Moose

Moose frequent ponds and streams to eat aquatic plants.

Common Name: Moose, elk – The Algonquian word moos-u means “he shaves or trims.” Native Americans applied the sobriquet to describe the characteristic stripping bark and the lower branches from trees. It became moose as colonists migrated north into their habitat. Moose are called elk in Europe absent any prior vernacular names in native languages. Elk is derived from elaphos, the Greek word for deer.

Scientific Name: Alces alcesAlces is Latin for elk. It is the only species in the genus so one name serves for both. The American elk is a completely different species from the European “moose elk.” In the deer genus as Cervus canadensis, elk are also called wapiti from the Shawnee word meaning “one with a white rump,” a prominent visual characteristic.

Potpourri:  Moose are solitary sentinels in the northern, boreal forests spanning the globe in both North America and Eurasia, where they are known as elk. Moose is metaphor for rugged individualism, surviving the extremes of ice and deep snow with diminished sunlight and plunging temperatures without the restful hiatus of hibernation. They are the giants of the deer family, their bulk sustained by an herbivorous diet. Moose are capable of consuming almost anything that they can find. During winter, they consume up to fifty pounds of twigs and shrubs a day. Summer is a relative smorgasbord with closer to sixty pounds of birch, willow, aspen, and maple leaves supplemented with a wide range of aquatic plants. [1] With towering columns for legs, they can pass through snowdrifts in pursuit of nature’s scant winter provender. Unlike their cervid cousins that form herds for some protection in numbers, moose keep to themselves. Their shear bulk wards off all but the most determined of predators, primarily wolves. From Teddy Roosevelt’s Progressive “Bull Moose” Party to the multitudes associated with Moose International, moose is metaphor … an indomitable animal astride the frozen tundra symbolizing strength and salubrity.

Moose have all of the characteristic features of the deer or cervid family to which they belong. Cervidae is derived from the Latin cervus, meaning hart or stag (applied now only to males) which in turn comes from keras, the Greek word for horn. Deer are hoofed mammals that subsist wholly on plants that have horns in the form of antlers. While the class Mammalia generally means warm-blooded, hairy animals that feed offspring with milk from mammary glands, Linnaeus, when he first introduced the taxonomic grouping in the tenth edition of Systema Naturae of 1758, also included four-chambered hearts, lungs, a covered jaw, five sense organs mostly with four feet and a tail as key traits. [2] All of these features are modified according to evolution to suit the particular mammalian environment in which survival is sought. In the case of moose, large body size, palmate antlers, dense hair, long legs, and an extended, snouted jaw are necessary and sufficient to eke out a living in the extremities of northern latitude.

Moose Habitat. Cascade Canyon, Grand Teton National Park

Large size and cold climate are related according to Bergmann’s Rule.  The eponymous correlation was first established by the German biologist Carl Bergmann in 1847 with the hypothesis that heat loss was proportional to the ratio of an animal’s surface area to its volume. The logic is that thermogenesis (“heat production”) is a matter of body mass and heat loss emanates mostly from its surface. In essence, larger moose, bear, and lynx are more likely to survive the cold to reproduce more effectively than those at the lower end of the size spectrum. The rule holds fairly well with warm blooded animals like mammals (71 percent) and birds (76 percent). There are other biological traits that vary according to latitude. Gloger’s Rule is that lighter colors prevail in northern areas as a matter of survival due to cryptic coloring for both predators and prey; the arctic fox is hard to spot and the snowshoe rabbit is hard to find. As moose are never predator nor rarely prey (except as calves), there is no environmental stressor to select for whiter fur.  Similarly, Allen’s Rule is that northern animals have smaller appendages like ears, tails, and limbs relative to southern cousins ― a corollary also based on heat loss. [3] Field studies have shown that moose do indeed get larger as you go from the southern end of their range to the north following Bergmann’s Rule but their ears and antlers get larger and wider at the same time, violating Allen’s Rule. [4]

