The Influence Of Nest Predation Rate To Ground-nest By Common Cuckoo Nestlings Begging Call

Nest predation is an important factor leading to the failure of most bird nests,and it is also an important selection pressure that affects and changes bird life history strategies and behaviors.Nest predation includes predation by natural enemies and man-made destruction.Avian parasitism is also a way of nest predation.Avian parasitism is a kind of social parasitic behavior.It refers to the special breeding behavior that some parasitic birds do not build nests,but lay their eggs in the nests of other host birds.The parasitical nestlings are larger than their hosts,and they get more food for growth by stimulating their parents to increase their feeding frequency through exaggerated and high-frequency begging calls,which are even higher than the sum of the host nest.High-intensity begging calls are more likely to increase the localizability of predators,which may increase the risk of nest predation.But the latest research on the effect of parasitic begging calls on nest predation rates shows that the high intensity of parasitic begging calls does not increase the risk of nest predation,however,this conclusion may not be applicable to terrestrial nests that are already at high risk of predation.In order to investigate the impact of parasites' begging calls on the predation risk of ground nests,in this study,the Common cuckoo(Cuculus canorus)nestlings and three local ground-nesting birds nestlings in the Liuzhi Special,Guizhou,from April to August 2020— —Grey Bushchat(Saxicila ferreus),Siberian Stonechat(Saxicila maurus),and Godlewski's Bunting(Emberiza godlewskii)nestlings begging to record and analyze and compare various characteristic parameters of sounds,combined with comparisons of predation rate between parasitic nests and natural nests in previous years and artificial nest playback experiments to explore the impact of the cuckoo's nestlings begging call on the predation risk of ground nests,so as to further explore and discover ground nest anti-predation and anti-parasitic life history strategies.The results from 2018 to 2019 showed that the predation rate of the parasitic nest of common cuckoo was significantly higher than that of the natural nest,and the predation rate of the recorded nest was also higher than that of the natural nest.Analysis of recorded begging calls showed that the common cuckoo nestlings begging calls were higher than those of three ground-nesting nestlings,but the call rate was significantly lower than that of grey bushchat and siberian stonechat,looking at the spectrogram,it was found that the structure of the begging call of the common cuckoo nestlings was similar to the begging calls of the grey bushchat and siberian stonechat nestlings,but quite different from that of the godlewski's bunting nestlings.In the local area,the common cuckoo is hosted by grey bushchat and siberian stonechat,which indicates that the higher begging call of the common cuckoo increases the predation risk of the ground nests.However,in terrestrial habitats where predation risk is already high,the common cuckoo may inhibit begging behavior and reduce the begging call rate,preferring instead to manipulate the host to increase feeding by mimicking the begging calls of the host nestlings,to reduce the chance of being spotted by predators.The experiment group and the control group were set up in the artificial nest playing experiment.The sound of common cuckoo begging call and the blank clip were played respectively,and the results of predation were recorded.However,the results showed no difference between the two groups.This results suggest that the loud begging call of common cuckoo may not be an important factor in the high predation rate.However,the reason of this result may be that the sample size is insufficient,the experimental condition is different from the natural condition,so the result has deviation.In conclusion,the results suggest that the high begging call of common cuckoo nestlings in parasitic nests is one of the factors affecting ground nest predation risk in high-risk terrestrial habitats.In addition to the parasites begging calls,the influence of nest parasitism on the ground nest predation risk,that is,the higher predation rate of the parasitic nest than that of the natural nest,may also be due to the behavior of the common cuckoo in arching its host offspring and the longer time of brooding,all of this increases the chance that the nest will be found by predators.