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Tree Swallows.JPG
Tree Swallow Pair


Tree Swallow

Tree Swallows at a Glance


Order Passeriformes

Family Hirundinidae – Swallows and Martins

(19 genera, 83 species)

Subfamily Hirundininae

Genus and species: Tachycineta bicolor



  • 12 cm length (5 3/4 inches)

  • Male: Glossy blue-green back and white under parts with blackish tail and wings. Under wing is grey-brown. Tail is short and slightly forked.

  • Adult Female: More dull (less blue and iridescence) than male; occasionally a female has a brown forehead.

  • Juvenile: Brown upper parts and grey-brown wash on part of white breast:

  • First year female: Brown above with some blue feathers.

  • Second year female: Less brown and bluer feathers.


  • Tree Swallows prefer open areas near lakes, marshes, coastal areas where they feed in the lee of the wind. Marshes and trees are preferred for roosting.

  • Tree Swallows prefer insects but they will eat mollusks, spiders, some fruit, berries (bayberry) and seeds (bulrush, sedge, bayberry and smartweed). They forage singly or in groups. Large numbers gather at insect swarms.


  • They arrive in early spring in Maine when seeds and berries are available. Other swallows that focus solely on insects in their diet arrive later.

  • The male courts the female with a vertical-display posture followed by flying to the nest giving a high-pitched call.

  • Tree cavities are used for nests as well as man-made nest boxes.

  • The nest is built of grass, pine needles, moss and aquatic plants, formed into a cup lined with feathers.

  • Starting in early may to mid-June the female incubates 4-7 eggs for ~14-15 days.

  • Incubation – 30-34 days

  • Starting in early may to mid-June the female incubates 4-7 eggs for ~14-15 days.

  • The chicks fledge in 18-22 days.


Distribution and Migration:

  • The Tree Swallow breeds throughout north and central North America spends the winter in southern USA coast, West Indies, and Central America to the northern coast of South America.

  • Tree Swallows migrate in small loose flocks along the east coast. Some groups stop at the mouth of the Connecticut River to roost in marshes along with a million other individuals from the end of August through September.

  • This mega-flock then breaks into small groups and they move south to their winter homes - taking approximately three months.



1. del Hoya, J, A. Elliot, and J. Sargatal. Eds. 2004. Handbook of the Birds of the World. Vol 9. Cotingas to Pipits and Wagtails. Lynx Edicions. Barcelona.

2. Weber, Charlotte. 2017. 1 Million Tree Swallows Prepare for Connecticut's Annual 'Avian Ballet"; NPR, wshu

3. Sibley, D.A. 2000. National Audubon: The Sibley Guide to Birds. Alfred A. Knopf, NY.

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