How useful are recoveries of North American passerines for survival analyses? |
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Authors: | Charles M. Francis |
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Abstract: | Of 17 000 000 passerines ringed in North America from 1955 to 1984, only 0.4% were ever recovered. Only 62 species had more than 100 recoveries, of which only 26 had more than 500 recoveries. Preliminary analyses using stochastic recovery models for four of the species with more than 500 recoveries suggest estimates of mean annual adult survival can be fairly precise (CV < 4%), but estimates of immature survival are much less precise (CV > 8%). Comparable estimates may be possible for other species with more than 100 recoveries, depending on the temporal and geographic distribution of ringings and recoveries. Further analyses are required to determine whether these estimates may be biased by heterogeneity in survival or recovery rates. |
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