December
December has a way of scuttling past us, powered by the distractions of national holidays. This is the month for recovery from Thanksgiving celebrations in November and eager anticipation of the holiday season at the end of the year. December brings brightly colored decorations, festive lights, parties with friends and family, and high hopes of a world transformed by a blanket of sparkling snow. With at least one snowstorm a usual part of the December weather mix, these hopes are realistic at some point in the month, although a white Christmas is far from guaranteed. Away from human affairs, the serious business of winter survival in the natural world is all-consuming. For the many creatures that are hiding away, snow cover offers some insulation against plunging air temperatures, whereas active animals, including birds, squirrels, and deer, must negotiate a world that shifts back and forth between freeze and thaw—together with snow, ice, rain, and sun—in their daily task to obtain sufficient food to survive until tomorrow.
Despite the frequently atrocious weather conditions in December, some animals are more than survival machines. Driven by natural selection, they also have sex on the brain. The imperative to find mates is the theme for the opening essay (“Love in a Cold Climate”) and plays a role in the final essay (“Duck Time”). In between, I consider the importance of winter nests for the gray squirrels in our neighborhood (“Squirrel Dreys”) and the biology of the coyotes we occasionally hear howling in the night at this time of year (“Coyotes”).
Love in a Cold Climate
The temperature was edging up toward freezing as we walked along the upper path overlooking Six Mile Creek. Faint sunlight shone coldly through the thin layer of cloud onto the bare branches of maple and beech trees and the deep green of hemlock. We were making our way to the lookout point over the reservoir, which offers a pretty view of trees and water but rarely has any wildlife of note.
As we approached the lookout, I told myself that the high point of our walk would presumably be the several sightings of flying moths along the way. This was not an especially exciting high point because one would expect to see winter moths on the wing in early December—and also because, let’s face it, winter moths are the poster child LBJs of the insect world. They sport a wingspan of an inch (a little less than three centimeters), and they are dull brown-gray. Nevertheless, they are interesting because any insect flying in subfreezing temperatures is decidedly odd.
Various insects can fly in chilly weather. For example, honeybees fly around on sunny days in early spring because they shiver their wing muscles to warm up. Winter moths don’t play it that way. Experiments using tiny temperature recorders inserted into the body of winter moths have shown, without exception, that they fly without warming up. The sort-of explanation is that these insects weigh next to nothing and flap their wings slowly. If that explanation doesn’t satisfy you, join the club, especially as our winter moths were being no sluggards. Winter moths are unexplained flying objects, the real UFOs of our world.
Our local UFOs may be unexplained, but they are not unidentified. These little moths were most probably males of the Bruce spanworm (Operophtera bruceata). They have just one thing on their to-do list: sniff out the females, which don’t fly but sit around on trees emitting plumes of an irresistible pheromone. Over the next few weeks, each female will deposit her 150 bright orange eggs in crevices of tree bark. Unless eaten by a chickadee, woodpecker, or other determined bird, the eggs will hatch next spring into ravenously hungry caterpillars that, if in sufficient numbers, can defoliate an entire tree. When fully grown, the caterpillars lower themselves to the ground on a thread of silk, pupating on the forest floor, and, unless eaten by a rodent, shrew, or beetle, will be next winter’s cohort of winter moths.
There’s an outside chance that our winter moths along Six Mile Creek weren’t O. bruceata but the close relative Operophtera brumata, which is, rather confusingly, known as the winter moth. That would be bad news because O. brumata is an invasive from Western Europe and a far more aggressive defoliator than O. bruceata. O. brumata arrived in Nova Scotia in the 1930s, and it has been spreading into the northeastern US in recent decades. O. bruceata and O. brumata can’t be distinguished by eye, and even the moths themselves have problems because hybrids between the two species have been reported. Entomologists have a solution: the two species can be separated by the detailed morphology of the dissected male genitalia.
I was wrong with my prediction that the winter moths would be the high point of our walk. As we climbed the slope to the lookout, we saw that the reservoir below us was partly iced over, and there was a mass of ducks in the ice-free portion. Many of the birds had a conspicuous white patch on their head, others were brown, and they came in two sizes.
The smaller ducks were seriously small. They had to be buffleheads, ducks that breed in the middle of Canada and migrate through New York State to their winter hangouts farther south. The bufflehead is the smallest duck in North America. Any evolutionary temptation to get bigger is constrained by the preferred nesting site of this species: tree cavities drilled out by woodpeckers. An oversized bufflehead would struggle to get into the cavity to lay and incubate its eggs or feed its young properly. We watched the buffleheads as they dived for food, preened, and generally kept an eye on the world. Then some of the birds took flight, the hazy sunshine illuminating the brilliant white on their bellies, wings, and heads as they streamed up and away.
