Tuesday, January 02, 2007

Raritan Estuary CBC

For the past three years, I have participated in the Raritan Estuary Christmas Bird Count, along with my mother and sister, both of whom are birders. We have responsibility for a sector that runs along the Raritan River between the Route 18 and the Route 1 bridges. It includes parts of Johnson Park in Piscataway and Donaldson Park in Highland Park. While this sector does not offer many unusual species, the count is a fun way to close out the year. When we started out last Saturday, the skies were blanketed by a heavy cloak of clouds, depressing bird activity and making it difficult to see the few birds that were active. By mid-afternoon, the sky had largely cleared, but by then we were winding down the day's activities.

While the day was not good for hawks generally, it was excellent for peregrines. We had one in Johnson Park and two in Donaldson Park, the latter two sitting together on top of a radio tower. Common mergansers - and waterfowl overall - were down from last year, possibly due to warm weather, with the caveat discussed here. Hairy woodpecker and hermit thrush made the list this year; absent were last year's killdeer, brown creeper, and red-winged blackbird. Canada geese topped the avian biomass for the day, followed closely by herring gulls. Starlings made a good run, but could not keep up with their larger relatives. The biggest surprise was that robins were entirely absent from the two parks on count day; last year we counted 356!

One flock of Canada geese in Johnson Park contained some interesting geese. The first, on the surface, looks a bit like a greater white-fronted goose. It has the white strip of feathers at the base of a pink bill and orange legs, and the overall color patterns look right. However, a closer look reveals that this bird lacks the expected black speckling on the belly and has a light brown cheek patch. In addition, the size of the bird seems too large for a greater white-fronted goose. It is, in fact a hybrid, a mix of a Canada goose with either a greater white-fronted or domestic goose.

As I was studying that goose, I noticed two other birds in the same flock that seemed smaller than the rest - about two-thirds the size of other geese in the flock. They had blocky heads and proportionately small bills. After consulting several resources, I decided that these are cackling geese, probably the "Richardson's" subspecies. (There is more on cackling geese here.)

The table below shows the total species and numbers for our sector.

Canada Goose950
Cackling Goose2
hybrid goose
Common Goldeneye5
Hooded Merganser5
Common Merganser8
Double-crested Cormorant26
Great Blue Heron2
Cooper's Hawk1
Red-tailed Hawk1
Peregrine Falcon3
Ring-billed Gull135
Herring Gull600
Great Black-backed Gull175
Rock Pigeon65
Mourning Dove60
Belted Kingfisher9
Red-bellied Woodpecker15
Yellow-bellied Sapsucker1
Downy Woodpecker15
Hairy Woodpecker3
Northern Flicker3
Blue Jay30
American Crow28
Fish Crow1
Black-capped Chickadee2
Tufted Titmouse40
White-breasted Nuthatch7
Carolina Wren8
Hermit Thrush1
European Starling400
Song Sparrow23
White-throated Sparrow140
Dark-eyed Junco40
Northern Cardinal27
Common Grackle100
House Finch30
American Goldfinch15
Total Species (without hybrid)
Total Individuals3287

The 2005 results from our sector are posted here.