中文摘要：

巢捕食是影响普通繁殖成功的重要因素,面对不同风险,其行为对策可能不同.2015—2016年3—7月,在吉林省左家自然保护区山地次生林通过摆放标本进行模拟实验,探讨了普通修饰洞口对防御捕食者入侵的作用.结果表明：普通对高风险捕食者花鼠（Tamias sibiricue）和蛇（Elaphe taeniura）反应最强烈;对低风险捕食者松鼠（Sciurus）反应强度较弱,说明普通修饰洞口具有防御巢捕食的作用,且普通有识别风险的能力,并能采取不同的行为对策应对不同风险.

英文摘要：

Nest defence is a key factor of breeding success in birds.They response differently when uncounted different predators.Eurasian nuthatch,Sitta europaeais a secondary cavity nesting species,and specially,they always reduce the size of the entrance hole and seal up cracks with mud.The aim in this study is to assess whether the reduced hole size makes the nest more secure.From March to July in 2016,at Zuojia Nature Reserve of Jilin Province,conducted dummy experiment to observe the nest defence behaviour of Sitta europaea when their nests exposed to three predator dummies with different size.The results showed that Sitta europaea responed more strongly to small size predator（snake and small squirrel dummy）than to larger ones（larger squirrel dummy）.The findings corroborated that the modification of size of the hole in Sitta europaea has a defensive effect on the predator.