Fall feathers….
Fall molt in birds is a critical seasonal process during which they shed and replace their old feathers with new ones. This molting typically occurs after the breeding season and before migration, allowing birds to maintain optimal feather condition for insulation and flight efficiency. The timing and pattern of the fall molt can vary among species, but it generally involves a gradual replacement of primary and secondary flight feathers as well as body feathers. This renewal is essential for birds to prepare for the upcoming colder months and long migratory journeys, ensuring they remain agile and protected against harsh environmental conditions.
During our most recent visit to Iona Island, we came across three species which exhibited the evidence of recent molts. The first we found was a group of European starlings.
European starling at Iona Island - Sept 12
Starlings turn from spotted and white to glossy and dark each year without shedding their feathers. The new feathers they grow in fall have bold white tips – that’s what gives them their spots. By spring, these tips have worn away, and the rest of the feather is dark and iridescent brown. It’s an unusual changing act that scientists term “wear molt.”
This earlier photograph of a starling during breeding season (April) shows the effects of “wear molt” resulting in a bright shiny dark plumage. As the months progress, the new white tipped feathers grow in pushing the older worn all black feathers out. Bottom line is, for the next few months, look for bright white spots on starling feathers as they prepare to migrate south.
Our next bird molting in the early fall is the Mallard. During their annual molt, when they shed their feathers in summer and early fall, drakes lack their bright breeding plumage and resemble the more dull-colored females. However, drakes are still distinguishable by their yellow bills and reddish breasts.
Mallard female followed by non-breeding plumage male
In the shot above, the subtle differences between female (left) and non-breeding male (right) show how difficult correct identification of the sex of this bird during late August and early September can be. The most definitive features are the all-yellow bill of the male (notice black mottling on the bill of the female) and the hint of the tail curl on the rear bird (male). A bit more black on the tail feathers is also a clue to the right bird being a male. A third characteristic which is not visible on this photo is the blue speculum on the male which is often obscure in any plumage. Finally, the breast of the male is a deeper reddish hue than that of the female. Molting mallards are basically flightless during molting and this period (known as an eclipse phase) camouflages the bird. Within a couple of weeks, the male will regain his brilliant green head and generally more vibrant plumage.
Great blue heron Sept 12
Great Blue Herons undergo a molting process in the fall, shedding old feathers to prepare for the colder months ahead. This molting is crucial for maintaining the bird’s insulation and flight efficiency, as worn feathers are replaced with fresh, robust ones. During this period, herons may appear scruffier than usual, but the renewal of plumage ensures they remain well-equipped to hunt and navigate their habitats throughout winter. The timing of molting also coincides with shifts in their behavior and habitat use, often leading them to more sheltered environments where they can conserve energy while their new feathers grow in. Is this perhaps why “Blue” was in this sheltered shallow “oasis” over the past month or more? This is today’s image (above) of “Blue” the Great blue heron we’ve been checking in on at Iona Island.
Here is our heron earlier this summer, “Blue” was looking a bit scruffier and more drab back then. But today, the heron appears to be quite pristine…much deeper hues and much “cleaner”. Again, we see evidence all around us that Autumn is indeed “A Season of Change”.
