Creatures vs. climate: The purple martin

With its food source in decline, the bird now depends on human aid — and flying scrambled eggs — for survival
By Tim Alamenciak - Published on August 13, 2018
a purple martin bird
Purple martins are aerial insectivores, meaning they eat bugs in midflight. (iStock.com/PaulReevesPhotography)

John Balga’s flock requires a special touch when it comes to feeding.

He’s one of many purple martin “landlords” in Ontario — dedicated volunteers who help the birds find food.

They do it by flinging scrambled eggs into the air.

Purple martins are aerial insectivores, meaning they eat bugs as they fly. This makes supporting their population a complicated matter. While bird feeders can keep other species fat during lean times, the purple martin demands a somewhat more interactive approach.

Balga chops the egg up into bird-bite-sized chunks and then uses a spoon to fling them up into the air. The birds swoop and snatch them — getting a boost of nutrients and practising their flying feeding skills at the same time.

“The whole colony survives by this process of feeding — otherwise, we'll suffer from a whole devastation of the population in this area,” says Balga, adviser for the Ontario Purple Martin Association. “This is what's getting the species through ... They still engage in natural predation, getting dragonflies and other insects.”

But there are now generally fewer tasty morsels in the air.

“The crux of the matter is there’s a decline in insects and insect cycles,” says Balga. “Sometimes the food source is not there when the birds have arrived. The timing they have is off. They're not really driven by a food supply issue; they're driven by instinct. They have to migrate at a certain time, whether it's cold up here or warm up here.”

Researchers are still trying to nail down just why there are fewer insects. What’s not in dispute is that there has been a decline — one 2017 study from Germany reported that insect biomass (meaning the weight of insects in the area) had declined by 75 per cent over the 27-year observation period. Separate studies done on the population declines of insects such as bumblebees and monarch butterflies point to climate change as one possible factor.

The purple martin population has been suffering as a result. In 2005, there were an estimated 25,000 of the birds in Ontario — now there are only 15,000, according to the OPMA.

 “Untangling all the causes of population decline is very difficult, and very rarely is there just one,” says Ted Cheskey, naturalist director with Nature Canada.

Purple martins have been reliant on humans for housing for a long time — birdhouses made from hollow gourds were hung by Indigenous people before Europeans arrived. Now the birdhouses are made of white plastic and have starling-resistant entrances to keep the predatory species out.

And warming temperatures and unpredictable weather patterns also put stress on the purple martin population.

“Climate change does not mean just general warming of the climate, although that is one of the overall things. It also means more unpredictable weather and changing patterns,” says Cheskey. “The bottom line is that birds have evolved in sync with these general patterns of climate. As climate change suddenly starts throwing wrenches in the wheel of these patterns, the patterns become unpredictable.”

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