Watch for green-collared swans

February 09, 2010 at 11:46 AM

CLEAR LAKE—In spite of the late date, a flock of 16 young trumpeter swans have just embarked on their first southward migration.  The birds departed from northern Iowa late yesterday and are scheduled to arrive at Arkansas’ Holla Bend National Wildlife Refuge sometime this evening.

The migration is different than most.  Instead of using wing power to get Down South, the giant waterfowl are thumbing a ride.  And, instead of navigating by nighttime stars and magnetic fields the way migrating birds normally do, they’re being chauffeured down interstate highways by DNR Wildlife Biologist and Swan Restoration Coordinator, Ron Andrews and DNR Wildlife Technician, Dave Hoffman.

Produced on Iowa wetlands last summer, the young swans are part of a three year, joint venture experiment between the Iowa DNR, U.S. Fish & Wildlife Service, The Trumpeter Swan Society, and the Arkansas Game & Fish Commission.  According to Andrews, the experiment is aimed at securing future swan populations in Iowa.

“The DNR has been releasing captive produced young swans on state wetlands since 1995,” said Andrews.  “The goal of these efforts has been to reestablish a wild, free flying population of trumpeter swans to Iowa.  So far, the program has been successful to the point that we had a new modern-day record of 40 successful nesting pairs of trumpeter swans during 2009.”

Andrews believes that Iowa trumpeter swans have now surpassed “threshold population levels” and are achieving self sustaining numbers.  He also admits that maintaining future populations may still present a challenge or two.  Scientists have noted, for example, that the young swans [cygnets] raised by wild, free flying parents currently enjoy much higher survival than birds produced from captive breeders.

“Trumpeter swans are extremely hardy birds, and don’t normally head south until really severe winter weather sets in,” said Andrews.  “Birds produced in the wild have the distinct benefit of parental guidance.  Swan families stick together through the winter and when weather finally forces a migration, adults lead youngsters south, following the same pathways the older birds have already flown.  By contrast, captive reared youngsters are on their own.  When wetlands freeze tight, they’re forced to sort things out by themselves.  Decisions are critical and must be made quickly.  Without knowing where to go, many of those young swans end up in trouble.

“The whole purpose of the Arkansas experiment is to increase the survival of young swans raised from flightless [captive] breeders,” said Andrews.  “Until recently, these 16 young swans have been free flying in the vicinity of the wetlands where they were raised by captive, wing-clipped parents.  Those free flights have hopefully fined tuned their inner compass and will guide the birds back north next spring.  Once they successfully complete the first round trip, the route will be permanently stored in their memory.  As those birds become adult breeders three or four years from now, they’ll be able to show their own young the safest way south.”

The Iowa swan cygnets are marked with green, individually numbered neck collars that will aid biologists in keeping tabs on the trumpeters as they travel the flyways.  So far, a total of 51 young Iowa swans have been liberated on Arkansas wetlands.  The success of the project is now up to the swans themselves as Iowa wildlife enthusiasts await the birds return.  Anyone observing a collared swan should report the location and collar color and lettering to their local DNR conservation officer or wildlife biologist.