Archive for July, 2010

How do Purple Martins Know the Party is Over?

Tuesday, July 27th, 2010

Tropical Storm Bonnie Passes with a Whimper But Scoots Martins Out

tropical-stormbonnie-7-23The last nest of 2 martin fledglings (which were a complete surprise) fledged the same day that Bonnie was supposed to dump rain all along the coast. Fortunately for some, the rain was more of a short drizzle but amazingly the purple martins seemed to know something was up.

Every morning our colony would get a faithful dozen or so visitors that would sit on the housing and chatter away. By about 11 AM they would leave only to return again the next morning. But the day after Bonnie not a purple feather was to be seen. Many speculate that birds, being so sensitive to changes in barometric pressures and the weather , could avoid bad weather by delaying migration to an area of poor weather or vice versa. Could it be coincidence?

According to Melvin L. Kreithen and William T. Keeton of the Division of Biological Sciences, Langmuir Laboratory, Cornell University in Ithaca, New York,(23 October 1973) Homing pigeons were able to to detect air pressure changes. As purple martin landlords can tell you, a purple martins homing ability is at the very least equal to that of a homing pigeon. So the correlation is fair.

By any account, the season is over here in South Florida and all martins have left.

The factors that affect a birds migration are complex and not completely understood. Click this article for Neotropical Migratory Bird Basics from the Smithsonian National Zoological Park. If you want to learn more about Neotropical Migratory Birds read this article on Birds Built-in Barometer.

Not that my birds needed a Tropical Storm to end their party, migratory birds know when it is time to go based on known factors such as the length of day and for some types of birds, even star patterns. There is nothing to be done for purple martins (or any other migratory bird-for that matter) that linger on. Some folks will tell you to lower or remove housing, but don’t bother. Just like the old wives tales that persist that tell hummingbird aficionados to remove hummingbird feeders to push hummers to migrate, nothing needs to be done.

So keep the feeders full, leave the housing up till you feel like it. Birds have been migrating for a long time and the only thing we need to do for them is support them, by way of a beak full of nectar, a belly full of seed or perhaps a dry place to sleep at night.

Purple Martin Roosts

Thursday, July 8th, 2010

Purple Martin roosts come in many shapes and sizes. There is no clear cut factor that makes a site roost material. The fact that huge numbers of purple martins gather and sleep over night is the only common thread.

Roosts can form under bridges, in trees or reed beds. You can find them in big cities or small towns, in bustling areas or in the middle of nowhere. They are sometimes well lit to keep predators at bay but can also be in the most secluded of areas.

The Purple Martin Conservation Association’s Project MartinRoost is dedicated to documenting roost locations and preserving them. You can look up roosts that have been reported in your area by visiting their Project MartinRoost Page.

joelevinsroostalabamaI found this interesting picture , posted with permission of the photographer (Joe Levins of Wetumpka, Alabama) of a colony site is being used for a small martin roost. It started around the first of June and has increased in number each day since. According to the landlord, Joe, last year they also roosted there, but did not start until after the first of July.

Southern Patriot

Southern Patriot

If you live in South Carolina and with an extra $27 dollars to spare, you can take a 2 1/2 hour cruise on The Southern Patriot” (that’s a 65 foot cruise boat) which will take you out to historic Bomb Island, where hundreds of thousands of Purple Martins roost on the largest Purple Martin sanctuary in North America. During the cruise you will hear narration about the Purple Martins and about the historic significance of how this island was used for bombing practice by Jimmy Doolittle prior to his raid on Tokyo during WWII. Don’t worry if you get thirsty as light refreshments are  served. Interested? Call the Lake Murray Marina in Ballentine, SC at: 803-749-8594

If you want to learn more about purple martin roosts you can also visit:

Coastal Carolina Purple Martin Society (Manns Harbor Purple Martin Roost)

Tulsa Audubon Society