Ancient Greeks thought birds hibernated in winter
Mankind used to hold some strange views about animal migration.
Mike Murphy, Hamden Slough National Wildlife Refuge manager, recently presented a program on "Flyways and Migration of Birds" at Minnesota State Community & Technical College in Detroit Lakes.
It was the latest in a series of monthly environmental forums presented by the Detroit Lakes-based environmental education group Natural Innovations.
Murphy is one of the members of the planning committee for the Festival of Birds.
During his 90-minute presentation, Murphy focused on how beliefs about animal migration have changed since ancient times, when the great Greek philosopher and scholar, Aristotle, believed that birds hibernated for the winter.
Around 1700 A.D., it was believed that several migratory bird species including storks, turtledoves, cranes and swallows spent their winters on the moon.
"It's only in the last 50 years that we have really been able to understand (bird migration)," Murphy said.
Ultimately, there is only one main reason why birds migrate: "They want to optimize the success of their reproduction," Murphy said. "That's the No. 1 reason."
Some other discoveries about bird migration in the last 50 years include:
Most birds migrate at night. This is because they expend less of their energy reserves (in the form of stored body fat) by traveling at night, when there is no sun to increase body temperature.
Another reason is that darkness provides a measure of protection from predators for the smaller birds. It also makes more sense for the birds to stop and feed during daylight hours, when it is easier to spot their prey.
Some larger bird species, such as loons, cranes, pelicans and hawks, migrate by day, however. And still others, such as diving ducks and snow geese, migrate during both day and night until they reach their destination.
"With all the different bird species -- 680 in North America alone -- there are always exceptions," Murphy noted.
Traveling in flocks affords several advantages: Protection from predators, greater efficiency in finding food, and conserving energy by flying in V-formation, which allows birds traveling behind the leader to receive a little extra lift (birds thus take turns flying at the front of the formation).
"The bird flying in front tires quickly, then drops back," Murphy said.
Adult birds are excellent navigators. They are able to orient themselves by landmarks, the position of the sun and stars in the sky, magnetism -- which affects the way they see and hear -- wind direction, and even pressure changes in the atmosphere.
Migrating birds tend to stay with their own species during travel, due to their flight speed, feeding and roosting habits being the same.
Mid-May is an ideal time to get a glimpse of the diversity of migratory birds passing through Detroit Lakes on their way north or south each year -- which is why the Festival of Birds is typically set for the third weekend in May.
More than 200 different birds have been recorded by birders during the festival, including some highly sought after species such as black-backed woodpeckers and Connecticut warblers.
This year's festival will include presentations by Jim Fitzpatrick, a Minnesota native, director of the Carpenter St. Croix Valley Nature Center -- and one of seven people who sighted the rare ivory-billed woodpecker (long believed to be extinct) in April 2005, and Al Batt, an avid birder, writer, speaker, storyteller and humorist from Hartland, Minn. There will also be field trips to the Tamarac and Hamden Slough wildlife refuges, Itasca State Park, and a tour of native prairies in Clay County. There will also be a silent auction and the aforementioned "birder's bazaar," with vendors selling everything a prospective birder would need. There will also be mini-workshops and children's programs.
To learn more, or to register, send e-mail to email@example.com, call 1-800-542-3992 or visit the DL Chamber of Commerce web site, www.visitdetroitlakes.com. (Register by April 28 and you will be included in a special "early bird" drawing for a pair of binoculars donated by Eagle Optics.)
To check on the progress of spring migration in this area, call for the Northwest Minnesota Birding Report at 1-800-433-1888.