We recently observed males of Roan and Waterbuck with broken horns in Bouba Ndjida National Park (North Cameroon), both antelope species occurring there at (relatively) high densities (>1-5 ind. km2 ).
Whereas regularly mention is made of horn breakage of antelopes in captivity, surprisingly little is reported from the wild. For example in the recent standard work Mammals of Africa (Hoffmann and Kingdon 2013), only in passing horn breakage is mentioned, and only for species such as Red-fronted gazelle, Giant Eland, Kob, Puku, (female !) Hartebeest, etc. The species accounts on e.g. Roan, Waterbuck, Topi, Bushbuck, Impala, etc. do not mention horn breakage, although known to occur (see also references below).
I am aware of only two quantitative studies on African antelope horn breakage: Gosling et al. (1987) on the relatively high level of horn breaking of Topi on leks in Mara (Kenya), and especially Packer (1983) who quantified for some ten thousand individuals of 13 antelope species the horn breakage frequency in Manyara, Serengeti and Ngorongoro (Tanzania).
With the rapid decline in antelope numbers in many African national parks, one expects that areas with high antelope densities, including leks (Kob, Lechwe, Topi, often in vulnerable floodplains), will decline, likely even disproportionally. The percentage of horn breakage may then drop (disproportionally) as well and may be used as indicator of the health of an antelope population. If confirmed, frequency of horn breakage should be reported as standard parameter in (terrestrial) counts.
Who has antelope horn breakage data or is aware of studies that can be used to underpin (or reject) this assumption?
References
Gosling, L.M., M. Petrie, M.E. Rainy. 1987. Lekking in topi: a high cost, specialist strategy. Animal Behaviour: 35: 2616–618
Kingdon, J. & M. Hoffmann (eds). 2013. The Mammals of Africa. Vol. VI. Pigs, Hippopotamuses, Chevrotain, Giraffes, Deer and Bovids. Bloomsbury Publishing, London.
Packer, C. 1983. Sexual dimorphism: the horns of African antelopes. Science 16: 1191-1193
What was the age of the Roan and Waterbuck with broken horns? My guess is that they were mature to passed their prime animals. The older the animal the higher will be the % with broken horns ! Like canine tooth damage in lions and tigers: old animal have almost always 1 or more damaged canines. Indirectly this also explain the relative rarity of horn breakage reporting: animal with broken horns are old animals less fit and so quickly eaten by opportunistic predators.
Please be referred to my pertinent observation (Oryx) in another Q&A on RG; this unicorn was sighted on private land in the southern Kalahari, Namibia. Further to your conceptual context, antelopes as a category are currently not declining in southern Africa, neither in state protected areas nor on private land; gemsbok, springbok and kudu are almost weeds to be seen live on any trip through the Namibian countryside and on the plate in most restaurants along the road; also other herbivores (e.g. elephant, zebra) are on the increase as well as carnivores (cheetah; lion) although the lion from a low base.
Floodplain antelopes may indeed show a different and long-term trend even here in the South (since the 1970s?). If supported by data, this would be an interesting divergence between dry-land and wetland antelope (bucks/bokkies in local lingo).
What would be the advantage of using horn breakage, a statistic difficult to get, for establishment of population trends based on available data?
Hi Maurizio, thanks for coming back on the issue of age. The 50 (?) cases of 'unicorns' (Kob, Roan, Red-fronted Gazelle, Waterbuck, etc.) that I have observed over a time-span of 20 years do seem to have had a diverse age background...I understand your reasoning and guess it will often be as you described. I have however never seen any work conducted on this, do you ?
Hi Hein, yes there is a major difference between southern vs. western/central and eastern Africa re. the state of antelope (and other wildlife) populations (see also reference below). We have quite a lot of difficulty in assessing antelope population size and especially their dynamics. My gut feeling is that there is shift towards lower population densities that are much more evenly distributed than at previous times. Possibly the horn breakage ('unicorn') phenomenon helps in understanding that…
Article Towards Understanding Large Mammal Population Declines in Af...
- Badges
- Science topic
- Similar topics
- Biological Science
- Zoology