Disentangling the spatial and temporal causes of decline in a bird population

The difficulties in understanding the underlying reasons of a population decline lie in the typical short duration of field studies, the often too small size already reached by a declining population or the multitude of environmental factors that may influence population trend. In this difficult context, useful demographic tools such as integrated population models (IPM) may help disentangling the main reasons for a population decline.

To understand why a hoopoe Upupa epops population has declined, we followed a three step model analysis. We built an IPM structured with respect to habitat quality (approximated by the expected availability of molecrickets, the main prey in our population) and estimated the contributions of habitat-specific demographic rates to population variation and decline. We quantified how much each demographic rate has decreased and investigated if habitat quality influenced this decline. We tested how much weather conditions and research activities contributed ...