Young eagle's life not a breeze

Our canoe was gliding along a still section of the St. Croix River when the peace was shattered by a series of loud and plaintive calls, indicating that some animal was really unhappy. We were mystified about what it could be until a turn around a bend revealed a young bald eagle hopping on a sandbar with a large snake clutched in its talons.

He very clearly didn't know what to do next, and seemed to be shrieking in exasperation as he finally flew off with the snake.

That episode hints at the life of young bald eagles, which undergo a long adolescence full of frustrations and dangers as they slowly learn the life skills they'll need. Truth to tell, big birds have as hard a time learning to survive on their own as small songbirds do.

I learned recently that the mortality rate among bald eagles is high, with only about one in five reaching adulthood, so I called eagle expert Scott Mehus at the National Eagle Center in Wabasha, Minn., to find out more.

Young eagles are essentially on their own at about 16 weeks old, often around the end of July in our area, and Mehus, the center's education director, notes that they have two critical jobs ahead of them — improving their flight skills and learning to keep themselves fed.

"As they leave the nest, their flight feathers are slightly larger than an adult eagle's flight feathers," he said. "These feathers act like training wheels on a kid's bike, and the additional wing area provides better lift from the ground and better soaring ability as they master the basics of flight."

These young birds have just entered the riskiest period of their lives and the stakes are high — some 50 to 60 percent won't make it to their first birthday.

What are the dangers? Many are hit by vehicles, some collide with power lines and a few break a wing after crashing into a tree branch. Then there are injuries from fights with other eagles over prey, but the biggest mortality factor for young eagles is starvation. Mealtimes in the nest had seemed so easy as young birds waited for hardworking parents to bring in fish, squirrels, rabbits and other prey. But catching food on their own presents a big learning curve.

Mehus noted that summer is a good season for picking up fishing skills: "Young eagles are lucky that fish are often found in shallow water in warmer weather."

Still, fishing isn't easy. It's not difficult to spot a rabbit out in a field, and not all that hard to learn to run one down, but catching a fish is more complex. Juveniles see their parents drop down to a lake and lift off with a fish, but add in water's refraction effect, and youngsters suffer more misses than hits.

As winter comes on, juvenile eagles often feed on dead fish, either in the water or frozen into ice. Their diet is augmented with young squirrels, injured ducks, maybe a muskrat or two. Roadkill is welcome but can be a hazard in itself by exposing youngsters to traffic.

By the time they're 3 or 4 years old, with several migrations under their belts, bald eagles' survival odds improve. Death now is not so much due to inexperience or starvation but more often to hazards caused by humans. Eagles run into power lines, or suffer lead poisoning from piles of deer gutted in the field, while some still collide with cars as they pursue prey.

Their numbers winnow down year by year, and only about 20 percent survive to begin raising their own offspring at 5 or 6 years of age.

"Next time you see an adult bald eagle in the wild, with that full white head and tail, remember that you are seeing the best of the best, an expert in flying, hunting and survival," Mehus says.

St. Paul resident Val Cunningham, who volunteers with the St. Paul Audubon Society and writes about nature for local, regional and national newspapers and magazines, can be reached at valwrites@comcast.net.