Purple Martins: A Summer Spectacle

By Amber Leung, Nature Programs Manager

Purple Martins, our largest swallow, spend their time demonstrating impressive aerial acrobatics as they eat and drink on the wing.  While it’s sadly not true that they eat a significant number of mosquitoes, they DO consume as many as 2,000 flying insects a day. They’re also the only bird that relies almost entirely on people to provide artificial nest houses.  With the nesting season now over, don’t worry if your Purple Martin houses now sit empty.  You can safely store them away so that they don’t give a boost to non-native starlings or House Sparrows. 

Once their young leave the nest, the stage is set for one of the most awe-inspiring natural spectacles of the late summer months.  By day, they fly alone to snatch insects on the wing, but in the early evenings they start to gather and swoop low over the trees in dizzying numbers to spend their nights in safety.  To some, it may look like a scene from The Birds, but it is a finely-coordinated dance as each bird perfectly maintains their appointed spot in the wheeling flock.  As the sun sets, with numbers up to the tens or hundreds of thousands, they settle into a group of parking lot trees.

It may seem counter-intuitive, but some of the best roosting spots for these large late-summer flocks are in the most urban of spaces.  This helps keep them safer from predators. One such roost is estimated to host 100,000 birds and is now gathering in Stafford at the parking lot of The Fountains.  A dense double-row of oak trees plays host to the impressive numbers each evening.  When the morning comes they take off all at once in numbers so dense it shows up as an expanding doughnut on weather radar!  These birds disperse over many miles to resume their free aerial pest control for another day.  As September fades into October, their numbers will dwindle as they depart to repeat the same evening spectacles in the cities of their wintering grounds in South America.

Learn how to become a Purple Martin Landlord next spring and join a watch party by checking out HoustonAudubon.org/PurpleMartins