The African wintering distribution and ecology of the Corncrake Crex crex

Abstract

SummaryThe Corncrake Crex crex breeds in the Palearctic but overwinters in central and southern Africa. While some information had previously been gathered about the Corncrake’s African wintering distribution, we here analyse a much more comprehensive database of 1,284 records based on a five-year desk study completed in January 2011 and use those records selected for spatio-temporal accuracy to build a continental distribution model. Our model was based mostly on climatic variables and predicts a high suitability for most eastern Africa countries south of the equator, but none of the western African countries with the exception of Angola and Namibia. Both the actual number of records as well as the distribution model thus indicates that the vast majority of Corncrakes migrate through and overwinter in the eastern parts of Africa. Because large parts of Angola, Mozambique, north-eastern Namibia, and Tanzania are predicted as suitable but have yielded very few actual records so far, they should be targeted for future field work. A very small number of Corncrakes may oversummer in Africa but such individuals are possibly unable to migrate due to sickness or injury, or may be first-year birds that are not ready to breed. An analysis of habitat and population density data indicates that, within the continental distribution, Corncrakes are mostly concentrated within grass-dominated habitats, mirroring their habitat preferences in the breeding areas. Corncrakes reach their wintering distribution mostly through an eastern migration route, but some individuals or subpopulations from the Western breeding population also use a western migration route. We also document the food choices, weights, and causes of injury and death within Africa. Because habitat conversion is accelerating all across Africa, we recommend constant monitoring of habitat availability and population densities within the Corncrake’s wintering distribution.