An online resource based on the award-winning nature guide

November

A Vagrant Brant

12-1-17 pale-bellied brant 049A7777Brants are small geese that travel long distances (up to 3,000 miles) several thousand feet up in the air between their Arctic breeding grounds and their coastal wintering grounds. No other species of goose nests as far north, and few migrate as far. The subspecies that overwinters off the middle of the East Coast, the Atlantic or Pale-bellied Brant, typically migrates from northern Canada to James Bay, where it remains for several weeks building up fat reserves. From there most birds fly nonstop to their wintering grounds in Jamaica Bay and other nearby estuaries of greater NYC and New Jersey, arriving in late October and early November.

Occasionally migrating birds, often juveniles, veer a bit off course (often due to weather-related causes) and end up where they don’t belong. Brants are common winter residents in coastal areas during the winter, but are not often seen far from salt water. This fall a lone juvenile vagrant Pale-bellied Brant appeared one day on the shore of a lake in central Vermont, giving inlanders the opportunity to view a Brant up close. While adult birds have a very sophisticated mechanism for plotting their migration from one point to another and for getting back on course if they are displaced because of weather, first-year birds often lack this skill.

Had this Brant been blown off course in this manner 75 years ago, there would have been concern for its survival, as Brants used to feed almost exclusively on intertidal seagrass during the non-breeding season. However, in the 1930’s a disease devastated eelgrass and consequently the Brant population dropped. Brants that survived adapted to an alternative diet which included sea lettuce, saltmarsh grass and lawn grass, making it possible for a 21st century Brant to exist just fine in the interior of New England, at least long enough to refuel before continuing on its way.

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The Architecture of a Bald-faced Hornet Nest

11-29-17 hornet nest 049A8063The exterior of a Bald-faced Hornet nest consists of an outer envelope of paper that is made up of a myriad of horizonal stripes of chewed up wood fibers that have been mixed with hornet saliva. Each stripe represents a single hornet’s contribution. The different colors represent different sources of wood. This outer envelope is only one of several (up to 12 or more) that serve to insulate the innermost, active part of the nest.

Inside these outer sheets are three or four horizontal tiers of hexagonal cells in which eggs are laid and brood are raised. Access from one level to another is at the periphery of the tiers, just inside the shell. The queen begins the nest, building a few cells and raising female workers that then take over the cell-building while the queen continues to lay eggs. As the number of hornets increases, so does the number of cells they build, and as a result the tiers become wider and wider. When space runs out, the hornets remove one or more of the innermost layers of insulating paper that form the envelope, while constructing new sheets on the outside. The nest continues to grow in this fashion until the queen’s egg-laying slows down at the end of the season.

The construction of these tiers of cells takes place upside down in total darkness, which is, in itself, quite a feat. When they are constructing a cell, the hornets keep one antenna inside the cell and the other on the outside. By monitoring the distance between the two antennae tips they can judge thickness of the wall. They do a similar thing with their mandibles, with one on each side of the wall, in order to straighten the cell walls and squeeze the pulp flat to remove water.

If the cells were built sideways or upwards they would require constant attention from the hornets until they dried in order to prevent them from sagging. Given that the cells are downward-facing, one might wonder why the hornet larvae don’t fall out. Water has a great affinity for uncoated paper (think of paper towels sucking up water against the pull of gravity). Because the larvae are damp, they actually stick to the paper cell walls. When they are ready to pupate, they must separate from the walls. They do this by attaching themselves to the cell with silk and then spin a silk cocoon.

In order to fully appreciate the intricate architecture of a Bald-faced Hornet nest, you must dissect one (they are only used for one season). Just be sure to wait until there have been a number of hard frosts, in order to assure that there are no residents. (Photo: Bald-faced Hornet nest – (left) envelope consisting of 12 layers & (right) cluster of cells it surrounded; inset:  dissected inner section showing four tiers of cells)


Black-throated Blue Warbler Nests

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It’s the lucky individual who happens upon a Black-throated Blue Warbler’s nest while it is in use, for these birds tend to build their nest directly under leaves which keep the nest very well hidden. Now that many of the leaves have fallen off shrubs and saplings, where Black-throated Blue Warblers typically build their nests, they (nests) are especially noticeable, being at eye level or below.

The female warbler builds the nest, using a variety of material including white and yellow birch bark for the outer layer (glued together with spider silk and saliva), shredded bark fibers for the inner wall and fine black rootlets, pine needles, bits of moss and strands of mammal hair (horse, skunk, human, moose, porcupine and deer) for the lining. This combination of material makes their nest very distinctive and relatively easy to identify.

 

 


Beechnuts & Black Bears

11-22-17 black bear scat and beechnuts 049A7821One need look no further than this Black Bear scat to know that American Beech (Fagus grandifolia) nuts (hard mast) are a preferred food for Black Bears, both in the fall and spring. They are an important food source for other wildlife as well, including White-tailed Deer, Fishers, Wild Turkeys, Ruffed Grouse and many small mammals and birds.

