One of the many injurious effects of climate change is the increase in Winter Ticks (Dermacentor albipictus) due to warmer New England winters. These parasites spend their entire lives living off of one host and they have had a major impact on the moose population, especially on calves. Research conducted by the University of New Hampshire over a three-year period found that moose calves suffered a 70 percent death rate as a result of winter ticks.
At this time of year, when moose are at their most vulnerable, adult female ticks living on them, most of which are gravid (the ticks), indulge in a “blood meal” that is unlike any of the meals that they take at any other stage of life. They feed for days, swelling to ten times their normal size before dropping to the ground and laying hundreds of eggs. The snow where a tick-infested moose has laid down is often spotted with blood and engorged female ticks. It may be of some comfort to know that Winter Ticks rarely bite and feed on humans. (Photo: A moose calf that had been walking along a packed snowmobile trail laid down , leaving spots of blood from tick bites and many 1/2″-long engorged and egg-filled female ticks.) Thanks to Kit Emery for photo op.
The pollinated and fertilized white flowers of Red Elderberry (Sambucus racemosa) have recently developed into the red fruit for which this plant is named. Many people are familiar with its relative, Common Elderberry (S. canadensis), which produces dark purple fruit that is used to make jams, jellies, pies and elderberry wine. While Red Elderberry fruit can be used to make all of these, its raw berries are toxic. Red Elderberry’s popularity is greatest with pollinators, birds and four-footed mammals.
The cyanide-producing toxins in its flowers, (raw) fruit, stems, bark, leaves and roots do not seem to discourage wildlife’s attraction to Red Elderberry. The odor of its flowers, its nectar, and its highly nutritious pollen attract many ants, bees, wasps and flies. At least 50 species of songbirds eat the bright red fruits, including red-eyed vireos, ruffed grouse, song sparrows, gray catbirds, brown thrashers, and thrushes. Squirrels, mice, raccoons, and black bears also eat the fruit. Porcupines, mice and snowshoe hares eat the buds and bark in winter. The foliage is usually avoided by herbivores, although white-tailed deer and moose browse on it occasionally.
In the winter Moose feed mainly by browsing on twigs and by scraping bark off of trees. Like White-tailed Deer and other ruminants, Moose lack incisors in their upper jaw; they bite off their food between their lower incisors and a hard pad on the upper gum.
An obvious sign of Moose is the “incisor scrapes” they make when removing bark from trees with their lower incisors. An upwards movement of their head enables them to scrape a strip of bark from the tree. Sometimes instead of a clean scrape, neatly cut at both ends, you will see shredded bits of bark flapping at the top of a scrape. This occurs when a Moose begins a scrape and then grabs the piece of bark between its incisors and hard palate and pulls it upwards, peeling off a strip.
When in Moose habitat, look for the incisor scrapes of Moose on Red and Striped Maple, Willow, Trembling Aspen, Balsam Fir and Mountain Ash. Moose scrapings can be found starting as low as ten inches from the ground and can extend as high as eight feet (most likely made by a Moose standing on snow).
Ruffed grouse, white-tailed deer and moose, all prey species and all plant eaters, share certain characteristics that have to do with food consumption and digestion. They all tend to eat large quantities rather quickly in one spot, and then move to another, safer, spot to digest their food. This technique minimizes the amount of time that they are likely to be out in the open and focused more on eating than on predators. Eating quickly and storing the consumed food in a chamber and digesting it later at their leisure, under cover, makes a lot of sense.
All three animals have a multi-chambered stomach and microorganisms efficient at breaking down cellulose and extracting nutrients from plants. After browsing on branches and buds, deer and moose seek shelter where they then regurgitate and chew their cud. Grouse do not linger over their meals – 20 minutes of foraging will sustain them all day. Leaves, buds and twigs are stored in their crop (a wide portion of the esophagus) until the grouse seeks shelter, where the food eventually reaches their gizzard. Here, with the aid of gravel, it is ground up.
