TREE SWALLOW. 
614. Jridoprocne bicolor. 6 inches. 
Male, steely blue or greenish above; female, duller 
and often plain gray above, but both sexes always en- 
tirely 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. 
Notes.—A twittering like that of the other Swal- 
lows. 
Nest.—Of erass, lined with feathers, in hollow trees 
on the border of water or in orchards, or in bird boxes 
erected for their use; eges white (.75 x .52). 
Range.—Breeds in the northern half of the U. S$. 
and northward to Labrador and Alaska; winters in 
southern U. §. and southward. 
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