There are very good reasons why beechnuts are a preferred food for so many creatures. They have about the same protein content as corn but five times the fat content. Compared to acorns, beechnuts have nearly twice as much crude protein, twice the fat of white oak acorns and about the same fat content as red oak acorns. Research on the importance of beech mast for Black Bear reproduction shows that in northern Maine, 22% of the female black bears that were reproductively available reproduced following falls when beechnut production was poor. The proportion of reproducing females increased to 80% following falls when beechnut production was high. (Photo:  Black Bear beechnut husk-filled scat, 1 1/2″ diameter)


White-tailed Deer Scent-Marking

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Scent-marking plays an important communication role in the animal world. A variety of species use glandular secretions to convey (for some distance) messages. From beavers spreading castoreum on scent mounds to fishers leaving their scent every time their hind feet touch the ground, the woods are alive with messages often undetected by most humans. Some of these are left by White-tailed Deer, which have two primary scent-marking behaviors: antler rubbing and scrapes.

One used to associate an antler rub with the act of a buck removing drying velvet from its antlers. However, it turns out that very few rubs are made by deer removing antler velvet, a process that’s normally completed within 24 hours. Instead, most rubs are made by relatively few dominant bucks to signal their readiness to breed and to mark their territory.

All White-tailed Deer possess specialized forehead glands that become increasingly active in autumn, particularly in adult males. All bucks spread their scent by rubbing their foreheads (which contain specialized scent glands) against trees and shrubs that have smooth bark, few, if any, lower limbs and are ½” to 4” in diameter. (Older bucks also will rub trees six or more inches in diameter.) In the Northeast, Trembling Aspen, Staghorn Sumac, Red Maple, and willows are often used for this purpose.

Mature, socially high-ranking bucks exude greater amounts of the glandular secretion than do younger males or females. They begin marking their territory soon after losing velvet and continue marking until they cast their antlers in December or January. The chemical signals left at a rub site tend to suppress the aggressiveness and sex drive of young males. However, those same signals stimulate females. The amount of rubbing an individual buck does depends on the level of testosterone in his blood, which in turn is largely determined by the animal’s age and dominance status.

We may not be able to detect the chemicals on a rub, but it’s hard to miss the sight of the light-colored blazes that magically appear in the woods at this time of year. (Photo: White-tailed Deer rub on Staghorn Sumac. Thanks to Chiho Kaneko and Jeffrey Hamelman for photo op.)

 


Bumper Cone Crop Year

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There is no denying that this year’s cone crop is a bumper crop. Just look up at the tops of conifers or down on the ground beneath them and you will see a plethora of cones. This may be the best overall cone crop in five years, and the best spruce cone crop in more than a decade in the Northeast.

Conifers produce cone crops erratically; some years are bountiful, and others are minimal. Part of the reason for this may be that in a year with a bumper crop (mast), predators can’t possibly consume all of the seeds produced, and thus the opportunity for conifers to have their seeds dispersed and germinate is markedly improved. In addition, erratic production may have partially evolved as a strategy to combat insect damage. An unpredictable cycle makes it much more difficult for insects to become a pest.

As to why some years are so productive, weather conditions are certainly influential. Often times people look at the most recent summer’s weather as a forecaster of the coming fall’s hard mast crop (nuts, cones). Although most conifer cones develop in six to eight months, not all do. Most conifers in the family Pinaceae take this amount of time, but cedar cones take a year to mature, and most spruce and pine cones mature in two to three years. Thus, the cone crop we are having this year may in part be a reflection on this year’s weather, but, depending on the species, it could have been influenced by last summer’s weather conditions or even the summer before last.

Regardless of why some years are lean and some plentiful, when we have a bumper cone crop such as this fall’s, the impact is felt far and wide by wildlife. Red squirrels, voles, waxwings, chickadees, nuthatches, grosbeaks, crossbills and siskins reap the benefits. Their resulting reproduction rates soar, and the ripple effect continues to be felt throughout the food chain.

In some circumstances, the ramifications of a bumper crop are evident before the crop even matures. It appears that red squirrels can predict when there is going to be a huge spruce cone year and produce a second litter to take advantage of the large food supply when it matures. It may be that when the squirrels eat the buds of a spruce tree the summer before cones develop (spruce cones take two years to mature — cone buds are produced in the first year and cones develop and mature in the second year) they can discern which buds are going to produce cones and which are destined to produce branches. An abundance of cone buds may be the clue that triggers their extended reproductive activity. (Photo: Red Spruce cones)

 


Bruce Spanworm Moths Emerging

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If you’ve walked in northern New England woods recently, chances are great that you’ve noticed light tan moths with a one-inch wing span flitting about — with temperatures in the 20’s, this seems slightly incongruous. However, there are some insects that are active in cool weather, among them the Bruce Spanworm Moth (Operophtera bruceata), also called Winter Moth and Hunter Moth (these moths are active during deer hunting season, which approaches winter). The adults of this species are active from October to December.

Bruce Spanworm Moths belong to the Geometer family, the second largest family of moths in North America. All the flying moths you see are males seeking wingless, and therefore flightless, females to mate with. The females crawl up the trunk or branch of a tree and send out pheromones to attract winged males. After mating, the female lays her eggs which hatch in the spring. Larvae pupate in the summer and adult moths emerge in the fall.

Many Geometers are considered agricultural and forest pests. Bruce Spanworm larvae periodically defoliate hardwood trees, preferring the buds and leaves of Sugar Maple, American Beech and Trembling Aspen trees. In 1958 in Alberta, Canada, at the peak of a 10-year infestation, over 50,000 acres were moderately or heavily affected by Bruce Spanworm larvae.