I disagree Bev, the peregrines are not coming to all the same spots. West Winnipeg is new, we have never had any birds express a nesting interest in the area until Ivy returned. He wanted to be here so we are accommodating him. The Grand Forks birds chose the Smiley Tower and the project installed a nestbox. In Saskatoon, the pair chose a nestledge much like the Radisson, new site, no nestbox or any other structure. The apartment block in Toronto is a ledge, not a nestbox construct. Can't remember where at the moment but a pair last year (at least) and this year chose to nest in the vegetation in an office building balcony planter - again not a nestbox. And those are just urban/suburban examples. We have new wild/cliff nestsites every year and we have unbanded birds turning up on territories in Canada and the US - they had to come from wild, unmonitored nests.
We provide nestboxes that some birds use, some don't. Sometimes we install them to encourage birds to nest, sometimes in response to unsuccessful nest attempts at the same location. Sometimes its just a flyer, never seen a peregrine near there but the site looks great so why not? Are they preferred to wild cliff faces, can't say, nor can any other peregrine biologists. Some birds like them and use them. Does being hatched from one help to influence the decision? Some could say yes, some could say no - Trey was hatched on the ledge, but Princess was hatched from a box on a smokestack. That ledge does not look like the smokestack she fledged from. Does knowing where the boxes are, i.e., because you were hatched there help? Perhaps - perhaps it gives birds a target to aim for - then when they are repelled from the territory, they find new territories. Some birds follow others - all the Radisson females are from the US - Nebraska & Minnesota - they are a little north and west of their natal areas, they had to follow someone.
So who and why and where and when are known only to the peregrines, projects like ours just try to sweeten the pot ...
