their prey spectrum: impala (Aepyceros melampus), hartebeest (Alcelaphus buselaphus), bontebok (Damaliscus pygargus), common tsessebe (Damaliscus lunatus), springbok (Antidorcas marsupialis), Eudorcas gazelles, gerenuk (Litocranius walleri), bushbuck (Tragelaphus sylvaticus), grey rhebok (Pelea capreolus), kob (Kobus kob) and mountain reedbuck (Redunca arundinum). These species can vary in weight from (i.e. gazelles) to (i.e. tsessebe) in newborns. For the newborn impala, weighing already , the martial eagle is the only bird considered to be a significant predator. Additionally, piglets of warthogs (Phacochoerus africanus) (of which only the martial eagle among accipitrids is similarly mentioned as a significant predator) and bushpigs (Potamochoerus larvatus) are taken. Adults of other small antelope such as suni (Neotragus moschatus) and blue duikers (Philantomba monticola) are probably also taken with relative ease. In general, the young of other antelope are usually attacked, including newborns. Occasional ambush attacks or successful predations are reported on adults of much larger species despite young ones being rather more vulnerable, including klipspringers (Oreotragus oreotragus), steenboks (Raphicerus campestris), both species of grysbok ( on average), oribis (Ourebia ourebi) and perhaps up to half a dozen larger duikers, potentially weighing from . One duiker dispatched via strangulation weighed an estimated , one of the largest known raptorial kill for any species on the African continent. Among extant birds of prey, only wedge-tailed eagles, reportedly capable of killing sheep and female red kangaroos (Macropus rufus) weighing up to , crowned eagles taking antelope of the same estimated weight and golden eagles, credited with taking adult female deer of several species with weights estimated at , and capable of apparently dispatching domestic calves weighing up to , have larger kills attributed to them. Birds Compared to the range and sizes of mammals included in their prey spectrum, birds taken by martial eagles may seem less impressive as a whole, but the morphology of the martial eagle, including large wing surface areas, pronounced sexual dimorphism and relatively long toes, shows that the species is at least partially specialized to hunt avian prey. Birds are universally considered by biologists more difficult to capture than mammals of the same size. In all, more than 50 bird species have been identified as the prey of martial eagles. The most significant portion of the avian diet is comprised by medium-sized terrestrial upland birds such as guineafowl, spurfowl, francolins and bustards. In total more than a dozen species of the galliform order and the bustard