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Recovery of African wild dogs suppresses prey but does not trigger a trophic cascade
Author(s) -
Ford Adam T.,
Goheen Jacob R.,
Augustine David J.,
Kinnaird Margaret F.,
O'Brien Timothy G.,
Palmer Todd M.,
Pringle Robert M.,
Woodroffe Rosie
Publication year - 2015
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/14-2056.1
Subject(s) - trophic cascade , trophic level , biology , herbivore , predation , ecology , population , abundance (ecology) , foraging , food web , demography , sociology
Increasingly, the restoration of large carnivores is proposed as a means through which to restore community structure and ecosystem function via trophic cascades. After a decades‐long absence, African wild dogs ( Lycaon pictus ) recolonized the Laikipia Plateau in central Kenya, which we hypothesized would trigger a trophic cascade via suppression of their primary prey (dik‐dik, Madoqua guentheri ) and the subsequent relaxation of browsing pressure on trees. We tested the trophic‐cascade hypothesis using (1) a 14‐year time series of wild dog abundance; (2) surveys of dik‐dik population densities conducted before and after wild dog recovery; and (3) two separate, replicated, herbivore‐exclusion experiments initiated before and after 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 before and after wild dog recovery. Despite strong, top‐down limitation between adjacent trophic levels (carnivore–herbivore and herbivore–plant), a trophic cascade did not occur, possibly because of a time lag in indirect effects, variation in rainfall, and foraging by herbivores other than dik‐dik. Our ability to reject the trophic‐cascade hypothesis required two important approaches: (1) temporally replicated herbivore exclusions, separately established before and after wild dog recovery; and (2) evaluating multiple drivers of variation in the abundance of dik‐dik and trees. While the restoration of large carnivores is often a conservation priority, our results suggest that indirect effects are mediated by ecological context, and that trophic cascades are not a foregone conclusion of such recoveries.