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Keywords:

  • Blue antelope;
  • Cape Floristic Region;
  • extinct species;
  • extinction;
  • migration;
  • palaeoecology;
  • Quaternary;
  • southern Africa;
  • zooarchaeology

Abstract

Aim

Palaeoecological data are crucial to understanding the historical extinction of the blue antelope (Hippotragus leucophaeus). This study examined late Quaternary fossil evidence bearing on the blue antelope's calving and migratory habits.

Location

Cape Floristic Region (CFR), South Africa.

Methods

Blue antelope mortality patterns were reconstructed from dental remains from fossil assemblages spanning the last c. 200,000 years and located in the CFR's winter and year-round rainfall zones. Two demographic measures were examined: (1) the frequencies of juveniles relative to adults; and (2) the frequencies of neonates relative to older juveniles. Geographical trends were examined across a longitudinal gradient of decreasing winter rainfall and increasing summer rainfall.

Results

There was a significant longitudinal trend in the blue antelope mortality data, with juveniles and neonates declining in frequency from west to east. This suggests that calving occurred primarily in the winter rainfall zone, probably during the winter months when seasonal rains promoted the growth of C3 grasses. The summer drought and lack of adequate forage forced blue antelope to migrate east, in time with summer rainfall and the increased availability of C4 grasses. The migration route probably depended in part on reduced sea levels during glacial phases of the Pleistocene.

Main conclusions

Blue antelope were probably migratory. Rising sea levels at the onset of the Holocene disrupted their migration routes, limited access to west-coast calving grounds, and fragmented populations. Such disruption would have devastated the blue antelope population and contributed to its vulnerability to extinction. Blue antelope survived previous marine transgressions, however, suggesting that other factors played a role in its demise. Agricultural expansion early in the colonial era may have further disrupted migration routes and played an important role in its extinction.