Martins are a group of bird species belonging to the family Hirundinidae, which consists of approximately 90 species worldwide. They are known for their aerial acrobatics, swift flight, and the ability to catch insects on the wing.
The bird family Hirundinidae includes the Barn Swallow (Hirundo rustica), Tree Swallow (Tachycineta bicolor), Cliff Swallow (Petrochelidon pyrrhonota), Purple Martin (Progne subis), Bank Swallow (Riparia riparia), Welcome Swallow (Hirundo neoxena), Red-rumped Swallow (Cecropis daurica), Wire-tailed Swallow (Hirundo smithii), White-throated Swallow (Hirundo albigularis), and Sand Martin (Riparia riparia).
Two things trigger the Martin migration. One factor is photo-period[1] or the length of daylight. Once the number of daylight hours reaches a certain point, then the birds wait for a favorable wind[2]. The wind is vital because the birds winter throughout much of South America and travel thousands of miles to their summer range; primarily the eastern half of the U.S. and extending into Canada. The first birds to arrive are not scouts. Early arrivals look for suitable areas to raise families and bring others to these locations but they are just older birds with better knowledge of travel routes and destinations arriving first.
Purple martins (Progne subis) are dependent on humans for housing. The natural nesting spots would be cavities in trees, but for whatever reason, the birds prefer houses and gourds that humans supply. It’s a relationship that began long ago. There is a myth that Martins eat tons of mosquitoes. One of the reasons is mosquitoes are more active at dawn, dusk, and at night.
Those times don’t overlap with purple Martins feeding during the day. They are generally found close to the ground while the birds fly higher in the air, so they just don’t come across each other. A purple martin’s diet consists of insects such as flies, beetles, and moths, but they also eat dragonflies[3] and that actually does the mosquito population a favor since dragonfly larvae eat mosquito larvae.
With a height of 7 to 8 inches and a wingspan of up to 15 inches, purple martins are the largest swallows in North America and one of the largest of the world’s roughly 90 swallow and martin bird species.
The longest recorded lifespan of a purple martin was over 13 years.
Purple martins can reach flight speeds of more than 40 miles per hour.
There are at least six types of species of martins seen in North America. The Purple Martin is the only native nesting martin among them. The Brown-chested Martin, Common House-Martin, Cuban Martin, Gray-breasted Martin, and Southern Martin are all vagrants. These non-native martins are visitors from Mexico and the southern countries and the Common House-Martin is the only exception, as it is a native bird of Eurasia.
Various raptors, including hawks, falcons, and owls, are known to prey on martins. These predators are capable of capturing birds in flight or targeting them while perched. Some snake species, such as rat snakes and black racers, may climb martin houses or trees to raid nests and consume eggs, nestlings, or adult birds.
In certain cases, mammals like squirrels, raccoons, and domestic cats can pose a threat to martins, especially when they attempt to raid nests or capture birds on the ground. Aggressive bird species, such as starlings or house sparrows, may compete with martins for nest sites or even attack martin adults or nestlings.
Putting up a Purple Martin house is like installing a miniature neighborhood in your backyard. In the East, dark, glossy-blue males and brown females will peer from the entrances and chirp from the rooftops all summer. You can put out crushed eggshells to give the martins a source of grit for digesting insect exoskeletons. Attach a guard to keep predators from raiding eggs and young.
Native Americans hung up empty gourds for the Purple Martin before Europeans arrived in North America. Purple Martins in eastern North America now nest almost exclusively in birdhouses, but those in the West use mostly natural cavities.
Almost every country tavern has a martin box on the upper part of its sign-board; and I have observed that the handsomer the box, the better does the inn generally prove to be.
John James Audubon[4], 1831
Cuban Martins are graceful, aerial feeders, found over a wide variety of open habitats, especially near water, including marshes and towns. They often choose exposed perches including power and telephone lines in villages. Commonly found in flocks of up to twenty birds, sometimes mixing with other swallows and martins. The adult male is entirely glossy purple-blue and is inseparable in the field from male Purple Martins. The male Caribbean Martin can be distinguished by its bright white belly. Female and immature Cuban Martins resemble females and immatures of both Purple and Caribbean Martin. The purple martin is the most common in my state of Georgia; it winters in South America – usually Brazil. Generally, it arrives in southern Georgia in early February, reaches northern Georgia by mid-February, and then leaves during the fall.
Purple martins are easily impacted by bad weather. During long periods of cold or rain, there may be no insects available for them to feed on, and, as a result, entire bird colonies can die off if the weather does not improve in two or three days’ time.
Purple Martins will typically build their nests out of straw, twigs, and pine needles. They may also build a mud dam in front of the nest. Nest building can take three-four weeks to complete and both sexes will construct the nest.