The other ducks were hooded mergansers, conspicuously larger than the buffleheads. Some of them were behaving just like the buffleheads: resting, preening, and feeding. Then we heard a strange and persistent sound, somewhere between a cat purring, a dog growling, and a frog croaking. It was the ducks—or, more correctly, the drakes. Several of the male mergansers were displaying their prowess to at least one female.
A male hooded merganser on top form is quite something to watch. His crest is raised up and over his head like a hood, displaying the large white patch on each side of his head. It looks almost like a white helmet fringed in black. With his crest in place, the bird rises up, bobs his head forward toward the female, gives it a good shake, and then abruptly jerks his head backward onto the back. Initially, three males were displaying to a single female, but she dived briefly and things got more complicated. A second female was in play, and then more males got in on the act. The diffuse group of romancers drifted along the edge of the ice until they were hidden from our view.
At first, it seems odd to be distracted with affairs of the heart while migrating south. However, hooded mergansers tend not to travel as far as the buffleheads do, and there’s no harm in getting an early start with choosing your mate for the next breeding season. It will be a temporary affair, after all. As soon as the female starts to incubate her eggs in April, the male will be off and won’t return. This is markedly different from the buffleheads, which, unusually for ducks, maintain a pair bond for years.
We went back to Six Mile Creek a few days later and found that the ducks had gone and the reservoir was entirely empty of birds. All we saw were the winter moths flitting among the trees in the cold.
Squirrel Dreys
The bare winter skeletons of deciduous trees are an annual challenge, requiring us to brush up on tree ID by overall shape, branching pattern, and characteristics of the bark without any leafy clues. It is also an opportunity to discover more about the lives of the gray squirrels that live in our neighborhood.
Our eastern neighbor’s box elder tree overhangs our driveway. When the leaves fell, we discovered a brand-new gray squirrel drey. It is high up, as the dreys always are, and perched at the point where a gently upward sloping branch divides into three, creating a small platform. We knew that the squirrels had been busy all summer in the box elder, but we had no idea there was a house construction project in progress.
Drey construction is a summertime job, perhaps extending into September, but its value for the squirrels starts with the rigors of the cold weather in December and beyond. The framework of the leafy nest is a collection of pliable twigs that the squirrel gnaws from the midsummer tree and then weaves into a lattice. Importantly, the squirrel does not remove the green leaves from the twigs. As the season progresses, the leaves turn brown but, isolated from the tree, never receive the hormonal signal to drop. The lattice of leafy twigs might look like a bit of a mess, but it provides protection from rain, snow, and cold. To improve insulation and comfort, the squirrel usually lines the inside of its drey with old grass, moss, and small pieces of shredded bark. In other words, a gray squirrel drey is a big hollow ball, about the size of a watermelon, with a good six inches of living space in the middle. The squirrel builds a single entrance hole into the leafy ball, usually facing down, so that it can race down the branch and tree trunk if disturbed.
Now that temperatures are plummeting—and anticipated to get even colder before winter is done—the box elder residence is a snug lifesaver for at least one of our squirrels. The housebuilder may be joined by one or more other squirrels, most likely close relatives. The warmth of several squirrels huddled together in their well-insulated nest can raise the temperature inside a drey tens of degrees above ambient.
Unsurprisingly, the drey is a high-maintenance dwelling, requiring continual attention to remain intact and waterproofed. This can involve adding more vegetation to fill the cracks and tightening up any parts of the lattice that come loose. The large leaves of the slippery elm at the far end of our backyard are highly prized for drey maintenance, and we routinely see individual squirrels carting these oversized, yellow leaves from the ground up into the trees. If the owner moves away or succumbs to a car or red-tailed hawk, its drey deteriorates rapidly. For example, there’s a drey in the large oak tree up the road that looks decidedly lopsided, with twigs and dead leaves hanging down precariously. This is vacant property, I am sure, and the next storm will likely destroy it altogether.
If gray squirrels had homeowner’s insurance to worry about, I suspect the builder of our box elder drey would be paying high premiums. Even the most desultory risk assessment would wonder at this ball of twigs and leaves so close to the tip of a branch. Surely, the inhabitants will get motion sickness in high wind, followed by a hefty repair job once the storm has passed. It would have been more sensible to build in a vertical V between two stout tree limbs close to the center of the tree. I made a quick check of other dreys in the neighborhood. Of the twenty-four dreys I observed, only three, including our box elder drey, were “out on a limb,” as it were. All the other ball-shaped dreys were located in the crotch between the trunk and a sturdy branch or between two substantive branches. We shall see how our box elder drey fares through the coming winter.
