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Violet-green Swallow

Tachycineta thalassina ORDER: PASSERIFORMES FAMILY: HIRUNDINIDAE

IUCN Conservation Status: Least Concern

These aerial insectivores perform acrobatic stunts over lakes and streams high in the sky in search of flying insects. Violet-green Swallows can look dark at first, but their true colors come to life when sunlight illuminates their metallic green backs and iridescent purple rumps. They are a common sight in the West in spring and summer, but they vanish to Mexico and Central America for the winter. They can be distinguished from other swallows by the white patches on the sides of their rump and their white cheeks.

At a GlanceHelp

Measurements
Both Sexes
Length
4.7 in
12 cm
Wingspan
10.6 in
27 cm
Weight
0.5 oz
14 g
Relative Size
About the same size as a Bank Swallow, but smaller than a Barn Swallow.
Other Names
  • Hirondelle à face blanche (French)
  • Golondrina verde-violeta (Spanish)

Cool Facts

  • Violet-green Swallows have been recorded flying at 28 miles per hour—a pretty respectable speed considering that the Peregrine Falcon, the fastest bird of prey, averages about 25–35 miles per hour in traveling flight.
  • Sometimes late hatching young are at a disadvantage, but female Violet-green Swallows invest more antimicrobial proteins in the eggs laid later within a clutch possibly reducing infection for late hatching young and giving them a leg up.
  • The Violet-green Swallow is very similar to the Tree Swallow, both in appearance and habits, but it is more closely related to two other swallows found in the Caribbean: the Golden Swallow and Bahama Swallow.
  • A pair of Violet-green Swallows was observed assisting a pair of Western Bluebirds in raising young. The swallows guarded the nest and tended the bluebird nestlings, and after the bluebirds fledged, the swallows used the nest site for their own young.
  • The scientific name for Violet-green Swallow is Tachycineta thalassina. Tachycineta means fast moving and thalassina means of the sea referring to the sea-green color of their backs.
  • The oldest recorded Violet-green Swallow was a male, and at least 9 years, 1 month old, when he was recaptured and rereleased during banding operations in California in 1993. He had been banded in the same state in 1985.

Habitat


Open Woodland

Violet-green Swallows breed in open evergreen and deciduous woodlands, especially woodlands with standing dead trees that feature woodpecker holes or other natural cavities. They breed across the western United States from sea level to as high as 11,500 feet elevation. In some areas, they also breed in and around human settlements and use nest boxes. In Mexico and Central America during the nonbreeding season, Violet-green Swallows inhabit coastal plains, interior mountains, cloud forests, and pine forests up to 10,000 feet.

Food


Insects

Violet-green Swallows feed on flying insects such as flies, leafhoppers, leafbugs, aphids, beetles, and winged ants that they catch and eat in midair. They skim low over water bodies and fields snatching up insects, but they also forage high above the ground.

Nesting

Nesting Facts
Clutch Size
4–6 eggs
Number of Broods
1-2 broods
Egg Length
0.6–0.8 in
1.6–2.1 cm
Egg Width
0.5–0.6 in
1.2–1.4 cm
Incubation Period
14–15 days
Nestling Period
23–24 days
Egg Description
Pure white, without markings.
Condition at Hatching
Naked with closed eyes and bits of fluffy down on the back, crown, and scapulars.
Nest Description

Male and female swallows gather grass stems, small twigs, rootlets, and feathers to build a loose, shallow cup nest at the bottom of a cavity. Nest construction takes anywhere between a few days up to 20 days. The nest cup measures about 3 inches across, but depends to some extent on cavity size.

Nest Placement

Cavity

Violet-green Swallows nest in cavities in trees and cliffs, or in nest boxes. They use old woodpecker holes or naturally occurring cavities in dead and dying trees. They nest solitarily or in small colonies of up to 25 pairs in open woodlands often near water bodies.

Behavior


Aerial Forager

Violet-green Swallows are gregarious birds all year long, on the breeding and nonbreeding grounds and during migration. They often forage in large groups, of up to several hundred, with other Violet-green Swallows as well as other swallow and swift species. They forage over water bodies, fields, and open woodlands capturing and eating insects on the wing. In flight, these swallows intersperse rapid, shallow wingbeats with long glides and appear rather fluttery and slightly off balance. Like other cavity-nesting species, Violet-green Swallows often have more parasites on their feathers than birds that nest in the open. To control the parasites, they sunbathe and preen frequently. They breed solitarily or in groups, depending on the availability of nesting cavities. Adults compete with other cavity-nesting species including House Sparrows, Western Bluebirds, Tree Swallows, and Mountain Chickadees for places to nest. Pairs are likely monogamous during the breeding season, but females may sneak off to mate with additional males.

Conservation

status via IUCN

Least Concern

Violet-green Swallows are common throughout the West, but populations experienced a decline of about 28% between 1966 and 2015, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population at 7 million, with 66% breeding in the United States, 16% in Canada, and 91% spending a portion of the year in Mexico. The species rates a 9 out of 20 on the Continental Concern Score and is not on the 2016 State of North America's Birds' Watch List. Although Violet-green Swallow populations are stable, aerial insectivores as a group were recognized as declining across North America in the State of the Birds 2014 report. Aerial insectivores have declined across much of North America and Europe perhaps due to use of neonicotinoids (an insecticide), climate change, and pollution. All of these factors can reduce the abundance of flying insects that these birds rely on and could contribute to population declines.

Credits

Range Map Help

Violet-green Swallow Range Map
View dynamic map of eBird sightings

Migration

Medium to long-distance migrant. Most individuals migrate to Mexico and Central America during the nonbreeding season, heading as far south as Costa Rica. Some individuals spend winters in California’s Imperial Valley, the lower Colorado River Valley, and coastal California.

Backyard Tips

If you live near an open woodland or lake, Violet-green Swallows may nest in your yard, especially if you put up a nest box or leave standing dead trees on your property. Nest boxes can be placed on buildings, live trees, dead trees, or a pole 9–15 feet above the ground. Because Violet-green Swallows often like to nest in small groups, consider putting up more than one nest box at least 30 feet apart. Find out more about nest boxes on All About Birdhouses, where you'll find plans to build your own nest box for Violet-green Swallows.

Find This Bird

One of the best places to look for Violet-green Swallows is to head out to a river, pond, or lake early in the morning and keep your eyes to the sky. Watch for birds swooping and twittering over the water snatching up insects. They tend to be in groups from 10 to over 100 and they often hang out with other swifts and swallows. To pick one out of the crowd look for the white saddlebags on the sides of the rump and a clean white belly. It can be difficult to get a good look at flying Violet-green Swallows, but you might have an easier time following one with your binoculars if you spot one a little bit further away. That way the swallow won't zip out of your field of view as soon as it enters. They often perch on power lines and dead trees, so you’ll be able to get a better look at perched birds in those spots.

Get Involved

Provide nesting habitat for Violet-green Swallows by building a nest box. Learn more at NestWatch and start contributing valuable information about the breeding biology of Violet-green Swallows.

You Might Also Like

Read about a unique observation of a large group of Violet-green Swallows bathing in the Naturalist’s Notebook: Violet-Green Swallows, Living Bird, Summer 2009.

In California’s Oak Woodlands, 5 Species Divvy Up Habitat To Improve Nest Success, All About Birds, May 18, 2016.

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