On a balmy Sunday afternoon in early April, an adult male purple martin returned from its Latin American wintering grounds to the martin house we installed two years ago.
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Even though temperatures at our Long Point-area home on the Lake Erie shore are relatively mild for Canada, this is a particularly early date for the return of these handsome insect eaters.
Biologists, like scientists and statisticians of any stripe, spend much of their time looking for averages to learn what’s going on in the environment. But this particular purple martin offers a reminder that it’s important not to lose sight of the stories individual birds can tell.
After a few quick circles overhead, the purposeful martin made a beeline for the 16-hole martin house. Based on its behaviour, we’re certain it’s from one of the half-dozen pairs that nested here last year. Within hours, a second advance guard arrived – a sub-adult male that likely hatched at the site last summer.
No rest for the travel-weary, though the two were forced to fend off several European starlings showing interest in the martin house. Starlings aren’t native, and often compete with native species. Interestingly, the purple martins were illustrating the potential benefits of risking an early return: securing and defending nesting sites and breeding territory in advance of the returning females.
Their rigorous defence of the nest site is particularly impressive given the magnitude of the migration. Martins winter in South America, and their one-way trip north may have exceeded 6,000 kilometres.
But the downside of showing up early was illustrated when a harsh April snowstorm suddenly arose. In sub-zero temperatures with a bitter wind blowing, the birds hunkered down inside the little house. Perhaps they ventured out occasionally in search of flying insects. Survival in times like this is tenuous, since martins rely on bugs for nourishment, and after such a long voyage, energy stores are greatly diminished.
Two days later, as temperatures started to climb, it appeared they had weathered several days of abysmally poor feeding conditions. Surprisingly, two more males arrived during this wintry period, having flown through the late storm.
“The trials and tribulations of these individual martins exemplify broader concerns,” observes Caroline Schultz of Ontario Nature. “Birds that eat flying insects are in big trouble. Populations and breeding ranges of swallows, nighthawks and chimney swifts are all in sharp decline in Ontario.”
The reasons are not clearly understood. Among the possible explanations are habitat loss on wintering and/or breeding grounds, contaminants and, possibly, direct or indirect effects of climate change.
In respect to the latter, erratic weather patterns may be affecting the timing of some species’ return to breeding grounds, making them susceptible to poor weather, or their breeding cycles may no longer be coinciding with peak insect hatches.
Sometimes we need stories like this to bring home the point that survival in nature comes down to strength, endurance and, often, the luck of individuals. In the weeks to come, we hope our early birds are joined by dozens more and that they can buck the widespread and sadly downward trend of insect-eating birds in Ontario.
LIFE AND TIMES OF THE PURPLE MARTIN
SNOW BIRDS They spend non-breeding time chilling in Brazil.
WELCOME HOME More than 1 million North Americans erect homes for them.
SO COUPLEY Have monogamous relationships (or so they swear).
EQUAL MARRIAGE Males and females share building of mud, grass and twig nests and feeding their young.
ON THE EDGE Vulnerable to shifts in weather – after a few days of heavy rain, insect numbers decrease and martins start to starve.
Gregor Beck is a wildlife biologist and co-editor of The Atlas Of The Breeding Birds Of Ontario. birdsontario.org.
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