WILDLIFE WATCHING -- The ducks that were hatched this spring have been flying for months. But ducks and even geese aren't the largest of all native North American wildfowl. 

The trumpeter swans that hatched in mid-June at Turnbull National Wildlife Refuge have required the entire summer and several weeks of autumn to grow, muscle up and feather out enough to flap their 15- to 20-pound bodies into the air from a dramatic running-on-top-of-the-water takeoff.

Carlene  Hardt has been following the Turnbull trumpeters closely this year and she has captured good photos of their development.

"The cygnets have all their flight feathers and could fly anytime," Hardt reports this week. On Sunday, one of the cygnets made a very short flight with the parents! The other two have not shown any interest so far but I am sure they will soon.

"The parents leave for about an hour each day. I wonder if they leave them so long to encourage them to learn to fly so they can follow!"

Even the adult turmpeters were flightless during a portion of the summer. They swam closely with their offspring at Middle Pond near the refuge headquarters while they molted their feathers.

Trumpeter swans are typically gray when they hatch. Cygnets steadily lose their gray plumage and molt in pure white feathers by the time they are one year old. The change is not complete in the Turnbull birds.

Cygnets require 110-120 days from the time they hatch to the time they fledge -- a moment that appears to be arriving this week at Turnbull.

Once they get the hang of it, these trumpeter swans will be able to fly between 40-80 miles per hour. They are susceptible to collisions with wires, especially when they migrate, but they offer an irresistible reason to crane our necks skyward for a look.

Click "continue reading" to see the difference in the Turnbull cygnets' wing development from the third week of August to the first week of October, as shown in Hardt's photos.