Tuesday, April 21, 2015

Hoping for a Big Migrant Fallout

Last Sunday I dodged heavy downpours as I made a birding arc around the south shore of Lake Norman from the public fishing access at Cowan’s Ford Dam around to Lake Davidson just north and east of Exit 30 at I-77. Unsettled weather with heavy storms and copious rainfall is a sure recipe for grounding migrants, many of which would otherwise pass right over without ever stopping. Sometimes a local rarity or two can be found among the fallout.

I did experience a bit of a fallout at the fishing access. A flock of six common loons obviously had put down due to the weather. They were in fine breeding plumage, much different from their more subdued winter garb. Not far from the shore female lesser and greater scaup gave great side by side comparison views.

At Ramsey Creek Park three Bonaparte’s gulls wheeled and dove several hundred yards out. At Lake Davidson a rock outcrop in the middle of the lake hosted four resting Caspian terns, four double-crested cormorants, one great blue heron and 18 ring-billed gulls. The Caspian terns were nice to see; they are regular spring and fall migrants through the area but occur only on the larger reservoirs. It would have been nice for a Forster’s tern to choose those rocks for a rest stop but I missed it if it was in the area.  Dozens of tree swallows skimmed the water’s surface in the fading light.

In the Davidson Creek channel off Torrence Chapel Road, a loafing flock of 50 ring-billed gulls was joined by a single immature herring gull. Nine Bonaparte’s gulls soon joined them, almost all of them sporting the solid black hoods of breeding adults. I was hoping for much rarer gull with a black hood, a laughing gull, but none ever joined the roosting flock. A pair of osprey voiced their displeasure with me and my spotting scope lingering too long close to their nest. Four more common loons in breeding finery cruised by. As it got darker and the rain began to fall again, I watched a large mixed flock of turkey and black vultures gather and wheel low into their nighttime roosts. It was time for me to go too. Below are some of the birds I saw during that afternoon.

Identifying the two scaup species can be challenging.. The differences can be seen in this photo below. the lesser scaup is on the upper left. Note the purplish tint to the head. The head is also more oval-shaped, with a peak at the top. The greater scaup on the lower right has a more evenly rounded head with a greenish tint.
Lesser and Greater Scaup by Phil Fowler

Caspian terns are our largest terns in North Carolina, as large or larger than some medium sized gulls. The two birds with the red bills shown below are Caspian terns. The other bird with the orange bill is a royal tern. Caspians pass thru the Piedmont during the migrations, royals are strictly coastal.
Royal and Caspian Terns by John Ennis

Common loons are gray, brown, and white during the winter...
Common Loon by Cathy Miller

but by April the adults have transformed their plumage into the black / white speckled upperparts with striking black head and neck bands.
Common loon by Jeff Lewis.