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Scale-dependent associations of Band-tailed Pigeon counts at mineral sites

Northwestern Naturalist

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Abstract

The abundance of Band-tailed Pigeons (Patagioenas fasciata monilis) has declined substantially from historic numbers along the Pacific Coast. Identification of patterns and causative factors of this decline are hampered because habitat use data are limited, and temporal and spatial variability patterns associated with population indices are not known. Furthermore, counts are influenced not only by pigeon abundance but also by rate of visitation to mineral sites, which may not be consistent. To address these issues, we conducted mineral site counts during 2001 and 2002 at 20 locations from 4 regions in the Pacific Northwest, including central Oregon and western Washington, USA, and British Columbia, Canada. We developed inference models that consisted of environmental factors and spatial characteristics at multiple spatial scales. Based on information theory, we compared models within a final set that included variables measured at 3 spatial scales (0.03 ha, 3.14 ha, and 7850 ha). Pigeon counts increased from central Oregon through northern Oregon and decreased into British Columbia. After accounting for this spatial pattern, we found that pigeon counts increased 12% ± 2.7 with a 10% increase in the amount of deciduous forested area within 100 m from a mineral site. Also, distance from the mineral site of interest to the nearest known mineral site was positively related to pigeon counts. These findings provide direction for future research focusing on understanding the relationships between indices of relative abundance and complete counts (censuses) of pigeon populations by identifying habitat characteristics that might influence visitation rates. Furthermore, our results suggest that spatial arrangement of mineral sites influences Band-tailed Pigeon counts and the populations which those counts represent.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Scale-dependent associations of Band-tailed Pigeon counts at mineral sites
Series title:
Northwestern Naturalist
Volume
91
Issue:
3
Year Published:
2010
Language:
English
Publisher:
Society for Northwestern Vertebrate Biology
Publisher location:
Olympia, WA
Contributing office(s):
Western Ecological Research Center
Description:
10 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Northwestern Naturalist
First page:
299
Last page:
308
Number of Pages:
10
Time Range Start:
2001-01-01
Time Range End:
2002-12-31
Country:
United States;Canada
Other Geospatial:
Pacific Northwest