TY - JOUR
T1 - Resolving a conservation dilemma
T2 - Vulnerable lions eating endangered zebras
AU - O’Brien, Timothy G.
AU - Kinnaird, Margaret F.
AU - Ekwanga, Steven
AU - Wilmers, Christopher
AU - Williams, Terrie
AU - Oriol-Cotterill, Alayne
AU - Rubenstein, Daniel Ian
AU - Frank, Laurence G.
N1 - Publisher Copyright:
© 2018 O’Brien et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2018/8
Y1 - 2018/8
N2 - When predators are removed or suppressed for generations, prey populations tend to increase and when predators are re-introduced, prey densities should fall back to pre-con-trol levels. In cases of apparent competition where there are alternate abundant and rare prey species, rare species may decline further than expected or disappear altogether. Recently, concern about the impact of recovering predator populations on wildlife in Laikipia County, Kenya, has led to questions of whether lions (Panthera leo, IUCN Red List Vulnerable) exert top-down pressure on Grevy’s zebra (Equus grevyi, IUCN Red List Endangered). We examined effects of lion predation on Plain’s zebra (E. quagga, IUCN Red List Near Threatened) and Grevy’s zebra populations in a 2,105 km2 area defined by lion movements. We used line transect surveys to estimate density of Grevy’s (0.71/km2) and Plain’s (15.9/ km2) zebras, and satellite telemetry to measure movements for lions and both zebras. We tracked lions to potential feeding sites to estimate predation rates on zebras. We compared field-based estimates of predation rates on both zebras to random gas models of encounters that result in predation to ask if lions prey preferentially on Grevy’s zebra at a sufficient rate to drive population declines. Lions preyed on Grevy’s zebra significantly less than expected in 15 of 16 (94%) scenarios considered and lions preyed on Plain’s zebras as expected or significantly less than expected in 15 of 16 scenarios. Population trend of Grevy’s zebra indicates that the Kenya population may be stabilizing. Recruitment rate to the population has tripled since 2004, making it unlikely that lions are having an impact on Grevy’s zebras. In Laikipia County, competitive displacement by livestock (Livestock: Grevy’s zebra ratio = 864:1) and interference competition for grass with Plain’s zebra (Plain’s zebra: Grevy’s zebra ratio = 22:1) are most likely the predominant threats to Grevy’s Zebra recovery.
AB - When predators are removed or suppressed for generations, prey populations tend to increase and when predators are re-introduced, prey densities should fall back to pre-con-trol levels. In cases of apparent competition where there are alternate abundant and rare prey species, rare species may decline further than expected or disappear altogether. Recently, concern about the impact of recovering predator populations on wildlife in Laikipia County, Kenya, has led to questions of whether lions (Panthera leo, IUCN Red List Vulnerable) exert top-down pressure on Grevy’s zebra (Equus grevyi, IUCN Red List Endangered). We examined effects of lion predation on Plain’s zebra (E. quagga, IUCN Red List Near Threatened) and Grevy’s zebra populations in a 2,105 km2 area defined by lion movements. We used line transect surveys to estimate density of Grevy’s (0.71/km2) and Plain’s (15.9/ km2) zebras, and satellite telemetry to measure movements for lions and both zebras. We tracked lions to potential feeding sites to estimate predation rates on zebras. We compared field-based estimates of predation rates on both zebras to random gas models of encounters that result in predation to ask if lions prey preferentially on Grevy’s zebra at a sufficient rate to drive population declines. Lions preyed on Grevy’s zebra significantly less than expected in 15 of 16 (94%) scenarios considered and lions preyed on Plain’s zebras as expected or significantly less than expected in 15 of 16 scenarios. Population trend of Grevy’s zebra indicates that the Kenya population may be stabilizing. Recruitment rate to the population has tripled since 2004, making it unlikely that lions are having an impact on Grevy’s zebras. In Laikipia County, competitive displacement by livestock (Livestock: Grevy’s zebra ratio = 864:1) and interference competition for grass with Plain’s zebra (Plain’s zebra: Grevy’s zebra ratio = 22:1) are most likely the predominant threats to Grevy’s Zebra recovery.
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U2 - 10.1371/journal.pone.0201983
DO - 10.1371/journal.pone.0201983
M3 - Article
C2 - 30157200
AN - SCOPUS:85052807023
SN - 1932-6203
VL - 13
JO - PloS one
JF - PloS one
IS - 8
M1 - e0201983
ER -