BY THE DARK OF THE MOON
Yesterday was a big birding day at the Cheyenne River Buffalo Ranch. We experienced the first 2022 sighting of seven species. It is true that rain and savage winds had kept us inside for several days, and so we might have missed these species’ first appearance on the ranch. But it still seemed strange that a White-breasted Nuthatch, a barrage of Loggerhead Shrikes, several pairs of Tree Swallows, a Magnolia Warbler, a trio of Belted Kingfishers, and a lone Spotted Towhee would all show up at their summer breeding grounds on the same day. And one other strange occurrence: On the very small pond situated a hundred feet from the house and on the way to the dog kennels, a Lesser Scaup appeared. Mallards and teal hang out there in pairs every year as breeding season approaches. But never a Lesser Scaup.Scaup, in fact, are not often found on small ponds. They are diving ducks that, in addition to diving deep for their food, often require long runs across the water to gain the speed needed for flight. Our little homestead pond is not a place that Lesser Scaup would normally bother with. This guy was a small, dapper, black-and-white duck with an iridescent purple head and a blue bill. He was clearly in breeding attire. But where were the females? I’ve come to believe that a species appearance on the ranch has to do with air temperature, insect and forage availability, and, most importantly, the photoperiod of the particular season. Of course, temperature and food availability vary from year to year but photoperiod - the amount of light in a given day - is pretty much a constant. The great celestial clock of sunlight and dark is only slightly altered by weather. It changes during the year, but the photoperiod of a cloudy April 20th is only slightly different from that of blue-sky April 20th. I’ve gotten used to seeing the dozens of bird species on this ranch dribble into the grasslands and brushy draws as the photoperiod slowly lengthens into summer and reaches the critical level that triggers each species migration, courting, nest building, and the raising of young. Today, I’m puzzling over the apparent change in bird behavior for this year of 2022.Some would say that what I am seeing is only an insignificant deviation brought on by drought conditions, food availably on wintering grounds, or, more likely, poor and random observations. But there is another explanation. It could be that what I’m noticing is the result of a photoperiod confusion that gives these birds mixed signals, significant enough to slightly alter their ancestral behavior. Some might argue that such small variances are meaningless. I caution that centuries of evolution have created these patterns of migration, breeding, and the rearing of young and that such evolution is critical to each species’ survival.
Of course, I’m thinking of the human light pollution that these bird species are subjected to as they winter and migrate through a world changed by the artificial photoperiods produced by the electric lights that humans seem to need for their comfort: lighted parking lots, buildings, sports venues, deserted streets, immense airports.There are almost no artificial lights on this ranch. We don’t find them comforting. In fact, we on the Cheyenne River Buffalo Ranch love the darkness of natural night and embrace it as an element of nature as essential as grass at our feet, wind in our faces, or the sound of coyotes from four directions. It is International Dark Sky Week around the world and it is more than an excuse to stumble around in the dark. It is an opportunity to savor and protect the darkness. Here, we venture out many nights and, if the sky is bright with stars, we expect to see the eerie silhouettes of thousands of birds migrating across the face of the moon. We fervently hope that will never change.
Photo Credit: Lesser Scaup - Brian Kushner
Crane Ascension - Jill O'Brien;
Northern Lights on the Prairie - Bonny Fleming;
Graphic James Madison University – Light Pollution: The Overuse & Misuse of Artificial Light at Night)