Black wildebeest
Black wildebeest act as hosts to a number of external and internal parasites. A study of the animal in Karroid Mountainveld (Eastern Cape Province, South Africa) revealed the presence of all the larval stages of the nasal bot flies "Oestrus variolosus" and "Gedoelstia hässleri". The first instar larvae of "G. hässleri" were found in large numbers on the dura mater of wildebeest calves, specially between June and August, and these later migrated to the nasal passages. Repeated outbreaks of mange (scab) have led to large-scale extinctions. The first study of the protozoa in blue and black wildebeest showed the presence of 23 protozoan species in the rumen, with "Diplodinium bubalidis" and "Ostracodinium damaliscus" common in all the animals.
Black wildebeest
A dominant male black wildebeest has a harem of females and will not allow other males to mate with them. The breeding season occurs at the end of the rainy season and lasts a few weeks between February and April. When one of his females comes into estrus, the male concentrates on her and mates with her several times. Sexual behaviour by the male at this time includes stretching low, ears down, sniffing of the female's vulva, performing ritual urination, and touching his chin to the female's rump. At the same time, the female keeps her tail upwards (sometimes vertically) or swishes it across the face of the male. The pair usually separates after copulation, but the female occasionally follows her mate afterwards, touching his rump with her snout. During the breeding season, the male loses condition as he spends little time grazing. Males are known to mount other males.