losing their spots

Signs of fall are beginning to appear as a few maple trees show some red and gold color in their leaves, the squirrels are busy collecting nuts off the trees, Canada Geese fly in V-formation overhead, and a few of the wildlife start growing their winter coats.  I first noticed the latter when the fawns suddenly appeared in the backyard without their spots.

White=tailed fawns-fall molt-

Just a trace of spots linger on the flanks of one of the twin fawns that have ravaged my wildflower garden all summer long.

White-tailed fawn - winter molt

The tawny brown coat with white spots is slowly being overgrown by the longer gray brown winter fur, which provides the deer with much needed insulation to survive the cold.

White-tailed fawns - winter molt

Not all of the fawns have started growing their winter coat, though.  It’s interesting that in these twins, one is clearly well ahead of the other in development of the winter fur — which lends further proof to the observation that twin fawns are usually fraternal, not identical.

What this tells me is that there have been at least two sets of twin fawns that have been eating up the backyard garden — and I thought it was just one hungry pair that had been doing all the damage.

a different look

This is the time of year we begin to see birds migrating back to their southerly winter homes, but many of them look very different than they did when they arrived here in the spring ready to breed.  Most birds have two outfits in their wardrobe:  a non-breeding basic plumage that may be drab but serviceable for all-around activities, like migration and over-wintering; and a brightly colored (in the case of males) alternate plumage that is meant just to show off their stuff in the breeding season.  In some cases, bills, skin around the eyes, feet, etc. may also be brightly colored, only during the breeding season.

Here’s a look at how this works in a small diving “duck” (not really a duck) called the Pied-billed Grebe, whose basic, non-breeding plumage gives no trace of the pied bill.

pied-billed grebe-basic, non-breeding plumage

Pied-billed Grebes were diving among the lily pads looking for small fish or crayfish lurking there.

pied-billed grebe-basic, non-breeding plumage

No trace of that characteristic marker of the broad black stripe on the bill though.  The one at the bottom of the image still has the faint head stripes of juvenile plumage.

pied-billed grebe juvenile

Typical juvenile plumage in the Pied-billed Grebe

pied-billed-grebe-breeding adult

A few months earlier adults looked like this, with a more definite black stripe through the pale, silver bill.

Pied-billed_Grebe_and young-Audubon

Earlier in the breeding season, both adults and youngsters looked quite a bit different than they will during the non-breeding season. Photo from Audubon field guide.

Of course seasonal changes in the grebes are far more subtle than those in some of the warbler species that take on completely different colors and color combinations between basic and alternate (breeding) plumages.  For example, gorgeous red Scarlet Tanagers molt to a green-gold plumage in the non-breeding season, making them look like a completely different species.

scarlet tanager plumage molts

good morning, little blue bird

Indigo Bunting

His tail looks a little worse for wear, but he has maintained the deep blue color of his body feathers throughout the summer.

I was barely out of my car at the Old Cedar Road parking lot when a beautiful Indigo Bunting hopped up on a tree nearby, posing briefly in the bright sunlight before flitting off into the forest.  What a nice treat for the first bird of the morning.

Indigo Bunting

In fact, he is a surprisingly uniform blue.

In the next few weeks, this colorful male will molt into its winter plumage and become drab brown, like the female, before migrating to its winter home in Central America. Indigo Buntings, like most other bird species, replace their feathers twice a year, but these brightly colored males take at least two years to become completely blue.

A new coat

In the fall, we often think it’s time to replace that old winter coat with a new one that has better insulative value.  Some animals follow a similar pattern of hair replacement (molt) that effectively replaces old, short, or sparsely distributed hair ideal for dissipating summer heat with a new layer of thick, curly, densely distributed hair that protects the animal from heat loss in cold weather.  That seems to be going on now in the deer population in the backyard.

Mom is looking a little scruffy as she replaces her thin brown summer coat with an underfur of thick, curly gray hair.  Another longer layer of brown guard hairs will grow in on top of the underfur to complete the insulation barrier.

Mom is looking a little scruffy as she replaces her thin brown summer coat with an underfur of thick, curly gray hair. Another longer layer of brown guard hairs will grow in on top of the underfur to complete the insulation barrier.  The fall molt typically begins at the head and neck and progresses rearward to the flanks.

Growing a new, and thicker layer of fur is an expensive endeavor, and deer preferentially seek out high carbohydrate sources of food in the fall to fuel this effort.  I think they must have found some acorns under the swing set that the squirrels missed.  They also love to chow down on apples and other mast crops. Nursing is incompatible (energetically) with molting, so it likely that her fawns are now weaned.

Curiously, one of her twin fawns has already completed the fall molt to adult fur pattern, while the other fawn doesn't seem to have started yet.  Molting can be slowed or halted in an animal suffering from poor nutrition, but it seems curious that these two would be on such a different schedule when they are probably eating exactly the same things.

Curiously, one of her twin fawns has already completed the fall molt to adult fur pattern, while the other fawn doesn’t seem to have started yet. Molting can be slowed or halted in an animal suffering from poor nutrition, but it seems curious that these two would be on such a different schedule when they are probably eating exactly the same things.

twin fawns

Still Bambi-like...

Still Bambi-like…

There is still a faint hint of spots on the neck of one fawn, but the fall molt is almost complete in this animal.

There is still a faint hint of spots on the neck of one fawn, but the fall molt is almost complete in this animal.