Americas Social Bird - The Purple Martin
The Purple Martin is the largest swallow in North America. It measures in at 7–8 inches (19-20 cm) with a wing span of 15–16 inches (45-60 cm). Considered a large swallow, it’s still a medium sized song bird. They have a large head and a thick chest. Its wings are broad and its tail is short and both are pointed. The male is unique in that it is the only swallow that doesn’t have a light belly and is a glossy blue-black all over including its bill. The female has basically the same color on the back but not as glossy as the male and she has a lighter chest and belly and sometimes has a gray collar around the neck. The immature martin is similar to the female but its color is drabber, with its under-parts a dirty white color.
If you’re thinking about putting up a Purple Martin house you certainly won’t be the first. People have been providing housing for martins for centuries. When the first Europeans came to North America they found that the original inhabitants were attracting martins by using hollowed gourds. Today in North America over a million people put out manmade housing to attract these beautiful birds.
Purple Martins have become quite tame and very comfortable nesting near humans. They have become so receptive to manmade housing that (according to a study by James R. Hill, III, the founder of the Purple Martin Conservation Association) the martins living east of the Rockies are the first birds to have completely altered its nesting behavior. This has caused them to become completely dependent on man to provide its housing needs. Part of the reason for this dependency is that the martin is a cavity nester. Natural nesting sites have been reduced due to logging, urban sprawl, or have been taken over by other species, such as the English House Sparrow, and European Starling, which were introduced by early Europeans. Martins reuse the same nesting site year after year. After time, immature birds become imprinted, knowing nothing but manmade housing.
Purple Martins are social or colony breeders, meaning they like to live in groups of their own kind. They spend the non-breeding season in South America and migrate to North America to nest. The adult birds are usually the first to arrive. These are birds that are making the return trip north for at least the second time with at least one year of nesting experience. Both male and female Martins will arrive around the same time, and it’s these first birds that were thought to be scouts. Because these first birds show up early and then seem to disappear, it was thought that they were scout birds for the flock and they were there to pick a breeding site and then they went back to lead the rest of their flock to the site. The truth is there is no such thing as scout birds. It’s too early to begin nesting so these early birds spend most their time getting to know the lay of the land, and wait for more birds to return. Being older with more experience it is believed they know that the earlier they get to the nesting site the more prime nesting compartments are available. The male usually picks the nesting compartment and then tries to attract a female. The female selects a male because of the nesting site he possesses. Martins pair bond and are monogamous for the breeding season. Both sexes cooperate equally in building the nest using mud, grass, and twigs, but in the end it’s the female that puts the final touches into the nest making it her own. The female lays two to seven eggs at a rate of one egg per day and incubates the clutch for about fifteen days. Once the young hatch both parents feed them continuously for about 26 – 32 days until the young fledge. The fledglings are dependent on their parents for food and training for another one to two weeks, and quite often during this period return to their manmade house to sleep.
Adult Male Purple Martin
Martins like all swallows eat only flying insects, which they catch in flight. They have a wide menu which includes dragonflies, grasshoppers, katydids, flies, mayflies, June bugs, butterflies, moths, cicadas, bees, wasps, flying ants, damselflies and just about any other insect that flies. The great myth of the Purple Martin is that they are big-time mosquito eaters. Even though this is claimed by companies that manufacture martin houses, it is just not true. A diet study conducted at the PMCA over a 7 year period failed to find a single mosquito among any of the diet samples collected from parent martins bringing insects to their young. The samples were collected from martins during all hours of the day, all season long, in numerous habitats, including some infested by mosquitoes. Martins are daytime feeders, and feed high in the sky; mosquitoes, stay low in damp places during daylight hours, and usually come out only at night.
Insects provide plenty of protein but they do not fill the needed calcium requirements the Purple Martin needs. A martin landlord can help to supplement their diets by offering eggshell or crushed oyster shell. This will not only supply needed calcium, but will also provide equally needed grit for their digestive needs. Crushed oyster shell can be purchased rather inexpensively, usually from feed stores, in 50# bags and can be stored and used for several years, or you can save your chicken eggshells which should be rinsed in cold water to remove the gooey albumin that lines the shells, but it is not necessary to remove the papery membrane that lines the shells. To kill bacteria such as salmonella, toast the eggshells in a 200 degree oven for about 10 minutes - spread them out on cookie sheets to make sure all surfaces are completely dry. Then crush the shells to roughly 1/4 inch size pieces and store in a ventilated container. Eggshell and/or oyster shell can then be spread on the ground beneath the martin house. Martins will migrate south for the winter but you can still put eggshell out. According to a study done by Cornell Lab of Ornithology, about 60 species of birds will consume them for the grit and calcium they contain.
