A sociable species, the fairy martin usually feeds in large flocks and nests in colonies (2) (3) (4). It generally forages high in the air, catching flying insects such as mayflies, termites, beetles, flies, wasps, ants and moths (2), which it pursues with great agility (6). This species has also been recorded feeding on moths on a lawn (2) (3).
The breeding season of the fairy martin generally runs from August to January or February (2) (3) (7) (8), and two to three broods may be raised each season (2) (3) (8). Fairy martins build their nests close together, forming colonies which generally consist of around 8 to 30 pairs, but which occasionally may number up to several hundred (2) (3) (8).
The fairy martin is the only Australian bird to construct an enclosed, bottle-shaped mud nest, and the nests in a colony are often clustered and fused together (9). Both sexes help build the nest, constructing it from mud pellets and lining it with grass and feathers (2) (3) (7) (8) (9). The fairy martin’s nest has a tunnel-like entrance (2) (3) and is commonly attached to an artificial site such as a culvert, bridge, mine shaft or under house eaves, or to natural sites like cliffs, caves, hollow trees or riverbanks (2) (3) (6) (9). The nest is commonly reused in the same season (8), and individual birds often return to the same breeding site in successive years (2) (3) (8) (9).
The clutch size of the fairy martin ranges from 2 to 5 eggs, which are incubated for 11 to 18 days (2) (7) (8). The eggs are white and often have reddish-brown specks (3). Both adults help with incubation, and both also feed the chicks, which leave the nest at 14 to 32 days old (2) (7) (8). Prolonged periods of cold, wet weather can often result in the adults abandoning their nest (2) (8), and the nests are also vulnerable to predators such as kingfishers, as well as nest competitors such as the house sparrow (Passer domesticus) (2) (3).