Moose antlers are employed in head butting contests to establish male pecking order dominance during the annual rut. This is as dangerous as it sounds. Weighing as much as a ton each, two bull moose jousting with bony, multi-tined weapons frequently break ribs and scapulae while frequently tearing through flesh. About five percent of moose die in combat every year and one third will die of wounds inflicted over the course of their short, brutish lives. The winners do most of the mating. All of this is nature’s pathway for the winning bull moose to perpetuate genes for  bulk, brawn, and big antlers without regard to latitude. Once this is accomplished, the antlers fall off in the winter only to be regrown from the scull up in time for the next mating season. In the wild where survival depends on serendipity, the handiwork of evolution is here evident. The energy needed to grow a set of bull moose antlers made from the same skeletal bone tissue that forms the framework of the body is up to five times that needed for sustainment metabolism. Bull moose can lose up to twenty percent of their body weight in the run up to the rut. This is about the same energy differential as that needed for a cow moose to give birth to a calf (sometimes two and rarely three). Getting enough protein from an herbivorous diet is hard enough, but getting enough calcium and phosphorous to make antler bone tissue is the real challenge. These minerals must be sequestered from extant bone, resulting in osteoporosis and weakness just in time for rut trial by contact combat. [5] While this must have be a good evolutionary result for moose in their current environment, it may not be sustaining in the long term. Evolution is a record of the past with no plans for the future.

The violence of antler assaults is  testimony to the importance of sexuality in the evolutionary cycle of life in the caldron of survival selection. It is just one of numerous characteristic traits that emerged as successful in promoting the moose brand with cows attracting bulls and vice versa. Reproduction is a biological mandate, not an option. Meeting and mating for moose that live alone out of sight in remote wilderness habitats must rely primarily on sound and smell. For enhanced audio, bull moose ears and antlers operate in synchrony with four key features to detect even the faintest cow moose bleat. The moose ear or pinna is about 65 square inches, more than fifty times larger than ours. Stereophony, the ability to determine sound  directionality is enhanced with a wide separation of a foot, twice that of humans. Moose ears operate independently, each rotational for a complete 360 degrees and tiltable by 90 degrees away from vertical. And lastly, like the hearing horn of yore, moose antlers concentrate sound to amplify the signal to enhance detection over background noise. Measurements using a taxidermic antlered moose head (there are regrettably many to choose from) revealed a fifty percent decibel increase when measured at the base of the antler. It is probable that the wide, palmate shape of moose antlers, unlike the tubular shape of most other deer, evolved as a more effective sound receiver. It is also probably not a coincidence that female moose have a better sound repertoire than their male counterparts, which is unique among cervids. [6]      

Pheromones as aphrodisiacs operate over time to establish a geographical datum to which a sound signal may only have provided a vector direction. Smells are considered to be the most enduring of animal senses. For moose, they are sine qua non. Mammalian olfactory systems consist of two separate “chemosensory” signals to different parts of the brain that end in the hypothalamus, the region controlling behavior and endocrine/hormonal response. The main olfactory system (MOS) samples the air for volatile chemicals across a broad spectrum for general situational awareness, such as food emanations. The accessory olfaction system (AOS) triggers response in a specialized sensor called the vomeronasal organ (Jacobson’s Organ) that is thought to be exclusively for reproduction related smells. There are four kinds of pheromones: Modulators influence general psychological state; Releasers have specific, immediate responses; Signalers are less specific and gradual; and Primers change behaviors over the longer term. For moose, bull rut urine is Cupid’s aromatic arrow. As a pheromone, it is a Releaser, causing “overt displays of attraction and copulation.” It is a complex compound that has not been fully characterized with over 100 chemical constituents. Courting consists of a rutting bull digging and urinating in a dirt pit, wallowing in the resultant muck to obtain a whole-body bridal bouquet. Cows attracted to the smell follow suit until the nuptial party is fully aroused and sex ensues.[7] Life goes on according the laws of nature, a new calf conceived.

