CHRONICLE: Count yourself lucky if you see this bird


Black tern population is declining, but they are going to great lengths to survive, says outdoor columnist

This column usually highlights a species that is “in your backyard,” a way of providing information about the myriad creatures that share living space in your neighborhood. But this week, I’m narrowing that scope a bit, discussing a species of bird that few of you have been lucky enough to have seen.

Black terns (sometimes called by their nickname, terns) are listed in Ontario as special concern, meaning they are not endangered or threatened with extinction – yet. But their populations are declining and scientists are monitoring the causes.

Terns, like their gull counterparts, are water-loving species, especially in large marshes with protected areas of open water. And therein lies their first challenge, just finding a large swamp with stretches of open water; few of these wetlands remain in southern Ontario.

While their cousins, the common tern and the Caspian tern, tend to hang out on the rocky islands of Georgian Bay and Lake Couchiching, black terns find refuge in the calm inland waters of places like Tiny Marsh and Wye Marsh.

The reason black terns avoid open water bays is that their nests are built to be floating rafts and are poorly constructed at the best of times, meaning moderate to violent waves will disturb or tear the nest structures, just like motorboats. if harvested near a tern colony.

One of the neat things about tern eggs is that they are more porous than your regular bird’s egg, which means they can withstand being soaked and then dry out again. Great!

Another survival technique is that this species will re-nest in July if the June nesting is unsuccessful. The challenge is to ensure that the young of this second breeding are all grown up in time for the fall migration.

And they migrate. Dave Moore of the Canadian Wildlife Service studied these elusive birds and captured and outfitted some with tiny backpack radio transmitters. When birds fly near a receiving tower, their unique radio signature is recorded and their flight path determined.

Four birds that were tagged at Tiny Marsh have been tracked for the southern and northern migration routes and some startling data has emerged. They left Simcoe County on July 19 and were noted to be in the Carolinas five days later. And on the 11th day they made a stopover in Panama.

From November to April, the terns circled the coasts of Peru and Ecuador, spending almost all of their time “at sea”. In April, they returned north to lay their eggs at Tiny Marsh, congregating first in Panama, then a short parallel trip to Texas, then overland across the United States to southern Australia. Ontario. That’s 16,000 kilometers of flight time.

Unlike the songbirds that overwinter in South America, pesticide use is a very small factor in the list of tern perils. And unlike waterfowl, which hold off, the tern is not hunted for its meat all along the way. So why are black tern populations dropping?

One cause is the wind. With global warming, there are more windstorms more often, and those fragile floating nests are getting hammered. (As a poignant note, as I wrote this column, high winds knocked out our power for 28 hours. We recovered but I wonder the level of devastation to the local tern colony.)

And second, there is the continued abuse and destruction of wetlands in southern and central Ontario. These terns need large, somewhat isolated areas, such as the Holland Marsh; as large wetlands are violated, there will be a continued loss of biodiversity. As nature goes, so do we.

Some people have developed an artificial nesting platform, anchored in place and designed not to tip over in strong winds and rough water. There seems to be only moderate acceptance of these islands by terns, but the effort helps.

Whether you’re an avid birder or simply someone who enjoys nature watching, seeing a black tern is a defining moment. Hopefully these floating island platforms will do the same thing for terns as nesting boxes do for wood ducks.


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