Purple Martins (Progne subis) are the largest swallow in North America that migrate in large flocks yearly from South America to predominantly the eastern half of North America in late January to nest and rear its young. Then soon after nesting season, will migrate back to South America for the winter.
Swallows are a family of birds that are very slender with long pointed wings. Great aerialists, they swoop and dive to catch flying insects. Purple Martins have a distinct forked tail and do glide more than other swallows. To distinguish a flying Martin from a starling or other swallows, the Martin often circles with short flaps then a glide. The female Martin is smaller with grey underneath, whilethe male is an attractive iridescent, dark, glossy purple-blue; hence the name.
For Florida, the Purple Martin is the first migrant breeding bird to return, and a common spring/summer resident throughout the state. Only in the Keys and the southern most tip of the peninsula is there an absence of breeding Purple Martins. Scouts, the birds looking for breeding spots, are seen sometimes as early as January. The Martins are rarely attracted to new breeding sites, but tend to return to sites where they previously bred. Sub-adults (last year’s young) will arrive about a month after the breeding adults and colonize new sites. Eggs are laid between March and June, with the young birds fledging by the first week of June. Migration then begins in the middle of June and large flocks can be seen underway back to South America.
Catching flying insects in flight is their forte andmain diet. Dragonflies, horseflies, grasshoppers, beetles, wasps, moths and mosquitoes are their daily buffet. Many people have enjoyed Purple Martins in Florida backyards for mosquito control. Not only are they enjoyable to watch swooping around, but that pesky mosquito population declines.
The Purple Martin population has declined over the years. This has been noted by many of the “landlords” throughout the country who house the Martins on the migration route. These birds no longer use natural habitat but depend on man-made nest houses, provided mostly by urban “landlords”, for reproduction. Hence, population numbers correlate to housing sites. Frankly, there simply are fewer nest houses in the past years. The species is in need of nesting housing or man-produced nesting cavities.
I am hoping that this Fall, more Marco Island residents will consider being Purple Martin Landlords! There are many resources out there to get educated and started. The Purple Martin Conservation Association (online at www.purplemartin.org) has vast amounts of history, scientific research, and other landlords’ experiences with Purple Martins. Briefly, here are ten basic suggestions to help succeed:
- Type of Housing The house cavities or gourds should be white. The floor dimensions should be a least 6 inches by 6 inches with a round entrance hole to the cavity of 1 ¾ to 2 3/8 inches. Also, cavity needs good ventilation and drainage.
- Choose the Right Location Martins are fussy! The farther housing is from trees, the better. Housing should be at a 10-17 foot height and preferably at least 40 feet from your house or trees.
- Put Up Manageable Housing Choose telescopic poles for maintenance of the housing cavity.
- Open Housing at the Right Time Starlings and sparrows are non-native nest site competitors to Purple Martins. They will take over cavities, destroy eggs, kill nestlings and even injure or kill adult Martins. If it is a new house/gourd, keep it closed until 4 weeks after nesting adults have arrived in our area. The sub-adults arrive 4-6 weeks after the nesting adults, so in our area, a new landlord should open the house beginning in early February. The strategy at active colony sites is to have your housing ready, but keep it closed until some Martins return.
- Increase Your Chances Offer a combination of houses and gourds, play a “dawnsong” recording (download at www.purplemartin.org), use a Purple Martin decoy and place 1-2 inches of nesting material (straw, dried grass) in the bottom of nesting compartment cavity. Have a mud source in the yard. Be patient!
- Don’t Close Housing Too Soon Don’t close entrances until late August, as fledglings will be searching for next year’s breeding sites in late summer.
- Protect Housing from Predators External guards on cavities will protect from owls, hawks and crows. Climbing barriers on pole help protect from snakes and raccoons. A ring of petroleum jelly on the pole will help prevent ants traveling up the pole to the nest.
- Conduct Daily Checks Walk under the housing to look for plucked Martin feathers, cast owl pellets, thrown out hatchlings, or hatched eggshells. These are clues of what needs to be managed to make the nesting successful.
- Supply Dietary and Nesting Aids Crushed eggshells or oyster shell provide calcium and grit and can be offered in elevated platform feeders as valuable dietary supplements. Nest materials such as dried pine needles, tics, straw can be scattered near by. A mud source nearby by is optimal for nest building also.
- Keep Housing in Good Repair Once all the young have fledged and the Purple Martins migrate south, and the fledglings have scouted the area, in late August remove nests and scrub the housing. Rinse and dry before closing cavity opening or storing housing in garage.
As we move into fall, now is the time to start preparing a Purple Martin house or houses. Check your yard for a good, open location, decide what type or types of housing cavities you will offer and get ready to be a landlord come February!