Coupled range dynamics of brood parasites and their hosts responding to climate and vegetation changes

As populations shift their ranges in response to global change, local species assemblages can change, setting the stage for new ecological interactions, community equilibria, and evolutionary responses. Here we focus on the range dynamics of four avian brood parasite species and their hosts in southern Africa, in a context of bush encroachment (increase in woody vegetation density in places previously occupied by savanna-grassland mosaics) favouring some species at the expense of others. We first tested whether hosts and parasites constrained each other's ability to expand or maintain their ranges. Second, we investigated whether range shifts represented an opportunity for new host-parasite and parasite-parasite interactions.
We used multi-species dynamic occupancy models with interactions, fitted to citizen-science data, to estimate the contribution of interspecific interactions to range shifts and to quantify the change in species co-occurrence probability over a 25-year period. Para...