Seasonal migration is a common practice among many bird species. They travel from areas with decreasing resources to areas with abundant food and safe nesting locations. However, the Purple Martin migration takes place continually, throughout the year, mainly because of their choice of diet.
Migration is one of the most critical life processes for any bird. They move to places that are thousands of miles away and often come back to the same wintering and nesting locations every year. Ornithologists study the migration path of all the species and laboriously sketch a migration map.
The Purple Martin migration has fascinated not just ornithologists but also birders who watch these birds flock around their backyard during their seasonal migration. Purple Martins, popular for their graceful flight and melodic singing, are one of the largest swallows in North America. What does migration mean to Purple Martins? Why do they travel so often, and where do they go when they leave their home? Keep reading to find out interesting facts about the Purple Martin and Purple Martin migration.
How to Identify a Purple Martin?
Unlike their name, Purple Martins are not actually purple in color. Despite being distinct in physical appearance, very often, they are mistaken with other bird species.
Coming from the swallow family, Purple Martins are the largest songbirds native to North America. They are almost 18 to 22 centimeters in length with a tiny bill. These birds are divided into four categories based on their age and sex.
Adult Males
The adult male Purple Martin is the only kind in its family to have deep iridescent purplish-blue and black feathers all over its body. It has a distinctly forked tail which is a dusky brown-black like its wings. It takes the male three years to reach adulthood and gain its plumage.
Subadult Males
The immature or subadult male is often a shade of grey, splotched with deep purple patches on its chin, throat, underparts, or tails. Solid black feathers are noticeable on its chest in a blotchy pattern as it molts to adult plumage.
Adult Females
The adult female Purple Martin has dark gray upper parts with purple coloration here and there. It, too, has a notched tail like its adult male counterpart. Its throat, flanks, and breast are a dusky brown that becomes paler in the center of its belly. The female Purple Martins take up to two years to acquire full adult plumage.
Subadult Females
The back feathers of a subadult female Purple Martin are a lighter purple to brownish color. The underside of their feathers is all white or light-colored, with brown pinstripes running down the middle. The immature females are very similar to adult females.
Both the male and female Purple Martins sing in a liquid, warbling chortle or gurgles, in a series of down-slurred notes. When it first arrives on the breeding grounds in early spring, the male sings a churring “dawn song” around potential nest sites in an attempt to attract females and other Martins.
Purple Martin Subspecies
The Purple Martin comes from the genus Progne and is known as Progne subis. There are three subspecies of the Progne subis, which are:
Progne subis subis
The nominate type, and has the usual features of the species and breeds in eastern and mid-western North America.
Progne subis hesperia
This is a subspecies found in Mexico and the southwestern United States, characterized mainly by its nesting habits.
Progne subis arboricola
This is a large species found in the western mountains, with females having paler underparts.
Purple Martin Imposters
Other species are sometimes confused with Purple Martins due to their similar plumage and flight styles. Often when these impostors visit backyards, people mistake them for Purple Martins. However, observing them carefully can help them determine the visitors.
Bank Swallows
Bank Swallows are much smaller than Purple Martins, with a brownish back and a white throat and belly. They also have a dark brown stripe across the upper chest.
Adult Barn Swallows
Adult Barn Swallows have longer and more strongly forked tails than those of Purple Martins. The back, wings, and tail of Barn Swallows are blueish-black, with a cinnamon-colored forehead and throat.
Tree Swallows
Tree Swallows are smaller than Purple Martins, with bluish-green backs, shorter tails, and snowy white bellies. They normally build their nests in single-unit cavities like Bluebird boxes, but they may try to take over Purple Martin homes.
Cliff Swallows
Cliff Swallows have shorter squared tails and are smaller than Purple Martins. They have a pale rump from above and a dark red throat, both of which Purple Martins lack.
Northern Rough-winged Swallows
Northern Rough-winged Swallows are very similar to female Purple Martins, but their small size and short, unnotched tails distinguish them from the Purple Martins.
Where to Find Purple Martins
Purple Martins are commonly found all over the temperate regions of North America. The most common subspecies, the Progne subis subis, encompasses the whole of eastern United States, ranging from Florida all the way northward into parts of Canada. Along the West Coast, they breed in parts of British Columbia and Mexico.
Purple Martins, over generations, have shifted their nesting sites to cities, towns, and other urban settlements, to nest in natural or artificial hollow gourds that people put up for them. They have become dependent on these structures in the East. For this reason, it is very common to spot them in colonies closer to the human population.
During the Purple Martin migration in winter, the migration path of Purple Martins leads them to Brazil and surrounding areas in South America, where they nest before returning to North America.
Among the other subspecies, Progne subis hesperia of Arizona and western Mexico uses only Woodpecker holes in Saguaro and other large cacti for nesting. In contrast, Progne subis arboricola of the west coast uses Woodpecker and other natural cavities, as well as nesting boxes and gourds.