Moose have a distinctive rounded, downward drooping snout from which a fleshy outgrowth called a dewlap is suspended. The bulbous snout houses an elaborate snorkel system comprised of two fatty nose plugs that are held over the nostrils by powerful muscles. [8] The moose snorkel seals air lines against water intrusion in like manner to submarines and reef divers. The delicate, conical deer family muzzle was transformed to moose snorkel-snout to facilitate consumption of aquatic plants, not infrequently with full immersion dives to lake bottoms. In one observed forage, a moose dove for almost an hour, covering 100 square yards, swimming at speeds comparable to a paddled canoe. Moose, then, are semi-aquatic deer. Their effect on riparian ecosystems is substantial, depositing the equivalent of one hundred pounds of commercial fertilizer in a year. The moose dewlap projection is similar to the swollen necks of lizards and to bird wattles. There are numerous hypotheses about the function of dewlaps that range from sexual attraction to predator avoidance. The former is based on the “peacock’s tail argument” in that having a huge encumbrance with no function must mean good genes and the latter is based on increasing apparent size to scare off would be attackers. [10] It is hard to see how this might apply to moose, where sexuality is a matter of olfaction and whose huge bulk hardly needs accentuation. Since bull and cow moose both have dewlaps, albeit with a substantial amount of sexual dimorphism (the male dewlap is much larger), it is more likely that it is vestigial like the tailbone coccyx in humans. The comical appearance of droopy snouted moose is epitomized by Bullwinkle, the sidekick of Rocky the Flying Squirrel, who lacks a dewlap altogether.

Moose have followed the same population fluctuations as the white-tailed deer from the bust of the nineteenth century to the boom in the twenty-first. The burgeoning human enterprise moving inexorably west and north through the 1800s depleted moose directly by hunting for both food and sport (moose would hardly call it that) and indirectly through tree removal habitat destruction. As the human diaspora reversed in the urbanization of the 20th century, newly fallowed fields progressed to forests and moose moved southward to their original range across the northern tier of states. With an estimated fifty thousand moose in the northeast alone (and more across the upper Midwest), moose crossing signs now proliferate, warning motorists to be wary ― due to their hood-high height, a direct collision with a moose results in a one ton weight through the windshield with usually fatal certainty. This is especially a problem in winter, when moose seeking salt learn that treated roads are covered with it. [11] Increasing numbers of hungry moose wandering near homesteads also increases the likelihood of human encounters, which are not always benign. Unlike deer, moose can be quite aggressive, particularly during mating season and when accompanied by calves. Man’s best friend is equally sworn moose enemy due to their penchant for barking and chasing. Dogs are accordingly subject to targeted moose attacks even without specific provocation. [12]

Moose population dynamics have long been a matter of scientific interest. Questions about environmental sustainability and the role of predators can only be properly answered with field observations, which are impractical to conduct in open ranges. Michigan’s Isle Royale National Park situated fifteen miles off shore in Lake Superior has served as an isolated experimental enclave for well over a century. In the 1900s, several moose crossed over to the 200 square mile island, and, absent wolf predation, proliferated. The moose population surpassed 3,000 in 1930, consuming most of the food supply, resulting in a period of starvation from which only one out of every fifteen moose survived. In about 1950, a population of wolves also immigrated to the island across a frozen channel, allowing for a comprehensive study of predator/prey behavior in the wild. Over time, a pack of about twenty wolves  preyed almost exclusively on the young, old, and infirm which stabilized the moose population at 500 with a self sustaining food supply validated by measuring tree ring growth. [13]  The now balanced ecosystem became one of the foundational bases for the reintroduction of apex predators to several western states. By 2017, the Isle Royale wolf population had dwindled to just a single mating pair. This was attributed to inbreeding, one of the unintended genetic consequences of the mammalian dominant male model. As a result, the moose population had tripled to 1500 with commensurate overbrowsing damage. To remedy the otherwise inevitable die-off, six wolves have been released on the island as part of new 20 year study by the National Park Service. [14]

