Cape Rockjumper Chaetops frenatus Scientific name definitions
Version: 2.0 — Published May 17, 2021
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The Cape Rockjumper prefers the windswept, Restionaceae-dominated mountain fynbos found on the upper mountain slopes and ridges, occupying generally contiguous territories along the ridgetops (15).
They are predominantly found in areas that have burned within 10 years, and it has a higher probability of breeding success in areas that have experienced recent burns (5). Throughout the Cape Fold Mountains, it is not found on mountains that are dominated by large (and older growth) Proteaceae (see Distribution). When fire sweeps through areas of thicker growth, birds were recorded establishing territories in this newly available landscape within 3 months (5). When fire moves through existing territories, birds may retreat onto large boulders and wait for the fire to pass, as birds have been seen in territories quite recently after wildfire (< 3 months; KNO).
fynbos mountain slopes have well-dispersed large granite and sandstone boulders, which the Cape Rockjumper can use to scan the area for predators or birds from adjacent territories. More open habitat likely allows them to see a larger portion of their territory (16). Birds defend year-round territories, with no difference between the breeding and nonbreeding season (4), and the same individuals being found in specific territories for multiple years (5).
Fynbos Avian Endemics
The fynbos is particularly susceptible to climate change due to its small size and highest proportion of endemism among the five Mediterranean-type biomes. The fynbos is known for its prolific and unique plant communities (close to 6,000 endemic plant species among 12 endemic families and 160 endemic genera) making it a biodiversity hotspot of priority for conservation (32). Among terrestrial vertebrates the fynbos holds one endemic mammal (although six near-endemics), and eight endemic bird species (seven passerines and a buttonquail). Of these seven passerine birds, two derive from “ancient lineages” of taxa (families Chaetopidae and Promeropidae), with low diversity and high phylogenetic distance from nearest relations, making these species distinctive amongst avian communities (22). Predictive climate change modelling indicates the fynbos heathlands will shift southward, contracting toward the southern coast of South Africa (33), which will result in correlative contractions of suitable habitat for all the fynbos’ endemics. Besides the Cape Rockjumper, the fynbos endemics are the Fynbos Buttonquail (Turnix hottentottus; recently renamed fynbos Buttonquail from the "Hottentot" ethnonym; 34), the Agulhas Lark (Certhilauda brevirostris), the Victorin's Warbler (Cryptillas victorini), the Cape Sugarbird (Promerops cafer), the Orange-breasted Sunbird (Anthobaphes violacea), the Protea Canary (Crithagra leucoptera), and the Cape Siskin (Crithagra totta).
The southwest corner of South Africa holds a small belt (ca 90,000 km2) of heathland that is the smallest of the six globally-recognized plant kingdoms — the Cape Floristic Region. The Cape Floristic Region, often referred to by its local name of fynbos, is one of five Mediterranean-type biomes across the planet, all considered biodiversity hotspots, and all areas of high conservation concern due to climate change (35).
Within the fynbos are two main ecoregions: Lowland fynbos and Renosterveld (“lowland fynbos”), and Montane fynbos and Renosterveld (“mountain fynbos”), often interspersed with small patches of Albany Thicket. As the name suggests, areas of mountain fynbos exist predominantly at higher elevations on quartzite and sandstone ridges (lowland Aspalathus and Proteaceae with mountain fynbos backdrop; Swartberg), with the sole exception of a small stretch at lower elevation in the Kogelberg Nature Reserve in the Overberg region that stretches down to the Southern Ocean. Climate change scenarios for 2050 predict a 51–65% reduction of the geographical extent of the fynbos biome, resulting in dramatic reductions in specific habitat for the inhabitants of this already rather small area (33).
Projected increases in drought and fire due to climate change (35) will likely result in a stunted successional cycle where the floral community structure does not advance past the early successional stage. There are also a few threats to fynbos (mostly recreation and agriculture) due to human impact in the area (see Conservation: Effects of Human Activity).