It is hunted by the Eurasian hobby (Falco subbuteo), and like other birds is affected by internal parasites and external fleas and mites.

The western house martin was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae as Hirundo urbica,[5] but was placed in its current genus, Delichon, by Thomas Horsfield and Frederic Moore in 1854.

In Africa, confusion with grey-rumped swallow (Pseudhirundo griseopyga) is possible, but that species has a grey rump, off-white underparts and long, deeply forked tail.

[14][15] The western house martin breeds across temperate Eurosiberia east to central Mongolia and the Yenisei River, and in Morocco, Tunisia and northern Algeria,[14] and migrates on a broad front to winter in sub-Saharan Africa.

[9] Migration brings its own hazards; in 1974, several hundred thousand birds of this species were found dead or dying in the Swiss Alps and surrounding areas, caught by heavy snowfall and low temperatures.

[21] The western house martin returns to the breeding grounds a few days after the first barn swallows; and like that species, particularly when the weather is poor, it seldom goes straight to the nesting sites, but hunts for food over large fresh water bodies.

[9][23] The western house martin was originally a cliff and cave nester, and some cliff-nesting colonies still exist, with the nests built below an overhanging rock.

[9] Breeding birds return to Europe between April and May, and nest building starts between late March in North Africa and mid-June in Lapland.

Rainfall in the African wintering grounds is a major factor in adult survival, although wet weather in the breeding areas has very little effect.

[9] For weeks after leaving the nest the young congregate in ever-increasing flocks which, as the season advances, may be seen gathering in trees or on housetops, or on the wires with swallows.

By the end of October, most martins have left their breeding areas in western and central Europe, though late birds in November and December are not uncommon, and further south migration finishes later anyway.

[9] Once established, pairs remain together to breed for life; however, extra-pair copulations are common, making this species genetically polygamous, despite being socially monogamous.

The paired male initially ensured that his female spent little time alone at the nest, and accompanied her on flights, but the mate-guarding slackened after egg laying began, so the youngest nestling was the most likely to have a different father.

[25] The western house martin has been regularly recorded as hybridising with the barn swallow, this being one of the most common passerine interspecific crosses.

[9] Although the western house martin is hunted by the hobby (Falco subbuteo), its aerial skills enable it to evade most predators.

[30][31] This is a species which has greatly benefited historically from forest clearance creating the open habitats it prefers, and from human habitation which has given it an abundance of safe nest sites.

[9] New housing has created more nest sites, and clean-air legislation has enabled breeding in the centre of major cities like London.

[32] Conversely, poor weather, poisoning by agricultural pesticides, lack of mud for nest building and competition with house sparrows can reduce numbers.

[34] William Shakespeare was clearly describing the house martin when Banquo brings the nests and birds to the attention of Duncan at Macbeth's castle, Inverness: "This guest of summer, The temple-haunting martlet, does approve By his loved mansionry that the heaven's breath Smells wooingly here.

No jutty, frieze, Buttress, nor coign of vantage, but this bird Hath made his pendant bed and procreant cradle; Where they most breed and haunt, I have observed

[34] The martlet, often believed to refer to the house martin, or possibly a swallow, was a heraldic bird with short tufts of feathers in the place of legs.