Study On The Patterns Of Vocal Activity And Interspecific Relationship Of The Cuculidae Species In Dabie Mountains

Human’s industrial production activities have brought negative impacts on the environment,such as habitat fragmentation,loss of species diversity,etc.Birds are sensitive to environmental changes,and bird species diversity can serve as an effective indicator of the health of the ecological environment.Monitoring vocal activity is an effective and low-cost way to monitor bird species diversity.To monitor bird species diversity by monitoring vocal activity,it is necessary to have basic knowledge of the patterns of vocal activity.Acoustic signal is an important method of communication,vocal activity of birds plays an important role in attracting mates and defending territories.The patterns of vocal activity are affected by internal factors(hormones),external factors(meteorological factors,vegetation cover,etc.)and social factors,among which social factors include intraspecific relationship(spouse availability,the number of potential invaders)and interspecific relationship.The"acoustic niche hypothesis" suggests that closely-related interspecific relationships may result in differences in vocal activity patterns which means acoustic niche partitioning in vocal activity.At present,little is known about how external meteorological factors and interspecific relationships influence the vocal activity patterns of birds.This study will answer these questions by monitoring the vocal activity patterns of Cuculidae species.Song Meter 4+(SM4+)was used to monitor the sounds of the ecosystem in Yaoluoping National Nature Reserve(YNNR),which located in the hinterland of Dabie Mountains.Seven Cuculidae species were identified and diurnal and seasonal patterns of vocal activity were analyzed.The influence of interspecific relationship of Cuculidae species and external meteorological factors on vocal activity patterns were explored and the results of the study are as follows:(1)Identification of target species and classification based on features of calls.By listening to the recording and combining with field observations,seven species of Cuculidae family were identified,including Indian Cuckoo(Cuculus micropterus),Himalayan Cuckoo(Cuculus saturatus),Common Cuckoo(Cuculus canorus),Lesser Cuckoo(Cuculus poliocephalus),Asian Koel(Eudynamys scolopaceus),Large hawkCuckoo(Hierococcyx sparverioides),and Chestnut-winged Cuckoo(Clamator coromandus).140,445 calls of these species were counted in total.Six features were extracted from the calls of seven Cuculidae species:minimum frequency,maximum frequency,center frequency,peak frequency,frequency bandwidth and duration.The classification model was established based on principal component analysis(PCA)and linear discriminant analysis(LDA),and the overall classification accuracy was 95.95%.Only two pairs of species(E.scolopaceus and C.micropterus,H.sparverioides and C.poliocephalus)were easily misclassfied during classification.The results showed that acoustic signals of the seven Cuculidae species’ could be distinguished effectively,indicating that seven species are partitioned in their acoustic signal space.(2)Diurnal and seasonal patterns of the vocal activity of birds.The call numbers of C.micropterus was the lowest and diurnal and seasonal patterns of C.micropterus were evenly distributed.The remaining six species exhibited significant diurnal and seasonal variations.As for the diurnal patterns,E.scolopaceus and C.saturatus increased their vocal activity at dawn and dusk and showed bimodal patterns.C.coromandus showed a unimodal pattern with peak values at 1:00 a.m.and the other three species exhibited unimodal patterns and peaked their vocal activity in the morning at about 4:00 or 5:00 a.m.As for the seasonal distribution patterns,five species showed significant seasonal variations with a peak in vocal activities earlier in the season(late May or early June)and a gradual decline after that,except for C.coromandus,which displayed two peaks(early June and early July)in seasonal calling activity.(3)The influence of temperature and humidity on the daily patterns of vocal activity.The results showed that the vocal activity of H.sparverioides and C.saturatus decreased significantly with the increase of temperature.The vocal activity of C.saturatus increased significantly with the increase of humidity.However,A similar increase in vocal activity for C.coromandus was observed as humidity increased,reaching a peak,and then decreased.(4)The influence of interspecific relationships on the vocal activity patterns.The partitioning of vocal activity in the acoustic niche was analyzed from the three acoustic dimensions(space,frequency,and time).The results indicated that the overlap in seasonal and diurnal patterns of the seven species’ vocal activity are very high;however,the actual time overlaps are very low,suggested that these species did not call simultaneously.Although,there is overlap in frequency range of some species’signals,but overall,these seven species exhibited partitioning in at least one of the three acoustic dimensions and avoid masking each other’s signals,which suggests that the mechanisms of acoustic partitioning in these species may be flexible due to complex ecological factors.Therefore,the vocal activity patterns of Cuculidae species are closely related to their interspecific competition.Using passive acoustic monitoring technologies,this thesis found that six of the seven Cuculidae species showed significant variations in the diurnal and seasonal patterns of vocal activity.The patterns of the vocal activity were not only associated with the interspecific relationship in the community,but also significantly related to meteorological factors.Therefore,it is an effective method to monitor bird diversity and interspecific relationship changes based on acoustic monitoring.The results of this study provide an important reference for further studies to track the changes of the ecosystem and biodiversity.