This is the largest, bulkiest swallow species in North America, and that factor alone renders it unlikely to be mistaken for any of our other swallow species. Furthermore, the entirely dark plumage of the male and the extensively grey and dark bluish-black plumage of the female are even more distinctive than the large size.
| The male’s song is a low-pitched, rich series of liquid, gurgling notes with occasional grating phrases interspersed (eastern subspecies P.s.subis has grating notes only at the end of the song, if at all). The female’s song consists of a mixture of chortle calls and downslurred whistles, with western P.s.arboricola giving a higher percentage of whistles than chortling calls (vice versa for eastern P.s.subis). The most commonly-heard call is a rich, descending cherr, often repeated in series, as well as a more complex chortle. Also gives a harsh, buzzy geerrtt, a dry, rattling skrrr, and a hard gip (given only by juvenal birds). Source: Brown (1997); Sibley (2000) |
Courtship
Males begin to court females once they have chosen a potential nesting cavity. They perform a ‘Claiming-Reclaiming’ display in which the male flies out from the chosen cavity, sails in a wide arc (as much as 800 m diameter), returns to the cavity and enters it, and then sings with his head poking out from the cavity. This display attracts the attention of nearby females, and mating occurs once the female has accepted the male and his cavity. Most pairs are monogamous throughout the breeding season, although a small percentage of males may be polygamous.
Nest
The Purple Martin is a highly colonial species, and rarely nests as single pairs. It traditionally nested in natural cavities or those excavated by woodpeckers, but almost all current nesting pairs are restricted to man-made nest boxes that have been erected for them as part of their recovery program. These nest boxes are erected on pilings within harbours, marinas, and other sheltered marine habitats where they can avoid being adopted by introduced European Starlings. Historically, some pairs also nested in crevices and crannies in tall buildings (such as in Vancouver and Victoria), but this has not occurred in B.C. in many decades. Both sexes contribute to the contribution of nesting material to the nest box, although the female’s contribution is generally much greater than that of the male. The nest is composed of a loose aggregation of leaves, grass, twigs, feathers, and strips of bark that is placed on the bottom of the nesting cavity or nest box; many nests appear to be lined with fresh green willow leaves. Some birds incorporate unusual materials such as string, aluminum tabs, pieces of bread, or nails into the nest.
Eggs
A single clutch of 4-5 eggs is laid between late May and early July (mostly during the first , but later clutches appear to be replacement clutches rather than second broods). The clutch is incubated by primarily by the female (sometimes by the male) for 15-18 days before hatching. The smooth, non-glossy eggs are pure white. Eggs are present in B.C. between late May to late July. This species does not suffer from Brown-headed Cowbird parasitism, despite occasional reports to the contrary.
Young
The young are altricial and naked upon hatching, lacking any natal down, with pink skin and pale yellow gape flanges. Both sexes tend to the young, although only the female broods. The young fledge at 26-37 days of age (usually 28-29 days of age), although they regularly return to the nest cavity afterwards for roosting. The parents lead the young away from the immediate area around the colony after fledging because of high levels of harassment from adjacent martins, and they often remain in this area for several days with the parents. The young become fully independent by 7-10 days after fledging. Nestlings and dependent fledglings are present in B.C. between mid-June and late August.
Source: Brown (1997); Campbell et al. (1997); Baicich and Harrison (1997)
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Like other swallows, the Purple Martin feeds exclusively on flying insects such as beetles, moths, butterflies, flies, dragonflies, and wasps (among others). It tends to forage much higher than other swallow species, often above 50 m and regularly as high as 150 m from the ground; in many cases, these birds forage so high that they are barely visible with the naked eye from the ground, yet their loud calls can be readily heard. Although nesting birds in B.C. are found in marine habitats, most birds forage over freshwater or upland habitats away from the nesting sites (sometimes up to several kilometers away). Individuals tend to prefer to forage in open areas, although some birds forage over forested habitats; during inclement weather, this species can often be observed foraging low over lakes and ponds in pursuit of low-flying insects. Most foraging is done singly or in pairs, and larger aggregations generally occur only during migration or when there is a significant mass-emergence of a flying insect.
Source: Brown (1997)
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