House Martin

About

The House Martin is a small passerine bird in the swallow family, Hirundinidae. It is characterized by its glossy blue-black upperparts, pure white underparts, and a distinctive white rump. Known for its aerial insectivorous feeding and colonial nesting habits, often building mud nests under the eaves of buildings.

Size & lifespan

Length

13-15 cm

Wingspan

26-29 cm

Weight

15-22 g

Lifespan

2-5 years (up to 10 years recorded)

Diet

Insectivore

Physical characteristics

Plumage

Adults have glossy blue-black upperparts, including the head, back, and upperwing coverts. The rump is conspicuously pure white, contrasting sharply with the dark back and tail. Underparts are entirely pure white. The tail is forked, but less deeply than that of a Barn Swallow.

Beak shape

Small, flattened, and triangular, adapted for catching insects in flight. Black in color.

Eye color

Dark brown

Leg color

Short, feathered white legs and feet, often appearing fluffy.

Distinguishing features

The most distinctive feature is the pure white rump, which is highly visible in flight. The feathered white legs are also unique among European swallows and martins. Its flight is typically more buoyant and fluttering than the Barn Swallow.

Juvenile appearance

Juveniles are duller than adults, with sooty-brown upperparts instead of glossy blue-black. The white underparts may be tinged with grey or buff, and the white rump is less bright. The feathers on the legs are less developed.

Seasonal changes

No significant seasonal plumage changes. Breeding and non-breeding plumages are similar, though plumage may appear slightly worn by the end of the breeding season.

Sexual dimorphism

Males and females are virtually identical in plumage and size. There is no discernible sexual dimorphism.

How to identify

1. 1

   Rump Color

   Look for the striking, pure white rump that contrasts sharply with the dark back. This is the most reliable field mark.

2. 2

   Underparts

   Observe the entirely pure white underparts, lacking any streaking or rufous coloration.

3. 3

   Upperparts

   Note the glossy blue-black upperparts, which can appear dark blue in good light.

4. 4

   Tail Shape

   The tail is forked, but relatively short and less deeply forked than a Barn Swallow's, lacking long streamers.

5. 5

   Legs

   If seen at rest or closely, the white feathered legs and feet are a unique identifier among European swallows/martins.

6. 6

   Flight Style

   Its flight is often described as more buoyant, fluttering, and less direct than the Barn Swallow, with frequent glides.

7. 7

   Nesting Sites

   Look for mud nests built under eaves of buildings, bridges, or cliffs, often in colonies.

Habitat & range

Biomes

Temperate grasslands, open country, agricultural areas, urban and suburban environments.

Geographic range

Breeds across most of Europe and temperate Asia, from Ireland and Portugal east to Japan and Kamchatka. Winters in sub-Saharan Africa and tropical Asia.

Elevation range

Typically found from sea level up to 2,000 meters, occasionally higher in mountainous regions during migration.

Preferred environments

Prefers open country with access to water and suitable nesting sites, primarily man-made structures like houses, bridges, and cliffs. Often found near human habitation.

Behavior

Activity time

Diurnal. Active from dawn to dusk, primarily foraging during daylight hours.

Feeding habits

Strictly aerial insectivores, catching insects (flies, aphids, small beetles, mosquitoes) on the wing. They forage at various heights, often higher than Barn Swallows, especially in good weather. They drink by skimming over water surfaces.

Social behavior

Highly colonial, especially during breeding. Nests are often built in close proximity, forming large colonies. They also roost communally outside the breeding season, sometimes in very large numbers.

Flight pattern

Graceful, buoyant, and agile flight, characterized by rapid wing beats interspersed with glides. Often flies in tight, erratic patterns when foraging. Less direct and more fluttering than the Barn Swallow.

Migration pattern

Long-distance migratory. European populations migrate south to sub-Saharan Africa for the winter, while Asian populations winter in tropical Asia. They migrate in large flocks, often following broad fronts.

Territoriality

While nesting in colonies, individual pairs defend a small area immediately around their nest. Foraging areas are generally shared.

Breeding & reproduction

Breeding season

Typically May to August in Europe, with two or sometimes three broods per season.

Nesting habits

Builds a distinctive enclosed cup-shaped nest made of mud pellets, lined with grass and feathers. Nests are typically attached to vertical surfaces under eaves, overhangs, bridges, or cliffs, often in colonies.

Clutch size

Typically 4-5 eggs, occasionally 3-7.

Egg description

Usually 4-5 pure white, unmarked, slightly glossy eggs. Approximately 19.5 x 13.5 mm.

Incubation period

13-16 days, primarily by the female, though both parents may participate.

Fledging period

22-32 days after hatching. Young are fed by both parents.

Parental care

Both parents participate in nest building, incubation (to a lesser extent for the male), feeding of nestlings, and post-fledging care. Young birds are fed for several days after leaving the nest.

Where to find

Field tips

1. Look Up. House Martins spend most of their time in the air. Scan the sky above buildings, open fields, and water bodies.
2. Observe Nests. During the breeding season (spring/summer), locate colonies of mud nests under eaves. Birds will be constantly flying to and from these nests.
3. Listen for Calls. Their characteristic 'chip' or 'chrrrp' calls are often heard as they fly, especially near colonies.
4. Migration Hotspots. During spring and autumn migration, large flocks can be seen passing through coastal areas, mountain passes, or gathering at roost sites.
5. Watch for Foraging. Observe their agile, buoyant flight as they chase insects. They often fly higher than Barn Swallows.

Similar species

Quick facts

Key ID Feature:

Pure white rump

Nest Type:

Enclosed mud cup under eaves

Diet:

Flying insects

Sociality:

Highly colonial

Migration:

Long-distance migrant

Fun facts

• House Martins often reuse their mud nests year after year, sometimes repairing them or building new ones on top of old foundations.
• They are highly dependent on human structures for nesting, making them one of the most synanthropic (associated with humans) bird species.
• A single House Martin nest can contain thousands of mud pellets, each collected individually by the birds.
• Despite their small size, House Martins undertake epic migrations, covering thousands of kilometers between their breeding and wintering grounds.
• They are known to occasionally hybridize with Barn Swallows, though this is relatively rare.

Scientific classification

Kingdom

Animalia

Phylum

Chordata

Class

Aves

Order

Passeriformes

Family

Hirundinidae

Genus

Delichon

Species

urbicum

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