As the avian reproductive season winds down here, the dominant chorus of bird song in the woods and fields typical of June and early July is rapidly becoming just a memory.
Although a few late nesters or parents raising a second brood continue to vocalize, the two main reasons for singing – mate attraction and territorial defense – are becoming almost irrelevant. Hence the diminishing of bird sounds overall.
At our place, there have been a couple of noteworthy exceptions. First, a very noisy family of fledged merlins are coursing overhead regularly and perching high in our red pines and those of our neighbors, screeching to the point of being almost annoying.
Merlins are small falcons, slightly larger than kestrels but more compact and robust. They are powerful flyers and chase down small flying birds and dragonflies as their primary prey.
In our area, they are rather uncommon and seem to prefer lakeside nesting locations, adopting old crow or hawk nests for their own. In recent years in North America, they have become more and more adapted to urban habitats and can be found here and there in the Twin Cities and other cities. When not nesting, they are solitary and rarely seen.
The other exception to quiet in our yard has been the riot of ruby-throated hummingbirds. At our feeders I have never seen so many. On July 25, the feeders were being overwhelmed by birds that appeared to be juveniles, likely raised close by.
Interestingly, with the sudden switch to northwest winds that night, the following day feeder attendance was very low. In my opinion, our local juveniles took advantage of the winds to begin their journey south to Mexico (we’re still in July!).
Since then, feeder attendance has slowly increased, mostly by juveniles I suspect have migrated in from more northern locations.
These exceptions aside, let’s return to the post-breeding quiet period. Most of our breeding adults, whose energies have been poured into procuring food for their growing young, are now experiencing physiological changes. Their flight feathers, which have not been renewed for a year, are pretty battered. Migratory species in particular need their flight feathers to be in top condition for the return trip south – the birds’ version of a new set of tires. Energy resources are now being directed to the molting and replacement of these feathers, as well as the rest of the smaller feathers that cover the body.
Although songbirds only lose a few flight feathers at a time during the molt, they are somewhat flight-impaired and more vulnerable than usual to predation. As a result, they become extremely secretive. Vocalizing and movements are severely curtailed.
It may take several weeks for the molt to be completed, but once complete, the birds come out of hiding and begin to fatten up for migration. There’s no more need for singing, so the only sounds they utter are little chips that keep them in contact with foraging partners.
So the quiet continues – it will be the better part of a year before they return and the countryside is full of singing once again.
Marshall Howe is a retired biologist with the U.S. Fish and Wildlife Service. He specialized in bird population studies. Howe has been a Park Rapids resident since 2010.