Why African wild dogs move outside the safety of a protected area; - - PowerPoint PPT Presentation
Hwange LTER Why African wild dogs move outside the safety of a protected area; testing the Ecological trap hypothesis for African wild dogs in and around Hwange National Park, Zimbabwe Esther van der Meer Dr. H.Fritz Dr. G.S.A. Rasmussen
testing the Ecological trap hypothesis for African wild dogs in and around Hwange National Park, Zimbabwe
Esther van der Meer
Hwange LTER
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Endangered social carnivore with large territories and high energetic requirements
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Territorial drift of African wild dog packs in Hwange National Park (HNP)
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Litter size in relation to distance of the territory to the Hwange National Parks (HNP) border
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Snare Car Shot Lion and Hyena Starvation Natural Unknown Total Inside HNP % 0.0% 5.4% 0.0% 17.2% 12.9% 20.4% 44.1% 28.4% Nr 5 16 12 19 41 93 Outside HNP % 25.6% 12% 18.8% 3.9% 11.5% 9.8% 18.4% 71.6% Nr 60 28 44 9 27 23 43 234
Main causes of mortality inside and outside Hwange National Park (HNP)
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Location territory Pack size start Pups born Mor tality pups Mor tality ad/yy Immi gra tion Dis per sal Pack size end Re cruit ment Inside HNP Mean 4.94 4.11 2.06 0.50 0.00 0.50 6.00 1.06 (n=18) SE 0.57 0.74 0.49 0.17 0.00 0.29 0.84 0.49 Border Mean 4.97 4.88 2.55 1.48 0.39 1.21 5.00 0.03 (n=33) SE 0.42 0.71 0.44 0.37 0.24 0.32 0.51 0.56 Outside HNP Mean 5.23 7.23 4.54 2.54 0.23 2.00 3.62
(n=13) SE 1.09 1.73 1.25 0.87 0.12 1.12 0.82 1.34 Total Mean 5.02 5.14 2.81 1.42 0.25 1.17 5.00
(n=64) SE 0.34 0.56 0.38 0.27 0.13 0.29 0.40 0.43
Average recruitment in relation to territory placement in, at the border or outside Hwange National Park (HNP)
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Animals migrate into low quality sink habitat (mortality>natality) when there is not enough high quality source habitat (mortality<natality) available (sink)
Animals migrate into low quality sink habitat (mortality>natality) even when there is enough high quality source habitat (mortality<natality) available (attractive sink – unaccounted risks – Extirpation!)
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Diet composition inside and outside Hwange National Park (HNP)
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Inside HNP Outside HNP Success Failure Success Failure Overall % 50.81 49.19 63.03 36.97 Nr 63 61 104 61 Main prey % 59.46 40.54 78.89 21.11 Nr 44 30 71 19 Impala % 65.00 35.00 86.92 23.08 Nr 26 14 30 9 Kudu % 44.83 55.17 84.38 15.63 Nr 13 16 27 5 Hunting success in and outside Hwange National Park (HNP)
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Chase dist (km) Inside HNP Outside HNP Overall 1.09 (n=35, SE=0.18) 0.87 (n=68, SE=0.13) Main prey 1.40 (n=24, SE=0.22) 0.91 (n=45, SE=0.17) Impala 1.28 (n=11, SE=0.23) 1.05 (n=17, SE=0.21)) Kudu 1.79 (n=10, SE=0.44) 1.14 (n=17, SE=0.37) Duiker 0.55 (n=3, SE=0.24) 0.33 (n=11, SE=0.08)
Chase distance in and outside Hwange National Park (HNP)
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Available vegetation in and outside Hwange National Park (HNP) based on random sites (n=148) Vegetation types in which African wild dogs made impala (n=41) and kudu (n=35) kills inside and outside Hwange National Park (HNP)
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Lion and/or Hyena Inside HNP Outside HNP Presence 16,23% (n=31) 5.65% (n=17) Kleptoparasitized 9.42% (n=18) 2.66% (n=8) Defended 6.80% (n=13) 2.99% (n=9) Mean lapse time (min) ± SE 11.33 ± 2.57 18.80 ± 4.32 Presence of, and kleptoparasitism by lion and hyena inside and outside Hwange National Park (HNP)
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Criteria to identify an Ecological trap (Robertson & Hutto 2006): 1) Preference or equal preference for one habitat over the other 2) Measure to allow idenitification of fitness differences 3) Fitness outcome in preferred habitat should be lower
Ecological trap = attractive sink = animals choose to be in habitat in which mortality exceeds natality This choice is based on formerly reliable cues that are no longer associated with an adaptive outcome due to a sudden environmental change
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