Quite a few species whose winter ranges once ended just south of us are now
being seen more regularly or in larger numbers on the count. This trend is more
likely due to a change in seasonal distributions than to population increases.
Good examples are ..
Great Blue Herons,
Fox Sparrow, and
Rough-legged Hawk numbers have plummeted since the early eighties. This
species is a winter resident, so perhaps the recent milder winters have
resulted in fewer birds coming this far south.
West Nile Virus
American Crows suffered a dramatic decrease in 2002 which corresponds to the
arrival of the West Nile virus in northern Illinois.
Pheasants and Coyotes
Ring-necked Pheasants have undergone a gradual decline since the mid
nineties. This is probably due to an increase in local coyote populations which
occurred at about the same time.
Canada Geese dramatically increased their numbers through the eighties to
become the most abundant species in the count circle. Since then the numbers
have remained stable despite large year to year fluctuations.
Cooper's Hawk numbers have increased dramatically since the early nineties.
This reflects increased numbers throughout the year.
Ring-billed Gulls increased sharply during the early nineties.
Mourning Doves and
Red-bellied Woodpeckers increased their numbers dramatically in the late
The House Finch Invasion
Purple Finches declined sharply in the late eighties this is about the time
when the closely related
House Finches expanded its range into the region.