If predictions for the future of our climate are accurate, and if no significant measures are taken to counter it, one of the hardest hit animals in North America will be the Moose. While well-adapted to winter conditions, Moose start experiencing heat stress when summer temperatures get above 57°F. Why this intolerance to heat? A highly insulative coat, thick skin and low surface to volume ratio. When faced with very warm summers, Moose start spending more time in the shade, in cool water and in locations with cooling winds. They also frequently move to higher elevations. When it gets really hot, they stop foraging for food during the one season they have to bulk up.
Not only will their chances of survival during the coming winter be compromised as a result of this, but successful reproduction is far less likely. In addition, heat stress can cause lowered immune response which leaves the affected animals more vulnerable to disease and parasites such as winter ticks and brainworm. Adding to these challenges, the make-up of woody plant species in boreal forests will also be affected by warmer temperatures, which in turn will affect both the browsing choices and the availability of shade for Moose.
It is theorized that within the next 100 years temperatures will rise on average 9 – 13°F. in winter and 6 – 14°F. in summer (New Hampshire Fish & Game). On top of that, Maine, Vermont and New Hampshire are at the southernmost part of the Moose’s range. The future does not look bright for the largest member of the deer family in the Northeast.
It is fairly well known that the Moose population in the Northeast (and elsewhere) has plummeted — New Hampshire has lost more than 40% of their Moose in the last decade, and this trend is occurring throughout northern New England. Global warming is at the heart of this decline. Warm winters have allowed the tick population to soar, and blood loss due to ticks has weakened Moose, making them susceptible to anemia and unable to fight off disease. The negative effect of warmer temperatures doesn’t stop there. Summer heat stress promotes weight loss, a fall in pregnancy rates and increased vulnerability to disease. Excessive warm weather drives Moose to seek shelter, rather than forage for much-needed food. This phenomenon has been described by Moose biologists as “one of the most precipitous non-hunting declines of a major species in the modern era.”
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Moose are in their element during northern New England winters. Their bodies are built for snowy, cold conditions. Moose lose relatively little heat due to their large body which gives them a low surface area-to-volume ratio. Long legs enable them to travel through deep snow. However, when the snow gets to be more than 28 inches deep, the energy expended to find food is not worth it. Under deep snow or crust conditions, moose often seek shelter in stands of conifers where the snow is not as deep and where browse is available.
Conifers are beneficial to moose in yet another way. Moose are able to withstand very cold temperatures –in fact, they become uncomfortable (and have been known to pant) when winter temperatures are higher than 23°F. Their coat consists of long, hollow outer hairs and a dense soft undercoat. Our winter temperatures can be quite variable and moose depend on the shade of coniferous cover to keep them cool during our warmer winter days.
Moose are ruminants, as are cattle, goats, sheep and deer; they have a four-chambered stomach, which is necessary in order to digest the cellulose in the vegetation they consume. Food goes to the rumen and the reticulum, the first two chambers, which contain bacteria and other microorganisms that help digest the cellulose as it mixes with saliva. Here the food separates into solids and liquid material and the solids clump together to form the cud, which is regurgitated and chewed a second time in order to break it down into smaller bits. The third chamber, or omasum, functions as a pump, sending the food to the final chamber, the abomasum, where the digestion process is completed.
As part of the rut, or breeding season, that they are in the middle of, bull moose seek to advertise their wares as far and as wide as possible. Information regarding the moose’s dominance is conveyed visually to cow moose (as well as other bull moose) by the size of a bull moose’s antlers. Additional information is conveyed olfactorily through the transfer of urinary pheromones via the bull moose’s bell, or dewlap (structure located under the chin of both bull and cow moose).
A moose’s bell increases in size with age (the pictured moose is just a yearling). While there are many theories as to the function of the bell (thermoregulation during the heat of summer, extra insulation for a moose’s chin when bedding down in snow and a secondary indicator of sex and age), it has been confirmed that the bell is an olfactory device that plays a role in communication.
