Swallow, Tree bird picturesTREE SWALLOW
614. Iridoprocne bicolor. 6 inches
Male, steely blue or greenish above; female, duller and often plain gray above, but both sexes always entirely white below.
These Swallows are also abundant about farmyards; except when they are skimming over ponds, they are almost always scouring the air above buildings or fields, at higher elevations than the Barn Swallows.
When weary they roost on dead twigs or telephone wires, hundreds often being seen in rows on the latter.
Like the Martins, these birds frequently nest in bird boxes, but usually not more than one or two pairs in a single house.
Note. - A twittering like that of the other Swallows.
Nest. - Of grass, lined with feathers, in hollow trees on the border of water or in orchards, or in bird boxes erected for their use; eggs white (.75 x .52).
Range. - Breeds in the northern half of the U.S. and north-ward to Labrador and Alaska; winters in southern U.S. and southward.