| Life-history theory predicted that animal need to balance between the anti-predation behavior and foraging for living and reproduction.Resent decades,animals were facing the challenges of adapting behavior appropriately under these new conditions introduced by humans.Human activities have both lethal and non-lethal effects on wild species,and wildlife usually consider human as potential predator and the frequent of human disturbance was one of the essential problem of wild animal invading man-made area.Flight initiation distance(FID)is defined as the distance between the flight animal and the approaching predator,which usually used as a standard and reasonable measure to estimate animals’ risk-taking behavior,and reflect the animals’ trade-off between energy needs and predation risk.Crested ibis(Nipponia nippon)is a medium-size wading bird and an "Endangered" species,and the unique wild population was distributing on southern Qinling Mountain.Since its rediscovered in a small mountain area(original habitat)in 1981,the wild population of crested ibis has been increased from 7 individuals to more than 1100 in 2014,and some of this population expanded and started to breed in lower plain areas(expanding habitat)since 1997.This ibis shows strong fidelity of the previous nest site if not disturbed,and to date,almost 21.1%of the crested ibis breeding in the plain area.The expanding habitat which has dense villages and large area of continuous cultivated land,and possess lower elevation and extremely more human disturbance.To test the anti-predation strategy at foraging in this unique wild population of crested ibis from original and expanding habitats,we test the influence of environmental factors,human disturbance and their interaction in ibis’s FID.In addition,to test the variation of these anti-predation strategy under different life-history pressure,we also analyses the FID in different season from two habitats.So we(a)tested the repeatability of FID in crested ibis;(b)evaluated the potential factors that affect crested ibis’s FID in two habitats;(c)the variance of FID during seasons;and(d)the different anti-predation strategy under two habitats and seasons.(1)To make sure the FID was a stability index of ibises’ risk-take behavior,we first test the consistence of FID during individuals.We collected a total of 192 flight initiation distances in adult foraging crested ibis from May to October 2015.The average FID was 25.54(SD=8.790),rang from 9.10 to 54.60m.We measured FIDs twice for 16 adult individuals at the same habitat in the same season.The repeatability of flight distance in these adult individual was 0.554(SE=0.176,P<0.001).(2)Crested ibises foraging in expanding habitat showed a significant shorter FID than they in original area(Mean±SE:24.86±0.82 m vs 30.08±0.89 m,F1,174=24.93,P<0.001).And the local terrain factors,landscape openness and the width of the valley,have no effect on ibises’ FID,which suggested that ibises foraging in expanding habitat have relatively higher tolerance of human than those in original habitat,and independence with local terrain.(3)Totally 236 FIDs were recorded with the average distance as 27.65±9.29m,ranging from 9.1 to 54.6m.The FID was significantly different among three seasons(F2,236=25.26,P<0.001;Fig.l)as the shortest FID in breeding season,with an average of 23.93±10.36m and the longest FID(33.83±7.90m)in winters on average.Ibis tend to take more predation risk in reproduction period,may because of they suffer from increased foraging pressure,and higher energy expenditure for themselves while feeding the nestlings.Moreover,the longer FID in winter might be caused by the low survival rate.(4)The landscape environments show a significant difference between two habitats,the human activity was significantly higher in expanding habitat and ibis foraging in expending habitat site significant closer away from residence compare to ibis foraging in original habitat(distance from residence:F1,158=8.62,P=0.004;human activity:F1,172=1.35,P<0.001).Human activity in breeding season was relatively higher than that of in wandering season(F1,110=22.30,P<0.001),while the distance of foraging site to road among breeding was shorter than wandering season(F1,174=12.36,P<0.001),which consist with our finding in FID,ibis in breeding season and foraging in expanding habitat shows more tolerance to human disturbance.We suggest,crested ibis breeding in expanding habitat show a higher tolerance to human disturbance which was serious in this area and breeding season,which may imply these ibis facing an extremely pressure.This may the reason there was a fraction of population could breeding in expanding area.So we suggest,the human activities,such as ecological tourism and photography,should be limited in this area and season,and the warning signs or rail was necessary for protect crested ibis in a certainly distance from human. |
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