Hooded Mergansers Returning To Nest
Hooded mergansers are present in most of the Northeast year round where there is open water, but many move south and southwest in winter. Some actually migrate north to spend winters in the Great Lakes and southern Canada. Their numbers swell in March and April, when migrants are passing through as well as returning. Often within days of when the ice goes out, this smallest (and arguably the most beautiful) of the three North American merganser species appears.
The courtship ritual of hooded mergansers takes place in groups of one or more females and several males. The males raise their crests, expanding the white patch, and engage in behavior known as head-throwing. They jerk their heads backwards until it touches their backs, while giving a frog-like croak. Females court by bobbing their heads and giving a hoarse quack.
Female breeding hooded mergansers select suitable cavities in both live and dead trees in which to nest. Stumps and snags near or in forested wetlands are their preferred nesting sites. Nest boxes are also used by this species, with those over or near water being the most sought after. After a month or a little more, the eggs hatch and downy, day-old chicks jump to the water (or ground) below, in response to their mother’s vocal urging.
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Wolf Spiders Active
Wolf spiders can already be seen scurrying around fields, active after a long winter’s nap deep inside tussocks of grass where they stay until the temperature begins to rise. Some are tiny and black, while others, such as the pictured wolf spider, are larger (1 ½”) and a shade of brown. These spiders hibernate in the winter, but other species have different survival strategies. Some, like the black-and-yellow argiope, or garden spider, only live one season and die during late fall or winter, leaving behind their egg sac for next season. Many of the more active species that hunt prey rather than trap it in a web, spend the winter as nymphs, or juveniles, becoming full grown in the spring or early summer. In several species of spiders, young spiderlings hatch out in the fall and then remain in a communal egg sac through the winter.
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Wood Frogs & Spring Peepers On The Move
Although the temperature hovered around 32°F. last night in central Vermont, wood frogs and spring peepers were on the move. Usually it is above 40° or 45° before you see the earliest of our breeding amphibians, but a few hardy souls ventured forth to their breeding pools and ponds under cover of darkness and rain yesterday. Those that breed in vernal pools are in a hurry to take advantage of every day, as the eggs they lay must complete metamorphosis by the time their pool dries up, often in mid- to late summer.
Both of these species of frogs are freeze tolerant. Wood frogs are coming out of a state in which they haven’t taken a breath and their heart hasn’t beaten for several months. Prior to hibernation they convert glycogen in their bodies into glucose, a form of antifreeze that helps prevent the water within their cells from freezing, which would kill them. However, the water outside their cells does freeze. Amazingly, wood frogs can survive having up to 65% of this water frozen, yet when warm weather arrives, they thaw and move about in a matter of hours.
If you rescue these woodland amphibians that are crossing roads (where so many of them get run over at night) during their migration to their breeding pools, take note of the temperature of their body. Often they are still quite cold to the touch — colder than the air, even – which fortunately makes it difficult for them to move fast enough to escape your helping hands. (Photo: Amorous wood frogs getting a head start as they cross a road to get to breeding pool.)
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Buffleheads Migrating
There is so much to love about Buffleheads. First and foremost, they are almost exclusively monogamous – one of the few ducks that often keeps the same mate for several years. They are relatively tiny – our smallest “diving” duck. (Ducks are divided into “diving” and “dabbling” ducks, according to their method of feeding.) So small are they that these cavity-nesting birds can fit in and often choose Northern Flicker holes in which to raise their young. We typically only see them during their nocturnal spring and fall migration to and from their breeding grounds in the boreal forests of western Canada and Alaska, when they rest and refuel on ponds and lakes during the day. If you chance upon a pair when the sun is out, be sure to notice the striking purple and green iridescent head feathers of the male (on right).
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Nest Box Residents : Out With The Old, In With the New
In order to prevent disease or the passing on of parasites, it is a good idea to clean out nest boxes after they’ve been occupied. In the fall, after the last brood of eastern bluebirds or tree swallows has flown the coop, many nest box owners often clean them out in preparation for the next summer’s residents, but some wait until spring. This habit of waiting provides white-footed and deer mice (and occasionally flying squirrels) with a ready-made winter shelter and/or larder.
