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Describing breeding territories of migratory passerines: suggestions for sampling, choice of estimator, and delineation of core areas
Author(s) -
BARG JENNIFER J.,
JONES JASON,
ROBERTSON RALEIGH J.
Publication year - 2005
Publication title -
journal of animal ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.134
H-Index - 157
eISSN - 1365-2656
pISSN - 0021-8790
DOI - 10.1111/j.1365-2656.2004.00906.x
Subject(s) - estimator , sample size determination , sampling (signal processing) , statistics , kernel (algebra) , sample (material) , independence (probability theory) , geography , ecology , econometrics , computer science , mathematics , biology , combinatorics , computer vision , chemistry , filter (signal processing) , chromatography
Summary1 The goals of this study were to investigate the possibility of using kernel techniques to estimate male breeding territory size and delineate core areas, focusing on a small nontransmitter bearing bird, the cerulean warbler. We then compared the performance of kernel estimators with traditionally used minimum convex polygons (MCP). 2 Given the lack of a consistent across‐male sample size–area relationship, we opted to use each male's full set of locations in the kernel calculation rather than standardizing sample size across males. 3 All locations collected for each male were biologically independent though statistically autocorrelated. Subsampling locations did not achieve independence even at time intervals far exceeding biological independence. 4 The physical space bounded by kernel and MCP methods differed drastically in certain cases, especially in situations where there were large areas within a territory that were never visited during our data collection sessions. 5 Kernel methods of territory estimation were far more accurate and informative than MCP for cerulean warblers. We suggest that evenly sampling individuals in a biologically relevant manner during a strictly defined study period is more important than standardizing sample size across individuals. Furthermore, sampling regimes can safely be guided by biological vs. statistical independence timelines. 6 Avian biologists should consider kernel estimators as an option especially for habitat selection studies where accurate territory boundary and size estimation is crucial.