Wild Columbine (Aquilegia canadensis) is in full flower, and its design and color beckon to a recently-returned migrant that is attracted to red as well as tubular flowers – the Ruby-throated Hummingbird. Not only does the flowering of Wild Columbine coincide with the arrival of hummingbirds in May, but the ranges of these two species are much the same. Wild Columbine’s five petals are in the shape of spurs, the tips of which contain nectar. Only hummingbirds and long-tongued bees can reach the nectar, and thus are its primary pollinators (there is a short-tongued bumblebee that tears open the tip of the spur in order to reach the nectar). While the hummingbird hovers beneath the flower and drinks nectar, its head rubs against Columbine’s long anthers, and the resulting pollen on the hummingbird’s head is brushed off onto the long styles of the next (Columbine) flower it visits, thereby pollinating it.
Looking as if it were stuck to the vertical cliff wall by crazy glue, a raven’s nest is often used for several years in a row. The nestlings remain in the nest for about 5 to 7 weeks, during which time they go from being an orange/pink color, sparsely covered with gray down, to the black plumage of an adult. The pictured nestlings are approximately five weeks old, and have just started to exercise their wing muscles in preparation for their first flight. They are panting with open beaks in an attempt to dissipate the heat of an unrelenting May sun. Within a week or two they will leave the nest, but will stay nearby for a few days. I couldn’t get close enough to give this nest a smell test, but supposedly raven nests can have an unbelievably unpleasant odor (due to the remains of leftover food/ carrion and feces).
This is the time of year when it pays to watch where you walk – there are a number of ground nesting birds, some of which, including killdeer, may choose your lawn or even your garden to build their simple “scrape” nest. Typically killdeer nest on the shoulders of roads, gravel roof tops, fields and gravel parking lots. The nest is very primitive, and there’s actually very little to it — killdeer scrape a slight depression in the ground, to which they often add bits of material, including white objects such as shells and bones. Their pigmented eggs are extremely well camouflaged. The young precocial killdeer chicks are on their feet and feeding themselves as soon as their down feathers dry. (Photo by Sadie Richards)
Although the common grackle, a member of the blackbird family, is the bane of many corn growers as well as a threat to songbirds trying to raise young (grackles eat other birds’ eggs and nestlings), it is quite a colorful bird, with its pale yellow eyes and iridescent purple plumage. Grackles have already begun nesting and defending their territory, as can be seen from the stance of the bird in this image. This “bill-up display” is a position assumed when a male is being approached on its territory by another male. It moves its head upwards so that its bill is almost vertical, signaling to the approaching grackle that it would be in its best interest to depart.
In the fall and winter, fruit makes up about 90% of an American robin’s diet. In the spring, only 10% of a robin’s diet consists of fruit; invertebrates make up the remaining 90%. (Summer is a fairly even mixture of both.) At this time of year, earthworms are a popular food item with robins. Watching a robin foraging for a worm can make you wonder whether the robin is using its ears or its eyes to locate the worm. It turns out that most worms are seen, not heard, by robins. Because the sound of worms burrowing in the soil is of low intensity, they usually cannot be heard by robins because of background noise. Using sight, not sound, the robin first aims one eye toward a spot on the ground in front of it, and after holding this position for a few seconds, rotates its head and draws a bead with its other eye on the same spot– an earthworm in its burrow. The robin then quickly thrusts its bill into the burrow in an attempt to get its next meal.
This week those of us in the Northeast have been inundated with dark-eyed juncos, often referred to as “snow birds” due to their presence in much of the U.S. only during the winter months. Although this member of the sparrow family breeds here and is found year-round in New England, over most of the eastern U.S. juncos appear as winter sets in and then retreat northward each spring. Many of the juncos that we are seeing now are transitory migrants on their way to Canada and the Arctic to their breeding grounds. They will remain there until next fall, when we will experience a similar influx. Research has found that males migrate earlier than females, and that females tend to migrate further south than males. The timing of this migration is regulated primarily by the lengthening spring days.
Common ravens are known for their aerial acrobatics, often doing rolls and somersaults and other amazing tricks. According to Cornell Lab of Ornithology, one bird was seen flying upside down for more than a half-mile. Young birds are fond of playing games with sticks, repeatedly dropping them and then diving to catch them in mid-air. The pictured raven, however, was much too busy to be doing cartwheels in the sky. It has a nest with eggs nearby, and during its morning patrol encountered a red-tailed hawk which it drove out of sight in a matter of seconds. Although small mammals make up most of a red-tail’s diet, they are known to also prey on smaller birds, including defenseless nestlings, which the ravens will have in the next few weeks. (Because of the angle, the 24-inch-long, 53-inch-wingspread raven looks disproportionally larger than the 19-inch-long, 49-inch wingspread red-tail.)
