人工巢箱繁殖鸟类主要巢捕食者及其影响因素

The main nest predators of birds breeding in artificial nest-boxes and its influencing factors

巢捕食是影响鸟类繁殖成功率的一个重要因素,也是鸟类繁殖生态研究中的一项重要内容。确定鸟类的主要巢捕食者及影响巢捕食的因素对于了解鸟类繁殖成功率、种群增长率及种群数量等具有重要意义。2009—2012年,对辽宁仙人洞国家级自然保护区人工巢箱中繁殖的杂色山雀(Parus varius)、沼泽山雀(P.palustris)、大山雀(P.major)和白眉姬鹟(Ficedula zanthopygia)四种鸟类的巢捕食率及影响巢捕食的因素进行了研究。研究共记录到238个繁殖巢(杂色山雀74巢、沼泽山雀21巢、大山雀118巢、白眉姬鹟25巢),其中35巢被捕食,捕食率为14.7%,雏鸟期被捕食占91.4%。巢捕食率在4种鸟类之间无差异(x^2=0.429,df=3,P=0.934)。以锦蛇(Elaphe spp.)为代表的蛇类是该地区小型森林洞巣鸟类繁殖期主要捕食者,占总捕食率的94.3%。对影响巢捕食的22个相关因子进行二元逻辑斯蒂回归分析发现,坡度、地面裸露率、草本盖度对巢捕食具有显著性影响;出雏时间、坡位、距碎石块距离对巢捕食的影响接近显著水平;而巢高、树粗、巢箱年龄、窝卵数、距路距离等对巢捕食无显著影响。因此,处于坡度较陡,坡位较高,草本覆盖率较高,地面裸露率较低,距碎石块距离较近,且出雏时间较晚的巢更容易被捕食。

Nest predation is one of the main drivers for the failure of avian breeding, and is therefore an important factor affecting avian breeding success rate. Consequently, it is an important research topic in avian breeding ecology. Identifying the main nest predators and factors affecting nest predation is critical for understanding the breeding success population growth, and population size of particular bird species. Nest predation rates are generally affected by the behavior of predators, the degree of habitat fragmentation, characteristics of nest, and the life history of the bird. The main nest predators of birds are mammals, raptors, crows, snakes and insects, with different predators present in different habitats. A 4-year period of field study was carried out from 2009 to 2012 during the breeding season of late April to early AUgust to investigate the nest predation rate of four artificial nest-box breeding passerines （Varied Tit Parus varius, Marsh Tit P. Palustris, Great Tit P. major and Browed Flycatcher Ficedula zanthopygia） and its influencing factors in Xianrendong National Nature Reserve, Liaoning Province. Six video cameras were randomly installed on the boxes that were used by the birds to record the nest predators after the nestlings were five days old. Each nest was monitored for three times, once every three days, from 8：00 am-12：00 noon. A total of 40 nests were monitored for a period of 480 hours. Of the 238 nests （74Varied Tit nests, 21 Marsh Tit nests, 118 Great tits nests and 25 Browed Flycatcher nests） recorded, 35 （14.7%） nests were predated, and 91.4% of which were predated during the nestling stage. There was no significant difference in the predation rates among the four species （X^2= 0.429, df= 3, P= 0.934）. According to our observation （Nest predators that we saw or recorded by the cameras）, seven nest predators were detected, and of which four were Korean rat-snake （Elaphe anmnal） and three were Dione rat-snake （Elaphe dione）. Thus it indicated that Elaphe snakes were the dominant nest predators, accounting for 94.3% of the nest predation of these four small nest-hole birds. We measured 18 habitats and counted four nests parameters of the 35 predated nests and 42 control nests, which were chosen at random near the predated nests. Binary logistic analysis incorporating the combined effect of the 22 different variables revealed that the main factors affecting nest predation were slope, the extent of bare ground and herb coverage, all of which had significant effects on nest predation. Other factors such as hatching time, slope position and distance to nearby roads, also affected nest predation, with their effects were marginally significant. There was no effect of nest height, tree thickness, nest-box age, clutch size and distance on nest predation. In all, nests in the steeper slope position, higher herb coverage, lower coverage of bare ground, and those that were closer to stones or hatched a later time were more vulnerable to nest predation. In addition, we also found that artificial boxes with smaller exits could prevent predation by rodents.