Grey-breasted Martin

About

The Grey-breasted Martin is a medium-sized migratory swallow characterized by its iridescent dark blue-black upperparts and contrasting grey underparts. It is a highly aerial feeder, often seen gracefully soaring and diving over open areas, water bodies, and human habitations.

Size & lifespan

Length

18-20 cm

Wingspan

39-41 cm

Weight

36-49 g

Lifespan

Typically 5-7 years in the wild, though can reach up to 10 years.

Diet

Strictly insectivorous, feeding on a wide variety of flying insects caught in mid-air. This includes flies, beetles, moths, butterflies, bees, wasps, and dragonflies.

Physical characteristics

Plumage

Adult males and females are similar. Upperparts are glossy, iridescent steel-blue to blue-black. The head and nape are also dark blue-black. Underparts are smoky grey, becoming whiter on the lower belly and undertail coverts. The throat and upper breast are concolorous with the grey underparts. The wings and tail are blackish. Juveniles have duller, less iridescent upperparts and browner underparts.

Beak shape

Short, conical, and broad at the base, perfectly adapted for hawking insects in flight.

Eye color

Dark brown

Leg color

Black

Distinguishing features

The combination of glossy dark blue-black upperparts and clear smoky grey underparts is the primary distinguishing feature. Its relatively large size for a swallow also stands out.

Juvenile appearance

Juveniles are duller than adults, with less intense iridescence on the upperparts. Their underparts are a duller, often brownish-grey and can appear streaky, especially on the breast, before their first pre-basic molt.

Seasonal changes

No significant seasonal plumage changes. Plumage remains consistent throughout the year, aside from the molting process.

Sexual dimorphism

Minimal. Males and females are largely alike in plumage. Some sources suggest males may be slightly more iridescent, but this is often not reliably distinguishable in the field.

How to identify

1. 1

   Plumage Coloration

   Look for the stark contrast between iridescent blue-black upperparts and smoky grey underparts. This is the most reliable field mark.

2. 2

   Size and Shape

   It's a relatively large swallow with a typical swallow-like, deeply forked tail (though less deeply forked than barn swallows) and broad, pointed wings.

3. 3

   Flight Pattern

   Observe its strong, soaring flight with graceful glides mixed with deep wing beats. It often flies higher than other swallows, but also patrols lower over open areas.

4. 4

   Vocalizations

   Listen for its distinctive gurgling, burry warble or sharp 'scheep' calls, especially around potential nesting sites or roosts.

Habitat & range

Biomes

Tropical and subtropical regions, including forests (edges), open woodlands, savannas, grasslands, agricultural areas, urban and suburban environments, and coastal areas.

Geographic range

Breeding range extends from Mexico, through Central America, and into South America as far south as Argentina. Also found on Trinidad and Tobago.

Elevation range

Typically found from sea level up to 2000 meters (approx. 6500 feet), occasionally higher.

Preferred environments

Highly adaptable, preferring open areas with access to water. Commonly found in human-modified landscapes such as towns, villages, and around bridges, buildings, and other man-made structures for nesting. Also frequents forest clearings, pastures, and riparian zones.

Behavior

Activity time

Diurnal. Most active during daylight hours, especially morning and late afternoon.

Feeding habits

Aerial insectivore, capturing all prey in flight. It performs impressive acrobatic maneuvers, including swift turns, dives, and glides, to catch a wide range of flying insects. Often forages at various heights, sometimes high in the sky, other times closer to the ground or over water.

Social behavior

Highly social, particularly outside the breeding season when they form large communal roosts, sometimes with other swallow species. During breeding, they can nest solitarily, in small groups, or in loose colonies.

Flight pattern

Graceful, strong, and agile. Characterized by powerful, shallow wingbeats interspersed with long glides. Often circles at height or flies low over open fields and water bodies. Highly maneuverable during insect pursuit.

Migration pattern

Northern populations (Mexico, Central America) are partially migratory, with some individuals making altitudinal movements or short-distance migrations south for the winter. Southern populations are largely resident or undertake regional movements. The species is known to make long-distance movements across its range.

Territoriality

While nesting, pairs or colonies will defend the immediate vicinity of their nest site. However, feeding areas are generally shared, and they are typically not aggressive towards other bird species unless directly threatened.

Breeding & reproduction

Breeding season

Varies geographically. In Mexico and Central America, typically from March to August. In South America, often from September to March, encompassing the local summer months.

Nesting habits

Nests in natural cavities, such as tree hollows or rock crevices, but very frequently utilizes artificial structures. These include holes in buildings, bridges, eaves, lamp posts, and occasionally martin houses. The nest is a cup-shaped structure made of grasses, leaves, and mud, often lined with finer materials like feathers. Both sexes contribute to nest building, incubation, and chick rearing.

Clutch size

2-5 eggs, most commonly 3 or 4.

Egg description

2-5 (typically 3-4) pure white, unspotted, slightly glossy, oval-shaped eggs.

Incubation period

Approximately 15-18 days, primarily by the female, though the male may assist.

Fledging period

21-28 days. Young birds are fed by both parents until they fledge and often for a period afterward.

Parental care

Both parents are actively involved in feeding the nestlings and fledglings. They bring a constant supply of insects to the nest. After fledging, the young birds remain dependent on their parents for a short period, receiving food and learning foraging skills.

Where to find

Field tips

1. Scan the Sky. Grey-breasted Martins are highly aerial, so spend time looking up, especially over open areas or near water. They often perch conspicuously on wires or antennas.
2. Check Man-Made Structures. Bridges, large buildings with eaves, and even martin houses are prime locations for observing them, particularly during the breeding season when they are nesting.
3. Listen for Calls. Their distinctive gurgling calls can often betray their presence before they are visually detected, especially at dawn and dusk around roosts.
4. Evening Roosts. In non-breeding periods, look for large communal roosts, often in reed beds or large trees, where they gather in significant numbers at dusk.

Similar species

Quick facts

Diet:

Strictly insectivorous

Sociality:

Social, colonial breeder

Flight:

Strong, agile, and graceful

Nesting Sites:

Cavities, often man-made structures

Global Status:

Least Concern

Fun facts

• Grey-breasted Martins are highly adaptable and have successfully colonized urban environments, often nesting directly on human structures.
• Like other swallows, they play a crucial ecological role in controlling insect populations, consuming thousands of flying insects daily.
• They are known for their impressive aerial agility, making sharp turns and dives to catch fast-moving insect prey.
• Some populations exhibit partial migration, making altitudinal or short-distance seasonal movements rather than long-distance ones.

Scientific classification

Kingdom

Animalia

Phylum

Chordata

Class

Aves

Order

Passeriformes

Family

Hirundinidae

Genus

Progne

Species

Progne chalybea

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