Feeding
Insects make up the vast majority of the martin’s diet. They are often seen high in the sky, snatching insects from the air. Flying ants, beetles, butterflies, damselflies, dragonflies, mayflies, moths, stinkbugs, wasps, and a few houseflies are among the insects they eat.
They mainly feed by hawking, which is a strategy of catching insects in the air while flying. Purple Martins also usually feed during the daytime and relatively high in the sky, at about 300 or 400 feet and sometimes as high as 1000 feet.
This disproves the commonly held misconception that they consume thousands of mosquitoes every day since mosquitoes are typically located within 15 to 20 feet of the ground and become most active at dusk.
The migration route during the Purple Martin migration period provides them with ample food choices.
Breeding And Nesting
Purple Martins almost predominantly breed colonially in artificial sites near human habitations in the East. They often breed alone in the West, most often in natural cavities in forested areas and saguaro cactus in the desert Southwest.
During the Purple Martin migration, males are the first to return to nesting areas and establish territories. They form a pair with the female martins and visit multiple cavities before settling on a nesting site. The cavity is usually found in a birdhouse, gourd, dead tree, or cliff, but it can also be found in traffic lights, street lamps, or dock pilings. Purple Martins are very selective about colony nest sites, but they like to breed in areas where there are other Martins.
They begin building their nest four to six weeks after arriving at their final breeding site. Purple Martins make their nests out of plant stems, twigs, mud, and pine needles. Finally, they layer the bowl of the nest with green leaves. The process may take three to four weeks, and both sexes work together to build the nest.
Females lay one egg per day, and incubation starts when the second to last egg is laid. Incubation lasts 15–16 days. The female has the sole responsibility of incubation because she has a featherless layer rich in blood vessels that transfers heat to the eggs.
The hatching process can take two or three days. Fledgling occurs between 26 and 32 days after hatching, and they will be cared for by both parents for at least a month.
Migration Patters
Purple Martins originated as a species of South America. Since the longer days of summer offered more hunting and feeding opportunities during nesting season, they evolved a seasonal migration to North America over time.
Like most other species, Purple Martin migration takes place for birds to go in search of the best, most abundant food sources, which will provide enough energy to nurture their offsprings. Purple Martins have developed distinct migration routes, times, and patterns to give themselves and their offspring the best chance of survival.
Range and Routes
Purple Martins spend the winter in Brazil, Bolivia, and parts of Peru before migrating to North America to breed in the spring. A migration map will confirm that the subspecies of the Purple Martin are not found anywhere except in the American continents.
During the Purple Martin migration, most Purple Martins winter in Brazil, which has a tropical to temperate climate, an extensive river system, and includes more than 60% of the Amazon rainforest.
Purple Martin migration in spring is somewhat phased, with arrivals in southern areas such as Florida and Texas in January but appearing in northern areas such as the United States in April and Canada as late as May.
The fall migration from the United States to Brazil is lengthier. It is one of the longest bird migrations because the Purple Martins travel 5000 miles. Some birds leave as early as July, while others remain until October. During this Purple Martin migration, they usually travel across Mexico and Central America.
Adult males migrate first, leaving wintering grounds in late December or early January, followed by adult females. It can take up to two months for the younger Purple Martins to arrive at breeding grounds.
Purple Martin Roosts
Thousands of Purple Martins gather and roost when they are not breeding to feed, socialize, and rest before making one of the longest bird migrations to South America.
Roosting draws tens of thousands of birds to one specific location. Purple Martins often form winter roosts on their wintering grounds in South America, where they flock with other Purple Martin species.
Roosts are commonly found near bodies of water, trees, or human-made structures such as bridges or pipes. In winter, roosting takes place in the Amazon rainforest.
Individual Purple Martins may use a roost for several weeks before migrating, but the roost as a whole may last 8-12 weeks or longer until all birds have left. Purple Martin roost sites can be reused for many years after they have been formed.
Purple Martins’ annual life cycle and ecology rely heavily on migratory and wintering roosts. Visiting a roost is a one-of-a-kind experience, and roosts can serve as a focal point for environmental education, birding festivals, or ecotourism development.
Final Words
Purple Martins have developed a relationship with humans over time and benefit from living in close proximity to them. Birders find them to be pleasant birds to have around as they are friendly towards humans. Eastern Purple Martin colonies are almost entirely reliant on human-supplied housing.
European Starlings and House Sparrows compete with Purple Martins for nesting sites. Both of these bird species are aggressive toward Purple Martins, attacking or even killing them. Other predators include snakes, raccoons, hawks, owls, squirrels, and feral cats. Some of them deliberately hunt Purple Martins, while others infiltrate their nests and destroy the eggs.
Purple Martins are true neotropical migrants, moving from North America in the summer to South America in the winter. Their complete migration path can take two to three months to complete as the bird’s rest and feed along the way.
The Purple Martin migration is an important life cycle for the birds because it allows them to shelter themselves, find ample food resources and raise their offsprings in a safe environment until they are ready to return home. You can set goals to bird-watch for these Martins and record your results.Â
