Nest Microclimate Adjustment Strategies In Three Secondary Hole-nesting Birds

For birds,nests microclimate is one of key factors influencing reproductive success.To maximize the reproductive fitness,birds adjust their nests microclimate by selecting the nest entrance orientation and nest materials,changing the nest material input,etc.At present,studies on nest microclimate of secondary-hole nesting birds are mostly restricted to a single species or a single factor,and interspecies comparison and multi-factor comprehensive research are lacking.In this study,I would like to figure out nest microclimate adjustment strategies in three secondary hole-nesting birds,Great tit(Parus major),European nuthatch(Sitta europaea)and Yellow-rumped flycatcher(Ficedula zanthopygia).We recorded the nest temperature at incubation period,hole entrance orientation and degree form horizon,insulation and drying rate of nest materials,and nest material input as multi-factors concerned with nest microclimate adjustment.The three species bred in artificial nest boxes during March to July of 2016 and 2017 at Zuojia Nature Reserve of Jilin Province.We obtained the major results and conclusions as follows:The three species start to breed variedly,,but there is no significant difference of maximum temperature and mean temperature in nests at incubation period among them,which suggests that all of them can regulate the nest microclimate to keep the temperature at the same level.The selection of hole entrance orientation might be effected by the local prevailing northwest wind and solar radiation during the early breeding season.The northwest-facing holes were little used by the three species(Great tit: 17.1%,European nuthatch: 18.8%,Yellow-rumped flycatcher: 15.8%),because they receive the least amount of solar radiation and face the wind.European nuthatch occupied most northest and southest facing holes(60.8%).It might be related that the population of European nuthatch has the earlist breeding season,so the individuals have proporties for the optimal nest-sites.Great tit and Yellow-rumped flycatcher used northest,southest and southwest facing holes evenly.All of the three species tend to select the nest boxes with a downward hole entrance angle to prevent rain from entering the nest.The selection of nest material might be related to the difference of breeding season and behavior characteristics among the three species.The insulation of nest materials of Great tit and European nuthatch are better than Yellow-rumped flycatcher.This could be due to the breeding seasons of the first two species are earlier,the environmental temperatures are lower,so the insulations for them are more critical than Yellow-rumped flycatcher,The soakage of nest materials in Yellow-rumped flycatcher is lower than European nuthatch,but the reverse for the drying rate.This may be caused by the increasing rainfall in breeding phase.The latter species was in the end of breeding season when the rains came,and the habit of plastering the hole entrance(behaviour non-existent in Yellow-rumped flycatcher)reduced the inundation risk,but the former was in breeding which was effected by rainfall very much.The difference of nest insulation and soakage but not drying rate between Great tit and Yellow-rumped flycatcher is significant.It might be related that the breeding season of Great tit population is longer,the nest materials were required to have a good insulation and reduce the influence of rainfall.The mass of lining material is negatively correlated with the first egg date(r =-0.410,p < 0.001)and ambient temperature(r =-0.302,p = 0.008)in Great tit.This result suggests that Great tits can change the lining material input to better adapt environment temperatures..The mass of nest material didn't increase along with the addition of artificial nest material,showing that the availability of artificial nest material in this study area did not affect the nest material input of Great tit.The results of this study indicate that,all the three secondary hole-nesting birds,to some extent,are able to adjust their nest microclimate based on the prevailing wind direction,solar radian,rainfall,ambient temperature and abundance of resources at a local scale.