Purple Martin Migration
Here is information to help you decide when to open up your purple martin house. Purple martins migrate from South America each Spring. Use first arrival dates (scout reports) for purple martins. Open the house on the arrival date for your area.
Purple martins migrate from South America each Spring. A good prediction of the expected arival date is important information for those who would provide a home for martins to raise their young. First arrival dates (scout reports) have been kept for purple martins arrival dates for decades. These dates will indicate when to expect the first martins in your area. These first to arive purple martins are sometimes called scouts and are more mature adult males. They are taking advantage of their experience and power to grab a nesting site where they have successfully nested before. Females and younger males will tend to arrive weeks later. If you have a new martin house, expect to vie for the younger birds that will be arriving as much as a month after the scouts. Its obvious that the martin house should be up and ready for the martins when they arrive, but when is that? Just as important is to not have the house open too soon as this invites other birds to take up residence. Sparrows and starlings are fierce competitors, particularly if they move in before the martins can.
When to Look for Purple Martins
Purple martins Winter in South America mostly in Brizil and then return each Spring to the same nesting area – usually to the same house. The scouts, which are mature males, arrive first in the Spring. Some say that the scouts survey the available food supply and then signal the rest of the martins that it is safe to return to the nesting area. Others say that the scouts are nothing more than mature birds heading back to the house they used last year. Females and younger males arrive in a few weeks. The martins don’t rush into nesting, but may wait for a month before starting a nest. The year-old martins may not show up for another month. Some of these first year martins never make a nest or just play at it. It is these first year martins that you must lure into starting a colony in your brand new house.
When are they to be expected? If you are waiting for the return of a mature colony, expect them about the time of the first scouts average arrival date. The Purple Martin Site provides three tools to help you predict the arrival date for you. See Average Arrivals. Also look at the Timing Map which shows first arrival dates. Use the scout arrival charts to predict when the martin scouts will arrive in your area. If you had purple martins last year, make sure that your house is ready by that date. Some houses come with door plugs which let you wait to open the house at the right time. Keep your house closed until the martins are have arrived. They are most likely your martins of last year.
If you have a new house, you can expect young (yearling) martins to straggle in up to a month after the scouts have been sighted. Keep a lookout for the martins which may show up at the house any time from one to four weeks after the first scouts had arrived in your area. Then open up the house. If you open up the house too soon, it will invite competitive species. See Enemies of the Purple Martin.
Scout reports are a good way to predict arriving scouts and to see when the first purple martins arrived in your local this year.
Martins will begin their southward migration within three weeks of the young leaving the nest. The adult males are the first to leave, followed shortly by the adult females and immature birds. The southward migration normally begins in July, and most birds have gone by the end of August. Martins often gather in enormous flocks during the trip. These flocks will stay in an area for several days if the feeding conditions are good.