A review of the avian post-fledging literature: Major themes and future recommendations

The post-fledging period is widely recognized as one of the most hazardous yet poorly described phases of the avian life cycle.  We reviewed 81 papers in the post-fledging literature to synthesize the status of known information about behavior, movement patterns, resource selection, and survival between and among bird groups.  The majority of the existing post-fledging information is based on three major groups including ducks/geese, raptors, and passerines.  Within the major groups represented, Northern Goshawk and Bald Eagle comprised 53% of raptor studies; Mallard and Snow Goose, 44% of waterfowl studies; and Wood Thrush 22% of passerine studies.  The temperate zone is well represented by the majority of studies in the northern hemisphere, but the tropic zone is poorly represented.  Most studies (80%) addressing a single objective involved estimating survival or recruitment.  Survival studies are well represented and typically involve testing for covariate effects such as body condition or weight and date of fledging or hatching. Other crucial aspects of the post-fledging period, including resource selection, behavior, and parental interactions that may affect survival are poorly represented in the post-fledging literature.  Survival estimates typically represent study periods less than 100 days for waterfowl and passerines, but frequently include true estimates of annual juvenile survival for raptors.  We recommend that future studies explicitly identify sample sizes for the subset of marked animals used in analyses, estimate interval and summary survival rates, test for independence among multiple brood members, and estimate cause-specific mortality.  Future studies should also focus on replicating studies within and across taxa to identify consistent themes among major taxonomic groups.