White-tailed deer

A white-tailed deer doe evidently not alarmed by a proximate hiker

Common Name: White-tailed deer, Virginia deer, Whitetail – The etymology of deer extends to the origins of Indo-European languages in Sanskrit as dhvamsati meaning “he falls to dust” (perhaps to indicate mortality). As new languages arose according to human migration and custom, the root was modified … in Old Norse dyr meant wild animal or beast. The interpretation of deer as any animal, such as in Shakespeare’s King Lear Act III, Scene IV – “But mice and rats, and such small deer,” dropped out of common usage long ago. A “modern” deer is any ruminant animal of the family Cervidae. The white underside of the tail is exposed by raising it vertically erect  as a warning signal to its cohorts as it flees from a perceived threat.

Scientific Name: Odocoileus virginianus – The genus name is from the Greek odon meaning tooth and koilos meaning hollow due to the pronounced indentations in the crowns of the molar teeth, prominent in herbivores. The species was first classified in Virginia.

Potpourri: The life and times of the white-tailed deer from bust to boom in the 20th century affords a case study in adaptation to human habitats. It is one of the species that have earned the coined scientific sobriquet synanthrope applied to any wild species that lives near and benefits from their association with humans ― like pigeons and possums, they are partners of the Anthropocene. For those who have been around for a half century or so, the renaissance of the deer is something of a miracle.  About the only way for an east-coaster to see deer around the middle of the last century was to go “deer stalking” in Pennsylvania’s Poconos, driving around the mountains at dusk hoping for the rare treat of seeing even one. The pre-Columbian deer population is estimated to have been about thirty million, held in check by Native American hunters who burned the forest underbrush in part to aid in their quest and by marauding wolfpacks seeking the young and weak. Everything changed with the onslaught of the Europeans moving into the wilderness believing that its resources were endless until it was no longer wild and they weren’t. By 1900, the North American deer population had plunged to about 500,000 and they had been largely extirpated in many states in New England and the Midwest. The tide turned with the passage of the Lacy Act proscribing the sale of wild animals which ended practices such as using deer hides as currency. [1]

After World War II, GI Bill-educated veterans moved away from farms to work in cities settling in suburban developments pioneered at Levittown near Philadelphia. The economics of farming was meanwhile transformed in favor of larger, consolidated fields. Many small farms became fallow as forest succession restored the original woodland habitats that once predominated. The combination of suburban housing tracts now abutting deep wood sanctuaries reconstituted the sustaining and nurturing habitats and the renaissance of the white-tailed deer. The absence of wolf predation and the diminution of hunting by humans removed the check that had once balanced burgeoning deer populations. The phenomenal  return of the white-tailed deer that was a symbol of ecological restoration has become dystopian due to their resurgent numbers. The deer-human relationship has come under strain due to crop damage, deer/car collisions, landscape plant damage, Lyme disease  epidemiology, and, most importantly, ecosystem imbalance. These five friction factors all arise from one of two innate and irrevocable deer behaviors: eating and roving. Remediation requires reduction of the deer population to that which is sustainable in a specific area. This can be done locally with barrier fencing but this is impractical for large fields and local roads and for the most part only moves the problem to another location since deer are both mobile and resourceful. Restoring predator populations would also be effective, but the acceptability of wolves lurking in the woods is contrary to an understandable Little Red Riding Hood mentality. The only action that can be controlled and widely implemented is to resort to human predation, euphemistically called culling the herd. [2]

An understanding of deer behaviors associated with browse foraging and procreation roving is necessary to appreciate both the nature of the overpopulation problem and the most effective way to resolve it. White-tailed deer are hooved ruminant animals in the Family Cervidae (Latin for deer) which also includes elk, caribou, and moose. There are 17 recognized geographically dispersed subspecies based on minor differences in physiological traits including the endangered Key deer of south Florida and the threatened Columbian deer of the Pacific Northwest. However, since DNA testing shows no distinctions, there is scant justification for retaining the regional variants. The closely related mule deer endemic to western North America that can and do hybridize with white-tailed deer are a separate species (O. hemionus) even though they look just like their cousins with marginally longer “mule-like” ears. Depending on the species, males are called stags, harts, bucks or bulls, females are called hinds, does or cows, and the young are called calves or fawns. The most recognizable and unique of cervid features are the osseous antlers that rise from the male (and female caribou) skull like a  crown of bony spears, nature’s most magnificent weapons.

