William Osler. On Track But Off the Rails

April 17, 2016 - Etobicoke - William Osler

Tracy Simpson Reports:

I have been out at the William Osler site several times over the past week attempting to identify the resident adults that are currently incubating 4 eggs in the nest tray.  This has not been an easy task as there have been too many birds to try and identify!  My first check in was late in the afternoon on Friday April 8th.  I pulled into the parking lot and found one peregrine on the eastern H, one peregrine on the ledge, one peregrine in the air.  I didn’t hesitate.  I jumped out and grabbed my camera.  I photographed anything the moved in the hopes that I could later come to understand what I was seeing and who these peregrines were.  The interactions continued for almost 40 minutes with birds in and out and all over the place.  The male finally zipped back into the tray and resumed incubation while another bird landed on the nest ledge to the north of the tray.  I could clearly see the bright blue tape on his USFW.  Wait…   …what?  Male in tray and male on ledge?  Just then the second male (blue tape) made an approach to the nest tray that got him almost in behind the sign when WHAM, out comes the resident male and the two take off to the north.  Then the resident female returned to the tray to cover the eggs. Blue tape boy is bold as brass and wants this nest all to himself.  I was sure he wasn’t going to give up easily after challenging the incubating male like that.

When I got the photos home for a look I was running through my head the events that I witnessed.  The first time I saw the three birds together there wasn’t a whole lot of aggressive attacking, instead it was the resident female that simply escorted the bird out.  The photos were able to answer why an attack was not more intense; this was a juvenile from last year.  The bird is banded and may have red tape but not clear shot could be had.  This young female was directed out of the area by the resident female before I could get anything definitive.  I was able to photograph the resident females bands and it is Chessie, black 49 over green AD, hatched in 2011 at the Central Terminal nest site in New York.

The resident male remained more elusive and I wasn’t able to get a band read on that Friday.  Bruce went out on the Saturday April 9th in an attempt to get the ID of the male and witnessed a similar scenario to what I had seen.  The only exception was that the juvenile female did not come around.  The male with blue tape on his USFW band was back and this time continuing with his bold behavior by landing on the southern H sign and eating the resident adults stash of food.  The fact that he got away with this act made me believe that our Hurricane, resident male for the past decade, has not returned and/or successfully taken back his nest site.  This intrusion would never have been allowed to occur under his watch and yet here was this intruding male eating a meal that he swiped off of the resident pair.  Where was the resident male?  Why was he allowing this?

The following day, Sunday April 10th, both Bruce and I attended the site in the hopes of an ID on the male.  Things were much more quiet this time and with little action, it made the task difficult.  We had a changeover that allowed us to get a clear view of the males bands and he is Casper, solid black 35 over Y, hatched in 2009 at a private residential site in Etobicoke.

Casper has been the resident male at the Viscount Road territory with his mate Claire from Michigan for the past 4 years producing young at a nest location we have struggled to discover.  Each season they begin nesting late and so we are busy with other sites by the time they are well hidden and incubating.  They are late nesting each year because Claire, like Hurricane, migrates for the winter and when she returns she finds her mate has slipped off to another location; William Osler.

So here’s how it works.  Claire leaves on migration from Viscount leaving Casper alone to deal with the winter influx of Red taileds and Snowy owls to the area on his own.  Hurricane migrates shortly after Claire has left, around late November, and that leaves Chessie on her own at William Osler.  Casper comes up from Viscount to Osler for the winter and hangs out with Chessie until Hurricane returns and kicks him out around the end of March.  Casper then goes back to Viscount, re-establishes his territory and waits for Claire who shows up around the first to second week of April.  It took us awhile to sort THAT out.  Phew.

The big change this year is that by April 10th Hurricane has still not been located and identified at the William Osler site leaving Casper in charge.  We have watched Casper leave the site and head southwest towards his old territory and a visit to the Viscount area revealed two adults courting around the bridge abutments of the 409 overpass.  So.  Is Casper trying to run two sites?  That would explain how little mister blue tape was able to get away with eating all the William Osler stashes for free.

While I did get a shot of the band off of the blue taped bird it is not a clear and complete read of the alpha numerics and so he remains a mystery at this time.  What I can tell you is that he is a solid black Ontario banded bird and the partial read has narrowed the possibilities.  I will hopefully have an ID on him soon for you.

I will be out for more observations this week.