It was just brought to my attention that today's New York Times contains the
following article about the irruption of northern owls this winter. A
boreal owl was actually spotted in Central Park in December.
In a Vast Hungry Wave, Owls Are Moving South
By E. VERNON LAUX
Published: March 8, 2005
Minnesota is being invaded. By owls. They started flying south in November
and they have kept on coming. This is what ornithologists and birders call
an irruption. And this one is of historic proportions.
This invasion is unprecedented and we may not see anything like this again
in our lifetime," said Dr. Mark Robbins, curator of birds at the University
of Kansas, who traveled north with a group of graduate students to observe
Owls that normally live in the boreal forest, the spruce belt that ranges
across the top of the Northern Hemisphere, have been driven south by a crash
in the population of rodents, in particular the red-backed and meadow voles,
the favorite food of the great gray owl.
The great gray owls have led the movement. More than 2,000 of them, along
with 200 hawk owls and 300 boreal owls are being reported. This compares
with last year's more typical numbers of 35 great gray owls, 6 northern hawk
owls and 1 boreal owl.
Dr. James Duncan, a rodent and owl expert in Winnipeg, Manitoba, has been
studying vole populations since 1986. He has reported that the vole
population at his study sites in summer and fall of 2004 was the lowest
since 1992. Vole populations fluctuate according to weather conditions, Dr.
Duncan said. Cold, wet weather is bad for their food supply and bad for the
The owls are not only in Minnesota. They have been moving into northern
Wisconsin and, in smaller numbers, the Upper Peninsula of Michigan.
In southern Ontario, there are now hundreds of great gray owls. During the
annual Audubon Society Christmas bird count in New York City, conducted last
year on Dec. 19, a boreal owl was seen in Central Park for the first time
since records of sightings have been kept.
The owl was found on the west side of Central Park near Tavern on the Green.
As the owls are following the rodents, birders are following the owls. The
incursion of these birds into Minnesota has brought birders from both coasts
and from other countries.
Among them, Dr. Robbins and a group of his graduate students looked for
birds one day from dawn to dusk. They found at least 226 great gray owls.
The irruption provides many opportunities for birders and scientists, but
the owls are encountering some problems.
They are low-flying hunters, and the birds from the far north have little
experience with automobiles. While hunting, they have been colliding with
"Nearly 500 birds have been found dead," Dr. Robbins said. "The vast
majority have been hit by cars. All these specimens are being preserved in
various museums and a great deal of information will be learned from this
"For example," he said, "ornithologists will be using stable isotopes from
the feathers of the specimens to determine their geographic origins as well
as determining sex ratio and age."
Some survivors are being nurtured back to health at the University of
Minnesota's raptor center.