This brings me to a further issue about dreys. There are two architectural designs for a drey. One is the big ball design, for a protective residence; the other is the platform design, for lolling about on, especially during the heat of the summer. The latter, often referred to as a rest site, is the squirrel equivalent of budget housing. It’s quick to put up, and there are no long-term expectations. Several likely remnants of gray squirrel rest sites were evident on my drey-checking walk.
There is one other kind of gray squirrel residence: the den. All things being equal, I suspect that our imaginary squirrel insurance company would favor a den over a drey. A den is a hole in a tree created, for example, by the drilling of a pileated woodpecker or by the rotting of one side of the trunk after a branch has been torn off in a storm. To my mind, the squirrel specifications for a suitable hole are rather demanding. It must be at least a foot deep and with an entrance about three inches wide. A smaller entryway creates a squeeze for the squirrel; anything much larger and a raccoon can get in. I suspect that holes of the right proportions may often be in short supply. The kingpins of the squirrel world presumably reside in dens, leaving the hoi polloi with no option but to build leafy dreys.
These animals certainly lead complex lives with endless decision-making about their food supply and housing arrangements. The decisions they make may have life-or-death consequences.
Coyotes
Although we live in the city, closely bounded by houses on all sides, it is usually quiet at night. The big exception is the all-night music of the crickets, which is fortissimo through August before gradually diminishing back to silence with the first hard frost or significant snowfall of the year. But one night last week, at about 3 a.m., I heard the unmistakable howling and barking of coyotes. The night air must have been very still, and perhaps, in the cold, the coyotes had strayed closer to town than usual.
A lone animal could not have been responsible. It sounded like a large pack, but a small number of coyotes can make an awful lot of noise. Even the formal name for the coyote, Canis latrans, meaning “barking dog,” reflects their noisiness. Incidentally, the coyote was named by Thomas Say, the father of entomology who also named the orange-crowned warbler (see October, “A Relocating Crown”), on the same expedition to the Rocky Mountains in 1819–20. Say was a busy man. Back to nocturnal entertainment, the howling pack of coyotes was almost certainly a small family group, probably parents and this year’s young, which generally don’t disperse till the spring after their birth.
No one has a good thing to say about coyotes. This is obvious from our online neighborhood chat group. Usually, the comments include recommendation requests for local plumbers or babysitters, advertisements for yard sales, notices about missing cats, and updates on the seemingly endless summer roadworks. Every now and again, though, someone posts that there was a coyote in their backyard. It’s usually a singleton, almost always described as large, and often called out as “mangy, could be rabid.” The description is followed by warnings to keep cats and small dogs indoors in the immediate neighborhood. That’s because coyotes have a reputation for enjoying these pets for dinner. (Could it be one of those missing cats from the chat group?) But pets aren’t the only thing on the menu. Coyotes also eat rabbits, voles, squirrels, snakes, insects, fruit, and berries. And they won’t say no to polishing off any food left on a bird table.
Coyotes are not only bad news. They are also reputed to be clever beasts. There’s an online story about how coyotes exterminated a colony of feral cats in Southern California. That might sound like a good thing to some of us, but a local charity was heavily invested in providing feeding stations for the cats. The charity workers didn’t realize for ages that their feline friends were no more, presumably courtesy of coyotes, because the food they provided with loving care was always consumed . . . by the wily coyotes.
The coyote’s relative, the gray wolf, has been rehabilitated in the minds of many people. Although gray wolves can attack livestock, causing understandable upset among ranchers in the western US, they are widely admired for their complex social lives, hunting skills, and ecological role as a top predator that keeps elk and other deer populations under control. The gray wolf is front and center in all discussions of rewilding the continent.
However, perceptions are different for the coyote. You might imagine that everyone who rails against the white-tailed deer would be glad that coyotes occasionally have deer on their menu. But no! As a neighbor once explained to me, yet another reason for hating the deer in our backyards is that “they attract the coyotes into town.” A coyote simply can’t win.
One of the problems for our local coyotes is that, in all honesty, they shouldn’t be here. That’s because the natural range of the coyote was the southwest of the continent, extending into modern Mexico and eastward to the Great Plains. I am rather hesitant about the term natural range because it refers to the pre-Columbian range when there were up to 18 million Indigenous people in North America. The ecological footprint of these pre-Columbian humans was far from negligible, and they may have influenced the distribution of coyotes.
