The Architecture of a Bald-faced Hornet Nest
The 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
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
One 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)
Sadie & Otis Update
Many of you have asked about Sadie and Otis, whom you have supported so generously. Sadie is remarkable – strong and resilient, single-parenting Otis and giving him so much love and attention that he is thriving. Your contributions have enabled them to stay put in their home and for Otis to continue going to pre-school.
As much time as I spend watching ants, listening to birds, and taking walks in the woods with Otis, I am well aware that I am competing with his strong penchant for anything with a motor in it. However, he did raise and release several monarchs this fall and still adores owls, so all is not lost!
I wanted to thank you, my Naturally Curious blog readers, once again for your incredible and compassionate response to the tragedy we experienced this summer. This Thanksgiving Sadie, Otis and I are giving thanks to you for your support. May you have a very happy Thanksgiving!
White-tailed Deer Scent-Marking
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
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
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.
Where Are All The Birds?
Even though signs as well as sightings of active bears are plentiful, and black-oiled sunflower seeds are an open invitation for them to visit and potentially become “nuisance” bears, many devoted bird-lovers have already hung out feeders in hopes of luring feathered friends closer to their home. Throughout northern New England so few birds have been attracted to these feeders that they have remained full, some not having been refilled since September. Our usual fall and winter visitors appear to have all but vanished, and concern has been growing amongst those who feed birds.
Those familiar with bird feeding habits know that in the fall, when seeds are abundant, feeder visits by resident birds typically slow down. However, this year, at least anecdotally, appears to be extreme in this regard. Warm weather extending into November certainly has lessened birds’ food requirements. But having sunflower seeds sprout in your feeder before the need to replenish them arrives is unusual, if not alarming.
Dr. Pam Hunt, Senior Biologist in Avian Conservation at New Hampshire Audubon, recently shared some of her personal research with the birding world (UV- Birders). Hunt has conducted a weekly, 10 km-long, bird survey near Concord, NH for the past 13 years. In addressing the current concern over a lack of feeder birds, she extracted the data she had accumulated on 12 common birds (Mourning Dove, Downy Woodpecker, Hairy Woodpecker, Blue Jay, Black-capped Chickadee, Tufted Titmouse, White-breasted Nuthatch, White-throated Sparrow, Dark-eyed Junco, Northern Cardinal, House Finch, American Goldfinch) over the last 13 falls, focusing on the period between Oct 1 and Nov 15. After extensive analysis, Hunt concluded that there has not been a dramatic decline in the number of birds this year, relative to the averages of the past 13 years. One cannot argue with scientific evidence (except for, perhaps, #45), but it does seem mighty quiet on the western (northeastern?) front this year.
Beavers Breaking Ice
We’re right on the verge of when beavers will no longer be able to smell fresh air, see the sun and obtain fresh bark. Until the temperature drops to around 16 degrees F. they continue to break through the thin ice covering their pond. Once the temperature remains in the teens or lower for several days, they no longer try to break through the ice and are sealed under it until spring, unless there’s a mid-winter thaw.
Once beavers are confined by the ice, their activities outside the lodge are minimal. Beavers leave their lodge in winter primarily for three reasons: 1) to swim out to their winter food supply pile and retrieve a branch which they bring back into the lodge to eat, 2) to defecate in the water, and 3) to mate in January or February. Other than these excursions, they spend most of their days in the dark, enduring life in a lodge that has a temperature of about 34 degrees F. (Thanks to Kay and Peter Shumway for photo op.)
Snow Geese Migrating
The eastern population of Snow Geese, one of the most abundant species of waterfowl in the world, migrate in very large flocks from their high Arctic breeding grounds to their wintering grounds along the Atlantic coast during October and November. Their migration is characterized as a combination of long stopovers with rapid and distant flights between areas. Birds from the same breeding population use many of the same stopovers sites, or staging areas where they rest and refuel, each year. Here they forage and eat the stems, seeds, leaves, tubers and roots of grasses, sedges, rushes in addition to waste grains such as wheat and corn in fields where crops have been cut.
