The Purple Martin, a resident of apartment-style birdhouses, is a familiar sight to those lucky enough to have a colony nearby. Our largest swallow species, this proficient hunter catches flying insects while on the wing. While the species feeds on many varieties of insects, it seems that dragonflies are one of its favourite foods – and some of these dragonflies are turning out to be very interesting scientific discoveries.
A Purple Martin house installed six years ago by Long Point Basin Land Trust’s (LPBLT) Conservation Science Director, Gregor Beck, is at the centre of some recent discoveries. The colony near Turkey Point started with one pair and has grown to 12 nests in 2012, meaning there could be around 50 hungry young mouths to feed this year.
“We really like having the Purple Martins around,” Beck commented. “They’re graceful, handsome and always entertaining with their vocal chatter in spring and summer. We’ve noticed dragonfly wings piled underneath the martin house in the past, so this year I started taking photos of martins bringing dragonflies back to the young. I’ve also been paying more attention to any insects or insect wings that have fallen to the ground.”
LPBLT’s species at risk biologist, Adam Timpf, has a strong interest in dragonflies and butterflies and was intrigued by the photos and growing collection of dragonfly parts. One such photo, posted to the Land Trust’s Facebook page, caught his eye in particular. “Right away, I had a suspicion it might be something interesting due to its large size and bright red abdomen. We don’t have many species that fit that description,” noted Timpf. The dragonfly photographed being fed to young martins was a male Comet Darner, a rare species which occasionally ventures north into Ontario. “Prior to this year, I’m not aware of any records of this species in Norfolk County making it a pretty cool nature sighting. There have also been a few other reports this year locally and in other parts of the province.”
This increase of sightings is likely occurring for a number of reasons. First, there is a growing number of people out looking at dragonflies. Another reason for the increase of uncommon “southern” dragonflies is the warm weather this year. Warm southern winds sometimes bring birds, butterflies and dragonflies. This phenomenon brought a widely-publicized “invasion” of butterflies into Canada earlier this year. And, in Norfolk County, there are relatively extensive natural areas providing wildlife habitat – thanks to private landowners and conservation organizations like land trusts.
“We saw a northward movement with the Red Admiral butterfly invasion earlier this year, and maybe we’re seeing it with Comet Darners. Several other dragonfly species have invaded recently also,” added Timpf. Just last year Timpf found a Tiger Spiketail, a species of dragonfly not previously reported in Canada. “The only known occurrences for this species in Canada are in Norfolk County. People have come from as far away as Kingston just to see them.”
For Beck, the discovery of unusual dragonflies at his martin colony is particularly interesting. “Given the decline in populations of Purple Martins and other insect-eating birds in many areas, I’m really glad our colony is thriving. I’m equally interested to learn about the diversity of insects the martins are feeding their young. It’s a lot of fun being able to let the birds do the research for us – they’re literally bringing new scientific discoveries to our doorstep!”