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Wednesday, March 30, 2011

Red-shouldered Hawks Nesting in Chester Co




Red-shouldered Hawk nest under construction
March 8, 2011~Uwchlan Township, Chester County, Pennsylvania

Back on March 8, 2011, I was walking my dog when I heard a Red-shouldered Hawk calling from behind a neighbor's house. This wasn't terribly surprising, as I'd been seeing and hearing an adult Red-shouldered much of the winter in my neighborhood. What was surprising is what I noticed next... I looked over towards the noisy calls, and noticed a hawk fly into a prominent crotch in a mature tree in my neighbors yard. Upon a closer look, I could see there was what appeared to be a nest under construction. Within minutes, I ran into the owner of the property, Catharine, and she had exciting news to share with me: "some hawks are building a nest in our tree!"
Later that day, I went down with my camera, binoculars, and spotting scope in tow in order to give Catharine closer looks at the amazing event that was taking place in her yard. She reported that the hawks were most active when the sun was rising and setting, but not too much during the day. From the literature I have read since, this is typical of their behavior while building the nest.
As we were standing there talking about how special it was to have Red-shouldereds nesting in Chester County, an adult flew over our heads, offering great looks at the classic translucent
"crescents" at the ends of the wings.















Adult Red-shouldered in flight near the nest site in Uwchlan Twp, March 8, 2011

To give you an idea of the history of this species in Chester County, it is not one that is commonly found, and breeding records are few. The Annotated List of Chester County Birds, published by the West Chester Bird Club in 1999, states this of Red-shouldered Hawk: "Uncommon migrant, uncommon winter and rare summer resident".
The Birds of Pennsylvania, by Jerry McWilliams and Daniel Brauning, 2000, wrote on the status of Red-shouldered Hawk in Pennsylvania:" Breeding Red-shouldered Hawks are uncommon statewide. They were most frequently reported during the BBA project in the northwestern counties and least frequently in the southeastern (Chester, Delaware, Philadelphia cos) and southwestern (Washington and Greene Cos)." The authors also state: "They are rather secretive during the breeding season".
During the first Pennsylvania Breeding Bird Atlas, only one confirmed record of breeding was noted in Chester Co.. During the second BBA (recently conducted 2004-2008) there were few reports of this species, and while I don't have access to those records, I can say that in those four years I only entered Red-shouldered Hawk once with a flyover observation denoting "possible" breeding species in the county.
What is more interesting and exciting is that within the last year, two separate nests were discovered and monitored right here in Uwchlan Twp, just a few miles from one another.
Josh, a local birder that discovered and monitored one of those nests, which that fledged two young in early summer, reports that this spring the Red-shouldereds in his neighborhood are once again getting vocal, and hanging around last year's nest site.
So, why are these uncommon breeders adopting nesting sites in a suburban township, choosing tree hosts all viewable from the street, and with a moderate amount of foot and car traffic? It's a good question. What I can say is that all of these sites fall within the Brandywine Creek watershed, and all boast small second and third order streams within a few hundred yards of the nest. It's an area rich in riparian habitat and mixed woodlands, which is favored by this buteo that specializes in a diet of small mammals, reptiles, amphibians, crayfish, and insects.
With good habitat available, and potentially lots of food on the menu here in Uwchlan Township, it's no wonder they are choosing to make it home.
Adult Red-shouldered Hawk sits in the nest, March 20, 2011

As time went forward after March 8, I continued to notice more activity around the nest site when I would pass by. On March 20, I noticed one of the adults sitting in the nest. The posture was a bit too elevated to suggest incubation, but hinted that egg laying may occur soon.
On March 23, I noticed what I thought was the top of a head peeking above the rim of the nest. Drenching rain that afternoon and evening prevented me from using the optics, and checking to confirm. On March 24, I was finally able to check the nest with my scope, and sure enough, the bird appeared to be postured low enough in the nest to suggest incubation had begun!
Cornell Lab of Ornithology's "Birds of North America Online", an online subscription database of all current species accounts of North American birds, states : "Incubation usually starts before clutch is complete, so eggs hatch asynchronously" and eggs are listed as having a 33 day incubation. This puts the possible hatching of the first eggs in this nest somewhere around April 24-26. Something very special to look forward to in the coming weeks.
Hopefully, my next blog entry on this topic will be news to share of hatchlings!

A Red-shouldered Hawk sitting low in the nest suggests incubation is underway. March 24, 2011. Chester Co., PA

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