Most of the eastern Snow Geese stage on the St. Lawrence estuary and many then migrate over Lake Champlain and fly southward along the Hudson River to their wintering grounds along the east coast, where the highest numbers occur along the shore of Delaware Bay. Those of us lucky enough to live near a staging area keep our ears tuned this time of year for the sound of baying hounds, for that is what an approaching flock of thousands of Snow Geese sounds like. (Photo taken at Dead Creek Wildlife Management Area, Addison, VT)
The bubbles you see is are the formation of a crude soap on the bark of a White Pine. During dry periods salts, acids and other particles from the air coat the surface of the bark. When it rains, these mix with the water and form a solution. The foam is from the agitation of the mixture when it encounters a barrier (bark) during its flow toward the ground.
As to why this occurs primarily on pines, botanist Ken Sytsma states, “Pines produce a whole array of natural hydrocarbons for herbivory defense. One set of these is “pine tars” that have been used in the past to make soap. As precipitation works its way down trunks of pines, they accumulate these compounds. What you may be seeing is natural pine soap in the making.” (Thanks to Brenda & Steve Hillier for Mystery Photo idea.)
Last Call For Calendars
Orders for the 2018 Naturally Curious Calendar can be placed by writing to me at 134 Densmore Hill Road, Windsor, VT 05089. The calendars are printed on heavy card stock and measure 11″ x 17″ when hanging. There is one full-page photograph per month. They are $35.00 each (includes postage). Please specify the number of calendars you would like to order, the mailing address to which they should be sent and your email address. Your check can be made out to Mary Holland and orders that reach me by November 15th will arrive at your door by mid-December (in time to be given as Christmas gifts). After the 15th, orders will be filled as long as my supply of calendars last. Thank you so much!
What is this white foam at the base of this White Pine, and how did it get there? Please submit answers under “Comments” on my blog site, http://www.naturallycuriouswithmaryholland.wordpress.com.
Clubmoss Spores Maturing
Creeping along the forest floor are small (6” high), evergreen perennial plants that resemble mosses or miniature conifers. Their leaves are usually narrow, shiny and pointed and frequently of similar size. These fern allies (not true ferns) are referred to as clubmosses. What look like individual plants often are upright stems that come off of one horizontal stem that grows along or under the ground.
Clubmosses evolved some 410 million years ago as one of the earliest groups of vascular plants (plants with special tissues, xylem and phloem, to conduct water and food, respectively). Roughly 300 million years ago, tree forms of both clubmosses and horsetails along with ferns dominated the great coal swamps of the Carboniferous geological period. Fossils reveal that tree forms of clubmosses once reached heights of 100 feet.
Pictured is Bristly Clubmoss (Spinulum annotinum, formerly Lycopodium annotinum). Like all ferns and fern allies, it reproduces with spores, not seeds, and thus has no flowers. The spores are borne on the single cone, or strobilus you see at the tips of the upright stems, and they are maturing now. A slight tap at this time of year will produce a voluminous cloud of yellow spores.
Post Published Prematurely
If you received a post this afternoon on the 2017-18 Winter Finch Forecast it was prematurely published. I was trying to schedule it to be posted on November 10th, when it will now be reposted. Pardon the repetition! (Photo: Pine Siskin)
Black Bears Raiding Brood
Previously this fall I posted about Black Bears foraging ferociously in the fall in order to store fat (sometimes doubling their weight) before hibernating. That post showed an ant-infested tree that had been ripped apart. As winter approaches, signs of bears’ frenetic gorging (hyperphagia) increase dramatically. Protein-rich sources such as Bald-faced Hornet nests (suspended from branches) and Yellow Jacket nests (in cavities in the ground) are highly sought after.
If you look closely, you’ll see that the claws of the bear that attempted to raid the hornet nest (suspended ten feet above the ground) were able to reach just the bottom portion of the nest, tearing the outer multi-layered, paper envelope but not reaching the brood-containing cells within. The Yellow Jacket cells containing brood (eggs, larvae and pupae), on the other hand, were all removed from the ground nest and consumed. All that remains is a portion of the outer envelope and a few adults.
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