PURPLE MARTINS MIGRATION
Everyone looks forward to the Purple Martins migration each year. Most of us think their arrival means spring is just around the corner. But, at this time of the year, no one really thinks about them anymore. Most people don’t know that they’re very busy getting ready to migrate south.
Preparations for migration begin in July and August when the birds form large flocks and roost (a place where birds or bats regularly settle or congregate to rest at night). There can be thousands of birds in a roost. They call this gathering “staging.” Some of the better-known roosts in the Houston area are Gordon Park in Stafford and around Willowbrook Mall. They spend their days eating flying insects to build up body fat for their long flight ahead.
So where do they go? In the spring of 2009, geolocators were attached to 20 birds from two Texas colonies. It was discovered that the birds wintered deep in the Amazon rainforest and traveled an amazing 250 to 300 miles per day! They can fly between 17 and 27 miles per hour unless a predator is chasing them when their speed can reach 40 miles per hour. They spend several months in South America in large roosts where they undergo their annual molt. Although their annual molt begins before migration, they don’t molt their flight or tail feathers until they reach South America. Molting is very beneficial because it replaces damaged feathers and helps get rid of parasites.
Purple martins will spend several months in South America before heading back to North America. The scouts typically show up in our area in mid-January through early February. The term “scout” is used to describe the first martin(s) observed. They will go to the same nesting site from the previous year. The scouts can be either an older male or female but are usually males. Arrival of the remainder of the birds depends on their age and sex. Older male birds arrive after the scouts followed by the older females followed by the younger ones. The younger ones, or subadults, may not appear until 4 to 12 weeks after the first ones arrive. They fledged the previous year so their first priority is to find a nesting site.
According to the Texas A&M AgriLife Extension Service, Texas martins nest almost exclusively in bird housing provided by humans.Once they have occupied a martin house, they will continue to use it year after year as long as you clean it out in the fall and keep the starlings and sparrows from moving in.
TWRC Wildlife Center has been serving the Greater Houston for 40 years. We admit nearly 5,000 injured, orphaned or displaced animals every year. Learn more about us at www.twrcwildlifecenter.org.
By Cheryl Conley, TWRC Wildlife Center