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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #312088
Title: Recovery of African wild dogs suppresses prey but does not trigger a trophic cascade

Author
item FORD, A - University Of British Columbia
item GOHEEN, J - University Of Wyoming
item Augustine, David
item KINNAIRD, M - Wildlife Conservation Society
item O'BRIEN, T - Wildlife Conservation Society
item PALMER, T - University Of Florida
item PRINGLE, R - Princeton University
item WOODROFFE, R - Zoological Society Of London

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2015
Publication Date: 10/27/2015
Publication URL: http://handle.nal.usda.gov/10113/61688
Citation: Ford, A.T., Goheen, J.R., Augustine, D.J., Kinnaird, M.F., O'Brien, T.G., Palmer, T.M., Pringle, R.M., Woodroffe, R. 2015. Recovery of African wild dogs suppresses prey but does not trigger a trophic cascade. Ecology. 96(10):2705-2714.

Interpretive Summary: The conservation of large predators has often been viewed has having important effects on ecosystems because predators can limit the abundance of herbivores and their impact on vegetation. We examined whether the restoration of the African wild dog influenced the effect of herbivores on woody vegetation (shrubs and trees) in an African savanna. In 2002, after a 20-year absence, African wild dogs (Lycaon pictus) recolonized the Laikipia Plateau in central Kenya. We studied the effect of this restoration using: (1) an 11-year record of wild dog abundance; (2) surveys of the dominant herbivore (dik-diks) conducted before (1999-2002) and after (2008-2013) wild dog recovery; and (3) two separate, replicated herbivore-exclusion experiments initiated pre- and post-wild dog recovery. The dik-dik population declined by 33% following wild dog recovery, which is best explained by wild dog predation. Dik-dik browsing reduced tree abundance, but the strength of their effects did not differ between pre- and post wild dog recovery. Consequently, and despite the finding that wild dogs reduce dik-dik population and that dik-diks suppress tree abundance, wild dog recovery did not indirectly enhance tree abundance. While the restoration of large carnivores is undoubtedly a conservation priority, our results suggest that effects of such recoveries on the ecosystem depend on many other factors affecting plant-herbivore interactions.

Technical Abstract: Large carnivores can powerfully shape ecosystems by directly suppressing herbivores, thereby indirectly benefitting plants in a process known as a trophic cascade. In 2002, after a 20-year absence, African wild dogs (Lycaon pictus) recolonized the Laikipia Plateau in central Kenya. We hypothesized that wild dog recovery would trigger a trophic cascade via suppression of herbivorous prey (primarily dik-dik, Madoqua guentheri) and the subsequent relaxation of browsing pressure on trees. We tested the trophic-cascade hypothesis using: (1) an 11-year time series of wild dog abundance; (2) surveys of dik-dik populations conducted before (1999-2002) and after (2008-2013) wild dog recovery; and (3) two separate, replicated herbivore-exclusion experiments initiated pre- and post-wild dog recovery. The dik-dik population declined by 33% following wild dog recovery, which is best explained by wild dog predation. Dik-dik browsing suppressed tree abundance, but the strength of suppression did not differ between pre- and post wild dog recovery. Consequently, and despite the presence of top-down forcing between adjacent trophic levels (carnivore-herbivore and herbivore-plant), wild dog recovery did not indirectly enhance tree abundance. A time lag in indirect effects, variation in rainfall, and foraging by herbivores other than dik-dik may have prevented a trophic cascade. While the restoration of large carnivores is undoubtedly a conservation priority, our results suggest that indirect effects of such recoveries are mediated by ecological context.