White-winged Tern Chlidonias leucopterus
Moonglow Dairy, Elkhorn Slough, Monterey County
Sunday, 19 September 1999
After having good luck with the Great Crested Flycatcher in the Carmel River this morning, I decided
to try for the White-winged Tern at Moonglow Dairy. I arrived at the third pond at about noon and was delighted
to see the bird was foraging over the back of the pond. I watched it for a while in my scope and finally the bird
landed allowing more detailed study. Several other birders arrived and we all had good views for the next hour.
Finally I left while the bird was still present.
It was a very active little bird, quite acrobatic in flight, with snappy shallow wing-beats and loopy dives.
It picked food from the surface of the water but did not plunge. When alarmed it sometimes joined flocks of Red-necked
Phalaropes. It was quite amazing to watch it in precision, chorus-line flight with the phalaropes. In fact it looked
somewhat like an oversized Red Phalarope when it did this. The following description is based on noted made while
watching the bird:
A small marsh tern superficially resembling Black Tern Chlidonias niger, but lacking the dark shoulder marks of that species. It was twice the bulk of adjacent Red-necked Phalaropes, but decidedly smaller than adjacent Cinnamon Teal.
The bill was black and pointed. In certain light a faint reddish tinge could be seen on the bill, particularly when seen against green leaves. This happened when it perched on a tall post with trees in the background. When the bill opened, the red mouth lining was visible.
The body and head were white. The coal black eyes stood out prominently and were completely surrounded by white. Behind each eye was a dark ear patch (ear muff) which connected over the gray streaked crown. A dark spot on the nape connected narrowly to the gray crown via a narrow nape stripe (ponytail).
The mantle was medium gray. The tail was very short and straight, not notched or forked. In flight the greater and median wing coverts were a paler shade of gray, contrasting somewhat with the darker flight feathers and lesser coverts. The outer primaries were somewhat darker than the inner ones. A molt limit could be seen at about p5 on each wing with the inner primaries appearing fresh and the outer ones old. A thin dark line on the underside of the wing represented the contact of the old outer primaries and fresh inner ones. Otherwise the underside of the wings were white, with dark visible on the underside of p10 and slightly darker tips to the primaries. A dark cubital bar and black marginal coverts were obvious both in flight and when perched. The wings were angled slightly in flight and the tips were distinctly pointed, although p10 seemed shorter than p9 resulting in a short dark line along the leading edge of the underside of the wings.
The legs were reddish and relatively long. No vocalizations were heard.
More detailed information and photographs are on Don Roberson's web site here. I saw this bird again with Robbie Fischer at the same location on 3 October 1999. The molt limit seemed to be in the same place indicating that the wing molt was arrested midway through the primaries.
Joseph Morlan