Among the major changes over the past 50 years is a dramatic reduction of trees in eastern Kruger. There are 60% less trees in the basaltic grasslands than there were in 1957. The decline has been influenced by burning patterns and tree devastation by elephants. This reduced woodland has seen a change in birding patterns that has favoured specialist grassland birds at the expense of fruit-eaters. It may also have attracted more of the larger birds of prey which prefer hunting over open grassland than in mixed woodlands.
Although the specific effects of global warming on Kruger remain unclear, several scientists believe the Kruger of the future will be a drier, hotter place with considerably more grassland than there is now. Officials believe that this could lead to the extinction of some localised species.
Freak weather in the form of extreme droughts and flash floods has also taken its toll on Kruger. A combination of both can be lethal. Floods often change watercourses, wash away huge trees and dump sand in all sorts of new places, while droughts see high tree mortality in marginal areas. Kruger experienced both extremes within a ten-year period around the turn of the century and the effects have yet to be understood.
One noticeable effect has been a significant drop-off in the numbers of Trumpeter Hornbills and Grey-headed Parrots in the Luvuvhu Valley. They depend largely on Sycamore Figs (Ficus sycamorus) which have declined since the last decade of the 20th century. Firstly, the severe drought of 1993 killed off many figs, while the rampaging floods of 2000 cleared many watercourses of these magnificent, shallow-rooted trees.
There are many other subtle birding cycles and trends that have not been studied. There is anecdotal evidence, for instance, of a change in the mix of Robin-Chats* in Kruger. Old hands will say that in the 1970s and 80s the Red-capped Robin-Chat* was the dominant robin but that during the past 20 years this role has been taken over by the White-browed Robin-Chat*. A personal observation by the authors is that Verreauxs' Eagle appears to be moving its range from the Luvuvhu River valley area into the northern Lebombo.