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Yesterday morning I took an early trip to check out migration at Roosevelt Island. There continues to be very little migration because of persistant northerly winds, but there are still birds moving through. Baltimore orioles, yellow-rumped warblers, and cedar waxwings filled the trees on both sides of the footbridge that leads to the island. I heard my first yellow-billed cuckoo and house wren of the year.
On the boardwalk I heard both waterthrushes, the Louisiana and the northern. (The latter was a first-of-the-year.) These two warblers can be difficult to tell apart by sight. Both have brown backs, light breasts with brown streaking, and white supercilia. Visual identification requires close attention to details: the Louisiana has a brighter eyebrow; the northern may have a yellowish wash on the breast and light streaking on the neck. Given that the birds are skulkers, these details can be hard to see. The identification is made easier by attention to the songs. Both have a somewhat similarly complex structure of whistled notes followed by chatter, but emphasize different parts of the song. The northern's song grows in volume and emphasizes the end of the song; it gives the impression of being three-parted. The Louisiana, on the other hand, emphasizes the long whistles at the beginning of the song, and drops in both pitch and volume as the song goes on. (For samples, see the CLO links above, and these additional links: Northern (2) (3); Louisiana. See Giff Beaton's Warbler page for more images.)
Towards the end of my walk, I heard one song that I could not identify. It was pretty clearly from a warbler - a thin, high-pitched note repeated several times. Eventually, using CDs, I narrowed it down to being either a blackpoll or a Cape May. It sounded more like the latter, but I am hesitant to call it based on sound alone, since I have no experience with the species and it is a rather uncommon migrant in this area. So I will leave it as a "maybe."
SPECIES SEEN: 44
Canada Goose
Wood Duck
Mallard
Turkey Vulture
Osprey
Red-shouldered Hawk
Ring-billed Gull
Rock Pigeon
Mourning Dove
Yellow-billed Cuckoo
Red-bellied Woodpecker
Downy Woodpecker
Pileated Woodpecker
Eastern Phoebe
Great Crested Flycatcher
Northern Rough-winged Swallow
Barn Swallow
Cedar Waxwing
Carolina Wren
House Wren
Gray Catbird
Wood Thrush
American Robin
Blue-gray Gnatcatcher
Carolina Chickadee
Tufted Titmouse
Blue Jay
American Crow
European Starling
House Sparrow
American Goldfinch
Northern Parula
Yellow Warbler
Yellow-rumped Warbler
Black-throated Green Warbler
Northern Waterthrush
Louisiana Waterthrush
Scarlet Tanager
White-throated Sparrow
Northern Cardinal
Red-winged Blackbird
Common Grackle
Brown-headed Cowbird
Baltimore Oriole