Because Purple Martins feed only on flying insects they are extremely vulnerable to starvation during extended periods of cold and/or rainy weather. If the weather turns cold and/or rainy for an extended period it is possible to help them. Due to hunger they may be receptive to an offering of meal worms or bits of ground beef. This will only happen when insects aren’t flying.
If you’re thinking about putting up a martin house or have one and are having trouble attracting martins, here are some things you can look at that might help.
· Housing location should be the first and probably the most important thing a person should look at when thinking about putting up a house or if you’re not able to attract a Martin Colony. Martins do not like trees close to their nesting sites. If your back yard is heavily treed your chances of attracting martins is very low. Martins need very open and unobstructed flight paths to get to their housing and if this is not available, then is should not be considered martin territory. Housing should be located as far away from any nearby obstruction as the obstruction is tall. A general rule of thumb is, if you have a 60 foot tall tree in your yard, the martin house should be at least 60 feet from the tree. Tall trees hide predators that feed on martins, and having trees taller than the housing in close proximity will afford predators the ability to drop out of higher limbs allowing them a head start in ambushing the martins. The same applies to any bushes close to the base of the supporting pole. They too, harbor climbing predators and martins shy away from such sites.
· You can improve the odds that a martin will be attracted to your house by purchasing a recording of the martin “Morning Song” and play this in the early hours of the day. This will attract Second Year birds, these are birds that were born the summer before and have migrated south and are now making their first migration north and have no ties to a breeding site. Banding studies have shown that only 15 to 20% return to their natal site. Instead, these Second Year birds will usually look elsewhere for a new site to set up housekeeping. This is nature’s way of preventing inbreeding. These same banding studies have shown that Second Year birds have been spotted as far as 200 miles away from their natal site.
· The control of nesting competitors is a must. Two of the worst problems for martins are the European Starling and the English House Sparrow. Both of these species were introduced into the U.S. in the 1800’s and have propagated to the point that they are extreme pests, and not just for martins, but for humans as well. Both are the Martins worst enemies, and both will usurp the martins nesting cavities, and then vigorously fight the martins off to defend it. Once obtained, they will fill the cavity with nesting material so the martins will never go into the cavity. You will never be able to start a Martin Colony if you allow these birds to take up residence in your martin house and if you have attracted martins and don’t defend against these birds you will never be able to keep a colony. Often, if a starling can trap an adult martin in its nesting cavity, it will attempt to kill the martin and often succeeds. The starling will then begin building a nest right over the dead body as if they weren’t even there. People that allow either of these two species to nest in their martin housing and believe that the two species are living in harmony are not educated about their birds and are only fooling themselves. Studies show that once starlings or sparrows are allowed to nest in a martin house, the existing colony declines, and soon disappear. Starlings can be deterred by making sure that your housing has SREH (Starling Resistant Entrance Holes. Older houses can be retrofitted with little effort. For dimensions and information on the SREH go to http://www.birdslivehere.com/category/bird-shelters/house-dimensions).
Sparrows are especially hard to control, they are small enough to go through any size hole, and one by one, they will fill each nesting cavity with nesting material until all martins are evicted. They are also known to go into unguarded nests and peck holes into eggs destroying them. Since martins only raise one brood per year, they often simply leave.
In order to have a healthy colony, these two pest species must be controlled. Trapping and relocating is not an option. They will immediately return to the nest site. Unfortunately the most successful controls are baiting and trapping with food, using nest box traps and shooting. If you are not willing or unable to control these two pest birds you should not host a Purple Martin Colony. These pest birds do not live in harmony with any other bird species and the problem with them is quickly becoming epidemic. In many areas where these pest species are not controlled, the purple martin population is in decline.
Without a doubt being a Purple Martin Landlord is a high maintenance hobby, but it is extremely rewarding and is certainly worth the effort. Good Luck and enjoy yourself.
Information for this article was researched through personal experience, Cornell Lab of Ornithology, PMCA, Purple Martin Conservation Association, Chuck’s Purple Martin Web Page
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