin G.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9022884/
https://www.ncbi.nlm.nih.gov/pubmed/35446906
http://dx.doi.org/10.1371/journal.pone.0267165
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author Pearson, Scott F.
Keren, Ilai
Lance, Monique M.
Raphael, Martin G.
author_facet Pearson, Scott F.
Keren, Ilai
Lance, Monique M.
Raphael, Martin G.
author_sort Pearson, Scott F.
collection PubMed
description The marbled murrelet (Brachyramphus marmoratus) is classified as a threatened species under the US Endangered Species Act in Washington, Oregon, and California USA due to population declines, loss of breeding habitat, and other factors. To date, population assessments have focused on breeding season at-sea surveys. Consequently, there is little information on this species’ distribution, abundance, and population trends during the non-breeding season, when murrelets are found exclusively in the marine environment. To address this information need, we assessed non-breeding (Sep—Mar) at-sea murrelet abundance patterns and population trends over 8 years, in a portion of its range where breeding season surveys indicate a 20-year population decline, Puget Sound, Washington, USA. This allowed us to assess whether non-breeding population trends mirrored those observed during the breeding season suggesting regional year-round conservation concerns and to also identify important over-wintering areas (areas of high abundance). We integrated our non-breeding abundance information with breeding season information to assess year-round patterns of abundance. This allowed us to test the prediction that murrelets move into the relatively protected inner marine waters of Puget Sound from harsher outer coastal habitats during the non-breeding season to molt and over-winter. Similar to trends from the breeding season, we observed strong murrelet density declines across the entire non-breeding period (Sep and Apr) with declines most pronounced in the fall and early winter (lateSep–Dec) survey windows when birds molt and in the spring just prior to breeding (Mar-Apr). Despite these declines, there was essentially no change in murrelet density in mid-winter (January—February) when overall density was lower. Puget Sound murrelet density exhibited a strong north-south gradient with relatively high densities to the north and low densities to the south; murrelets were largely absent from Central Puget Sound. For strata other than Central Puget Sound, density varied seasonally with birds more evenly distributed among strata between September and December but in the late winter/early spring period (Jan–Apr), murrelets were largely absent from all strata except the most northerly Admiralty Inlet Stratum, which appears to be important to murrelets year-round. Depending on the year, non-breeding season densities were nearly the same or higher than breeding season densities indicate that murrelets were not moving into the relatively protected inner marine waters of Puget Sound from more outer coastal environments during the non-breeding season as predicted.
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spelling pubmed-90228842022-04-22 Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines Pearson, Scott F. Keren, Ilai Lance, Monique M. Raphael, Martin G. PLoS One Research Article The marbled murrelet (Brachyramphus marmoratus) is classified as a threatened species under the US Endangered Species Act in Washington, Oregon, and California USA due to population declines, loss of breeding habitat, and other factors. To date, population assessments have focused on breeding season at-sea surveys. Consequently, there is little information on this species’ distribution, abundance, and population trends during the non-breeding season, when murrelets are found exclusively in the marine environment. To address this information need, we assessed non-breeding (Sep—Mar) at-sea murrelet abundance patterns and population trends over 8 years, in a portion of its range where breeding season surveys indicate a 20-year population decline, Puget Sound, Washington, USA. This allowed us to assess whether non-breeding population trends mirrored those observed during the breeding season suggesting regional year-round conservation concerns and to also identify important over-wintering areas (areas of high abundance). We integrated our non-breeding abundance information with breeding season information to assess year-round patterns of abundance. This allowed us to test the prediction that murrelets move into the relatively protected inner marine waters of Puget Sound from harsher outer coastal habitats during the non-breeding season to molt and over-winter. Similar to trends from the breeding season, we observed strong murrelet density declines across the entire non-breeding period (Sep and Apr) with declines most pronounced in the fall and early winter (lateSep–Dec) survey windows when birds molt and in the spring just prior to breeding (Mar-Apr). Despite these declines, there was essentially no change in murrelet density in mid-winter (January—February) when overall density was lower. Puget Sound murrelet density exhibited a strong north-south gradient with relatively high densities to the north and low densities to the south; murrelets were largely absent from Central Puget Sound. For strata other than Central Puget Sound, density varied seasonally with birds more evenly distributed among strata between September and December but in the late winter/early spring period (Jan–Apr), murrelets were largely absent from all strata except the most northerly Admiralty Inlet Stratum, which appears to be important to murrelets year-round. Depending on the year, non-breeding season densities were nearly the same or higher than breeding season densities indicate that murrelets were not moving into the relatively protected inner marine waters of Puget Sound from more outer coastal environments during the non-breeding season as predicted. Public Library of Science 2022-04-21 /pmc/articles/PMC9022884/ /pubmed/35446906 http://dx.doi.org/10.1371/journal.pone.0267165 Text en https://creativecommons.org/publicdomain/zero/1.0/This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 (https://creativecommons.org/publicdomain/zero/1.0/) public domain dedication.
spellingShingle Research Article
Pearson, Scott F.
Keren, Ilai
Lance, Monique M.
Raphael, Martin G.
Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
title Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
title_full Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
title_fullStr Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
title_full_unstemmed Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
title_short Non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (Brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
title_sort non-breeding changes in at-sea distribution and abundance of the threatened marbled murrelet (brachyramphus marmoratus) in a portion of its range exhibiting long-term breeding season declines
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9022884/
https://www.ncbi.nlm.nih.gov/pubmed/35446906
http://dx.doi.org/10.1371/journal.pone.0267165
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