During rut a bull often digs a depression (wallow) in the ground in which he urinates. He then proceeds to stamp and wallow in this depression, thoroughly soaking his antlers, belly and bell with his pheromone-laden urine. Cows are attracted to this pungent scent. Suspended from the bull’s body, the bell is an excellent way of dissipating these pheromones into the air – an innovative means of sexual advertising.
Antlers grow faster than any other mammal bone — a big bull moose can grow an 80-pound rack in a summer, adding a pound of bone a day. While genetics has an influence on antler growth and size, nutrition is by far the most important factor, and males in high quality habitats grow much larger antlers.
In the early stage of growth, antlers are covered with a fuzzy skin called velvet, which contains a tremendous concentration of nerves and as well as a supply of blood. The velvet nourishes the growing antler for about five months, during which time the antlers are extremely sensitive to touch, and if injured, may be permanently misshapen. Eventually, when the bone stops growing, the velvet is shed. Bull moose then use their antlers to attract and fight for mates, as well as to root plants from the pond floor. A month or two after they have served their purpose of securing a mate, antlers are shed.
In moose, antlers may act as large hearing aids. Moose with antlers have far more sensitive hearing than moose without, and a study of antlers (with an artificial ear) confirmed that the antler behaves like a parabolic reflector.
Moose spend a great deal of time in and near bodies of water, feeding, cooling themselves and avoiding insects. They are powerful swimmers, exhibiting great speed and endurance. Moose have been observed swimming distances up to 12 miles, and are known to occasionally swim from one point of land to another when the distance is shorter by water than by land. (Adult moose usually swim with only their head out of water, whereas yearlings have most of their back exposed.) Moose can spread their hooves, and this is ability is thought to enhance their paddling skills.
Much of a moose’s summer diet is semi-aquatic and aquatic vegetation, thus they feed near shore as well as in deeper water. Studies have shown that moose will dive as deep as 18 feet to obtain submerged plants. It is slightly unsettling to see them totally disappear for up to nearly a minute while foraging under water!
While the mating season, or rut, for moose peaks between late September and early October, mating behavior can already be observed. It is widely known that male, or bull, moose often paw a pit in the ground, urinate in it and then stomp in it in order to splash their underside, slap the urine with their antlers to disperse it, and lay down in the pit and wallow in their urine, soaking their undersides and neck. Their pungent urine serves as an aphrodisiac for female, or cow, moose, which are attracted to the pheromones it contains. A cow will enter a wallow, aggressively displacing the bull at times and even drink his urine.
However, it’s not just bull moose urine that attracts the opposite sex. The urine of a cow in heat (defined as the two days of their estrous cycle when they will allow a bull to mount them) is equally as attractive to bulls. At this time of their reproductive cycle cows frequently will urinate in the water and along the shoreline of lakes and ponds (look closely at photo).
Being an ardent admirer of moose, I am devoting today’s post as well as the next two posts to the largest member of the deer family. Even if it weren’t seven to ten feet long and didn’t weigh over a thousand pounds, a moose would be an impressive mammal, with its high, humped shoulders, broad, pendulous muzzle and long, coarse hair.
Moose are voracious eaters, consuming roughly 44 pounds of plant material a day. In the winter their diet, mainly the bark of woody plants, provides only about 70% of the energy they need to survive. Thus, during the spring and summer they spend up to 12 hours a day foraging, often for aquatic plants, and acquire more than 200% of the energy they need. Hundreds of pounds are gained, with the excess stored as fat reserves for the coming months. Even so, moose lose up to 20% of their weight over the winter. (Thanks to all who wished me happy recharging!)
