BOB WEBER
EDMONTON, ALBERTA
THE CANADIAN PRESS
PUBLISHED JUNE 21, 2020 UPDATED JUNE 21, 2020
There may be many, many more songbirds in Alberta
forests than previously thought, say University of Alberta scientists who have
come up with a new way of counting them.
But researchers say that while the new counts may
be good news – some estimates are more than 10 times higher – they don’t change
the overall declining trend of the province’s boreal songbirds.
“Our estimates just highlight that our
understanding is incomplete,” said Peter Solymos, whose paper was recently
published in The Condor, the journal of the American Ornithological Society.
“We need to understand the limitations.”
Bird populations across the continent have been in
decline for years. A paper last fall estimated populations have dropped by
three billion overall since the 1970s.
Numbers have been estimated for years using data
from the Breeding Bird Survey, which uses a standard, consistent method across
North America.
Solymos said that survey uses assumptions and
techniques that may distort Alberta results. It sends counters out along
prescribed roads, stopping at regular distances and counting birds heard and
seen within a certain time. Those raw numbers are adjusted to account for
factors such as birds singing more at some times of day than others.
Solymos said that may work in southern Alberta and
the United States, where roads go almost everywhere. But northern Alberta is
full of roadless bush. Roadside counts bias results in favour of roadside habitat.
“Roads are usually built in upland environments
and go through upland vegetation. (As well), you get the disturbed habitat
along the road.
“You get a nonrandom sample. You have to go into
the bush.”
Solymos took the bird survey data and combined it
with dozens of off-road bird surveys done over the years for forestry companies
and agencies such as the Alberta Biodiversity Monitoring Institute.
Out of 81 bird species, Solymos came up with
significantly higher estimates for 45 of them. Four species – crows,
goldfinches and two types of sparrow – came in lower, and the rest were
comparable.
Solymos came up with populations estimates that
are, on average, 3.7 times higher.
Some differences are huge. The Breeding Bird
Survey puts 70,000 blackpoll warblers in Alberta; Solymos reckons 1.3 million.
Jeff Wells, head of boreal conservation for the
Audubon Society, calls Solymos’s work significant.
“It may show that there are more birds in the
intact boreal than we thought, which is good news. It means we still have lots
of chances to keep them that way.”