The symbolism of antlers permeates the cultural history of the hominids who hunted the animals that bore them. From the cave paintings of Chauvet in France to many heraldic coats of arms of medieval Europe, antlers are metaphor for strength and courage. Hung over the fireplace of the iconic hunting lodge, they are meant to convey honor on the hunter, even if the hunt was less so. Antlers are the weapon that one buck wields against an opponent in contesting for conjugal rights, a survival of the fittest ordeal of the highest order. Success depends on a combination of bulk strength and antler effectiveness. Size matters, and the winner spreads the genetic heritage that will produce even larger antlers with more projections. Cervid buck antlers can extend up to four feet upward and arch backward halfway across the back. The ramose headgear is an impressive feat of physiology that seems impossible as an annual event; but antlers are shed every winter and regrown the following spring. [3] Growth at the rate of up to one inch per day to produce 20 pounds of bone tissue is necessary to complete the process to meet rutting time constraints. Aside from doubling the buck’s energy input needed over baseline, antlers require calcium and phosphorous that must be drawn from existing bone resulting in seasonal osteoporosis. That this is a truly remarkable trait is supported by genomic analysis which suggests that it arose from a single evolutionary mutation of an ancestral cervid. Antlerogenesis, as the process is now named, offers potential insights into tissue generation that could plausibly be used to produce bone tissue prostheses for amputees. [4]

The deer life cycle starts in early summer, when does give birth to one or two fawns, although quintuplets have occurred. Fawning areas are selected for the safety of the suckling fawns as they gain a half pound a day to triple their weight in a month. During the first few postpartum weeks, the doe keeps the fawns hidden from predators by leaving them separately in dense undergrowth while foraging. The fawns remain immobile, even withholding their feces and urine until the doe returns, ingesting the waste to eliminate any vestige of telltale scent. Even with this exceptional maternal care, forty percent of the fawns succumb to a variety of mishaps and maladies, the majority to coyote predation.  Leaving the palladium of the fawning area, the extended family of does, their fawns, and female offspring from previous years assembles with as many as twelve deer. Moving about together in their home range averaging one square mile, they forage in the crepuscular light of dusk and dawn. Ruminants like deer have a four chambered stomach that allows them to digest almost anything.  Food travels to the rumen which contains bacteria to break down the vegetation.  The reticulum circulates the food back to the mouth as cud to be chewed again, whence the omasum pumps the food to the abomasum to complete the process.[5] The deer diet is therefore diverse, consisting of over 600 plant species broken down according to type: 46% browse (sedges, shrubs, and trees); 24% forbs (herbaceous flowering plants);  11% mast (nuts and berries); 8% grass; 4% agricultural crops; and 7% other (like fungi and lichens). These wide-ranging menu options provide adaptability to ensure deer species survival during weather and climate vagaries.  However, although deer are consummate herbivores, they have preferred foods as all animals must.  Crops and mast top the list whenever available and forbs trump browse as provender. Soybean scavenging in farmed fields and begonia bodegas in suburban gardens is an integral part of the deer population debate.

A newborn fawn left by its foraging mother in a secluded area.

Male deer separate from the maternal group when they become yearlings and form loose-knit and unrelated bachelor groups of as many as five individuals. As the summer wanes and autumn colors appear, bucks ready for the annual procreative ritual by prepping antlers. Growing from a skull projection called a pedicel, the antlers are at first covered with a nurturing blanket of nerves and blood vessels with the texture of velvet. At maturity, the covering falls away in shredded tatters that are scraped off by rubbing the antlers against a tree. These “buck rubs” impart a glandular secretion to mark out the buck’s home turf. In the late fall, nominally November, the rut race begins with bucks setting the pecking order by locking horns and pushing one against the other like furry Sumo wrestlers until brute force prevails; finesse has nothing to do with it. Bucks attract females by creating a scrape, a two-foot diameter area that has been cleaned of underbrush to expose the bare earth to which generous amounts of his urine have been applied.  When a doe enters one of up to seven estrous periods that last for one to two days every month, pheromones are exuded from glands on the inner side of the back legs at the knee joint. Drawn by the scent of the buck rubs and marked scrapes according to primordial evolutionary attraction, the doe urinates there to provide a beacon for the dominant buck to follow. A successful buck may mate with as many as twenty does, fighting off competitors whenever challenged. The resultant fawns emerge in the spring to complete the cycle. With ample food and moderate weather conditions, deer populations double every two to three years. [6] Because does are motivated during the rutting season to move independently at speeds that can reach 35 mph, most collisions occur in November along rural roads.

Two bucks browse together until mating season begins.

