Determinants of emigration and their impact on survival during dispersal in fox and jackal populations

Abstract

Animals disperse in response to poor resource conditions as a strategy of escaping harsh competition and stress, but may also disperse under good resource conditions, as these provide better chances of surviving dispersal and gaining fitness benefits such as avoiding kin competition and inbreeding. Individual traits should mediate the effect of resources, yielding a complex condition-dependent dispersal response. We investigated how experimental food reductions in a food-rich environment around poultry-growing villages interact with individual-traits (age, gender, body-mass) in two sympatric canids, red foxes and golden jackals, to jointly affect emigration propensity and survival during dispersal. Sub-adult foxes emigrated more frequently from the food-rich habitat than from the pristine, food-limited habitat, while adult foxes showed the opposite trend. During dispersal, adults exhibited lower survival while sub-adults did not experience additional mortality costs. Although fox mortality rates increased in response to food reduction, dispersal remained unchanged, while jackals showed strong dispersal response in two of the three repetitions. Jackal survival under food reduction was lowest for the dispersing individuals. While resources are an important dispersal determinant, different age classes and species experience the same resource environment differently and consequently have different motivations, yielding different dispersal responses and consequences.

Feeding responses of the golden jackal after reduction of anthropogenic food subsidies

“…During the winter, the amount of available food is relatively scarce [17, 46] without anthropogenic food subsidies (S1 Film). With these, as in our study area, jackals were the heaviest in the December-April period, which is also the mating season of the jackal [40], which is associated with more intense daily and territorial activity [11, 21, 31] and therefore greater energy requirements. Although the amount of the big game viscera drastically declined in spring and summer (period of pupping or calving and early parental care), carcasses were still available in large numbers during this period (it was impossible to remove them all).…”

“…Furthermore, in the second survey, reproduction among one-year old females was also observed. Presumably, food reduction in less productive areas [5, 21] compared to areas of high ungulate density can result in greater impacts of decreasing population density and survival, and increasing home range size of medium-sized canids. To better understand the ecology of the jackal, during a long-term period, for example population size, reproduction and habitat use, parallel with feeding habits should be analysed in relation to food abundance (or: amount of food available).…”

“…It was found [5] that removing anthropogenic food increased home range size and decreased survival of red foxes ( Vulpes vulpes ). Similarly, others [21] found that golden jackal ( Canis aureus ) survival under food reduction decreased and was lowest for dispersing individuals. Experimentally confirmed [22] that human-resource subsidies alter the dietary preferences of dingoes ( Canis lupus dingo ).…”

“…The range and abundance of the golden jackal (hereafter jackal) has been rapidly increasing throughout Europe [27–28]. The population growth and expansion of jackals might be facilitated by several factors, including flexible social behaviour [8, 29–30], varied dispersal patterns [21, 31], legal protection (e.g. in Bulgaria in 60’ [32]), the scarcity of larger competitors [28, 33], poor population management [32], abundant food resources [9, 11, 15, 17], poor sanitation conditions around settlements [6], transformation of habitats (e.g.…”

Why did the buffalo cross the park? Resource shortages, but not infections, drive dispersal in female African buffalo (Syncerus caffer)

“…Matthysen () suggests that increased population density can modify habitat quality, influencing dispersal propensity, for example, western bluebirds ( Sialia mexicana ) produce more aggressive young with high dispersal propensity when nest cavities are limited (Potticary & Duckworth, ). Kapota et al () in an experiment, restricting food sources, found an increased dispersal propensity in golden jackals ( Canis aureus ); however, under the same conditions red foxes ( Vulpes vulpes ) did not show an increased dispersal propensity. Erigone arctica and E. dentiplapis when starved also showed a decreased propensity to disperse (Bonte, Lukáč, & Lens, ), while increased density dependence did not impact female red deer ( Cervus elaphus ), but decreased male dispersal propensity and increased dispersal distance (Loe, Mysterud, Veiberg, & Langvatn, ).…”