Feathers incorporated into the pictured grass nest indicate that tree swallows once occupied this nest box. After the last of the avian nestlings had fledged, mice moved into the box. After constructing a roof over the nest, the mice succeeded in renovating the former bird nursery into a winter mouse house. The remaining space inside the box served as a larder for nearby high-bush cranberries.
Unfortunately for the mice, but fortunately for the swallows or bluebirds that will reside here this summer, the responsible nest box owner dutifully cleaned out the nest box this spring, in accordance with avian-mammalian timeshare policies. (Thanks to Jim Lafley for the use of his photo.)
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Ice Pancakes
I was amazed at the familiarity many Naturally Curious readers have with “ice pancakes!” For those of you who, like myself, may not be familiar with these creations, these formations are essentially frozen foam.
Ice pancakes usually form on ocean water or lakes around the Arctic Circle where the movement of water keeps the ice from forming a flat sheet. Small needle-like crystals called frazil crystals rise to the surface of very cold water and accumulate together. In calm water these typically form a greasy film that freezes into a flat surface ice. However, in rough or choppy water, these crystals congeal together into slushy circular disks. As these disks bump into each other and are buffed by the water, they develop ridges and raised edges, giving them a distinctive dinner plate appearance. In the polar seas these can sometime have a thickness of close to 4 inches and diameter of between 12 inches and 9 feet. Eventually the plates fuse together to form consolidated sea ice that can have ridges that are up to 60 feet thick. In northern freshwater rivers, pancakes can accumulate downstream of faster water that is thought to have created foam, that then froze. (Thanks to Jim Moul for the use of his photograph of New Hampshire ice pancakes.)
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Mystery Photo
Do you know what the white objects are? Photo (by Reuben Rajala) taken along the Androscoggin River in Gorham, NH recently.
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Ruffed Grouse Drumming
A majority of male passerines, or perching birds (also called songbirds) claim territories and secure mates through song. With the help of a syrinx, or voice box, musical notes, some more complex than others, are created. There are species of birds in different orders that use other parts of their bodies for territorial and courtship displays, among them ruffed grouse (wings), American woodcock (wings) and Wilson’s snipe (tail).
Male ruffed grouse, also known as partridge, are aggressively territorial throughout their adult lives, defending roughly 6-10 acres of woodland which is usually shared with one or two hens. The male grouse claims his property by engaging in a “drumming” display during which he creates a sound reminiscent of a lawn mower starting up. This sound is made by the male beating his wings against the air to create a vacuum, as lightning does when it makes thunder. The drummer usually stands on a log, stone or mound of dirt roughly 10-12 inches above the ground when drumming and this substrate is called a “drumming log.” He does not strike the log to make the noise, he only uses the drumming log as a stage for his display.
Grouse occasionally drum in the summer and fall, but in the spring, drumming becomes more frequent and prolonged as the male advertises his location to hens seeking a mate. This phenomenon is heard but rarely seen by humans; Lang Elliott has captured both the sight and sound of a ruffed grouse drumming in this extraordinary video: http://langelliott.com/mary-holland/ruffed-grouse/ (Sound recording © Lang Elliott – langelliott.com)
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Painted Turtles Basking
Being an aquatic species, most painted turtles hibernate in the mud at the bottom of ponds. They dig down as far as ten feet where they spend the winter hovering around 43°. In the spring, when the temperature of the water approaches 60°, painted turtles begin actively foraging, but the first priority upon awakening is to warm up their bodies. Turtles are ectothermic, or cold-blooded, thus the temperature of their bodies is determined by the environment that surrounds them. To be active, painted turtles must maintain an internal temperature of 63°- 73°. They reach and maintain this temperature by basking in the sun, particularly in the cold, first weeks of spring. Once warmed up, the turtles will forage, and when they begin to cool off, basking resumes.