Returning to the five major deer population – human activity impacts, long term ecosystem deterioration due to deer overbrowse and traffic fatalities due to deer collision stand out as exceptional. Tick infestation, garden grazing, and crop consumption are relatively minor issues in almost all cases. Lyme disease is a tick-born pathogen that has severe medical consequences if left untreated. Deer are one of the hosts of the black-legged tick which carries of the disease’s bacterial vector Borrelia burgdorferi, resident parasites of white-footed mice. The rising incidence of Lyme disease over the last several decades correlates with the increasing number of deer. However, correlation is not causation, and numerous field studies have been completed in the last thirty years to separate scientific fact from emotive fiction. In one New Jersey study, the deer population was reduced by half from 45.6 to 24.3 deer per km2 over a three-year period without any appreciable change in the tick population except that it increased in the second year. [7] In Connecticut, the epicenter of Lyme disease named for one of its towns, a more robust venery reduced the deer population to 5.1 deer per km2  corresponding to an 80 percent reduction in reported disease incidence. [8] A study in Massachusetts by Harvard researchers was based on data from a deer culling operation that was carried out from 1983 to 1991 that reduced the deer population from 400 to 100 without any decrease in Lyme disease incidence. The analysis of this data considered the population dynamics of mice, ticks, and deer, concluding that to have an appreciable effect, the deer population would need to be reduced to .07 deer per km2. [9] It is reasonable to assert from these examples that deer do contribute to the number of diseased ticks and therefore to the frequency with which ticks infect humans. However, effecting a measurable diminution in Lyme disease incidence would necessitate near extirpation of white-tailed deer which is not an option.

Deer consumption of plants grown by exurban homeowners to landscape an expanse of manicured grass is a nuisance at worst. Garden center horticulturalists are generally competent in recommending plants that have evolved natural repellents like thorns or bitter leaves. Even deer delicacies like young tree saplings can be deer-proofed with chemical sprays that mimic predator smells, protected by netting and fencing, or surrounded by metallic, wind-powered “scare deer” devices. Deer consumption of plants grown by farmers to feed cattle for beef and corn for hogs and ethanol is another matter; agroeconomics and food security outscore lawn aesthetics. The economic loss to farmers due to wildlife in the United States is approximately $4.5 billion annually, about one percent of the annual $450 billion Gross Cash Farm Income (GCFI) tallied by the USDA. While measurable, this is hardly catastrophic. The particular crop eaten and the specific animal snacking on it varies significantly by locality due primarily to the extent to which fields abut woodland wildlife refuges. Indiana provides a good benchmark as it is 65 percent farmland with average farm income. An independent  study recently conducted by Purdue University provides quantitative data concerning wildlife crop losses to corn and soybeans, its major crops. White-tailed deer, raccoons, and groundhogs were the main culprits with rabbits, squirrels, and wild turkeys contributing at the low end of the scale. Racoons were responsible for 87 percent of corn predation, eight times more than deer. Deer and groundhogs were the primary soybean consumers. Questionnaires filled out by farmers provided the interesting feedback that, while they thought that deer were mostly responsible for all damage, only one in five considered deer a nuisance. Economically, most fields surveyed had damage of less than $100 and even the most damaged fields did not exceed $500. Indiana, like most states, strikes a delicate balance by allowing farmers to kill deer only if they submit proof of excessive damage ($500 in this case). [10] This is a reasonable tradeoff between allowing for wildlife survival (it is their land too) with some degree of control.

Deer collisions, particularly when fatal, are surely consequential. While official numbers are approximate, insurance claims provide a good  surrogate. According to the Insurance Institute for Highway Safety, there were 185 deaths due to deer collisions in 2019, one half of one percent of the 36,120 automobile fatalities reported by the National Highway Traffic Safety Administration.  State Farm Insurance reported  2.1 million animal collision insurance claims nationwide from July 2020 to June 2021 of which two thirds were deer. The highest incidence was in West Virginia and the lowest in Washington DC. [11] The only three ways to deal with this problem are to change driver behavior, change deer behavior, or reduce the deer population. Deer crossing warning signs are an attempt to address the former but these are now so common that they are largely ignored. Driving slower at dusk on rural roads from October to December is good practical advice, but so is don’t drive drunk. Deer behavior controls consist of fencing and wildlife passage corridors along and around major highway routes but this is impractical on side roads.[12] Evolution may play a role as deer have been observed stopped at the side of the road waiting for traffic to pass, a trait that would be passed along as those that bound ahead are removed from the gene pool. Reducing the deer population is the only option that remains.

