What's black and purple and eats dragonflies and mosquitoes?
A bruised bat?
Nope--a purple martin!
Last week I wrote about being dive-bombed by purple martins as a youngster and reported observations from my fellow birders about the bird's population locally.
Looking at the life history of martins we can see the perils they face.
Like their kin, the swallows, purple martins have long, pointed wings and are strong, elegant fliers. They have notched tails, short legs and although their bills are relatively small, their mouths are wide forcapturing insects in the air. Purple martins are the largest swallows in North America. Gregarious by nature, they're often seen in large flocks of mixed species of swallows.
Adult males are exquisite with their iridescent ebony and deep purple feathers. Females, juveniles and first-year males are light-bellied and could be confused with smaller swallows. They also sport iridescence
feathers, but to a greatly limited extent and generally only on the head and top of the wings.
The martin diet consists of dragonflies, mosquitoes and other arial insects.
Purple martins and their relatives are colonial nesters. In the East and areas with dense human populations, martins use man-made nest boxes with separate apartments.
In the western part of their range, martins may nest singly in natural tree cavities and in holes in saguaro cactus. Native Americans were the first to provide martins with nesting options in the form of hollow gourds.
Nesting material consists of mud, sticks, twigs, feathers, bark and paper. Fresh green leaves are added during incubation.
Females usually lay eggs in the early morning. They are smooth in texture, white and ovate or elliptically ovate in shape. An egg is shy of an inch
long and a little over half an inch wide. A martin egg is approximately equal to the weight of one and a half U.S. pennies. Clutch size varies from three to six eggs.
Incubation takes 15 to 18 days. The eggs of a clutch usually hatch within 24 to 48 hours of each other. Both parents participate in incubation duties and the eggs are guarded to protect them from predation.
After a chick hatches, a parent will carry the eggshell away from the nest and discard it.
Eggs lost early in the incubation period to house sparrows and European starlings may be replaced by a second clutch. Eggs lost to a larger-sized predator such as a snake or raccoon may likely cause the martins to abandon their nest and possibly the colony site.
Professor Thomas B. Dellinger, a purple martin expert, it has been estimated that only one out of four young martins survives the first year.
How many juveniles come back to their natal colony the following year?
Dellinger has kept extensive records of his colony in north central Texas.
For 21 years the young martins produced from his colony, about 2,800 in number, have been banded before they fledged. He found that most of the birds fledged from his colony choose to go as yearlings to other nearby colonies.
Catching and banding martins and other birds may only be done legally by experienced individuals who have permits from the required state and federal agencies.
In spring, males return from wintering in South America to arrive in Minnesota before the females and yearlings. They often return to the same nesting site each year. If a martin house has a history of occupation, it is likely to be reoccupied. Living in close proximity to humans doesn't seem to bother the birds.
However, some people and communities have tried to get rid of martins.
According to Terry Anne Suchma, a few years ago, a rubber company in Alabama, had the pleasure, unbeknown to them, of hosting a large flock of purple martins on the factory property. Thinking that these birds that left a mess on the employees' cars in the lots were more black birds, the rubber company contracted a wildlife nuisance company to rid the property of the so-called black birds. In doing so, the wildlife nuisance company applied a product to the trees on the property that caused birds' feet to stick fast and tight to the substance. Death for these birds was horrible.
When it found out that they were not killing only starlings, but also protected native species, including purple martins, the US Fish & Wildlife Service smacked them with a huge monetary fine and educated them fast on the laws that protect native bird species.
After nesting, young and adult birds gather in premigratory roosts. Often the martins congregate with other swallows prior to and during migration.
While concentrations may cause some inconvenience to people, it is important to keep in mind the birds are only following prehistoric migratory paths that were firmly established long before shopping malls and urban sprawl.
Along with habitat destruction and fragmentation, pesticide poisoning, storm-related mortality during their migratory route over the Gulf of Mexico and inclement weather in the spring after they arrive in Minnesota one can understand why our state has seen a dramatic decline in the number of purple martins.
Later I'll write about making a martin house. We can only hope that if we build it, they will come.
Source: Purple Martin Society; Thomas B. and Maria Dellinger and daughter Rebecca Dellinger
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