The birdy breeding cycle 2020 – 4: growing into adult plumage

As mentioned in a previous blog, when young birds are ready to leave the nest, they don’t necessarily look like their parents. Many of the altricial birds (ready to move about and forage on their own) may resemble fluffy versions of the adults, as is the case with these hooded merganser ducklings (Lophodytes cucullatus) following their mother.

The brown-headed nuthatch babies (Sitta pusilla) look very much like their parents. Sharp-eyed observers might notice that the tops of their heads are not as brown as those of their parents.

The Eastern meadowlark juveniles (Sturnella magna) resemble their parents but lack the bright yellow and black coloring on the throat and breast.

 

The difference between adult and juvenile downy woodpeckers (Picoides pubescens) is subtle. The female woodpecker has no coloring on the top of her head, which is simply bedecked with the white and black feathers that cover the rest of her body.

The male woodpecker has a red patch on the back of his head.

The immature woodpecker has a red patch on top if the head and this is lost as the bird reaches adulthood.

The Northern mockingbird youngling (Mimus polyglottos) resembles mom and dad quite a bit except for some spotty streaking on the chest.

In other species, the babies start out looking quite different from their parents. Spots characterize many members of the thrush family, with birds like wood thrushes (Hylocichla mustelina) and hermit thrushes (Catharus guttatus) retaining the spots in adulthood.

   

The Eastern bluebirds (Sialia sialis) and American robins (Turdus migratorius), on the other hand, are only strongly speckled as immature birds, losing their spots as they mature.

In some cases, the birds undergo color changes. Male summer tanagers (Piranga rubra) start out yellow-orange with their reddish coloring appearing in patches until they finally achieve their very bright adult red hue. Some of the immature birds are really quite beautiful with their mottled colors.

 

   

The male blue grosbeaks (Passerina caerulea) start out brown and gradually achieve their dark blue feathers with some reddish/brown wing accents.

 

 

Among the birds that undergo a major change are the European starlings (Sturnis vulgaris). The young birds start out with dullish brown or gray hues with some streaking. Eventually, they begin to develop some spotting and then ultimately achieve the beautiful adult summer glossy feathering with green and purple hues mixed in.

 

 

The females of the Eastern towhee species (Pipilo erythrophthalmus) have a brown back above a white breast with reddish sides, while the males have black backs.

The young developing towhees keep you guessing as to their sex since they undergo quite a lot of color changes as they develop. They do have the white in their tails, which helps you identify them as to species.

 

  And then we come to the hawks and owls. It is not unusual for the young raptors to look nothing at all like their parents. The red-shouldered hawks (Buteo lineatus) start out looking like fluffy and then becoming gradually kind of scruffy looking.

     

As they get a little older and leave the nest, they start to resemble their parents more but have more streaking on the breast. As they near adulthood, they look much more like mom and dad.

 

And we end with an example of another raptor. There is a real difference between the baby great horned owl (Bubo virginianus) and its parent as you can see. Many birds are impressed by the adults but ooh and aah over the nestlings. It must be the combination of those big eyes and fluffy feathers that take away attention from the already formidable claws!

               

Next up – a foray into the world of amphibians and reptiles!

Growing up barred – Part 1: becoming independent

From the ages of about 8-19 years, I lived in a house that had a nice backyard and was not too far from some neighborhood woods with a creek. As a child, I read under backyard trees, planted a flower garden and played in the woods with friends. While I became familiar with squirrels, robins, frogs and some bugs and loved being outdoors, I didn’t spend lots of time looking for wildlife. And I never saw an owl in the wild.

Now decades later, I’ve had the good fortune to learn a good deal about various members of the wildlife community while spending time finding and watching them. And in the past couple years, I’ve been privileged to see owls up close in the wild; for example, the owl below was perched next to a pathway at dusk when I walked by a few days ago.

This past summer was unique for me, however, because I was able to observe a pair of juvenile barred owls (Strix varia) at the Mason Farm Biological Reserve as they set off on their life’s journey outside the nest. I’d like to share a bit of what I saw with you in a three-part blog. This one is about them finding their independence. The next two will focus on their grooming and interactions.

Barred owl pairs usually bond for life; if one mate dies, the survivor will seek another partner soon after. They tend 2-4 eggs, which hatch after 4 weeks’ brooding and the young leave the nest after four or five weeks. They remain dependent on their parents for food for some time after that even though they may be almost as large as the adults at 16-25 inches in length (40–63 cm); their wing span can stretch up to 3-4 feet (38-49 in, 96–125 cm).

When I first spotted the young owls in June, they could already fly. Nevertheless, they did need to find their balance occasionally as they perched and moved along branches and snags.

 

The owlets were making a keening noise the first time I saw them. At first, I didn’t recognize it, and I thought perhaps some small mammal was in distress.

Eventually, the plaintive call helped me locate them above me in a tree. This particular call apparently is used by the babies to call to their parents. I figured mom or dad was close by as the owlets kept looking upwards and eventually the parents did fly in with a meal – crayfish as far as I could tell.

 

On several occasions over the next 6 weeks or so, I would hear the owlets making that keening call and staring upwards. I figured the parents were nearby, but they were obviously just keeping an eye on their offspring and not feeding them (at least not when I was there).

It was time for the young ones to learn how to get their own meals.  Although barred owls usually hunt at dawn and dusk, the young owls were busy looking for food during the day. The mammals they eat include voles, mice, shrews, squirrels, rats, rabbits, bats, moles, opossums, mink, and weasels. Birds are also a food source and their prey may include woodpeckers, grouse, quails, jays, icterids, doves, pigeons, cardinals, cedar waxwings and grackles. They also eat amphibians, reptiles and insects (e.g., snakes, slugs, lizards, frogs and toads, salamanders, crayfish, turtles, scorpions, beetles, crickets, grasshoppers) and it was the latter group of prey animals that I saw the owlets hunting. Here for example, it appears one young owl had caught a crayfish.

One day, one of the pair was grasping a twig in its beak; I’m not sure what it was doing but it seemed to have some purpose. Perhaps it was testing how strong its beak was.

  

That a strong beak can be an asset became apparent on another occasion. One of the juvenile owls suddenly flew from one tree on the other side of a water ditch to one above my head. There was much rustling of branches and leaves and when I got into a spot where I could see the bird, it became obvious s/he had caught the largest stag beetle I had ever seen at Mason Farm Biological Reserve. It appears that the giant stag beetle (Lucanus elaphus) drinks tree sap, which must have been what it was doing when the owlet got hold of it. The problem for the owl was how to eat the beetle when those large pincers were in the way.

     

The owl would try to grab hold of a pincer but lose its grip; s/he would turn the beetle around but was having a very difficult time getting those defensive appendages off. This went on for quite a long time, which made me feel a bit sorry for the beetle.

 

Finally, the owl had success and was able to settle in for a crunchy meal.

 

They expel the indigestible parts of their prey in owl pellets that they cough up regularly. Here you see the contents of one a friend found under a favorite perching branch at the reserve.

Another day I saw one owlet suddenly fixate on the water ditch.It turned out that quite a large rat snake (Elaphe obsolete; Pantherophis alleghaniensis) was swimming by. The owl watched it carefully as it climbed out of the ditch and eventually crossed the adjacent walking path, never making a move to tackle the reptile. I had remarked on this encounter to the reserve’s land manager, who said it was probably a smart move on the owlet’s part, since the snake was large enough that it could have wrapped around the owl’s head and choked it.

The young owls seemed to have learned a lot about life as a predator as they grew older. It was fascinating watching them explore their world.

Next up: how the owlets cared for themselves.