Immature Cooper's or Sharpie? - Larimer

[Gregg Somermeyer]

Late yesterday I spent some time observing what I believe to be either an immature Cooper's Hawk or Sharp-shinned Hawk on stick nest about 20 ft up in crotch of tree. Yellow eye, yellow and black beak, buffy head, barred tail. Is this possible? How old are they when they first breed?

Gregg Somermeyer, Ft. Collins

[joe...@betterbirdwatching.com]

Raptors breed early, late winter/early spring,  so it could be a "nestling".


Joe LaFleur
Woodland Park

[David Suddjian]

Some raptors nest early (Great Honed Owl, for example), but many begin in spring proper, and some are still in the early stages of nesting now. Accipiters may fall mostly in the latter category; I think this is the prime season for incubation. It is too early for a fledgling from this year to be out and about, I think. Generally they are still incubating.

For the Cooper's Hawk it takes two years to reach an adult type plumage, and sometimes nesting pairs are seen with one member that is not yet in an adult plumage...i.e., not an adult. I've never seen pairs with both as immatures, but maybe that happens, too.

David Suddjian

Littleton, CO

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[Gregg Somermeyer]

I plan on returning tomorrow in hope that a mate will appear. Perhaps that will solve the mystery...

On Thursday, May 12, 2016 at 7:34:44 AM UTC-6, Gregg Somermeyer wrote:

[Douglas Kibbe]

Although the age of first breeding by Cooper's Hawks is often given as 2 years of age, published data indicates that one year old females and males often nest.  The following is from: Curtis, Odette E., R. N. Rosenfield and J. Bielefeldt. 2006. Cooper's Hawk (Accipiter cooperii), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/species/075
doi:10.2173/bna.75


They state:
Age At First Breeding
Usually 2 yr but year-old immatures reported as 6% to 22% of breeding females (Meng 1951, Hennessey 1978, Reynolds and Wight 1978, Millsap 1981, Moore and Henny 1984, Asay 1987). Those studies detected no males nesting as immatures but two such cases given by Rosenfield and Wilde (1982); similar proportions of yearling breeders in both sexes in Wisconsin, 1980–1992 (RNR and JB). Also, in Tuscon, AZ, where pairing was assorted by age, 83% of pairings were adults, 13% were mixed and 5% were subadults (N = 184, Boal 2001b); 16% of breeding females and 7% of breeding males were subadults. A pair of subadults successfully nested in Indiana (Dancey 1993), Wisconsin (RNR and JB) and New York (Rothstein 1993).


Doug Kibbe, Littleton

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Date: Thu, 12 May 2016 22:34:33 -0700
From: gsome...@gmail.com
To: cob...@googlegroups.com
Subject: [cobirds] Re: Immature Cooper's or Sharpie? - Larimer

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[Gregg Somermeyer]

Thanks all. Confirmed nesting pair of Coops yesterday with good set of photos of female on nest and male perching watch in nearby tree.

GreggSomermeyer
Fort Collins