The impact of lions on the demography and ecology of endangered African wild dogs

Abstract

It has long been recognized that superior carnivores can impact on the demography and ecology of smaller members of the guild, although exact mechanisms remain unclear. Here we use original data from a unique natural experiment to study some of the mechanisms by which African lions Panthera leo impact on African wild dogs Lycaon pictus. Using a study site where wild dogs outnumbered lions for several years prior to lion population recovery, we aimed to investigate whether or not, and by which means, wild dog populations are regulated and influenced by lions. We used 38 pack‐years of demographic and behavioural data across two 4‐year periods where lion density differed 20‐fold (pre‐lion era: 1996–1999 and lion era: 2010–2013) to assess how lions may affect wild dog pack size and age structure, litter size and pup survival (n = 329 pups), as well as den site selection (n = 46 dens). Pack size was significantly greater during the pre‐lion era. The pup to adult ratio was lower during the lion era and the change in pack composition was directly attributable to significantly greater lion‐induced pup mortality. We also demonstrate a behavioural shift, with locations selected for the vulnerable denning period being in more rugged terrain and in areas with lower prey densities during the lion era, as compared with the pre‐lion era. Lower adult recruitment into a population of an obligate cooperative breeder like the African wild dog can have complex consequences, including on feeding and defence of young, and mate finding.

Niche overlap and dietary resource partitioning in an African large carnivore guild

“…The expected expansion in protected area size by 53.55 km 2 will increase the estimated population size of wild dogs by a single individual. Our estimate of seven adult members is within the range analogous to the mean pack sizes observed in other savanna ecosystems (Fuller et al, ; Somers et al , ; Groom, Lannas & Jackson, ). The ratio of lions, leopards and cheetahs to wild dogs is expected to approximate to 4:2:1:1, respectively.…”

Hot dogs: High ambient temperatures impact reproductive success in a tropical carnivore

“…Equally, however, rising ambient temperatures could provide an alternative explanation for declining wild dog body size; similar effects have been documented repeatedly in other species (Gardner, Peters, Kearney, Joseph, & Heinsohn, ), potentially because smaller‐bodied animals have greater capacity to dissipate heat (Speakman & Krol, ). Further study would be needed to disentangle the inter‐relations between climate change, prey abundance, body size, and reproductive success (at our other sites, prey densities declined over the monitoring period in Kenya (Ford et al., ) but increased in Zimbabwe (Groom, Lannas, & Jackson, )). Nevertheless, this alternative explanation for the year‐on‐year trend in recruitment in Botswana does not undermine the clear link between high ambient temperatures and low reproductive success documented across all three sites.…”

No evidence of handling‐induced mortality in Serengeti's African wild dog population

“…The resulting spatial variability in lion and hyaena densities facilitates avoidance by subordinate wild dogs (Mills & Gorman, ) and the development of a landscape of fear where high‐risk habitats are avoided and competition refuges are actively selected, particularly during the vulnerable denning season when rugged and densely vegetated areas, with fewer lions, are selected by wild dogs (Davies, Marneweck, Druce, & Asner, ; Jackson et al, ). Indeed, fluctuations in lion densities have been shown to elicit changes in wild dog behavior and habitat selection (Groom et al, ). In the absence of strong top‐down regulation, behavioral flexibility would likely see profitable habitats, such as the plains, being exploited.…”

“…What then could have caused the wild dog population decline and disappearance, and still hinder recovery decades later? Evidence from several ecosystems indicates that wild dogs are vulnerable to competition from lions and hyaenas, both through direct mortality (Groom, Lannas, & Jackson, 2017;Woodroffe & Ginsberg, 1999) and kleptoparasitism (Carbone et al, 2005). The high risk posed by lions results in wild dogs avoiding them at all times (Webster, McNutt, & McComb, 2012) and, at the landscape scale, wild dog densities are inversely correlated with lion and spotted hyaena densities (Mills & Gorman, 1997).…”