Partial life-cycle analysis: a simplified model for post-breeding census data

Age-specific demographic data are not available for many species of conservation concern, and conservation biologists must rely on incomplete demographic data which can be collected much more easily. Models that allow demographic analyses based on incomplete demographic data have recently received substantial attention. Such models (hereafter, partial life-cycle models) are particularly appropriate for situations where age-specific demographic data are not available, and when perturbation analyses involving ages at first and last reproduction are desired. Here, I present a partial life-cycle model appropriate for the analyses of incomplete demographic data collected from post-breeding censuses when estimates of age at last reproduction are not available. Using example calculations, I have shown that results of the simple model resemble those obtained from corresponding age-structured models, and that ignoring age at last reproduction for demographic analyses of long-lived organisms results in little or no loss of information. These results justify the use of the simple model presented here, and should be encouraging to investigators working on long-lived organisms for which estimates of age at last reproduction are rarely available.