The last stage in the nest building is lining the bowl of the nest with green leaves. The function of the green leaves is still unknown; they may act as an insecticide, help regulate the temperature and moisture levels in the nest, or help keep the nest clean. Purple Martins will normally start egg-laying soon after bringing in green leaves.
The nest itself is flat, only about one to three inches high. The female Purple Martin lays one egg per day, generally in the morning, for a total of two to eight pure white eggs. The average number of eggs per nest is four to six. Incubation begins with the penultimate (second to last) egg laid. Only the female can incubate the eggs because they have a brood patch, a featherless area rich in blood vessels that transfers heat to the eggs.
Males may sit on the eggs for short periods of time, but they cannot incubate the eggs. Incubation lasts 15-16 days, although incubation can be delayed due to weather. Hatching may be spread out over two or three days. The young will fledge between 26-32 days after hatching and can receive care from both parents between one to two weeks after fledging.
Plans for Martin House from GizmoPlans
Footnotes
- The photo period, also known as the length of daylight, refers to the duration of time between sunrise and sunset in a 24-hour period. It varies throughout the year due to the tilt of the Earth’s axis and its orbit around the sun, resulting in the changing seasons. The length of daylight influences various biological processes in plants and animals, including the regulation of circadian rhythms, growth, reproduction, and migration. Many organisms, such as migratory birds, use changes in photo-period as a cue for important behaviors like breeding or preparing for seasonal changes. The photo period can be calculated or measured using astronomical data and is an essential factor in understanding and studying the natural rhythms and cycles of life on Earth. [Back]
- A favorable wind, in relation to bird migration, refers to wind patterns that assist and facilitate the movement of migratory birds during their seasonal journeys. Birds often take advantage of specific wind conditions to conserve energy and optimize their flights. Favorable winds may include tailwinds, which blow in the same direction as the bird’s intended migration route, providing a boost to their speed and reducing the energy expenditure required for long-distance flights. Additionally, birds may benefit from updrafts or thermals generated by specific wind patterns, allowing them to gain altitude and soar effortlessly. These wind-related mechanisms enable birds to cover vast distances efficiently and maximize their chances of survival and successful migration. [Back]
- Dragonflies are a fascinating group of insects belonging to the order Odonata. They are characterized by their large, elongated bodies, transparent wings, and their remarkable flying abilities. Dragonflies undergo incomplete metamorphosis, starting their lives as aquatic nymphs before transforming into winged adults. They are highly efficient predators, primarily feeding on other insects, which they catch in mid-air using their strong jaws. Dragonflies are known for their exceptional flight agility, with the ability to hover, fly in all directions, and even perform acrobatic maneuvers. They are found in diverse habitats worldwide, including freshwater environments such as lakes, ponds, and rivers. Dragonflies play important ecological roles as both predators and prey, contributing to insect control and serving as indicators of environmental health. Back
- John James Audubon (1785-1851) was a renowned American ornithologist, naturalist, and painter, best known for his monumental work “The Birds of America.” Audubon was born in Haiti (then Saint-Domingue) and later moved to the United States. His passion for birds led him on extensive expeditions across North America, where he meticulously studied and observed various bird species in their natural habitats. Audubon’s artistic talent allowed him to create lifelike illustrations of birds, showcasing their intricate details and vibrant plumage. His collection of bird illustrations, published in a series of large-format books, remains an iconic and influential contribution to the field of ornithology and natural history. Audubon’s work played a significant role in promoting public interest in birds, conservation, and environmental awareness. [Back]
Further Reading
Sources
- “Fun facts about purple martins. Spoiler alert: What grandma told you probably isn’t true” (March 2, 2022) https://www.usatoday.com/story/news/2022/03/02/purple-martins-facts-mississippi-you-may-not-know/6926234001/
- “Field Guide for all the Birds of North America – Martins” https://www.birds-of-north-america.net/martins.html
- Gill, F., Donsker, D., & Rasmussen, P. (Eds.). (2021). IOC World Bird List (v11.2). Retrieved from https://www.worldbirdnames.org/
- “Cuban Martin” https://ebird.org/species/cubmar
- “All About Birds – Purple Martins” https://www.allaboutbirds.org/guide/Purple_Martin/overview
- “NESTING” https://www.purplemartin.org/purple-martins/biology/9/nesting/
- “Fun Facts About Purple Martins” (Updated on 04/11/21) https://www.thespruce.com/fun-facts-about-purple-martins-387110
- Audubon, J. J. (1827-1838). The Birds of America. Retrieved from https://www.audubon.org/birds-of-america
- “Purple Martin Birdhouse Plans” https://www.gizmoplans.com/product/purple-martin-birdhouse-plans/
