I have seen what corvids do to small birds,their young and their eggs!...Don't just scare them off,give them some lead!....As soon as your back is turned they will be raiding the birds nests and catching the fledglings!...I have seen crows and magpies at the crack of dawn raiding nests of song birds eating the eggs and carrying the young on to a roof or tree and dismembering while still alive....Any of the Weihrauchs will do the job!