Staying or going might have less to do with the site and more to do with the birds' genetics. Our birds all leave but we did have a female, from the US, who overwintered in Winnipeg from 1990 to at least 2005. She was a mix of subspecies which is more common in the US than it is here in Canada where there was a concerted effort in the beginning to breed true to the subspecies in our captive-breeding program. In the US, their breeding programs were more flexible. Is this the reason that all peregrines stay at sites like this, no way to really say unless one did a genetic breakdown and comparision of all the birds that stay and all those that leave. I could be one explanation or part of an explanation, say in combination with warmer winters and urban nest sites and perhaps even more pressure to maintain control of nestsites. No one has any real answers, but its always interesting to watch, wait and see.
