I'm pleased that you know of my connection to the name of our beautiful lake, which was named by Pierre Le Moyne, Sieur d'Iberville after the French Minister of Marine, Louis Pontchartrain. However, I am grieved that you have Old Blake confused with Julia Street. It is she who is associated with a parrot named Poydras, and I am told that he is the brains behind the duo. Nevertheless, I will answer your question.
I am sure that Miss Street's perspicacious parrot was not responsible for the birds' leaving. In fact, they come and go every year, since New Orleans is a major gathering spot on their migration back to Brazil and Argentina for their winter home -- a journey that, for some, can be 8,500 miles. As many as 200,000 of these amazing little birds share a final roosting place underneath the Causeway. It is North America's largest known roost.
Purple Martins are the largest member of the swallow family, and they are such delightful birds that the Nature Society has dubbed them "America's Most Wanted Bird." They have a beautiful song, a graceful flight, and a voracious appetite for flying insects, with mosquitoes being a particular favorite. These are not birds that like to sit down at a feeder to dine. Instead, they eat on the wing and can devour up to 2,000 insects a day per bird!
Long ago the birds were attracted to Native American villages with hollowed-out gourds. But by the middle of the 20th century their natural habitat had almost disappeared, and the birds became a near-endangered species. Fortunately, in 1962 the Jaycees of Griggsville, Illinois led by J. L. Wade began an aggressive program to bring the plight of the birds to public awareness. It worked. Folks started providing suitable houses for the "cavity nesters," and today virtually all of them depend on man-made buildings.
There are organizations dedicated to the preservation of the birds, in particular the Purple Martin Conservation Association, which has since 1986 been "devoted to research, education, and developing and improving products for martins." You can contact them on the Internet at www.purplemartin.org and learn, among other interesting information, how to attract the birds to your back yard and become a "landlord." Here you will also discover that there are current experienced landlords all over Louisiana who would like to be mentors.
You can also write to Project Swallow, P.O. Box 7066, Metairie, La. 70010 if you want to help provide a sanctuary for the Purple Martins and the millions of other swallows and migratory birds that pass through this area twice a year. New Orleans is fortunate to be at the end of the Mississippi Valley Flyway, where birds refuel on the way south and north (smart birds that stop in the Big Easy for a meal!).
The Purple Martins arrive in New Orleans in late January, after one or two scouts have checked out the area. Throughout the spring the birds arrive en masse, and their numbers peak in the summer. They take up residence in available places all over the area. Egg incubation takes about two weeks, and the babies fledge about four weeks after hatching. Martins from the entire area gather to help the little ones take their first flight. After this, the birds begin to gather in roosting areas.
Because of the safety from predators, the Causeway provides the birds with a better chance of survival. At night the local martins, coming from more than 30 miles in all directions, leave their houses and gather under the Causeway to roost.
When November comes, we sadly wave goodbye to the last ones. But just like the swallows that return to Capistrano in March, Purple Martins will return to New Orleans in January. Hey, somebody ought to write a song!