In recent years, moose populations have plummeted, most notably in Vermont and Minnesota. While speculative, the effects of climate change are thought to play a key role. Three factors are germane: rising temperature; changes to forest species composition; and changes in the species and numbers of parasites. The dense, double-layer pelt that protects moose from the rigors of winter becomes a heat blanket when temperatures rise. Heat stress in moose occurs when summer temperatures exceed 57 degrees F and winter temperatures exceed 23 degrees F. The only cooling remedies available are seek shade, get wet, or move north, and many do. Tree species migrate north for the same reason ― they evolved to operate within a temperature band that balances evaporation with uptake. The maple and birch trees that are staples of moose cuisine are being driven out by the less palatable tough-barked oaks and hickories. [15] But the primary culprit for the struggling moose population is parasitic. White-tailed deer are carriers of the black-legged tick that causes Lyme Disease in humans. They are also carriers of the winter tick (Dermacentor albipictus) that infests moose. It has been concluded by some researchers that the winter tick is the primary cause of moose mortality in New England. Individual moose can have up to 50,000 ticks, causing lesions that result in the loss of almost all of the protective fur. In some areas, more than fifty percent of juvenile moose succumb. [16] The plight of polar bears has been the focus of climate change Cassandras. Moose may be next.

References:   

1. http://www.env.gov.nl.ca/snp/Animals/moose.htm    

2. Drew, L. I, Mammal, Bloomsbury Publishing, London, 2017, pp 9-25.

3. Millien, V. “Ecotypic variation in the context of global climate change: Revisiting the rules”. Ecology Letters. Volume  9  Issue 7, 23 May 2006  pp 853–869.

4. Nygrén, T. et al “Moose Antler Type Polymorphism: Age and Weight Dependent Phenotypes and Phenotype Frequencies in Space and Time.” Annales Zoologici Fennici 19 December 2007 Volume 44, Number 6,  pp 445-61.

5. Emlen, D. Animal Weapons, Henry Holt and Company, New York, 2014, pp 117-122.

6. Bubenik, George A.; Bubenik, Peter G. “Palmated antlers of moose may serve as a parabolic reflector of sounds”. European Journal of Wildlife Research. August 1, 2008, Volume 54 Number 3 pp 533–535.

7. Whittle, C. “Identification and Function of Male Moose Urinary Pheromones” PhD Thesis, University of Alaska, 2005.

8. . Sharp, D. “Researchers take a look at the moose’s enigmatic nose”. USA Today. May 5, 2004.

9. Pennesi, E. “This diving, pooping moose is saving the ecosystem – for now” Science, 21 October 2018.

10. Bro-Jorgensen, J. “Evolution of the ungulate dewlap: thermoregulation rather than sexual selection or predator deterrence?” Frontiers in Zoology. 18 July 2016 Volume 13 Number 1 p 33.

11. Schueller. G. “Moose in a Mess” Defenders of Wildlife Magazine,  Winter 2007

12. Alaska Department of Fish and Game “What to Do About Aggressive Moose” at http://www.wildlife.alaska.gov/index.cfm?adfg=aawildlife.agmoose     

13. Lack D. “Population, Biological” Encyclopedia Britannica Macropedia W. Benton Publisher, University of Oxford, Volume 14 p 839.

14. Mlot, C. “Classic Wolf-Moose Study to be recreated on Isle Royale” Science Volume 361 Issue 6409, 28 September 2018. Pp 1298-1299.

15. . Rines, K.. New Hampshire’s moose population vs climate change. New Hampshire Fish and Game Department Report 5484.

16. Debow, J. et al “Effects of Winter Ticks and Internal Parasites on Moose Survival in Vermont, USA”. The Journal of Wildlife Management. 2 August 2021 Volume 85 Number 7 pp 1423–1439.

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