RELATIONSHIP BETWEEN MAYFIELD NEST-SURVIVAL ESTIMATES AND SEASONAL FECUNDITY: A CAUTIONARY NOTE

Abstract Estimates of nest survival are commonly used as indices of reproductive productivity in a wide range of studies, including examinations of population dynamics, habitat fragmentation, and wildlife management. However, the strength of the relationship between estimates of nest survival and of seasonal fecundity has rarely been tested. To examine that relationship, we used 16 years of demographic data from an intensively studied population of individually marked Black-throated Blue Warblers (Dendroica caerulescens). We found a positive relationship between Mayfield nest-survival estimates and seasonal fecundity (i.e. number of fledglings produced per female). However, seasonal-fecundity predictions based on nestsurvival values underestimated observed seasonal fecundity by an average of 33% and population growth rate by 20%. Our results suggest that, though nest-survival estimates may be useful as indices of pressures on a population (e.g. nest predation), care is needed in using them as the basis of...