The Purple Martin is the largest swallow in all of North America, and the males of the species are easily recognizable by their unique, iridescent coloring. This fascinating songbird has, unfortunately, waned in numbers over the last few decades, although thanks to human intervention and a renewed sense of interest, the Purple Martin continues to be the only species of martin left on the continent.

The Purple Martin (Progne subis) is a rather beneficial bird to have around as it feeds exclusively on flying insects while soaring through the air several feet above the ground. Some studies have found that a single martin can eat up to 2,000 insects in a single day. Purple Martins are quite vulnerable to the climate and weather conditions as too much precipitation, or extreme temperatures will affect the insect population, and ultimately cause the birds to starve.

Purple Martins spend their winters near the warm Amazon River and as far south as Sao Paulo in Brazil before migrating each spring back to North America when it is time to nest. The adults return first, followed by the younger martins, or sub-adults as they are referred to, four to six weeks later.

Breeding season for martins are roughly 70-day cycles, during which time the birds busily construct their nests before welcoming their young. After hatching, the nestlings receive 27 to 32 days of care and nurturing until they are strong enough to test their wings and start exploring the outside world. After another 10 days to two weeks, the young martins and their families begin the long journey back to Brazil, flying tirelessly over many miles of water and land.

Quick Tips for Identifying the Purple Martin

- The average length of the adult Purple Martin is 7-1/2 inches (19 cm) and they weigh 1.9 ounces or 55 grams.

- These birds feature tiny bills and are most often spotted while flying, or coming and going near communal martin birdhouses.

- Adult Males: The adult male Purple Martin has a forked tail with deep, dark purple plumage that is so dark it almost seems to be a bluish black color. For males that haven't quite reach maturity, the color of the feathers may be a splotchy purple.

- Adult Females: Also having a forked tail, the adult female features dark gray with some purple on the upper portion, and whitish feathers underneath. Females also have a gray throat and breast band, as well as some speckles on their sides and bellies.

Helping Purple Martins to Survive

Today, the Purple Martin is reliant upon humans for survival in most every location throughout North America, particularly east of the Rocky Mountain range where nest-boxes, or birdhouses, are needed for the birds to breed. In western states such as Oregon and Washington, successful nest-box breeding programs by concerned residents have rescued the bird from dangerously low numbers, and over one million people are currently acting as "landlords," although many are unable to attract breeding Purple Martins despite their efforts.

For more information, groups such as The Purple Martin Society and The Purple Martin Conservation Association (PMCA) are organizations that focus on educating people on becoming hosts to these wonderful birds, helping to increase their numbers before they become yet another beautiful species that no longer has a place to sing its songs or perform its aerial acrobatics.

Ranging from simple multi-level birdhouses to complete systems, birdhouses, or nest-boxes as they are often called, for the Purple Martin are designed to provide a safe nesting place for the birds to breed and raise their young. Protecting the birds from predators, such as larger birds, snakes, squirrels, and raccoons should be a top priority, and both wooden and metal poles should be equipped with pole-guards, or owl guards if necessary. Martin houses should be checked at least on a weekly basis, as well as watching for signs of predation near the housing, such as dropped owl feathers or plucked or damaged martin feathers.

Birdhouses for the Purple Martin should have starling-resistant openings located approximately one inch from the floor that are anywhere from 1-3/4" to 2-1/4" in diameter, however, 2-1/8" is usually the recommended size. As for the size of the compartment's floor dimensions, it should be no smaller than 6 x 6 inches, while sizes up to 7 x 12 inches offer more protection from predators as well as from the elements. The height of the compartment should be anywhere from 5 to 7 inches, and the proper sizing really does matter for attracting and maintaining these interesting birds.

White birdhouses and nest-boxes seem to attract martins the best, and white, or very pale pastel colors, also reflect the heat radiating from the sun, keeping the nests at a more comfortable temperature. Some houses are ingeniously designed to raise and lower, allowing for easy access for nest checks without the need for a ladder. Also, predators and nest competitors may need evicted on a regular basis, as well as the weekly nestling check, so a lowering system is a convenient feature to have. Some houses have poles that telescope up and down, while others are raised and lowered with a pulley and winch.

Remember that the same Purple Martins will return to their "homes" each year, so extra care must be taken if the housing needs replaced for some reason, as most will abandon a new site if the box they've been used is gone or extremely altered in some way.

For replacing one single birdhouse, place the new one right next to the old one, giving the birds ample time to accept and get used to the new box. Some birds will need an entire season to make this transition, so don't remove the old one until at least some of the flock has began using the new house for the season. Since the birds are already used to the other nest-box, it's simple to just add another one to attract even more martins instead of removing the old one.

Here are the three styles of birdhouses most often used for attracting and housing Purple Martins:

- Apartment Style: These houses can be elaborate apartment-style boxes to attract larger numbers of the songbirds. Look for heavy-duty poles, guard rails, and hinged doors for easy cleaning and nest checks.

- Gourd Style: Plastic gourd-shaped birdhouses for the Purple Martin are molded and designed for the bird's comfort and usually feature vents and drainage holes.

- Nest-boxes: Nest-boxes are best when made from either cedar wood or a lightweight aluminum, as either works well provided there's ample ventilation as well as a reflective roof.