Tuesday, December 29, 2009

A Waterlogged Christmas Bird Count

After not being able to participate in the Lower Hudson Christmas Bird Count due to snow, I was really hoping for good weather for our local count, the Raritan Estuary CBC. We could not have asked for better weather on the day of the count – it was sunny and mild with only a light breeze. However, the day before the count, it rained all day. That rain, combined with the melting of eleven inches of snow, created two problems for us. One was a rapidly moving river that swept waterbirds out of our count area. The second was that much of Johnson Park was flooded, with some areas inaccessible even on foot. You can get a sense of the flooding in the image above.

As a result we had to adjust our plans. Flooding, for example, made it impossible to count waterfowl along the river bank, something my sister has done for the past few counts. It also meant that I could not venture into some areas that are typically good for songbirds. Flooding also dispersed the Canada Geese so that they were not concentrated around a few large ponds.

Despite the mess, we still managed to get good results. We recorded 46 species, which is higher than last year but below our high of 51 in 2007. The local Canada Goose population has been much greater than in past winters, and that is reflected in our count of 3420. The difference this year seems to be a lack of persecution from the county. Over the past weeks, there have been consistently 600-800 geese present at Donaldson Park, with many more supported in the much larger Johnson Park. Mallards also were present in good numbers, and there were much smaller numbers of a few other waterfowl species.

We did not see any true rarities in our area, but we had a few nice birds. My sister located a Gray Catbird near the railroad bridge in Johnson Park. This bird has been present at the location since about Thanksgiving. It was good to see that it survived last week's snow and cold snap. My gull counting at Donaldson Park was interrupted when a Bald Eagle put all the gulls to flight. Other raptors were also present in good numbers, even though our Red-tailed Hawk count was down from last year. In addition, we saw a variety of winter migrants that are common but not guaranteed, such as Yellow-bellied Sapsucker and Brown Creeper.

We finished the day by striking out on the Peregrine Falcon that sometimes roosts at the Route 1 bridge.

Oddly enough, Bald Eagles are considered rare enough birds for this count to require a rare bird form. (Speaking of which, why does Audubon's rare bird form (pdf) use MS Comic Sans, of all fonts?) Writing rare bird documentation for a Bald Eagle feels a bit like writing documentation for a Blue Jay or Northern Cardinal. It is a bird that is easily identifiable with unmistakable field marks, yet I tend not to note an individual bird's characteristics because they are so familiar. Luckily, my sister took a photo so we have visual documentation if that is deemed necessary.

In addition to the eagle form, I submitted rare bird forms for two exotic waterfowl. As discussed on BIRDCHAT over the past few weeks, exotic birds are countable on Christmas Bird Counts, something that many birders do not know (partly because Audubon does not make this clear). This year, I am submitting observations of two Egyptian Geese (a species I have written about before) and the bird below.

My first thought on seeing the bird in the photo above was Snow Goose, perhaps a mix of white and blue morphs. However, on closer inspection of the photograph, this is clearly not the case. First, size makes this doubtful, as the average Snow Goose is smaller than the average Canada Goose. (Size also makes several other native goose species unlikely.) Second, this goose's bill lacks the sneer patch typical of a Snow Goose's bill. Third, “Blue” Snow Goose flight feathers usually have a dark center surrounded by a white edge; this goose has all gray flight feathers with no white edge; in addition, the wing tips appear to be dark gray rather than black.

So what is it? The closest match for the features listed above appears to be a feral domesticated Greylag Goose (a.k.a. barnyard goose). I have no illusions about this being a wild bird even though it is free-ranging. Most likely it escaped from Johnson Park's small zoo, which holds a variety of exotic waterfowl; since the enclosures are fenced but not capped, local and exotic waterfowl can intermingle, and some of the latter escape. Occasionally other free-ranging Greylags have produced hybrids with Canada Geese. I am submitting both this and the Egyptian Geese because I think it is important to document the phenomenon of exotics mixing with our local waterfowl and the possible establishment of new populations.