RAISING THIS BREED OF SWALLOW MEANS RISING ABOVE THE NEST
Editor’s Note: This is the second in our series of three articles on Purple Martins. Previously, we discussed reasons to become a Purple Martin landlord and how to select housing designed specifically to attract this species.
As any realtor will tell you, the three most important factors in choosing a home are location, location, and location. This helps to explain why proper placement of your Purple Martin house is vital to attracting them. Incorrectly placed housing is a major reason why landlords fail to attract Purple Martins.
In the few areas where Purple Martins have not become dependent on humans, their natural nesting sites include cavities in trees or cactus, cliff faces, and even sometimes on the ground in large boulders. Because they nest in fully-enclosed cavities, they can’t make a slow descent from above like other birds with open air nests. Instead, Martins like to enter and exit their nests while still in full flight and swoop into their cavity. For these reasons, your Martin house should be mounted on a pole at a height of approximately 10 to 20 feet.
Make sure the housing you select can be easily raised and lowered so that you can access the compartments at least once a week. (Raising and lowering your Martin house will not disturb the colony.) Marshall Grain offers pole systems equipped with winches or pulleys that makes this an easy task.
The air space around the housing needs to be unobstructed so that the Martins can fly directly in and out on a straight line. Martin houses should be placed at least 40 feet from any trees and at least 30 feet from your home or other buildings. The farther your Martin house is from trees, the better. On the other hand, Martins like to be near humans. Research shows that Martin houses placed more than 120 feet from human housing have a lower chance of being occupied.
There should be no wires leading to the house or the pole as these can be used by predators to access the nesting compartments. Ideally, you should also install a guard on the pole to keep out predators. Martins are easy prey for raccoons, snakes, owls, hawks, crows and cats. They also need protection against squirrels, who will steal their food. Another danger is fire ants. To keep ants out of nests, treat the pole with a ring of grease, Teflon spray or tape. Likewise, keep the area at the base of the pole free of any shrubs or vines.
Poles must also be set in concrete or within a ground socket to keep the house from turning in the wind or tilting. Purple Martins will abandon their nests if the orientation of the nest cavity changes. Ground sockets usually have a clamp at the upper end to prevent the pole from rotating. They also make it easier to relocate the pole later if necessary. The socket hole should support a socket 18 to 24-inches long, plus two inches of gravel at the bottom for drainage.
Although nesting season occurs in the spring, there are some things you can do in the meantime to prepare for the next group of arrivals. One is to put out some ground oyster shell. This high calcium supplement is not only nutritious but also provides needed grit for digestion, and helps to prevent calcium deficiencies in nestlings. Leave a supply of this out in an open feeder throughout the year.
Spring migration usually begins in North Texas between February 15 and March 1. However, Martins will have their eyes open for potential spring nesting sites as they migrate south in the fall, which means your housing should be up in September to attract birds for the following spring. Until then, sit back and relax.
We will conclude this series with a basic guide to the landlord’s duties during the nesting season.
Additional sources of information on Purple Martins include the Texas Parks and Wildlife Department, the Purple Martin Conservation Association, the Audubon Society and various bird-watching organizations.