Western Purple Martin Foundation
Not all Purple Martins are purple!!
Adult male birds possess the dark, iridescent purple plumage that gave the species its name. It takes a full two years for male birds to develop this dark plumage.
Adult female birds are the same size as the males, but have the shiny purple colour on the head, neck and shoulders, dark backs and grey, speckled bellies. Subadult (1 year old) females lack purple plumage on their head and shoulders and are uniformaly dark above and speckled grey below.
Subadult males resemble adult females, except in the dark splotches which typically adorn their head, face and pale speckled undersides, the first traces of their all-purple adult plummage.
What Do They Eat? Insects!!
Purple Martins fly up to high altitudes to catch large flying insects such as dragonflies, moths and beetles, as well as many smaller insects. Dragonflies especially are a good sized package for a martin parent to bring back to hungry nestlings.
Migration and Arrival at Nesting Colonies
Purple Martins are neotropical migrants, like other members of the swallow family. They migrate from wintering areas in north and central South America to the USA and southern Canada each spring to breed during the summer months and return south in the fall. Western Purple Martins reach the northern limit of their breeding range at the north end of the Georgia Basin in southwest BC, near Campbell River on Vancouver Island.
Spring migration timing depends on age. Adult martins are the first to make the long journey back from South America, arriving in BC from early-mid April to early May to re-establish their colonies and claim the best nesting sites or risk losing them to other competing cavity-nesting species. They will usually return to the sites at which they successfully raised young in the previous year.
Younger subadult birds arrive later in May and June and have to settle for whichever nest boxes are left. If all the nest boxes in the colony are occupied, young martins may go off to find and colonize a new nesting site.
The largest active colony in BC is at the Ladysmith Maritime Society marina in Ladysmith Harbour on southern Vancouver Island. In 2008, it had 67 nests!
Most colonies of western Purple Martins contain <5-30 nesting pairs in artificial housing and <10 pairs where they still occur in the wild in the western USA. For comparison, colonies with over 250 pairs of eastern martins and a few 'super-colonies' with over 500 pairs in artificial housing have been reported in the eastern United States.
Where Do They Build Their Nests?
Purple Martins build their nests in cavities. The western martin traditionally used old woodpecker holes in snags, usually close to water and in burned over forested areas. Now they mainly use nest boxes provided by people. These nest boxes are usually clustered together on groups of marine pilings near or on the water.
While eastern Purple Martins prefer using hanging gourds or condo-style apartment blocks in people’s back yards, western Purple Martins use individual nest boxes in loose clusters as shown here. The clustering is important to prevent other competing territorial-nesting species (swallows and starlings) from occupying more than one or two boxes in a cluster, leaving some boxes available for martins to re-establish their colonies in spring.
Western Purple Martin colony site at Oyster Bay, Campbell River, showing
nest boxes on marine pilings.
What Are Their Nests Made Of?
Nests can be made of coarse grasses, twigs, leaves, wood chips, seaweeds ... even scrap metal or seashells! Nests are often lined with fresh leaves and cedar twigs. This may help reduce nest parasites.
The female does most of the nest building in late May or June, with some help from the male. The male continues to add fresh green leaves during the incubation period and for a week or so after hatching.
How Many Eggs Do They Lay?
The female martin generally lays 4-5 eggs in late May, June or early July, which she then incubates for 15-19 days. Sometimes nests contain 6-7 eggs. Females may also lay eggs in another female’s nest, thereby increasing their genes in the population for little to no effort.
Do Both Parents Incubate The Eggs?
The female martin does most of the incubation and has a heavily vascularized "brood patch" on her belly to transfer body heat to the eggs. The male martin does not have a brood patch, so can not incubate the eggs for long periods. The male does sit on the eggs to keep them warm while the female takes short feeding breaks. Both parents feed and care for the young after hatching.
How Old Are Young Before They Can Fly?
In BC, young birds fledge (fly) about 28 (26-30) days after hatching. Most fledge in late July or early August though a few may remain in late nests until late August or early September. Martins produce only a single brood of young in a season unlike some of the smaller swallows.
Where Do Martins Go For The Winter?
Our martins begin to fly south in early-mid August and most have left BC by the first week of September. They may move to a temporary staging or "pre-migratory roost" area in the southwest US or Mexico with good late summer-fall insect supplies. They may spend a few weeks at this roost area gaining weight before leaving for South America, likely arriving in South America in October.
The migration route and timing, stopover areas and winter range of our western martins are currently being studied and previous assumptions are based on information known for the eastern subspecies. Prior to the migration study, the most reliable evidence for western martin wintering areas was from two banded martins from Oregon that were recovered about 30 years apart in southwest Brazil, near Sao Paulo. See our on-going 'geolocator' migration tracking project for additional information as it becomes available.
Wintering martins congregate in large numbers nightly at communal roosting sites in trees in the wild, in city parks, and at large structures with some roost sites in Brazil containing over 100,000 martins!!
Website funded in part by the Ladysmith Maritime Society
Original website design by Danielle Morrison
Page last modified 1 Oct 2010