Thursday, November 19, 2009

Baiter Terns

Baiter certainly seems to attract its fair share of birds in inclement weather. Today the loafing Gulls were joined by five Sandwich Terns sitting out the very strong winds although for a change it was sunny.

Three of the five Terns

The bird below shows more extensive yellow in the bill including along the cutting edges. It also had bright yellow primary shafts.
This bird is just completing its primary moult with both P10s only half grown. You can also make out dark on the outer tail.

Close up of bill and wings. P9 has a particularly striking yellow primary shaft

A different bird here. With the white tail presumably an adult

Below is the same bird with what appears to be thin white edgings on the inner webs, apparently a diagnostic feature of acuflavida American Sandwich Tern!

This shows the pattern a bit better. Here the white edgings on the inner webs of the outer most four primaries stop before they get to the outer web, rendering half of the wing tip grey. On sandvicensis (next pic) the white should continue to the outer web to form a white 'hook' rendering the wing tip white.

The white edgings are clearly broader on this sandvicensis and hook over the outer web

The problem is that the bill and head pattern is completetly wrong for acuflavida which show a much broader based dagger bill and strong contrast between an almost pure white forehead and unflecked black area.
So it isnt an acuflavida. The only thing I can think of is that it could actually be an immature bird which do show thinner edges to the primaries, although the all white tail doesnt fit. On the shot below one can see dark centres to the secondaries which is a feature of younger birds. (But also a feature of adult acuflavida)

This one is definitely a first winter!

Couple of Brents coming in to land