Wednesday, April 04, 2007

Skepticism

Though I spend considerable time birding throughout the year, I have a mere handful of state records for early arrivals, lates and rarities. Finding rarities really isn't why I bird, though. This spring, there have been several interesting sightings reported to the Wisconsin Birding Network, generating a lot of discussion on the listserv and in backchannel. Early arrivals have included Palm Warbler, Great-crested Flycatcher, Common Nighthawk, Broad-winged Hawk, House Wren, Eastern Wood Pewee, Bobolink among others. Some of these are likely novice birder confusions, like phoebe versus pewee and the “peent” calls of American Woodcock being mistaken for nighthawks, but other sightings are just plain weird.

I'm naturally skeptical when it comes to such reports, but I usually don't bother to question the birder directly. Clearly, migratory birds are arriving earlier to Wisconsin this year versus last year. For example, Yellow-rumped Warblers are about a week early. There were early reports of Chipping Sparrows in early March (some of those were probably American Tree Sparrows, though). But just compare the Ruby-throated Hummingbird migration from 2006 to 2007. Check out maps from the late 1990's – the hummingbirds are showing up in northern Illinois about a month earlier compared to 2007.

If an "interesting" listserv bird is close enough, I'll try to make the effort and drive to the location to verify the sighting. About a week ago there was a sighting of a Loggerhead Shrike near Stoughton and then another possible sighting of one at Shoveler's Sink a few days later. Yesterday, after an apparent "confirming" report of the shrike to the listserv, my colleague Jason and I made the short drive over to Shoveler's Sink to check it out. We quickly found and photographed a Northern Shrike. Though not a high-quality image, it's enough to make a valid identification from.



But a few days ago, it happened to me...

Monday morning, Jim and I had been birding for a good hour along the Pheasant Branch Conservancy stream corridor and were heading west from the trail entrance at Park Street. We had been enjoying many of the usual early spring migrants that I've been reporting to eBird and wisbirdn over the past several days. The skies were mostly cloudy with the sun making hints that it might poke through at any moment.

Continuing west, at approximately 8:30am and without using his binoculars, Jim announced and pointed to a "small hawk" about 80 to 100 yards away. The bird was at about a 35 to 45 degree angle and heading northwest from our position on the trail. My estimation is that the bird was between 100 and 150 feet up in the area over the stream corridor. Its trajectory would have put it over the athletic fields behind Middleton High School prior to our sighting, with it heading into the direction of the Bruce Company on Parmenter Street.

The Pheasant Branch stream corridor trail is surrounded by trees on both sides, but open areas in the center above the trail. Luckily, we were in one of the relatively open areas and I was able to glass the bird for about 15 seconds with no obstructions using high-end 8x binoculars. I immediately got on the bird and instantly recognized it for a nighthawk. In excitement I said, "That's a Common Nighthawk!" We watched the bird until it was obstructed by the tree line on the opposite side of the stream. It was a uniformly dark colored bird, very slender with long pointed wings. Each wing had a bold white dash on the primaries that was perpendicular to the wing. The bird flew in a zig-zag, floppy flight with rapid wingbeats and occasional breaks. I got to see both the underside and the upper parts of the bird in good light.


(artistic rendering of how it looked to me)

It was suggested by John Idzikowski that it may have been a Lesser Nighthawk because their migration is far earlier than Common and our weather has been freaky. That's is an interesting possibility, but I maintain that the wing shape on the bird I observed were more elongated and pointed with the white dash not at an angle relative to the wing layout. Additionally, and to the best of my recollection, the white dashes were not as close to the wingtips compared to images of Lessers in flight that I have studied after John brought up this possibility.

I have no experience observing Lesser Nighthawks and can only convey the above observation in the context of my experiences with Commons. I would wager that any of the excellent birders that I regularly bird with at Pheasant Branch, had they been there that morning, would maintain that there was at least a species of nighthawk in Middleton. I will always maintain it whether the records committee accepts the sighting or not. It's interesting how skeptical I would be of this sighting if it had come from a birder I do not know. And now birders are going to view this sighting with the same level of skepticism and incredulity.

No comments:

Post a Comment