Juvenile birds of mid-summer
Do you recognize this common backyard species of bird? It is a robin in juvenile plumage. — Photo by Bruce Mactavish/Special
We are at the mid-way point of summer. Now that we have adapted to this warm weather, we can relax and enjoy the second half of summer to the fullest.
For most of the woodland birds, the busiest part of the summer is over and, yes, now they too can relax a little.
The nesting season is fast paced for birds. A lot happens in the space of a few weeks. From the pairing off of adult birds to nest building, laying and incubating eggs and then feeding the hungry young until they are too big for the nest, the birds waste no time.
Now the woods and countryside are full of young birds that only a few weeks ago were eggs! Young birds are out on their own and seeing the world beyond the nest for the first time. They are feeding themselves, finding their own place to sleep in the night and watching out for danger.
They are like young teenagers stepping out into the great big world. During the day they hang out in loose groups. They interact through calls and passing encounters in the vegetation. Life is relatively easy as the young birds learn to be fully independent. There is plenty of insect life in the lush vegetation in the woods which is the food for the young warblers, thrushes and sparrows. Mid-summer is a good time to learn how to be a bird.
During the trial period between hopping out of the nest to becoming a completely self-governing bird, most birds wear a plumage different from the adults. It is known as the juvenile plumage. Typically it resembles the adult plumage but is overlaid with a pattern of stripes, spots or general dullness.
By the end of summer, the young birds that survived the basic survival and living skills course 101 lose their juvenile stripes and spots. The young bird graduates earn a new set of body feathers, a brand new uniform, making them look like the adults. It is like taking the novice driver notice out of the back window. They are now fully in control and responsible for their own survival. From now on it is live life to the fullest or die. It is the only way to survive when you are a bird.
Not all juvenile plumages are that different from the adults. Juvenile blue jays and crows look very similar to the parents. However, the juvenile plumage of most of the warblers, sparrows, thrushes and other woodland birds is so different from the adults that it creates an identification challenge.
For example, take the swamp sparrow. It is a very common bird in all of Newfoundland and southern Labrador. The adults have a clear silver-grey breast and a solid reddish brown cap. Yet the juvenile swamp sparrows have a strongly streaked breast and streaked cap. Except for body shape, the calls and habits, they barely resemble each other. In fact juvenile swamp sparrows look more like an entirely different species of sparrow called the Lincoln’s sparrow.
Books rarely do a good job of showing the juvenile plumages of birds so you are left to learn from your own experience. Even familiar birds can look like a different species. The juvenile starling has a smooth fawn-coloured plumage giving it a totally different appearance from the rough, blackish looking adults.
Every year I get emails from readers wondering what these birds are. Even our friendly neighbourhood robin can throw us for a loop when we see them in juvenile plumage. They resemble a normal looking robin except for a heavy dose of the black measles across the beast.
By September, all the spots will be lost and they will have the smooth red breasts, making them unidentifiable from the adults. Luckily the identification challenges of juvenile birds lasts for only four to six weeks each year.
I have been talking about woodland birds up to now. Ducks, seabirds, shorebirds and hawks also have juvenile plumages. Some are very similar to the adult plumages. Others, like the gulls and gannets, retain an immature plumage for three years that separates them from the adults. Young dark-brown herring gulls are starting to appear now.
The immature plumages of birds add a challenge to birding. It also tells you something about the age of a bird. Once a bird reaches adult plumage, there is no way to know how old it is.
Now that you read this column, please go outside and enjoy this summer!
Bruce Mactavish is an environmental consultant and avid birdwatcher. He can be reached firstname.lastname@example.org, or by phone at 722-0088.