With winter temperatures still upon us, it can be challenging to find signs of spring in the hills of Vermont. However, subtle signs do exist if you know where to look! Notice the fresh greenery in this nest – it confirms that recent refurbishing has taken place by returning red-shouldered hawks. Roughly two feet in diameter, a red-shouldered hawk’s stick nest is lined with moss, lichen, bark and conifer sprigs. Other items that have been used as building material for these raptors include ears of corn, corncobs, corn husks, tissue paper, nests of songbirds, straw, mullein, leaves, twine, various deciduous tree leaves, entire plants, dried tent caterpillar webs and plastic grocery bags. The pictured nest will serve as a nursery for two to five red-shouldered hawk chicks in about a month’s time, and as the nesting season progresses, sprays of conifers such as the hemlock sprigs you see here will continue to be added.
It’s been my life’s dream to witness the fledging of young wood ducks from their tree cavity nest in response to their mother’s calls below – perhaps this will be the year! Adult wood ducks have recently returned to northern New England, having already formed mating pairs. They now proceed to perform a number of courtship displays which enable them to maintain this pair bond. The most common display involves the male’s turning the back of his head towards the female as he swims in front of her while holding his wings and tail high. Chin-lifting, feather-shaking, wing-preening, neck-stretching and bill-jerking are just some of the displays that occur during wood duck courtship.
Common mergansers can be seen year round in northern New England, but in the spring their numbers peak around the first week in April, due to the large number of birds that wintered further south and are migrating to Canadian nesting grounds. These birds are fish eaters, known to consume at least 50 species which they easily grasp with their bill due to the sharp projections along its edges. Egg-laying is still a couple of months away, but coveted tree cavities where they nest are being scoped out. (female common merganser on left, male on right)
It’s well known that owls have an acute sense of hearing — some species, such as the barn owl, hunt nocturnally by sound alone. An owl’s asymmetrically-placed ears are located beneath the feathers at the edge of its facial discs. This placement, along with the shape of the external ear canals, is thought to contribute to an owl’s keen ability to locate sound. The flesh-colored fold of skin that you see in front of this barred owl’s ear is movable, and reflects and concentrates sound waves coming from behind the bird.
The most prominent courtship behavior of male wild turkeys (toms) consists of two displays: gobbling and strutting. Both begin in late February in northern New England, before the females (hens) are receptive, but by late March the males begin to reap the fruits of their labor. The gobbling of the males attracts females or competing males over considerable distances. The tom turkey begins to “strut” only after a hen appears. While strutting, he fans his tail, lowers his wings with the primaries dragging on the ground/snow, elevates the feathers on his back and throws his head backward as he appears to glide around a female. If she is receptive, she assumes a “sexual crouch” on the ground, signaling to the male that he may mount her. (Thanks to Chiho Kaneko for this photograph.)
A cooper’s hawk made short work of a mourning dove near my bird feeder recently, killing and apparently, given the large number of feathers scattered on the snow, plucking the dove on a nearby snow bank. If you look closely you can see whole sunflower seeds in amongst the feathers. These came from inside the mourning dove’s crop. Mourning doves generally feed quickly, filling their crop with seeds which they digest later, when they’ve found a safe spot in which to roost. Unfortunately for this particular dove, it didn’t live long enough to have that opportunity.
Male red-winged blackbirds have returned to Vermont, and their most notable features are the brightly-colored reddish-orange feathers on their “shoulders”, referred to as epaulettes. In the military, an epaulette is a shoulder ornament that indicates, through its position, color, length and diameter, the bearer’s rank. Some birds, including male redwings, also possess this badge, or visual cue, which indicates the social status of the bird to other birds of the same species. Studies of male red-winged blackbirds and their epaulettes indicate (through dyeing their bright orange/red shoulder patches black) that epaulettes play a significant role in the male’s defense of his territory. Over 60% of the redwings that had their epaulettes dyed black lost their territories to other males. Further research revealed that aggression by a territorial male redwing is proportional to the epaulette size of the encroaching male redwing. It also indicated that male redwings intruding into redwing-occupied territories greatly limit the exposure of their epaulettes by covering them with black feathers. (Female red-winged blackbird plumage is brown and lacks epaulettes.)
If you find clumps of empty burdock fruits lying on top of the snow, there may well be wild turkeys in the area. During the winter, especially when the snow pack is deep, wild turkeys feed on vegetation poking up above the surface of the snow, such as burdock seeds. There are tell-tail signs when turkeys have been eating burdock, even if no tracks are evident, because of the way in which they consume the seeds. Turkeys somehow pluck the burdock fruits off and then turn them inside-out, exposing the seeds which they then eat. Typically several of these empty fruits will be “velcroed” together, leaving small bunches of them scattered over the snow.
They may not be sweet, plump and juicy, but the fruits of staghorn sumac play a crucial role in the lives of many birds that overwinter in New England. True, they’re not a preferred food for these birds, but because they persist through the winter, these fuzzy fruits are an important source of food in late winter and early spring, when very little else is available. Ruffed grouse and wild turkeys rely on sumac fruit as a source of food throughout the winter, and bluebirds, robins, cardinals, mockingbirds and starlings are frequent visitors to staghorn sumac shrubs this time of year.
