Bird Diversity In Nanjing Laoshan Based On Scientific Monitoring And Public Birding

A series of threats such as habitat loss and fragmentation,and the increasing urbanization process caused by human interference have posed serious threats to bird diversity.Monitoring bird diversity in urban mountains can help to fully understand the disturbed habitat status of bird resources,which is important for future scientific conservation and management of species resources.The Laoshan Mountain Range is a typical urban mountain range located in Nanjing,Jiangsu Province,the main part of which includes the Laoshan Forest and the Laoshan National Forest Park established that on the basis of it.Laoshan has always been one of the areas with the richest bird diversity in Nanjing;it also attracts many birdwatching enthusiasts due to its advantageous location,convenient transportation and ecological environment.In this study,the bird diversity in the Laoshan area was investigated in the field using the line transect from July 2020 to June2021.The relationship between vegetation characteristics,landscape structure and bird diversity in the study area was also analyzed using multivariate linear models.Considering that the status of bird diversity may not be completely recorded by a single method,infrared camera technology was used to conduct additional surveys from October 2020 to October 2021.At the same time,publicly available birdwatching data from July 2015 to June 2022 were collected,and the species composition of birds recorded by public birdwatching activities was counted.These data that obtained from scientific monitoring and public birdwatching were compared each other,and the similarities and differences between different bird diversity monitoring methods were compared to explore their advantages and shortcomings in the bird monitoring process.The main findings were as follows:(1)A total of 19,853 bird individuals were recorded,which belong to 131 species,43 families,and 16 orders,were recorded by the line transect.The Spring has with the highest species richness(112 species)and Shannon diversity(3.72),while the autumn has the highest number of bird individuals(7167).The area with the highest bird species richness was Siwa Reservoir(82species),the highest number of bird individuals was also Siwa Reservoir(1814),Dadingshan Reservoir(3.79)was the area with the highest Shannon diversity index.The results of model fitting showed that water landscape ratio,landscape heterogeneity,average height of arbors,herbage coverage could explain the variation of Shannon diversity index,and all of them were positively and significantly correlated with Shannon-Wiener diversity index.(2)A total of 25 species,belong to 11 families,and 6 orders were recorded by the infrared camera,with 4 species of national class II protected animals.Among all recorded species,the highest three species with effective detections observations were Oriental turtle dove(Streptopelia orientalis),Little egrets(Egretta garzetta)and Masked laughingthrush(Garrulax perspicillatus),which accounted for 22.8%,10.1% and 9.7%,respectively.(3)From July 2015 to June 2022,data of 144 bird species,which belong to 44 families,16 orders,were recorded in Laoshan from public birding.The number of species recorded varied from year to year,with an average of 92.14 ± 6.50 species annually,of which 117 species were recorded between July 2020 and June 2021,accounted for 81.25% of all bird species recorded by public birding.Birding activities mainly occurred in May-June,and observation sites were concentrated in the southwestern and central parts of the study area.Comparing the reporting rates of species between bird watching and line transect,the largest differences in reporting rates were breeding birds,raptors,and rare birds in this study area.The average number of bird species recorded per trip by birdwatchers was greater than that monitored by the sample line method,with 22.32±13.27 species for birding and 19.81±6.84 species for the line transect.(4)Based on the line transect,infrared camera technology and public birding,as of June2022,150 species of birds belonging to 44 families,16 orders,were recorded in Laoshan area.131 bird species were recorded from the line transect,25 species were from the infrared camera,and 144 species were from the public birding activities,which accounted for 87%,16%,and 96%of all bird species recorded,respectively.There were 23 bird species recorded by only one monitoring method,of which only 5 species were from the line transect and 18 species were from birding.Compared with the historical bird records of Laoshan,55 new bird species were recorded in this study.In summary,the landscape heterogeneity and the complex and diverse vertical structure of vegetation play an important role in maintaining the local bird diversity in Laoshan.Therefore,the homogenization of the landscape structure and vegetation structure on bird diversity should be avoided in the process of development and construction.the camera-trapping technology is less effective than that of the line transect or public birding in Laoshan area.For both the line transect and public birding,neither method can completely record all birds in the study area in the short term,but both of them can compensate for each other.From the longterm effects,public birding can increase the chance of discovering new species record potentially.However,public birding activities are easily influenced by participants’ preferences,with biases in time,space,and species reporting rates.In order to reduce the biases in citizen science data sets,and hence provides a broader data base for bird research and conservation,a further design and specification of public birding,therefore,need to be strengthened.