Endemic Fynbos Avifauna: Comparative Range Declines a Cause for Concern


The winter rainfall district of the Western, Eastern and Northern Cape Provinces in South Africa is home to the Fynbos biome, which extends from the Cedarberg mountains, south to the Cape of Good Hope, and eastwards to Algoa Bay. The Fynbos biome as an outstanding global biodiversity hotspot for its high levels of plant diversity and endemism. Approximately 8 600 plant species have been recorded in this biome, of which about 70% are endemic, but there are surprisingly few endemic birds (Table 1).

The Cape Fynbos supports six restricted-range bird species, which are all considered widespread within the biome (BirdLife International 2010a) and are all ranked by IUCN conservation criteria as Least Concern (BirdLife International 2010b). This ranking means that for these species their Extent of Occurrence is not less than 20 combined with a declining range size, habitat extent/quality, a small
number of locations or severe fragmentation. The ranking also implies that the population trends appear to be stable, and hence the species do not approach the thresholds for Vulnerable under the
population trend criterion (greater than 30% decline over ten years or three generations). This ranking is given when populati believed to be >10 000 mature individuals with a continuing decline estimated to be less than 10% in ten years or three generations.

Lowland Fynbos, however, is highly threatened by crop farming and urbanization, and both lowland and mountain Fynbos are affected by commercial afforestation, alien plant species invasion, dam and uncontrolled burning (e.g. Kemper et al. 1999) these threats, climate change models predict substantially drier warmer conditions in low-lying areas of the winter rainfall zone within the next 100 years. All this does not bode well for the Fynbos endemics.

The first Southern African Bird Atlas Project (SABAP in 1986. Approximately 5 000 citizen scientists distribution data from six countries in southern Africa the publication of The Atlas of Southern African Birds in 1997 (Harrison et al. 1997). By 2007, fifty research publications and eight Ph.D. and master’s degrees had emanated from the database (Harrison et al. 2008). In July 2007, the follow
launched. These projects have been recognised as important tools to assess how local bird populations are shifting in response to climate and land-use changes (Hockey et al. 2011).

Comparing SABAP1 and SABAP2 data in terms of species distribution can be difficult (Res Altwegg et al., manuscripts in prep.) Are apparent gaps in the distribution true reflections of species’ responses to environmental change, or a function of incomplete coverage, differences in survey effort or protocol, or differences in scale? We look at the current apparent patchy distribution of six Fynbos endemic species and compare them to species that are ecologically and/or morphologically similar, which occur in the Fynbos biome, but also have ranges beyond reasoning is that by comparing similar species, issues of coverage and scale are reduced as ecologically similar species should often show at least broadly similar trends in coverage or apparent range contraction (or expansion).