Effects of climate change on life-cycle events in southern African birds

Birds follow an annual cycle that seems to be structured so that life cycle events take place at the most favourable time of the year. A common example is reproduction with respect to air temperatures and optimal food abundance. However, this breeding-centred thinking is open to debate, with the recognition of moult as a major element in annual cycles of all bird species and some studies finding that in the tropics some species show a high selection pressure for the timing of moult to match with variable peak environmental conditions in order to ensure long-term survival.
Seasonality in an environment is established by examining the amplitude of seasonal fluctuations and the precision with which these fluctuations occur each year. For some seasonal fluctuations (e.g. photoperiod) but not others (e.g. precipitation), the amplitude and the year-to-year precision of these fluctuations decreases from high to low latitudes. Therefore, in temperate areas the life history states of birds might be more strictly controlled by long-term predictors, especially photoperiod, than at lower latitudes, whereas at lower latitudes other factors may play more important roles.
In the last 15 to 20 years, there have been a large number of published studies which show some extent of the correlation between global climate change and changes in biological phenomena. Specifically the degree of climate change has been implicated in significant changes in phenology and ranges of some bird species, but there are also conspicuous differences between species. Species’ responses, and their variability, are poorly understood especially outside intensely studied high latitude regions.
This study will be among the first to analyse seasonality from historical databases on breeding (NRC, nest record cards), and moult, across a wide range of species and environmental conditions. The NRC database itself contains records from roughly 1950 to 1990, and covers a variety of raptors and passerines, migrants and residents from across southern Africa. As the data base covers a large area of southern Africa the environmental conditions will vary significantly. Some of the ecoregions that will be represented in this study are temperate, Mediterranean, desert and even some tropical areas. To our knowledge a study with these extensive information sources and at such a scale of environmental heterogeneity has not been done in the southern hemisphere.