when i was a kid i had some mixed bantam chickens . had them for a year and then in the spring i had 30 babies in a period of a week . i was very happy but the next day i found 5 of them with no heads on ,i tried to find out what killed them but i could not, the next day all remaining baby chicks were found around the coop with heads missing or partly eaten and a large rat under the roof ,i was so angry i graped it (it bite me to the bone) but i slammed it on the concrete until nothing was left of it , i used to have mallards free in my yard (before i got the dogs)and every year i had maybe 1/3 of the babies taken by rats. i normally like all animals (i am a biologist so its my job ) but i feel no remorse about killing rats or mice ,i really hate them for the losses i had to suffer over the years .you cant even call rats wild animals they are just parasites that follow humans and thrive . they will kill any young bird they find