|In Costa Rica|
The collared whitestart is around 13 centimetres (5 in) in length with a weight of 10.5 grams (0.4 oz). It has a chestnut crown bordered with black, and a black forehead. The rest of the upper parts are slaty black, and the tail is black with white edges, hence the bird's name: "start" is an old English word for "tail". The face and underparts are bright yellow, with a black band across the breast.
The sexes are similar, but young birds are duller, with a browner back, weakly yellow underparts, and the head entirely slate-coloured, with no yellow on the face or red on the crown.
The call is a sharp pit, and the song is a mixture of slurred whistles, warbles and trills.
The collared whitestart feeds on insects, frequently fanning its striking tail as it pursues its prey. It will join mixed feeding flocks, and will follow cattle and occasionally humans for the insects they flush.
The roofed nest has a round side entrance and is built on the ground or a steep bank, hidden amongst rocks, tufts of grass or under a fallen log. It is constructed from strips of bark, plant fibres, leaves, and grass. From March to May, the female will lay 2 or 3 white or cream eggs that are speckled with fine brown spots. Incubation lasts about two weeks, but other nesting details are largely unknown.
The collared whitestart is common at heights between 1500 m and the timberline in mossy mountain forests, ravines, second growth, and adjacent pastures.
- Curson, Quinn and Beadle, New World Warblers ISBN 0-7136-3932-6
- Stiles and Skutch, A guide to the birds of Costa Rica ISBN 0-8014-9600-4