|Pangani Longclaw Macronyx aurantiigula is perhaps the best example |
of a species extending west, having colonised Serengeti recently.
So, what did we do? In brief, we took all the records of some 139 savannah bird species and lumped them into two different time periods - 1960-1989 (before most of the current climate changes had generated much change) and since 2000. We then built statistical models that accounted for changing patterns in observer effort, to identify places where each species had colonised or vanished (local extinction) between the two time periods. As well as telling us where these birds occur, this also allowed us to identify the climate that was preferred by each species during the initial time period. We then analysed these changes to look for consistent patterns in the places where colonisations or local extinctions had occurred, looking particularly at changes in climate suitability for each species, trends in land degradation, and protected area status in each place.
|From Beale et al 2013 The overall pattern of changes in distribution among 139 Tanzanian savannah bird species. (a) Continuous presence, (b) colonisations, (c) local extinctions, (d) continuous absence. Square size indicates average transition probability across all 139 bird species, with colonisations and extinctions magnified 10 times relative to continuous presence and continuous absence.|
|Another classic dry bush species, the Scarlet-chested Sunbird|
is not yet shoing major movements.
Colin M. Beale,, Neil E. Baker,, Mark J. Brewer,, & Jack J. Lennon (2013). Protected area networks and savannah bird biodiversity in the face of climate change and land degradation Ecology Letters DOI: 10.1111/ele.12139