Nature Notes: A Maine Naturalist Afield
Transcript
As the days begin to shorten, I start to speculate about which birds will remain within our local fields and forests through the autumn and winter months. Heavy drops of beechnuts draw in roving troops of Wild Turkeys while a good crop of conifer cones typically keep a few Red-breasted Nuthatches from pushing further south. If the more northerly spruce and fir mast crops are poor, we may even entice a few boreal crossbills, redpolls, and siskins for a time. During years such as this, when the oaks bear and drop an abundance of acorns, it’s safe to suspect a healthy number of Blue Jays will stick around. Indeed, the prevailing soundscape of late summer and early autumn has been the plunking of acorns and jeering of the jays.
Forecasting whether our breeding Red-shouldered Hawks will pass the winter with us is far more challenging. There’s no question about their presence come spring. They frequently glide and wheel above our clearing, issuing an endless stream of emphatic vocalizations. As the breeding season progresses, they all but vanish, leading secretive lives rearing young in the woods beside the beaver flowage where they can occasionally be spotted. They are rarely, if ever heard, during this period. By autumn, however, their inclination towards vociferousness appears to somewhat return. The calls of Red-shouldered Hawks can frequently be heard emanating from throughout the forest. Sometimes one red-shoulder can be heard vocalizing in response to another hawk among the clamoring of jays. In fact, it’s not at all uncommon to see a Blue Jay glide into a leafy red oak or swamp maple and hear a string of Red-shouldered vocalizations issued forth from the very same cluster of crimson foliage. Scrutinize the area more closely and you will find only the jay in attendance. We’ve been duped.
In addition to being visually striking and highly social birds, Blue Jays are masterful mimics. Indeed, these birds have long been documented imitating the calls of Red-shouldered Hawks and several other raptors in addition to their already robust and varied repertoire of vocalizations. The function of this raptor mimicry has been speculated upon for some time, however, trickery of foraging competitors – both other jays and other bird species – is the prevailing theory explaining this behavior. A fellow jay may think twice about foraging for acorns in this patch of oaks if it thinks a Red-shoulder is on patrol.
An experience in the North Woods illustrated that jay mimicry is not limited to only the blue variety. I recently made a trip to the township labeled T12 R16 (just across the border from Daaquam, Quebec) to conduct work on our recently launched Motus receiver station. Waking at the bunkhouse early, I stepped outside to make note of the birds vocalizing in the area. While walking the thick border of conifers and poplars that rings the clearing, I heard the familiar refrain of a Merlin and added it to my list of straggling warblers and sparrows. I scanned the treetops hoping for a glimpse of the small, dark falcon. Imagine my surprise when I put eyes on the vocalist and found, not a Merlin, but a Canada Jay perched atop a spruce spire and piping out a rapid string of Merlin notes. The imitation was pitch perfect. I amended my list and made the mental note that all suspected Merlins would now need to be visually confirmed.
Back home within the woods of Palermo a short time later, I heard Red-shouldered Hawk vocalizations echoing above the treetops. Reluctant to make the call, I picked up my binoculars hoping for a confirmation. Sure enough the issuer was a bonafide Red-shoulder, cruising above with crescent-shaped “windows” visible within its wings, backlit in the morning light. Seconds later, another bird began repeating the call from within the canopy overhead. Intermingled with this treetop response, however, was a lone “jeer” call, typical of Blue Jays – a rare slip up and auditory clue for attempted deception.
In his 1908 work, “Birds of Maine”, Maine ornithologist Ora Knight, made no mention of Red-shouldered Hawks remaining through the winter months. Today, however, they will, in fact, regularly remain within the southern portion of the state, particularly along the coast and a short distance inland. I have spotted them here in Palermo through the winter, particularly along the margins of fields with little snow cover. Some winters they are more reliably seen than others.
So if the days are short and the oaks have been generous, note any would-be raptors you’ve heard on frosty winter mornings with a grain of salt. Reach for your binoculars a skeptic or else risk being fooled like the other tree nut-hunting jays.