Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models
ABSTRACT Alaska (USA) contains a large proportion of the breeding population of trumpeter swans ( Cygnus buccinator ) in the United States. However, tracking population trends in Alaska trumpeter swans is complicated by variables such as an increase in survey effort over time, periodic surveys (1968...
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crwiley:10.2193/2008-262 2023-12-03T10:21:44+01:00 Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models SCHMIDT, JOSHUA H. LINDBERG, MARK S. JOHNSON, DEVIN S. CONANT, BRUCE KING, JAMES 2009 http://dx.doi.org/10.2193/2008-262 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2193%2F2008-262 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor The Journal of Wildlife Management volume 73, issue 5, page 720-727 ISSN 0022-541X 1937-2817 Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics journal-article 2009 crwiley https://doi.org/10.2193/2008-262 2023-11-09T14:26:03Z ABSTRACT Alaska (USA) contains a large proportion of the breeding population of trumpeter swans ( Cygnus buccinator ) in the United States. However, tracking population trends in Alaska trumpeter swans is complicated by variables such as an increase in survey effort over time, periodic surveys (1968 and every 5 yr after 1975), and missing data. We therefore constructed Bayesian hierarchical negative binomial models to account for nuisance variables and to estimate population size of trumpeter swans using aerial survey data from all known breeding habitats in Alaska, 1968–2005. We also performed an augmented analysis, where we entered zeroes for missing data. This approach differed from the standard (nonaugmented) analysis where we generated estimates for missing data through simulation. We estimated that adult swan populations in Alaska increased at an average rate of 5.9% annually (95% credibility interval = 5.2–6.6%) and cygnet production increased at 5.3% annually (95% credibility interval = 2.2–8.0%). We also found evidence that cygnet production exhibited higher rates of increase at higher latitudes in later years, which may be a response to warmer spring temperatures. Augmented analyses always produced higher swan population estimates than the nonaugmented estimates and likely overestimate true population abundance. Our results provide evidence that trumpeter swan populations are increasing in Alaska, especially at northern latitudes. Changes in population size and distribution could negatively affect tundra swans ( Cygnus columbianus ) breeding in Alaska, and biologists should monitor these interactions. We recommend using nonaugmented Bayesian hierarchical analyses to estimate wildlife populations when missing survey data occur. Article in Journal/Newspaper Cygnus columbianus Tundra Alaska Wiley Online Library (via Crossref) The Journal of Wildlife Management 73 5 720 727 |
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Open Polar |
collection |
Wiley Online Library (via Crossref) |
op_collection_id |
crwiley |
language |
English |
topic |
Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics |
spellingShingle |
Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics SCHMIDT, JOSHUA H. LINDBERG, MARK S. JOHNSON, DEVIN S. CONANT, BRUCE KING, JAMES Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models |
topic_facet |
Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics Nature and Landscape Conservation Ecology Ecology, Evolution, Behavior and Systematics |
description |
ABSTRACT Alaska (USA) contains a large proportion of the breeding population of trumpeter swans ( Cygnus buccinator ) in the United States. However, tracking population trends in Alaska trumpeter swans is complicated by variables such as an increase in survey effort over time, periodic surveys (1968 and every 5 yr after 1975), and missing data. We therefore constructed Bayesian hierarchical negative binomial models to account for nuisance variables and to estimate population size of trumpeter swans using aerial survey data from all known breeding habitats in Alaska, 1968–2005. We also performed an augmented analysis, where we entered zeroes for missing data. This approach differed from the standard (nonaugmented) analysis where we generated estimates for missing data through simulation. We estimated that adult swan populations in Alaska increased at an average rate of 5.9% annually (95% credibility interval = 5.2–6.6%) and cygnet production increased at 5.3% annually (95% credibility interval = 2.2–8.0%). We also found evidence that cygnet production exhibited higher rates of increase at higher latitudes in later years, which may be a response to warmer spring temperatures. Augmented analyses always produced higher swan population estimates than the nonaugmented estimates and likely overestimate true population abundance. Our results provide evidence that trumpeter swan populations are increasing in Alaska, especially at northern latitudes. Changes in population size and distribution could negatively affect tundra swans ( Cygnus columbianus ) breeding in Alaska, and biologists should monitor these interactions. We recommend using nonaugmented Bayesian hierarchical analyses to estimate wildlife populations when missing survey data occur. |
format |
Article in Journal/Newspaper |
author |
SCHMIDT, JOSHUA H. LINDBERG, MARK S. JOHNSON, DEVIN S. CONANT, BRUCE KING, JAMES |
author_facet |
SCHMIDT, JOSHUA H. LINDBERG, MARK S. JOHNSON, DEVIN S. CONANT, BRUCE KING, JAMES |
author_sort |
SCHMIDT, JOSHUA H. |
title |
Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models |
title_short |
Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models |
title_full |
Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models |
title_fullStr |
Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models |
title_full_unstemmed |
Evidence of Alaskan Trumpeter Swan Population Growth Using Bayesian Hierarchical Models |
title_sort |
evidence of alaskan trumpeter swan population growth using bayesian hierarchical models |
publisher |
Wiley |
publishDate |
2009 |
url |
http://dx.doi.org/10.2193/2008-262 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2193%2F2008-262 |
genre |
Cygnus columbianus Tundra Alaska |
genre_facet |
Cygnus columbianus Tundra Alaska |
op_source |
The Journal of Wildlife Management volume 73, issue 5, page 720-727 ISSN 0022-541X 1937-2817 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.2193/2008-262 |
container_title |
The Journal of Wildlife Management |
container_volume |
73 |
container_issue |
5 |
container_start_page |
720 |
op_container_end_page |
727 |
_version_ |
1784269539571138560 |