Competition for basking sites such as floating logs and rocks can be fierce. It is not unusual to see many painted turtles lined up on a floating log, or turtles piled one upon the other on a rock in an effort to maximize the effect of the sun’s rays. The heat they’re obtaining increases their metabolism, aids in digestion and allows males to start producing sperm. The sun also strengthens their shells and reduces the amount of algae on them, thereby reducing the chances of bacterial or fungal infection.
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Brown Creepers Singing
The high, thin notes of the brown creeper’s song are one of the first avian signs of spring. Their delicate “tinkling” song is sung only by males on their breeding grounds, most often during territory establishment. Specifically, males sing more often before and during nest construction than during egg laying, incubation, and the nestling period. Singing activity increases again after young have fledged.
At this time of year, when there are relatively few other birds songs, the brown creeper’s song stands out, although it is so high-pitched some people have trouble hearing it. In mixed-deciduous forest, a brown creeper’s song is audible up to 400 feet away, a bit farther than the length of a football field. In addition to this song, several calls are given by both male and female creepers throughout the year. To hear the brown creeper’s song (thought by some to resemble the words, “trees, beautiful trees”) go to http://langelliott.com/mary-holland/brown-creeper/ (Sound recording © Lang Elliott – langelliott.com)
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Beavers Seeking Herbaceous Plants
A recent light snow provided an opportunity to confirm that northern New England beavers have gained access to land and are seeing the sun for the first time in several months. They, along with any beavers living north of the 39th parallel, may well reap some benefit from the change in our climate. Further south, there is no real winter and beavers do not have to cope with a limited amount of stored food for there is usually no ice on ponds. Milder winters and early springs mean more time for Northeastern beavers to access herbaceous food and fresh bark, and less time locked under the ice.
Unbeknownst to many, a large portion of a beaver’s spring, summer, and fall diet consists of herbaceous food – grasses, sedges, ferns, fungi, berries, mushrooms, duckweed and even algae. When beavers first leave their ponds in the spring, one of the first foods they head for is skunk cabbage, as it is one of the earliest flowering plants to emerge (often when snow is still on the ground). Beavers also relish the new foliage of aspen, willow and alders. When they are accessible, the rhizomes, leaves and flowers of both yellow and white pond lilies are favorite foods. Come late fall, when lush greenery has disappeared, beavers up their intake of bark (cambium) and store a pile of branches on the bottom of the pond close to their lodge, where they have underwater access to it all winter.
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Bald Eagles Turning Eggs
Bald eagles are on their nests, incubating their one-to-three eggs. Although there isn’t much activity at this point, what activity there is, is extremely important to the survival of the embryos inside the eggs. Maintaining the temperature of the eggs is crucial. Bald eagles must incubate their eggs for 35 days. During this time, the eggs must remain at a steady temperature of 99.5 degrees Fahrenheit. If the incubating parent is frightened away from the nest or leaves the nest even very briefly, the egg may become too cold or too hot, depending on the weather.
During the entire incubation period, the eagle parents continuously turn the eggs with their feet and beak. The main function of this action is to prevent the embryos from sticking to the inside of the egg shell. In the early days of incubation, it’s important that the embryo floats inside the egg while the membranes that support its life are growing and developing. Turning optimizes membrane growth. Eventually the membranes will be pressed to each other and to the shell. If these membranes adhere too soon the chick will not be able to move into the hatching position later and get out of the egg. To see a nesting bald eagle turning eggs, go to http://www.eagles.org/dceaglecam/.
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Woolly Bears Wandering
Woolly bears (larvae of the Isabella tiger moth) are on the march again- several weeks before I have seen them in past years, no doubt due to the warm weather we’ve experienced lately. They are one of the few moths or butterflies that overwinter as caterpillars. In the fall, often around the time of the first frost in the Northeast, woolly bears are often seen crossing roads as they wander frenetically prior to hibernation. At this time their body produces a chemical called a cryoprotectant that acts like an anti-freeze which protects living tissue against damage from freezing and thawing. They remain curled up in a protected spot, such as in leaf litter or under loose bark, nearly frozen solid all winter. When spring arrives and the temperature reaches the high 40’s and 50’s they become active again, feed for a few days, and then pupate inside a cocoon made with their own bristles. Adult Isabella tiger moths emerge in about a month, anywhere between April and June, mate, and lay eggs. Within two weeks the eggs hatch. In New England a second generation of woolly bears will be produced and these are the larvae that overwinter. (In even colder regions, such as the Arctic, there isn’t enough time for woolly bear caterpillars to consume enough food to achieve adulthood within a year, so they spend several summers feeding, hibernating each winter, for up to 14 years.)
