Saturday, March 16, 2013

"You ain't in Kansas, neither"

On August 19 2010, a 36 day old male Peregrine Falcon that had previously been marked with a colored leg band (25 A) was seen flying from its natal site.  It was later "camera trapped" at a neighboring nest site that contained 2 other nestlings (27 A and 73 E).  Motion sensitive camera images showed that the adopted nestling remained at the neighboring site for several days during which time it shared the nest ledge with the two resident nestlings and was fed by the adults that occupied the site.   The juvenile falcon then returned to its natal site where it again shared the nest ledge with its natural sibling and received care from its natural parents.
A full decription of the observation has been accepted for publication and will appear in the June 2013 issue of Arctic, the following images complement the note.
Images are generally only a few seconds apart, but check the top left corner of each image for time-stamps.  Temperature is recorded in the top right corner and site number in lower left (Click on images for larger versions).

  25 A at adopted site with 27 A and 73 E within 3 hours of leaving his natal site on August 19.
27 A and 73 E spent the night of August 19 alone on the nest ledge

Adult female feeding all three nestligs

27 A and 73 E  spent several hours alone on the nest ledge; then when the adult female returned to the nest approximately five hours later with another prey item, 25 A quickly returned to the ledge.

Adult female deivers a prey item

On August 20 and August 21, the adult female resident at Site 28 delivered prey items on 4 more occasions. Each time 25 A was present on the nest ledge with the resident nestlings and competed for a share of the prey item that was delivered. An adult and the adopted nestling were observed together on the nest ledge at Site 28 on August 23, more than 3 days after flying from its natal site (Site 29).

At Site 29 on August 24 in the morning, an adult falcon delivered a prey item to 62 E (the natural sibling of 25 A); within a few seconds 25 A appeared on the ledge at Site 29 with 62 E after spending nearly five full days away from the site. 

The following day, the resident adults at Site 29 made several prey deliveries which were mostly consumed and cached by 62 E. However, photographs of 25 A indicated that the male was on the nest ledge at least twice that day, and clearly showed that 25 A either consumed or shared prey items that had been previously cached by 62 E.