Via Cousin Ernie, Lena has laid four eggs. She and her husband Spike are sharing duties keeping them warm. Now we have to wait 32 days until something else happens. Following are interesting tidbits that Ernie has shared.
Peregrine Nest Boxes
Someone asked last week why they are so rudimentary. Falcons in the genus Falco don’t build nests as such.
In N America, Kestrels (F. sparverius) are cavity nesters using Woodpecker holes, natural openings in snags, or covered nest boxes provided by humans.
Merlins (F. columbarius) usually take over Crow or Magpie nests.
The three larger falcons, Prairie’s (F. mexicanus), Peregrine’s (F. peregrinus), and Gyr’s (F. rusticolus) usually nest on relatively high cliff face ledges. They lay their eggs in a shallow bowl scraped out of the substrate soil or gravel.
The Peregrine nest boxes merely hold the substrate (pea-gravel) that gives them a place to create a “scrape”.
Highrise buildings look like cliffs to these birds and with an abundance of prey (pigeons, etc) they are very attractive nest sites.
The nest boxes were never meant to “lure” the Peregrines in. The birds were already here and already making attempts to breed. In ’92 we found a nest in a planter box on the balcony of a downtown Seattle Condo. It was unsuccessful.
Placing the nest boxes was just an attempt to provide the birds with relatively safe locations to raise their chicks.