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Connecting Young Children with Nature
With spring about to burst, it’s the perfect time to introduce your infant or toddler grandchild, son, daughter, niece, nephew or young friend to the great outdoors. A child is never too young to encounter nature — in fact, the younger the better! According to the National Association for the Education of Young Children (NAEYC), recent studies document the importance of introducing children to the natural world, beginning in the early years. The development of their social, emotional, and physical health depends on this exposure.
If you can’t get your infant or toddler into nature, bring nature to them! It’s well known how children observe, listen, feel, taste, and take apart any and everything they encounter in an effort to become more acquainted with it. A very young child, presented with anything from a leaf to a pine cone to a snake skin (or the tail end of a snake) will engage his or her innate curiosity. Infants and toddlers do not associate nature, be it a fuzzy caterpillar, a slimy frog or a honey bee visiting a flower, with fear. Quite the opposite. Connecting young children with nature is a golden opportunity to foster curiosity and appreciation for this amazing natural world of ours. (Photo: Otis Brown investigating a red oak leaf.)
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Early Arrival Dates & Climate Change
As yesterday’s post indicated, the progression in which signs of spring appear remains much the same, but the timing of this progression is changing. Ornithologists have determined that modern climate change has resulted in an advancement of spring phenology throughout the Northern Hemisphere.
Many birds are arriving on their breeding grounds earlier in response to these changing conditions. Past research has focused on correlating climatic changes on breeding grounds with early arrival. However, it appears that climate variability on the wintering grounds of temperate species also plays a part in these short-distance migrants’ arrival on their breeding grounds.
Many climatic factors are involved in this phenomenon. The annual variation in temperature on the wintering grounds of American robins was found to be strongly related to their first-arrival date. Red-winged blackbirds’ first arrival dates were most influenced by precipitation during winter and spring months.
These and other changes in migratory patterns can have life or death consequences — birds arriving early on their breeding grounds face the possibility of adverse conditions and limited resources.
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Sequential Signs of Spring
Most of the spring signs we’ve started to see have feathers on them – eastern bluebirds, common grackles, turkey vultures, killdeer, American woodcock, eastern phoebes – but there are others, as well. Eastern chipmunks are active and black bears have been sighted. New sounds as well as sights are greeting our ears: woodpeckers are drumming, saw-whet owls are calling and tufted titmice are singing. Sap has started to run and buds are soon to swell. Seasons, such as the winter we’ve just experienced, are subject to more and more dramatic changes but the relatively consistent and orderly fashion in which spring always announces itself is reassuring as well as exhilarating.
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First Killdeer Returning to Northeastern Breeding Grounds
Killdeer that breed in the southern half of the U.S. are year round residents, and do not migrate, but in the northern half of the U.S. killdeer are migratory. Their wintering range extends across the southern tier of states, through Mexico and the Caribbean and along the coastal regions of western South America (Columbia, Venezuela, Ecuador and Peru). Killdeer that breed in the Northeast overwinter in Gulf and southern states that border the Atlantic Ocean.
The first returning killdeer have been sighted in Vermont. While the spring migration of killdeer is early, it is also prolonged, peaking in late March or early April in New England. Killdeer migrate during the day as well as at night, in flocks of 6-30 birds. When they stop to rest and/or forage, the birds typically do not go within 13 to 20 feet of each other, and are met with aggression from other flock members if they do. Once on their breeding grounds, killdeer are even less tolerant of each other. The courtship behavior in one pair often elicits aggressive behavior from neighboring pairs.
