A Yukon biologist says ptarmigan and gyrfalcon
populations could be in decline across Canada's northwestern Yukon territory.
Dave Mossop says the fluctuations in these two "key" species could be
a sign of greater trouble across the food chain.
 |
| Robert Massolini photo |
Both populations usually peak in a 10-year cycle
but recent bird surveys do not indicate a peak as expected. Mossop says the
unexpected change in the cycle could be a result of climate change or other
factors.
"For the last cycle yes, it declined, for
reasons that we don't understand," says Mossop. "But the great hope
is that things will re-establish themselves. The 10-year cycle in the boreal
system is one of the most obvious things that's happening, and for some reason
it faltered. That's kind of where we are now."
Mossop says gyrfalcons depend on ptarmigan as a
source of food and that the predatory birds will stop breeding when there
aren't enough ptarmigan to eat.
He says the Yukon Research Centre has access to
a database on arctic birds which dates 50 years. Mossup says tracking willow
ptarmigan and gyrfalcons is important because the birds are respectively at the
bottom and top of the food chain.
"A lot of the research went into
understanding the amazing intricacies between these two species," he says.
"They evolved together and depend on each other. But recently as everybody
knows the tundra systems are in harm's way and things are changing. In
particular at the top of the food chain because the gyrfalcon is dependent on
the whole thing working properly. What we're seeing is a change in the birds'
ability to maintain their populations."
Scientists recently counted gyrfalcon eggs in
the Ogilve Mountains in central Yukon as part of a falcon survey.
Mossup says the predators are relatively easy to
monitor because they build nests in the same place year after year.
No comments:
Post a Comment