The frigid weather may have many birds that breed in Schuylkill County flying to warmer southern temperatures, but a few hummingbirds from one species are making the trek east for the winter.

Pulitzer prize-nominated nature author and Hawk Mountain board member Scott Weidensaul said Friday that while the ruby-throated hummingbird breeds in Pennsylvania during the summer, it is not the same hummingbird that can be seen here in the winter.

The ruby-throated hummingbird heads south and would not be able to survive the cold temperatures. Weidensaul said Sheri and Danny Ney, 67 Frantz Road, Pine Grove, recently saw a hummingbird at their feeder, which he banded Nov. 30 and identified as the rufous hummingbird.

Sheri Ney reported last seeing the hummingbird as recently as Dec. 9 and a lot of local birders have been coming by their home to see the bird.

The hummingbird was an adult female, which Weidensaul said had made this migration at least once before.

From the Pacific Northwest, this particular species typically breeds in northern California, Oregon, Washington, British Columbia and Alaska.

"The species that we're dealing with is not the same as is here in the summertime," Weidensaul said. "Over the last 30 years, increasing numbers are showing up in the east and southeast. We're seeing the evolution of a new migratory route."

While Weidensaul said that it's only a tiny fraction of the population of rufous hummingbirds, what he thinks is happening is these are birds that were "born with bad software."

He said that since birds are born with an instinct to fly in a certain direction, they are genetically programmed on where to fly to their wintering area and anything genetic is subject to mutation.

"Instead of instinctively flying south, some are instinctively flying east," he said.

The rufous hummingbird began showing up in Pennsylvania in October and November. There were six known to have overwintered in Schuylkill County last year.

Increasing yearly, there were about 95 hummingbirds of this and other species that overwintered in western Pennsylvania last year. There are usually about 25 to 30.

"We don't really know why there were so many last year," Weidensaul said.

Weidensaul started banding humming birds in Pennsylvania back in 2001 to study those coming into the state.

He and his colleagues banded 48 hummingbirds last year.

He said that while Sheri and Danny Ney were starting to panic about the hummingbirds, since they are typically associated with summer and are delicate, these hummingbirds are able to tolerate the harsh winter weather.

The rufous hummingbird breeds as far north as central Alaska, so one reason they are able to tolerate the cold is that they go into torpor at night, a state of physical or mental inactivity.

"Their body temp drops from 104 degree to 50 degrees," Weidensaul said. "It's basically like going into hibernation. You would think it was dead and frozen to the branch."

In doing this, these hummingbirds are able to reduce their energy usage to stay alive then bring it up again before daybreak.

Telling just how extraordinary of a feat that is, Weidensaul said that a hummingbird's heart beats 1,200 times per minute and since it has such a high metabolism, it has to eat its weight in food each day to stay alive.

"The kind of weather around here is certainly cold, but not unusually cold for them," he said. "They're usually here until Christmas time. We know from banding, they go from here to the Gulf Coast."

About March or April, these birds head up to their breeding grounds, so they are flying about 7,000 to 8,000 miles each year.

A tiny lightweight aluminum leg band with a unique series of letters and numbers, similar in weight as a wristwatch is to a person, tells researchers like Weidensaul if these are same birds coming back year after year.

While some people may be scared that, by leaving their feeders outside, they are making it so the birds won't migrate, Weidensaul said people shouldn't worry.

"The birds already migrated 4,000 miles to get here," he said. "You can't stop a bird from migrating. These are birds that have evolved with cold weather. It can be dangerous for them, but these may have pushed the envelope."

Distributed by MCT Information Services