Now is the time to keep ears and eyes open for this inland-nesting shorebird. Corn fields, lawns and parking lots are a good place to start. For a perfect example of onomatopoeia, listen to Lang Elliott’s killdeer recording: http://www.langelliott.com/mary-holland/killdeer/ (Sound recording © Lang Elliott – langelliott.com)
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Determining An Eastern Chipmunk’s Gender
Ordinarily, one can’t tell a male from a female eastern chipmunk as they look identical –but there are two times during the year when it is possible, with luck and good eyesight, to tell one from the other. One is right now, in the early spring, when chipmunks first emerge from their underground burrows. Male chipmunks appear first, followed by females one or two weeks later. The first of two breeding seasons is beginning for chipmunks. Upon emerging, the males’ testicles descend, making the males distinguishable from the females. Their scrotal sac is covered with whitish-gray fur; the darker the fur the more mature the chipmunk is.
During their breeding season, males travel outside of their home ranges, often some distance, to locate females and check on their reproductive condition. The females chase and wrestle with the males to see who can keep up with them. When a female comes into estrus (the end of February/ beginning of March) she chooses her mate. The chosen male flicks his tail vertically and screams prior to copulation (another way to distinguish the sexes). After the first mating season, the testicles ascend until the second breeding season in middle to late summer, when the chance to determine the gender of chipmunks once again presents itself.
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Mixed Emotions Greet Returning Common Grackles
The first common grackles of the year have been sighted — not something to be celebrated by all, for there is a lot to dislike about common grackles. They are among the most significant agricultural pest species in North America, causing millions of dollars in damage to sprouting corn. They also eat other birds’ eggs and nestlings, and occasionally kill and consume adult birds. However, one has to admire the intelligence that some of these actions plus others reflect.
These members of the icterid, or blackbird, family have learned to follow plows in order to consume the invertebrates and mice that are exposed. Grackles engage in “anting” – letting ants crawl all over their bodies in order for the ants to secrete formic acid which may then rid the grackles of parasites. They rotate acorns between their mandibles, utilizing a ridge inside their mouths to open the acorns. And at least one common grackle was crafty enough to live for 23 years before being killed by a bird of prey – an extraordinarily long life for a passerine, or perching, bird.
Regardless of how we regard any one species, the phenomenon of spring migration and the remarkable birds that survive its rigors every year are cause for celebration.
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Puzzling Kill Site
Close examination of the bits of fur scattered over a 15-inch-diameter patch of snow reveals that the animal to whom the fur belonged was very small and would have appeared brown to an observer. (The hairs are black, but they have a brown tip.) This eliminates gray/black shrews and moles, leaving a white-footed mouse (due to habitat) or a species of vole (most likely meadow vole) as the victim. Striped skunk tracks led to the remains of this rodent, which is not surprising, as mice (Peromyscus sp.) and voles (Microtus sp.) are high on their list of preferred vertebrates. What is puzzling is why the fur wasn’t consumed and why so many of the internal organs (top of photo) were among the discarded fur. A skunk would neither skin nor eviscerate its prey. Explanations welcome!
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Carrion a Vital Food Source for Bald Eagles
Eagles obtain food mainly in three ways — by direct capture, scavenging for carrion and stealing food from other birds and mammals. When securing their own live prey, they hunt from perches or soar over suitable habitat, taking most prey on the wing. Bald eagles’ preferred food is live fish, but they are opportunistic foragers that select prey based on availability. Twenty studies from across their range found that the composition of bald eagle diets averaged the following: fish-56%; birds-28%; mammals-14%; and other 2%.
In addition to capturing live prey, eagles rely heavily on fish, bird and mammal carrion, especially during the winter. Ice fishermen’s leftover bait and/or rejected catches, roadkills and deer that have slipped and died on ice-covered ponds and lakes are three heavily-used sources of food at this time of year. If the carrion is small enough, it is often carried to a perch (see opossum in photo) where it is inconspicuously consumed. Larger carrion, such as white-tailed deer, salmon and waterfowl, that are too big to carry off, are eaten on site and repeatedly visited until consumed.
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