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On the importance of controlling for effort in analysis of count survey data: Modeling population change from Christmas Bird Count data

OCLC: 44821381
By:
,
Edited by:
Andreas J. Helbig, Martin Flade

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Abstract

Count survey data are commonly used for estimating temporal and spatial patterns of population change. Since count surveys are not censuses, counts can be influenced by 'nuisance factors' related to the probability of detecting animals but unrelated to the actual population size. The effects of systematic changes in these factors can be confounded with patterns of population change. Thus, valid analysis of count survey data requires the identification of nuisance factors and flexible models for their effects. We illustrate using data from the Christmas Bird Count (CBC), a midwinter survey of bird populations in North America. CBC survey effort has substantially increased in recent years, suggesting that unadjusted counts may overstate population growth (or understate declines). We describe a flexible family of models for the effect of effort, that includes models in which increasing effort leads to diminishing returns in terms of the number of birds counted.

Additional Publication Details

Publication type:
Book chapter
Publication Subtype:
Book Chapter
Title:
On the importance of controlling for effort in analysis of count survey data: Modeling population change from Christmas Bird Count data
Year Published:
1999
Language:
English
Publisher:
AULU-Verlag
Publisher location:
Wiebelsheim, Germany
Contributing office(s):
Patuxent Wildlife Research Center
Description:
402
Larger Work Type:
Book
Larger Work Subtype:
Other Government Series
Larger Work Title:
Bird numbers 1998: where monitoring and ecological research meet: proceedings of the 14th International Conference of the European Bird Census Council (EBCC) in Cottbus (Brandenburg), Germany, 23-31 March 1998.
First page:
119
Last page:
124
Number of Pages:
402