Coyotes benefited big time when Europeans pushed west into the continent, persecuting the gray wolf as they went. The problem for coyotes is that they are strongly outcompeted by gray wolves. For example, when gray wolves were reintroduced to Yellowstone National Park in the 1990s, the coyote population declined substantially. Furthermore, studies using radio-collared wolves showed that the wolves chased coyotes away, especially from deer kills, and occasionally killed coyotes. Europeans moving west also changed habitats, replacing dense forest, which coyotes don’t like, with coyote-friendly scrubby country and ranchland. There are even stories of fox cubs being sent from the west to fox hunters in the east for release into the areas where they hunted—except that the fox cubs were actually coyote cubs.
And so, the coyote spread eastward, arriving in the Finger Lakes probably in the 1940s. It is a bit more complicated than that. The coyote came not from the west but from the north, Canada. On the way, our coyotes encountered remnant populations of gray wolves. The interactions extended beyond growling and squabbling over dead deer to some matings, such that the coyotes in our area are, genetically speaking, about 26 percent wolf. (For purists, that is 13 percent gray wolf and 13 percent eastern wolf, but people argue about whether the eastern wolf is a subspecies of the gray wolf or a different species.) The genetic admixture is used to explain why the coyote subspecies in the northeast of the continent, including our local patch, is bigger than other coyotes, more prone to staying together in groups and howling loudly, and tends to hunt deer in groups . . . like a wolf.
That’s not all. Our local coyotes also have about 10 percent domestic dog in their genomes. In short, coyotes “get about a bit,” not only with wolves but also with dogs. Much is made of the so-called coydogs. Although male coyotes are mostly uninterested in domestic dogs, except as food, some male domestic dogs are not as fussy in their affairs of the heart. However, unlike male coyotes, which are superb fathers, dog fathers are strictly looking for one-night stands, leaving the female coyote to raise her offspring alone. This is generally a rather unsuccessful endeavor, but the genomic data tell us that some coydogs survive to adulthood and reproduce.
There is a fair amount of chat about coyotes getting more common in our area. I am uncertain whether this is true. The coyote populations in New York State did increase between the 1940s and 1970s, but, since then, it has been fairly stable at an estimated twenty to thirty thousand individuals (New York State Department of Environmental Conservation n.d.). What is happening is that these clever animals are changing their behavior, increasingly taking advantage of the rich and easy pickings found in human settlements.
There is much discussion about how we can keep coyotes wild. Some say that hunting and trapping is the answer to controlling the numbers and ensuring the animals are scared of humans. I don’t know enough to judge whether this is an effective strategy. What does make sense is to yell and gesticulate wildly whenever you see a coyote—to remind them that humans are nasty and should be avoided.
Duck Time
Our local area hosts a total of twenty-four species of ducks, but not all at the same time (Sibley 2003). The distribution maps for these species inform us that just four species are resident species: the mallard and its close relative the American black duck, plus two species of merganser—the hooded merganser and the common merganser. Most of the rest of our two dozen ducks are migrants, passing through our area on their annual trek north to Canada to breed or south to their winter feeding grounds on the coast or on inland ponds and lakes in the southern US and Mexico. For the sake of completeness, I should add that we boast one winter visitor, the common goldeneye, and two summer visitors, the wood duck and the ring-necked duck.
The bottom line of all this detail is that duck spotting should be a low-diversity activity during most months of the year. Luckily for us, nothing could be further from the truth because many species of duck move around during the winter months. Some of these movements are very local, such as finding sheltered places in cold weather. Others are more far-ranging, such as cadging a ride on winds ahead of a cold front. When wind speeds and directions change frequently in unsettled weather, ducks can drop out of the sky to rest and feed on ponds or lakes in unexpected places. This happens again and again. Just as for our visit in early December to the reservoir on Six Mile Creek (“Love in a Cold Climate”), a trip to Cayuga Lake and local ponds can yield a nil return, the same ducks as last time, or a completely different set of species.
We have had a cold snap during the last week of December. It’s been nowhere near the record lows for late December, but it’s definitely wrap-up-warm-don’t-stay-out-for-long weather, hitting 0°F (–20°C) at night and struggling toward the teens during the day (23° to 14°F [–5° to –10°C]), with a gusty westerly wind that gives a windchill that is best not to think about. In these conditions, along with an inch or two of powdery snow, we sprinted around Allan H. Treman State Marine Park at the southern end of Cayuga Lake. The path runs just inland from the lake’s edge and behind a line of cattails and other tall reeds. This vegetation gives a bit of protection from the wind and hides us from any birds that are close inshore.
