The Attracting Effect Of Artificial Nest Boxes On Secondary Cavity-nesting Birds And Effectiveness Of Nest Boxes Site

Appropriate cave nests are very important for the reproduction of cavity-nesting birds especially secondary cavity-nesting birds,and they are closely related to the population size and reproductive efficiency of secondary nest birds.Beijing Songshan National Nature Reserve has a large number of young secondary forest,and natural cave are relatively scarce.Artificial nest boxes are common tools for increasing cave nests artificially.People can not only control the site of nest boxes for easy searching,but also design the nest box with different style and material according to the attracting species and experimental plot.In 2016 and 2017,we set out a total of 248 nest boxes in Beijing Songshan National Nature Reserve to attract secondary cavity-nesting birds,increase bird diversity and population size,control forest pests and promot forest ecosystem to develope healthily.In 2016,2017 and 2019,we did bird survey on experimental line and control line through line transect method,analyze the attracting effect of artificial nest boxes on secondary cavity-nesting birds and changes of bird community.The research on selection of different breeding habitats of secondary cavity-nesting birds is of great practical significance for establishing attract strategies of secondary cavity-nesting birds,and it can also provide references for the selection of artificial nest box sites.We analyzed preference for different ecological factors of sencondary cavity-nesting birds in 2017 and 2019,and explored their habitat demand during breeding period.Through clutch size and fledging rate we can verify whether the habitat requirements are consistent with the actual reproduction results.The main results are as follows:(1)The utilization of artificial nest boxesWe used artificial nest boxes attracted 6 species and a total of of 209 nest birds in 2017 and 2019.The success rate of attraction was 52.9% and nest boxes set out too close(average distance 30m)may be the reason of success rate not high.We suggest increasing distance between nest boxes(about 50m)in future experiment to avoid territory competition between birds and improve utilization rate of nest boxes.(2)The attracting effect of artificial nest boxes on secondary cavity-nesting birdsThe result of bird survey in 2016,2017 and 2019 shows that the experimental line Si Gou,which has 54 nest boxes set out,its quantity percentage of secondary cavity-nesting birds increased from 31.03% to 50.00%,evenness index increased from 0.773 to 0.995 from 2016 to 2019.The percentage of secondary cavity-nesting birds,diversity index and Simpson index of secondary cavity-nesting birds in Sigou increased in 2017(one year after nest box were set out),and changed steadily during 2017?2019,indicating artificial nest boxes can attract secondary cavity-nesting birds in a short period and its attracting effect is stable.(3)The utilization of artificial nest boxes by different bird speciesThe quantity percentage of great tits in known species is 57.04%,mean fledging rate(±SD)is 96.39±13.52%,indicating that the artificial nest box has a better attracting effect on great tits.We presume the reasons are:(1)The breeding density of great tits is higher than that of other secondary cavity-nesting birds.(2)The shortest nest distance,average nest distance and average tree height of great tits are more easily to be satisfied compared with willow tits and daurian redstarts,the habitat requirements of great tits are relatively loose.(3)Great tits mainly nesting in middle and late April,they start breeding earlier.(4)Great tits have strong competitive ability,they are relatively bigger than most secondary cavity-nesting birds.(4)Different breeding habitat requirements of secondary cavity-nesting birdsChoose the best GLM model of artificial nest box selection for secondary cavity-nesting birds in different habitats through AIC value.The result shows that the probability of nest boxes being used by great tits is positively correlated to the number of trees(p=0.003)and negatively correlated to the DBH of nest boxes fixed trees(p=0.016)and the number of dead trees(p=0.007).The probability of nest boxes being used by willow tits is positively correlated to the average tree height(p<0.001)and negatively correlated to the DBH of nest boxes fixed trees(p<0.001).The probability of nest boxes being used by daurian redstarts is negatively correlated to the height of nest boxes set out(p=0.024),the DBH of nest boxes fixed trees(p<0.001),the number of dead trees(p=0.009)and the coverage of 3m from the ground(p=0.013).The great tits and willow tits prefer more vegetation coverage to hide while daurian redstarts prefer more vegetation coverage and illumination during breeding.Correlation analysis also shows that the ecological factors which have significant correlation with clutch size and fledging rate are mainly related to illumination.Breeding habitat requirements are consistent with actual reproductive efficiency.Based on the results above,we have suggestions for the selection of artificial nest boxes as follows:(1)Choose dense forest which has tall trees and high concealment to set out artificial nest boxes can improve the safety of the nest boxes and reduce the disturbance of natural enemies.(2)The illumination requirement of birds should be considered as well as safety of the nest boxes,we can through many ways to increase solar radiation,like make nest entrance toward sun etc.(3)We can increase distance between nest boxes to 50 m to reduce pressures of intraspecific and interspecific competition.