Fall Migration

As climate becomes colder, leaves begin falling and birds begin the migration south.

September first marked the first day of meteorological autumn that will be from now until Nov. 30.

This is known as the transition period between summer and winter and differs from the astronomical season of Fall which starts on Sept. 21st, the fall equinox.

The National Weather Service and Center For Climate Data reports an average high temperature of 86 degrees in August and an average low of 66 degrees.

In September, that number drops to 79 degrees during the day and 57 during night.

This dip in temperatures in largely controlled by upper atmospheric patterns.

The polar jet stream in the summer is located over the far northern continental United States during the summer.

During the transition to winter, the jet stream slowly begins moving south and gaining strength.

This is also a major factor in what kinds of weather we receive in fall and winter.

The earth’s tilt is the driving factor between why fall occurs and our days become shorter.

In fall/winter, Earth’s orbit puts the Northern Hemisphere away from from the sun. The sun’s rays are then less direct and a cooling period happens.

Leaves will start to change color, the first frost affects plant life and birds journey down south where it is warmer.

“Nowadays when birds are getting ready to fly down south, we’re seeing the beginnings of that right now in September but it will probably reach its peak in October,” said MWSU Assistant Biology Professor Dr. Julie Jedlicka.

Most of the migration is instinctual for these animals.

The subtropical jet acts very similarly to the Polar Jet. It pushes further south during the fall and winter months, and birds are attracted to the warmer climate.

Now the supply of insects and other food sources becomes better where the soil is still moist and temperatures are still favorable.

“There are some birds that stash,” Jedlicka said. “It is sort of a rare behavior, but really intelligent birds might be able to store acorns over a large area such as Jays.”

These birds are able to dig up their food in the exact spot they buried it months after harsh winter’s snowfall.

“Other birds like Black Capped Chickadees that are around all winter may not stash food but rely on feeders,” says Jelicka.

She suggests to put out unshelled peanuts, sunflower seeds and suet.

If squirrels are stealing food from the feeder, adding a spice such as black pepper will turn the mammal away and still be safe for bird consumption.