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Vulture Ecology and Conservation

Vultures are the only vertebrates that feed exclusively on carrion. The unpredictability of this resource is a strong selective force on the morphology and behaviour of these scavenging birds. At TCD we have explored the adaptations of vultures to this unique mode of life with a combination of theoretical modelling and field work which has involved international collaborations. Dr Adam Kane has joined this list of collaborators in his new position since graduation with a PhD from my group in 2014. This research is timely given the precarious state of many vulture populations.

Social behaviours are common among many of the Gyps species. One piece of our research has helped us understand why these animals roost communally (Dermody et al 2011); by being clumped in space the birds can form foraging groups each morning which allows them to better discover food. While in flight, vultures keep in visual contact with each other, often following a bird that has discovered a carcass to the ground. By using computer models we demonstrated how this social foraging will suffer as their populations decline (Jackson et al 2008). Fewer birds mean less efficient foraging.

In collaboration with researchers in Kenya and Swaziland we showed how vultures also take visual cues from scavenging eagles (Kane et al 2014). The low flying eagles typically arrive to a carcass before the vultures but once they have made their discovery the vultures follow and fight them off the food.

Aside from poisoning, one of the major threats to the future of these scavengers is declining food availability. One of our most recent papers was developed in combination with researchers from the University of Bern underscored this threat by modelling the amount of carrion available to the avian scavenging guild of Swaziland (Monadjem et al 2014). We identified periods of food scarcity and recommend creating supplementary feeding stations, so-called ‘vulture restaurants’ to compensate for this hazard.

In the near future we hope to develop our field site in Swaziland which is being fitted with a vulture capture site so that we can tag the birds to investigate their movement ecology. Discovering where and when these wide-ranging birds fly is important for their international conservation given how easily they can pass over national borders.

We have also employed similar foraging models for gannets to help explain the behavioural mechanisms behind the pattern of 12 neighbouring colonies that forage in mutually exclusive areas. Although driven by density-dependent competition, our behavioural models showed that information transfer on food location at colony sites leads to cultural evolution and divergent strategies among colonies (Wakefield et al 2013).

Kane, A., Jackson, A.L., Ogada, D.L., Monadjem, A. & McNally, L. 2014. Vultures acquire information on carcass location from scavenging eagles. Proceedings of the Royal Society of London B, 281 (1793) doi

Monadjem A., Wolter K., Neser W. & Kane A. 2014. Effect of rehabilitation on survival rates of endangered Cape vultures. Animal Conservation, 17(1), 52-60. doi

Kane, A., Jackson A.L., Monadjem, A., Colomer, M. A. & Margalida, A. In press. Are vulture restaurants needed to sustain the densest breeding population of the African White-backed Vulture? Animal Conservation doi

Wakefield, E.D., Bodey, T.W., Bearhop, S., Blackburn, J., Colhoun, K., Davies, R., Dwyer, R.G., Green, J., Grémillet, D.,Jackson, A.L., Jessopp, M.J., Kane, A., Langston, R.H.W., Lescroël, A., Murray, S., Le Nuz, M., Patrick, S.C., Péron, C., Soanes, L., Wanless, S., Votier, S.C., & Hamer, K.C. 2013. Space Partitioning Without Territoriality in Gannets. Science, 341(6141), 68-70. doi

Dermody, B.J., Tanner, C.J. & Jackson, A.L. 2011. The evolutionary pathway to obligate scavenging in Gyps vultures. PLoS ONE 6(9) e24635. doi (Open Access)

Jackson, A.L., Ruxton, G.D. & Houston, D.C. 2008. The effect of social facilitation on foraging success in vultures: a modelling study. Biology Letters 4(3) 311-313. doi