Biologists estimate that moose defecate anywhere from 13 to 21 times a day. The appearance of moose scat, as well as deer, varies throughout the year. Its form depends in large part on the amount of moisture in the moose’s diet. Summer scat often looks like loose plops, or patties, due to heavy consumption of herbaceous aquatic and semi-aquatic vegetation. As fall approaches and a moose’s diet includes more woody vegetation, its scat consists of clumps of soft pellets. In the dead of winter, when moose are browsing almost exclusively on trees, individual dry pellets are produced. Spring scat is similar to fall scat, as moose are transitioning into a different diet during both of these seasons.
As the moose rutting season comes to a close, signs of their breeding behavior are fewer and not as fresh. The pictured moose wallow, or rutting pit, was most likely created by a bull moose as a means of spreading his pheromones to receptive cows (although cow moose have been known to make them). After scraping the ground, the bull then urinates in the depression and stamps in it to splash the urine on his antlers (“antler perfuming”) and/or lies down in it, soaking the under side of his body, including the dewlap, or bell, that dangles beneath his neck. Every soaked surface serves to advertise his presence to cows in the area. Often the sound that the bull makes splashing the urine attracts cows, who run toward the bull and, by head bobbing and attempting to drink the urine (the sipping sound is attractive to both cows and bulls), encourage him to urinate more. (Thanks to Alfred Balch for photo op.)
During their breeding season, or rut, bull moose display a number of behaviors that are not commonly seen any other time of year, and many of these behaviors leave obvious signs, including broken branches, scraped bark, wallows and tracks. Bulls roam their home ranges, thrashing their antlers back and forth against shrubbery and saplings while leaving their scent. The sound of their antlers beating against vegetation is thought to signal the bull’s dominance to other males, as well as serve to attract females. The pictured broken balsam fir sapling and its frayed bark are evidence of this behavior.
The highlight of a recent trip to Maine was watching a bull moose feed on submerged aquatic vegetation. It would swim a short distance, and then sink, much like a submarine, until only the top of its back was visible, and then it, too, completely disappeared, leaving no sign of a moose. Seconds later the moose’s head would reappear, with its mouth full of green plants. When these plants were consumed, the moose would submerge underwater again and come up with another mouthful. It proceeded to do this at least a dozen times before eventually swimming to shore. When moose are feeding on submerged vegetation they are capable of reaching plants in water over 18 feet deep, and they can remain under water for up to 50 seconds or longer before resurfacing. It’s thought that they remain submerged by paddling and perhaps by releasing air from their lungs.
Many mammals have two molts a year, producing a winter and summer coat. Moose only have one annual molt, and it occurs in early spring. Their winter coat consists of long (up to six inches on neck and shoulders), hollow guard hairs and a thick undercoat. In early spring the faded and ragged winter hairs are shed and replaced with short, dark, shiny hairs. Molting starts on the shoulders and proceeds along the sides of the neck and back over the moose’s body. Adult bulls molt first, the cows and yearlings shortly after. Pictured is a beaver-cut tree which was used by a moose to scratch off loose winter hair.
Even with the knowledge that the moose is the largest member of the deer family, the discrepancy between the size of its hoof and that of a white-tailed deer’s is impressive. A moose’s front foot track is somewhere between 4 ¼ ” and 7” long, whereas a deer’s front track is between 1 ¼ “ and 4” long. Both have hooves that are heart shaped, and point in the direction of travel. Deer are more hindered by snow than moose, so finding a deer taking advantage of a moose’s trail by stepping directly in the moose’s tracks (see photo) makes perfect sense. (The moose’s foot was dragging as it stepped into the snow, thus causing the groove that leads to the track.)
The mating season for moose (Alces alces) is just starting, and it peaks around the end of September or the first week in October. By this time bulls have shed the velvet that provided a blood supply to their antlers while they were growing during the summer. Occasionally you see the remains of the velvet hanging from their antlers at this time of year (see photograph). During mating season, bulls are rushing through the forest, seeking a receptive cow and engaging in mock battles with other bulls for the female’s attention. A bull uses his antlers in these challenges, engaging in “antler-pushing” with other males. He also uses his antlers as a tool for thrashing brush and for rooting plants from the bottom of ponds.