These Trumpeter Swans were photographed a week ago at Crex Meadows wildlife area north of Grantsburg, Wis. This is a family of two adults — male, the cob, and female, the pen — and five cygnets. As I was photographing — because I was photographing, even from my car — the birds were seeking cover in rushes.

The cygnets eat aquatic insects and crustaceans for their first five weeks. Then they switch to a diet that includes vegetation. You can see strands of pond weed hanging from the mouths of two cygnets, offering a guess at age.

At hatch, the cygnets weighed about a half pound each. As adults they could weigh as much as 30 pounds. Their wings will be strong enough to break a human leg if the bird gives you a good swat. Trumpeter Swans are a conservation success story, the Minnesota population built in the past four decades from a few Alaskan transplants to several thousand birds in the state today. On a visit to Sherburne National Wildlife Refuge at Zimmerman, Minn., a few days before the Crex trip, we counted over 100 trumpeters, almost all of them unmated. We saw two pair with cygnets. The unmated birds were all found on one side of the auto-tour road, the families on the other. There was no obvious reason for this.

The young birds will be half their adult size when eight weeks old. They will be fully feathered then, retaining gray juvenile plumage until their second winter, in this case the winter of 2018. They will fly at age 13 to 15 weeks. That figures out roughly to some time in September for the birds shown here.

In the meantime, they offer good birding at both Sherburne and Crex. Early flight should provide particularly interesting viewing.