E-Fauna BC: Electronic Atlas of the Wildlife of British Columbia

Progne subis Linnaeus
Purple Martin
Family: Hirundinidae

Species account author: Jamie Fenneman

© Tim Zurowski  Email the photographer   (Photo ID #7967)


Distribution of Progne subis in British Columbia.
(Click on the map to view a larger version.)
Source: Distribution map provided by Jamie Fenneman for E-Fauna BC

Species Information

Adult male
The head and body plumage is entirely dark, glossy blue-black or purplish-black and the long, pointed wings and shallowly forked tail are black. The iris is dark, the tiny bill is blackish, and the legs and feet are blackish.

Adult female
The back, scapulars, rump, and lesser upperwing coverts are glossy blue-black, contrasting slightly with the duller blackish wings and tail. The underparts are dingy greyish-white with darker grey smudging that is heaviest on the breast; the underwings are wholly dark. The crown is glossy blue-black and lores and the ear coverts are duller blackish, although the cheeks are often washed with pale grey; the forehead is pale greyish-white. The chin, throat, and neck are pale dusky-grey, forming a broad collar around the neck. Bare part colouration is similar to that of the adult male.

Immature male
This plumage is acquired on the wintering grounds and is held throughout the following spring and summer. Males in this plumage are very similar to adult females but usually show a variable amount of dark, glossy blue-black feathering on the head and body, sometimes becoming so extensive as to form a hood. Some immature males that lack this blue-black feathering are very difficult, or possibly impossible, to tell from adult females in the field.

Juvenile
This plumage is held briefly during the summer of the first year, but is lost by fall (on the wintering grounds). It is very similar to the plumage of the adult female, but the upperparts are drabber and browner and lack any dark blue gloss. The head and collar are browner than in the adult female, and the underparts are whiter with only a few very fine, short, dark streaks.

Measurements
Total Length: 19-20 cm
Mass: 56-59 g

Source: Brown (1997); Sibley (2000)

Biology

Identification

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.
Vocalizations

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)

Breeding Ecology

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)
Foraging Ecology

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)

Habitat


Nesting colonies occur only in artificial nest boxes that have been erected in sheltered marine waters, such as in harbours, lagoons, bays, estuaries, marinas; pairs originally nested also in freshwater habitats such as lakes and ponds, but all current populations breed in marine habitats. Foraging birds occur over coastal mudflats, lakes, marshes, ponds, open fields, and forested habitats. It ranges more widely into a greater diversity of habitats during migration, especially in the fall.

Source: Campbell et al. (1997); Fraser et al. (1997); Fraser et al. (1999)

Distribution

Global Range

Breeds widely throughout eastern North America, from northern Alberta east to Nova Scotia and south to southern Texas and Florida. Additional populations breed throughout the Rocky Mountain region of the United States (Utah, Colorado), in the southwestern states (Arizona, New Mexico), along the Pacific coast from southern B.C. south to Baja California, and locally in northern and central Mexico. Winters in South America.
BC Distribution

Breeding
Fairly common, but local, on southeastern Vancouver Island from Sooke north to Parksville, as well as in the Gulf Islands, becoming uncommon farther north to the Campbell River area. It is also uncommon and local on the Sunshine Coast and in the Lower Mainland (primarily in the vicinity of Vancouver and east along the Fraser River to Mission).

Migration and Vagrancy
The first spring migrants arrive in southwestern B.C. in mid-April (occasionally in early April), with most birds appearing between late April and early May. Fall migrants depart B.C. primarily during August, and can often be observed in unusually large flocks at this time of year in areas where it is not normally encountered during the breeding season. Most individuals have left the province by mid-September (rarely lingering into late September); exceptionally late birds have lingered into October.

Casual during spring and summer on northern and western Vancouver Island, as well as in the Lower Mainland east of the normal breeding areas (as far east as Hope; may breed in the Chilliwack area). In the interior, it is casual during the spring and summer in southeastern B.C. and casual in summer in the northeastern part of the province east of the Rocky Mountains (most records from the Peace River area).

