Migration, patchiness and population processes illustrated by two migrant pests

New technologies are improving scientists’ understanding of the links between sources and destinations of subpopulations of migrants within populations as a whole (metapopulations). Such links and the importance of environmental patchiness are illustrated by migrations of two major pests, the red-billed quelea (Quelea quelea) and the desert locust (Schistocerca gregaria). The spatio temporal distribution of rainfall determines where and when Quelea can breed, as shown for Quelea populations in southern Africa. Numbers and distributions of swarms of desert locusts in four different regions of their huge invasion area (29,000,000 km2) were analyzed as local populations of a metapopulation. Lagged cross-correlations of seasonally adjusted monthly data demonstrate links between the local populations, which vary in significance according to the pairings of regions analyzed and the lengths of the lags, illustrating the strength of the connectivity between them. Understanding such relationships is essential for predictions concerning future climate change scenarios