Our bird list for that frigid walk was short but interesting. A continuous layer of ice extended from the shoreline to about twenty yards into the lake. Just beyond the ice, a single pair of buffleheads was cruising back and forth in the chilly water, bobbing from side to side in rhythm with their vigorously paddling legs. Both sported the telltale white patch on the head: hers, an oval patch behind each eye; his, a single large patch extending around the back of the head. Every now and again, one or both lifted its head up and, in an instant, dived down into the water in search of food. At this time of year, buffleheads are said to favor water snails and pondweed.
Apart from the buffleheads, all the ducks were far out on the lake, mostly beyond the resolving power of our binoculars. Our eyes were watering in the bitter wind, but we could make out two sizes of ducks. Curiously, two of the large ones kept on rising up and flapping their mostly white wings (possibly tipped in black, but it was difficult to be sure of that). For the several minutes that we watched, these two individuals repeated this antic, again and again. Our best bet is that they were displaying common mergansers. These birds indulge in what is called courting parties, involving lots of wing flapping, which we could see, together with stretching their bodies out of the water with beaks pressed down to the breast, which we had to imagine. It seems very early to be courting. Apparently, common merganser courting parties generally start in earnest in February or March, although there have been reports of this behavior as early as November. Still, the early date of our displaying birds is not as surprising as the fact that these birds could be thinking amorous thoughts in such bitterly cold conditions.
In the two days following our bufflehead-and-probably-merganser visit, the wind shifted to the south and the temperatures increased to above freezing. We wondered if the change in the weather might have brought any more birds to the lake. When we returned, the ice still formed a continuous layer along the southern shore, but, from a duck’s perspective, we were in a different world. There was no sign of our peaceable bufflehead duo. Instead, the place had been invaded by scores of mallard ducks, all quacking, preening, bathing, and generally shuffling about. It sounded like a city park. We wondered where they had been in the cold weather; perhaps farther out on the lake, perhaps taking shelter in the nearby woodland and other protected spots on land.
They weren’t all mallards, though. There were several American black ducks among them. The two species are very similar in shape and size, but both sexes of the American black duck are a dull dark brown. Although we can distinguish the mallard and black duck readily, they get confused and hybrids are not uncommon.
We continued scanning the lake. There were lots of small ducks marked with white cheeks extending all the way forward to the beak and a dark cap. Some individuals had a narrow tail of stiff feathers that were stuck up, as if courtesy of hair spray. That made them stiff-tailed ducks, and the ruddy duck is the only plausible stiff-tail in our region. Each bird would be here one moment and then, with the flick of the bill, it would dive down and bob back up like a cork a bit farther along. It is said that the ruddy duck is a supreme diver among ducks. Just before it goes down, it breathes out (yes, breathes out; I would breathe in before diving), tucks its wings and all its feathers close to its body, and then pushes itself forward and down with its legs and outsized feet positioned far back on the body. As is general for diving ducks (but unlike penguins), the ruddy duck doesn’t use its wings for swimming.
The ruddy duck is another of the duck species that are described as being found here only on migration from the Great Lakes, where they breed, to the Carolinas and south for the winter. Nevertheless, here were some tens of them making a midwinter visit to our lake during the complex shift in weather conditions.
I find a special pleasure in watching ruddy ducks in their natural habitat. They have a bad reputation in Europe where, after their accidental release during the 1950s, they expanded dramatically and took a liking to mating with the related but rare white-headed duck. As a result, there have been large-scale efforts to cull the ruddy duck and hybrids in the UK and other European countries. At the millennium, there were an estimated six thousand ruddy ducks in the UK, and the number now is between ten and fifteen, at an estimated cost to the taxpayer of 3,000 GBP per bird killed. All sightings of the ruddy duck are required to be reported so any remaining birds can be eliminated. There was a problem, though. Not everyone was happy about this cold-blooded slaughter of ducks, and total extirpation of the ruddy duck may prove to be a difficult task.
Whatever you think of ruddy ducks on the other side of the Atlantic, it is worth a moment to pause and appreciate the fact that there were probably more of them bobbing around the southern end of Cayuga Lake this week than in the entire British Isles. And let’s take a second moment to wonder how long they will be there. For sure, they will move on before long, taken by the power of their wings and the winds to . . . who knows where?