An online resource based on the award-winning nature guide

Cervids

Moose Antlers Growing

moose antlers 795Antlers 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.

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White-tailed Deer Scraping Bark

3-3-15  deer scraping2IMG_0490During the winter, white-tailed deer browse on the twigs, buds and bark of trees. Deer have incisors in the front of their bottom jaw, but none in the front of their top jaw, just a hard palate. They grip the bark with their bottom front incisors and scrape their jaw upwards, leaving behind grooves the width of their bottom incisors. Often there are frayed ends of bark at the top end of the groove, due to the deer having to use its hard palate and incisors, rather than two sets of incisors, to separate the bark from the tree. Favorite trees include red and striped maples, oaks, poplar, pines, hemlock, arborvitae and balsam fir.

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The Silent Communication of White-tailed Bucks

9-23-14  antler rub IMG_7310Rising levels of testosterone circulating in a buck’s blood toward the end of summer results in the maturation of antlers and the drying up of the velvet that was providing nutrients to them. It used to be thought that bucks engaged in rubbing their antlers against saplings at this time of year in order to remove the velvet, but research has shown there is much more behind this behavior. Rubs are visual and olfactory sign posts that transmit important information to other bucks and does in the area prior to and during rut, such as individual buck identification, breeding readiness, age and hierarchy.

The positioning of the antlers against a tree is not random — a buck generally rubs the base of his antlers and his forehead skin against the tree. The skin between antlers contains a multitude of scent-producing skin glands called apocrine glands (humans have them and utilize them during emotional sweating). These glands typically are inactive during the summer months, but in response to rising testosterone levels, they become increasingly active in the fall. The most active glands are found in mature dominant bucks.

Thanks to recent studies we know that more rubs are made in years of good acorn production than in poor mast years. Young bucks appear to make fewer rubs than mature bucks, and they tend to start rubbing much later in the fall (so rubs you find now were most likely made by mature bucks). Research suggests that older bucks may be making more than 1200 rubs during the roughly 90-day rubbing period, which comes to about 15 rubs per day.

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Moose & Water

moose shaking 472Moose 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!

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White-tailed Deer Pheromone Glands

11-15-13 white-tailed deer glands 582Animals communicate with their own species through strongly scented chemicals known as pheromones. Many mammals have glands that generate pheromones. The messages the scents convey vary according to the pheromone that is used – they can indicate alarm, territorial boundaries, the age of an animal and/or its sex, hierarchy and the receptiveness of an animal during the breeding season, among other things. White-tailed deer have scent glands where you might not expect them – their heads, legs and feet. Their primary glands and their functions are: forehead (scent left on antler rubs and overhanging branches), preorbital (near eye, doe uses it to communicate with fawns), interdigital (between the two toes of each hoof, foul-smelling yellow substance left on the ground with every step a deer takes), nasal (inside nose, may produce a scent, or may just lubricate the nose), preputial (on inside of buck’s penal sheath, function unknown), tarsal (inside of hind legs near middle joint, urinated on to spread scent, used intensely by bucks during rut) and metatarsal (outside of hind legs between ankle and hoof, function, if any, unknown).

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Moose Wallow

11-1-13  moose wallow 010As 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.)

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Thrashing: Moose Rut Sign

10-23-13 moose thrashing sign 051During 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.

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