Tree SwallowTachycineta bicolorWhere and when to see them

The Tree Swallow is a glossy-backed aerial insectivore whose association with river wetlands depends on both food and nesting cavities. This profile concerns the Upper Mississippi refuge from Wabasha to Rock Island. It is a bird to look for over backwaters and shorelines, not simply any swallow seen following the main navigation channel. Species reference: https://www.allaboutbirds.org/guide/Tree_Swallow/lifehistory

Size

12–15 cm (4.7–5.9 in) total length, Macalester College species account (https://www.macalester.edu/ordway/biodiversity/inventory/treeswallow/).

Weight

16–25 g (0.56–0.88 oz), Macalester College species account.

Lifespan

Species-specific lifespan not verified.

Status

Formal global conservation category not verified.

Fast turns and repeated passes over sheltered water reflect aerial hunting. Birds may gather where insects concentrate, while nest-site activity brings repeated returns to a cavity or box. Cornell describes existing holes rather than excavation of a new tunnel: this distinguishes its nesting requirements from those of Sand Martins and other bank-nesting swallows.

• It nests in existing cavities.
• Old woodpecker holes can be used.
• Nest boxes can provide breeding sites.
• Flying insects dominate its diet.
• It can also eat plant foods.
• The refuge checklist records spring, summer and fall presence.

The refuge’s long-term checklist marks Tree Swallow abundant in spring and summer and common in fall. It explicitly defines those seasons as March–May, June–August and September–November. March–November is therefore supported as a seasonal-presence matrix for the registered refuge, with abundance and weather varying within that interval.

Fields, marshes, shorelines and wooded swamps are documented breeding habitats, usually close to insect-producing water. Dead trees and old woodpecker holes can supply nest sites. Refuge wetland mosaics therefore offer both hunting space and potential cavities, though an occupied box should never be assumed merely because swallows are feeding nearby.

Flying insects dominate. Cornell lists flies, mayflies, caddisflies, dragonflies and many other groups, while also documenting occasional other animal and plant foods. During poor conditions, berries can supplement the diet. No Upper Mississippi dietary percentages were verified, and the presence of a visible insect hatch does not identify every swallow attending it.

Common name

Tree Swallow

Scientific name

Tachycineta bicolor

Animal group

Birds

Size

12–15 cm (4.7–5.9 in) total length, Macalester College species account (https://www.macalester.edu/ordway/biodiversity/inventory/treeswallow/).

Weight

16–25 g (0.56–0.88 oz), Macalester College species account.

Lifespan

Species-specific lifespan not verified.

Status

Formal global conservation category not verified.

Identification

Adults combine glossy blue-green upperparts with clean white underparts and a relatively short, slightly forked tail. Young birds and some younger females are browner, so gloss is not universal. Compare breast pattern carefully with Bank Swallow and other species in mixed flocks; a brown swallow is not automatically a different species.