Source: Campbell et al. (1997); Georgia Basin Ecological Assessment and Restoration Society (2009)

Conservation

Population and Conservation Status

As a peripheral species in British Columbia, populations of Purple Martin in the province have historically been relatively low and subject to large fluctuations. Following the arrival of settlers to the south coast in the 1800s, there is some evidence that populations may have increased and expanded as new cavities became available in poles and pilings, as well as in buildings. Populations subsequently declined in the early 1900s and continued to fluctuate at relatively low levels until the 1940s. Rather suddenly, populations in British Columbia and all along the Pacific coast of North America plummeted in the 1940s. This massive decline is generally attributed to the arrival of two aggressive, exotic cavity-nesting species at that time: House Sparrow and European Starling. Both species were able to either out-compete or even aggressively overtake virtually all cavity nests that were available to Purple Martins, thus resulting in a population crash. Other factors, such as changes in the structural design of buildings after WWII, which resulted in fewer artificial cavities, may also have contributed to the decline, and by the 1980s and early 1990s the population of Purple Martins in B.C. had declined from 150-600 pairs to only 5 pairs at a single colony on Vancouver Island (a decrease of 96-99% or more over a period of ~50 years). The few remaining birds were now nesting only in natural cavities in offshore pilings that were presumably not targeted by European Starlings due to their presence offshore over marine habitats.

An aggressive nest box program was initiated in the early 1990s in an attempt to bring populations of Purple Martins back from the brink of extirpation. This program was also initiated in the Puget Sound area of Washington, which had also lost virtually all of its nesting Purple Martins by the 1980s. Fortunately, due to a nest box design that proved unattractive to starlings as well as the continued placement of boxes over water in sheltered marine habitats, the recovery program proved to be a significant success, and populations of Purple Martins began to increase almost immediately. By 2000, the population had reached ~180 pairs at 11 colonies, which was similar to some historic estimates of the breeding population in the province. A sharp increase then occurred between 2003 and 2006, when the population in the province jumped from ~200 pairs to ~650 pairs. Although the population has retracted slightly since 2007, presumably due to a series of relatively cold springs, it remains high and there are currently (as of 2008) approximately 570 pairs breeding at 45 sites on Vancouver Island, the Gulf Islands, the Sunshine Coast, and the Lower Mainland. The population has therefore increased from 5 pairs to 570 pairs over only ~15 years, and the number of colonies has increased from 1 to 45 during this same period. The recovery of Purple Martins in the Pacific Northwest is one of the most successful conservation efforts in the region in recent memory. Despite the increase, however, the B.C. Conservation Data Centre (CDC) retains the Purple Martin on the provincial ‘blue list’ as a species of special concern due to the continued threat of population fluctuations and even sustained declines.

Source: Campbell et al. (1997); Georgia Basin Ecological Assessment and Restoration Society (2009)

Taxonomy


Three subspecies of Purple Martin are recognized throughout its range, two of which are found in British Columbia (one only as a vagrant). The males of all subspecies are essentially indistinguishable, but there are subtle differences in the plumage of the females which enable identification in the field.

The subspecies occurring in B.C. are as follows:

Progne subis subis
This is the widespread and common eastern North American subspecies, but in B.C. it is known only from a handful of records of vagrants from the northeastern part of the province (primarily the Peace River area). Slightly smaller than P.s.arboricola. Females of this subspecies are noticeably darker and duskier than females of other subspecies, particularly on the head and underparts, with a less boldly contrasting pale collar around the neck.

Progne subis arboricola Behle
This subspecies occurs along the Pacific coast of North America, north to southwestern B.C., as well as in the southern Rocky Mountains of the U.S. It averages slightly larger than the nominate P.s.subis, and females are noticeably paler with a whiter forehead, paler grey throat and collar, and more extensively whitish underparts.

Source: Brown (1997)

Status Information

Origin StatusProvincial StatusBC List
(Red Blue List)
COSEWIC
NativeS3BBlueNot Listed
BC Ministry of Environment: BC Species and Ecosystems Explorer--the authoritative source for conservation information in British Columbia.

Additional Range and Status Information Links

Additional Photo Sources

General References


Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2017. E-Fauna BC: Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab for Advanced Spatial Analysis, Department of Geography, University of British Columbia, Vancouver. [Accessed: 17/08/2017 4:13:49 PM]
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