Synanthropic animals impose a burden on ecosystems that is comparable to that of invasive plants.  Both result directly from the Gargantuan footprint of almost 8 billion humans. People transport plants (and animals like pythons in the Everglades) both wittingly and unwittingly from places where they evolved to places where they didn’t which frequently means that there is no natural way to stop their invasion. Synanthropes mostly do what they have always done, taking advantage of those human landscapes and structures to which they are suited. Pigeons nest on rocky cliffs like tall city buildings, Canada geese throng in grassy wetlands like golf courses, and deer browse along wooded glades like housing developments. From the ecological standpoint, deer are by far the most insidious in subverting the entire process of forest succession. All trees eventually die and must therefore be replaced by saplings that resulted from the seeds that they dropped. Deer browse removes the shoots at the ground level so that there are no saplings to succeed … ultimately, there would be no forest. The disruption of natural ecosystem processes has cascading effects due to the complexity of association. One study compared the bird populations on islands which had no deer to those with deer and found that there was a 55 to 70 percent reduction (depending on species), with the largest reductions in those birds that depended on forest floor plants. [13]   To make matters worse, deer removal of native plants from the understory creates disturbed areas which are havens for weedy invasives. Forty areas that were fenced off from deer for three years in Pennsylvania and New Jersey had fewer invasives than the surrounding woods. [14] Since deer are considered ecologically excessive in 73 percent of their North American range, the implications are clear. Something must be done.

Deer population control has always been a contentious issue. The “Bambi effect” predisposes many to decry killing altogether. Disney’s namesake fawn barely survives his mother’s death at the hands of  hunters and the raging fire that spread from their untended campfire to succeed his father as prince of the forest. There are humane methods to reduce the fawn count but these are labor intensive and therefore expensive. Contraceptives in the form of vaccines that cause antibodies to block pregnancy or inhibit reproductive hormones must be periodically administered, practically impossible for roving herds. Tranquilizing and sterilizing deer is a better option since it is permanent. Doe  sterilization has been unsuccessful since bucks continue to seek out and impregnate those still in estrus. A program to sterilize bucks on Staten Island by performing five minute vasectomies has reduced fawn births by 60 percent and the deer population by one fifth at a cost of $6.6 million. [15] This would be unaffordable on a scale needed to deal with the 30 – 40 million deer wandering around the continent. Most people are now willing to accept the inevitable and condone managed deer hunts. A legitimate rationalization is that humans have preyed on ruminants like deer for at least as long as they have made cave drawings depicting the hunt. The U. S. National Park Service has established a deer culling program to “protect and restore native plants, promote heathy diverse forests, and preserve historic landscapes.”  The 6,500 pounds venison harvested from the parks in 2020 was donated to local food banks. [16] While some may still object to killing deer, it cannot be without a tinge of hypocrisy. The automated killing in slaughterhouses to produce hamburger made from the flesh of another ruminant is accepted practice.  How can hunting free range ruminants be worse?

References

1. Jarvis, B. Animal Passions, The New Yorker, 15 November 2021, pp 38-44.

2. Swihart, R. K. and DeNicola, A.  Public involvement, science, management, and the overabundance of deer: Can we avoid a hostage crisis?  Wildlife Society Bulletin 1997 Volume 25  pp 382-387 

3. Emlen, D. Animal Weapons, Henry Holt and Company, New York, 2014 pp 2-4. 

4. Ker, D. and Yang, Y. “Ruminants: Evolutionary past and future impact” Science, Volume 364, Issue 6446, 21 June 2019, pp 1130-1131.

5. https://dnr.maryland.gov/wildlife/Pages/hunt_trap/wtdeerbiology.aspx       

6. https://www.fs.fed.us/database/feis/animals/mammal/odvi/all.html     

7.  Jordan, R. et al “Effects of reduced deer density on the abundance of Ixodes scapularis (Acari: Ixodidae) and Lyme disease incidence in a northern New Jersey endemic area” Journal of Medical Entomology, Volume 44 no. 5 September 2007 pp 752-757.

8. Kilpatrick, H, et al “The relationship between deer density, tick abundance, and human cases of Lyme disease in a residential community” Journal of Medical Entomology, Volume 51 no. 4 July 2014 pp 777-784.

9. https://www.hsph.harvard.edu/news/features/kiling-deer-not-answer-reducing-lyme-disease-html/    

10. McGowan, B. et al. “Corn and Soybean Crop Depredation by Wildlife” FNR-265-W, Department of Forestry and Natural Resources, Purdue University. June 2006. https://www.extension.purdue.edu/extmedia/FNR/FNR-265-W.pdf      

11. https://www.iii.org/fact-statistic/facts-statistics-deer-vehicle-collisions     

12. Hallock, Timothy J. Jr (2016) “The Effect of the Deer Population on the Number of Car Accidents,” Journal of Environmental and Resource Economics at Colby: Vol. 3 : Iss. 1 , Article 14. Available at: https://digitalcommons.colby.edu/jerec/vol3/iss1/14.   

13. Staedter, T. “Deer Decreasing Forest Bird Population” Scientific American, 31 October 2005.

14. Stokstad, E. “Double Trouble for Hemlock Forests” Science 19 December 2008.

15. Jarvis. Op cit.

16.Hedgepeth, D. “Deer cull set for parks in Md., W. Va.” Washington Post 7 November 2021

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