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Factors associated with arrival densities of grasshopper sparrow (Ammodramus Savannarum) and baird's sparrow (A. Bairdii) in the upper great plains

Auk

By:
, , and
DOI: 10.1525/auk.2009.08154

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Abstract

Although critical to habitat and population management, the proximate cues that birds use to establish territories are largely unknown. Understanding these cues is important for birds, such as many grassland birds, that exhibit high annual variability in population density and make new habitat-selection decisions annually. Identifying the actual cues used is difficult in the field, but the factors associated with the arrival densities of birds can help uncover variables that are involved in or correlated with cues used for selection. During the summers of 2002-2004, we investigated how weather and local vegetation factors were related to arrival densities of Grasshopper Sparrows (Ammodramus savannarum) and Baird's Sparrows (A. bairdii) at three locations across North Dakota and Saskatchewan. Spring densities of Grasshopper Sparrows were positively correlated with concurrent May precipitation, whereas densities of Baird's Sparrows were negatively correlated with the previous winter's snowfall. We used a model-selection approach to evaluate the vegetation characteristics associated with arrival densities of birds. Grasshopper Sparrow densities showed a strong negative relationship to woody cover, and Baird's Sparrow densities showed a negative relationship to vegetation height and vegetation density near the ground. Our results provide a first detailed look at habitat and weather associations immediately after arrival in spring and an important first step in uncovering factors that may be involved in habitat selection in two grassland species. Received 13 August 2008, accepted 20 April 2009. ?? The American Ornithologists' Union, 2009.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Factors associated with arrival densities of grasshopper sparrow (Ammodramus Savannarum) and baird's sparrow (A. Bairdii) in the upper great plains
Series title:
Auk
DOI:
10.1525/auk.2009.08154
Volume
126
Issue:
4
Year Published:
2009
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Auk
First page:
799
Last page:
808
Number of Pages:
10