Bohemian waxwings breed in Alaska and northwest Canada, but are known for their tendency to move south in the winter when their winter diet of fruit becomes scarce. These irruptions can occur in huge numbers – thousands of birds, in some cases. Their name reflects their nomadic tendency (much like gypsies, or bohemians) and their unpredictable migration patterns. Mountain ash, juniper, cedar and holly berries are among their favorite foods, and typically they will stay in an area with an abundant food source until that food is stripped before moving on. Like their relatives, cedar waxwings, with whom they often flock, they are susceptible to alcohol intoxication, and even death, from eating fermented fruit. Someone I know who was unaware of this phenomenon was alarmed when she observed a number of waxwings lying on the ground outside her house, looking for all the world as if they were dead. To her great relief (and disbelief), an hour or two later the ground was bare, the inebriated birds having sobered up and departed.
Winter must be on the wane, as a tufted titmouse was recently singing its fast-repeated, clear whistle song, “Peter—Peter—Peter,” in nearby woods. Male titmice repeat this phrase over and over, up to 11 times in succession. Occasionally females sing a softer version of this song. The calls of tufted titmice, on the other hand, are very nasal and mechanical-sounding. Songs are typically more musical and complex than calls, and are often sung only by males during the breeding season, to attract a mate and claim territory. Calls, on the other hand, have many purposes – there are calls for aggression, warning, identification, flocking, hunger and to announce a food source, among others.
Raucous crow and raven calls alerted me to the fact that something, most likely a bird of prey, was in the area (crows and ravens often mob and harass hawks and owls). Through the trees I got a glimpse of a raven flying beside another bird that dwarfed the raven. Soon there were two of these large birds, dipping and diving in the wind, seemingly enjoying themselves no end. They turned out to be juvenile bald eagles, last year’s young. Perhaps they were practicing for the acrobatic courtship flight displays they’ll be performing in three or four years.
A pileated woodpecker’s diet often shifts with the seasons. One study found that the primary food of these woodpeckers was fruit in fall, carpenter ants in winter, wood-boring beetle larvae in early spring, and a variety of insects in summer. During the winter, with the help of its impressive beak, the woodpecker pries off long slivers of wood from trees containing carpenter ants and exposes the ant galleries. It then uses its long, pointed, barbed tongue and its sticky saliva to catch and extract ants from the ant tunnels inside the tree. This winter diet can be confirmed by examining the contents of a pileated woodpecker’s droppings. Finding these droppings is simply a matter of locating a tree that has a considerable pile of wood chips at the base, indicating that a pileated woodpecker has spent a lot of time working on the tree – long enough to have deposited droppings in and amongst the chips. The droppings crumble easily and reveal a multitude of tiny, black, shiny carpenter ant body parts. (The whitewashed end is due to uric acid.)
Winter provides an opportunity to get a close look at last year’s bird nests to see who might have been nesting under our very noses without divulging their presence (Peterson’s Field Guide to Bird Nests is a great resource). A walk near wetlands in winter often reveals a yellow warbler nest. It is quite easy to recognize as it is lined with downy plant fibers and is fairly thick-walled. Yellow warblers are often victims of brown-headed cowbirds, which lay their eggs in other birds’ nests and therefore avoid the labor of raising their own chicks. Many birds don’t recognize a cowbird’s egg, and incubate it and raise the young cowbird chick as their own. Yellow warblers, however, can distinguish between their eggs and a cowbird’s. Upon returning to her nest and finding a cowbird egg (often laid before the host bird begins laying her eggs), the female yellow warbler simply builds another nest right on top of the nest containing the cowbird egg, and begins anew. As many as six stories of nests have been found with cowbird eggs buried in each layer.
A trail of ruffed grouse tracks in the snow led me to the spot where two grouse had bedded down for the night behind a fallen tree. With snow too shallow to burrow into, this was as protected a location as they could find. More often than not, a grouse defecates in its night roosting site before leaving in the morning. Grouse scat comes in two forms, one a dry, fibrous cylindrical pellet with a white-wash of uric acid at one end, and the other a softer, darker brown plop. The vast majority of a grouse’s diet (buds, twigs, leaves, catkins) goes directly through its digestive system and forms the dry, courser scat. Finer (and more nutritious) material such as the cambium layer of woody plants enters the caeca, two specialized pouches, before passing through the large intestine. The caeca contain bacteria which break down cellulose and produce the more digested, and therefore more liquefied, scat. Sometimes the two kinds of scat are deposited separately and sometimes, as in the bed on the right in the photograph, together. (Thanks to Dr. Alcott Smith who clarified grouse digestion for me.)
If the majority of your diet consisted of one type of food, and that food was concentrated in certain spots, it would make sense to frequent those spots. Bird-eating predators, such as the sharp-shinned hawk, are frequently seen at bird feeders for this very reason. Although not very large — roughly the size of a blue jay (the female is a third again larger than the male) — this accipiter is a formidable predator, and one which causes feeder visitors to either disappear or become motionless for a considerable amount of time. The sharp-shinned hawk is the smallest hawk in North America and derives its common name from the sharp-edged “shin” on the lower part of its legs. Its long tail and short wings make it extremely adept at flying through dense woods in search of small birds.