Acoustic Based Kin-recognition And Signal Detection In Azure-winged Magpies

In this research,we studied the acoustic communication during brood period of azure-winged magpies(Cyanopica cyana Pallas)live in Luqu,Gannan city,Gansu province.In first section,we study the kin recognition between parents and their offspring by acoustic comparison analysis.According to the kin selection theory,interaction between individuals was mainly influenced by their relatedness,so creatures should have ability to discriminate related individuals from unrelated individuals.Parental care behavior in brood process is the most efficient model to test such theory.Previous experiential research have shown that adults' provision strategy was affected by their recognition ability.We designed a cross foster experiment and a playback experiment to study the way they constructed the parents-offspring recognition,included when and how.Random cross foster experiment between different nests result in that when the age of foster-parents' nest before 11 days,14 groups of nestling who been relocated into foster-parents' nests were accepted by their foster parents,and raised by their foster-parents to their fledge.Instead,when foster-parents' nest age at 11 days,3 of 8(37.5%)groups of nestling who been relocated were rejected by their foster-parents.At last,their foster parents abandoned the nest.There are in total 6 of 13(53%)nests were rejected by their foster parents when the nestling age from 11 days to 13 days.We concluded the timing of parent-offspring recognition construction is around 11 days after hatch.Logistic generalized liner model(Logistic GLM)analysis show both nestling age and foster parents nest age display positive effect on rejection by foster parents to strange nestling in their own nest.According to the previous research,calls from nestling play an important part in the process of parents-offspring recognition.We suggested the begging calls from nestling can be the signature trait for parents-offspring recognition.We collected begging calls from nestlings whom age from 8 to 13 days.And we compared the Mel-Frequency Cepstral Coefficients(MFCCs)of these begging calls to calculate the distance between different voices.We confirmed that the begging calls have identity intra individual.However the timing of kin recognition construction show delay to the timing of identity express.We speculated several reasons for parent won't recognize their nestling until 11 days.First one is the matter of voice development speed.The speed getting slow after the age of 10 days,so the adults can remember and recognize the characteristics.Another reason is begging calls show no significant differential between inter-siblings and inter-stranger.On the other word,begging calls can't be the label of relatedness.So the EPC events have no selection effect on voice recognition,and parents have no reason to pay extra cost to recognize the offspring during early period.Instead they tend to start identifying their nestling near the day of fledging,so they can find their fledgling in crèche.In second section,we study the mechanism of nestling detect begging calls from adults.According to the inclusive fitness theory and signal detection theory,the evolution of communication system was influenced by selection of signal attenuation and noise interference.Avian usually use acoustic signal to carry out long-range communication.But ambient noise affect this acoustic communication systems seriously.Different species evolved different way,including manipulate the feature of acoustic signal and change detection rules,to improve the efficiency of acoustic communication system,and increase the possibility of correct response and avoid mistake.Breeders use begging calls to stimulate nestling for begging is the most frequent communication situation.We use a play back experiment to study the frequency dependent signal detection in nestlings.We play different frequency part of begging call to nestlings and record the their response.We find out that at early stage of hatching,nestling show more sensitive to low frequency part than to high frequency part.But instead,their sensitivity to low frequency part getting weak with nestlings growing up;on another side,they become more sensitive to high frequency with their age getting old.Then we play three different frequency voices to nestlings respectively and record their response.Same as before,nestlings show less sensitive to low frequency voice but show more sensitive to high frequency with their age getting old.We consider this phenomenon is adaptive strategy to frequent conspecific noise interfere from neighbors in their high nest density habitat.Such behavior can avoid response to noise and reduce the risk from predator and the energy waste.