White-Tailed Deer: Grim Reaper of the Deciduous Forest Perhaps no animal in Pennsylvania can bring about more controversy or generate more emotional attachment than the white-tailed deer, Odocoileus virginianus. The white tail can be found in a variety of habitats that includes farmland, suburbs, and forests; it is even capable of surviving in urban patches of green (“Deer hunt comes,” 2011). The whitetail’s range extends from southern Canada to northern South America and most of the United States; it is absent in the southwestern U.S. (Fergus, 2000). The history of the whitetail in Pennsylvania mirrors that which happened in other areas. Once abundant, overhunting, combined with deforestation resulting from the change in land use to agriculture and its accompanying habitat degradation, nearly drove the while tail into extinction by the mid-1800’s. The alarming drop was the impetus for the creation of the Pennsylvania Game Commission in 1895. The organization quickly established bag limits for the white tail for the purpose of allowing the animal to recover its population. Since that time, white tail populations have climbed, aided by the elimination of natural predators and the improvement in habitat quality created when abandoned farmland gave rise to secondary growth forest (Cote et al., as cited by Morissette, Lavoie, & Huot, 2009) consisting of even-aged economically valuable species such as white ash, as white ash, sugar maple, red maple and black cherry (McClenahen & Hutnik, as cited by Stromayer & Warren, 1997). Although no one is certain of the deer population of pre-Columbian times, today’s estimated 25 to 27 million individuals may exceed the pre-Columbian numbers (Shedd, 2000). This may be partially due to the whitetail’s biology; female deer have a remarkable ability to respond to decreases in habitat quality; a reduction in food availability resulted in smaller female deer who maintained their reproductive rate. It was only when a drastic reduction in vegetation quality occurred before a corresponding decrease in density occurred (Anouk-Simard, Cote, Weladji, & Huot, 2008). The whitetail eats between five and nine pounds of food daily, feeding on plant material such as tree bark, twigs, lichens, wildflowers, grasses, garden vegetables, acorns, and ornamental plants (Fergus, 2000). The white tail’s propensity for eating is the root of the problem. Considered by many to be a keystone herbivore (“White-tailed deer management plan,” 2006), they are capable of upsetting otherwise stable ecosystems with densities as little as ten individuals per square mile (deCalesta, as cited by “White-tailed deer management plan,” 2006). Browsing pressure exerted by the Pennsylvania’s state mammal is threatening the future of Penn’s Woods; Pennsylvania’s high quality mixed hardwood forests are giving way to regenerated stands made up of red maple, black birch, and other less economically viable valuable trees (Shedd, 2000). Hunting is one method of keeping the white tailed deer population in check; Pennsylvania hunters take 350,000 to 400,000 deer annually of the estimated 1.4 million that reside within the state (Fergus, 2000). In 2002, the Pennsylvania Game Commission responded to the deer overpopulation crisis by altering the hunting seasons so that the doe season now occurs prior to the antlered season, allowing females to be culled prior to breeding (“QDMA,” 2010). This allows antlered males to remain in the population, resulting in healthier deer herds since the 1 stronger males are doing the breeding, rather than smaller males who survived antler season (Shedd, 2000). Today, despite the successful game laws and initiation of doe seasons, the southeastern part of Pennsylvania is crippled by a deer population that has grown beyond carrying capacity. In an area where few people are traditional hunters and where hunting in densely populated areas is difficult and unsafe, alternative methods of controlling the white tail need to be examined. This is not without controversy, however. The anthropomorphizing of the white tailed deer, depicted in the Walt Disney film Bambi, has led to misunderstanding of the role of hunting in curtailing populations of this ecologically destructive mammal. Commonly referred to as the Bambi Syndrome (Cartmill, 1993), people in the suburbs do not always support or understand the need for culling the population (Decker & Gavin, 1997). White-Tailed Deer Impact on Vegetation There have been numerous studies attesting to the negative impact that white tailed-deer have on vegetation and on ecosystem functioning. A common method of evaluating the whitetail’s impact on an ecosystem is through the utilization of deer exclosures; fenced off plots that scientists compare to unfenced plots to fenced plots (Martin, 2006). Exclosure fences have also been used to measure the impact of deer on agriculture; exclosures result in greater masses of high-quality corn produced than in unfenced plots (Stewart, Mcshea, & Piccolo, 2007). The role of white-tailed deer as a keystone species of eastern United States forests (“White-tailed deer management plan,” 2006; Holmes, Curran, & Hall, 2008) is creating alterations in tree density, regeneration, and species composition (Stromayer & Warren, 1997) in a variety of forest types (Royo, Stout, deCalesta, & Pierson, 2010). In the New Jersey pine region, over-browsing is eliminating the Atlantic white cedar (Stromayer & Warren, 1997), a relatively stable tree species that has survived centuries of natural disasters and harvesting, while old growth fir stands are being replaced by spruce trees (Morissette, Lavoie, & Huot, 2009). In riparian areas, regenerative growth is substantially reduced by deer grazing (Opperman & Merenlender, 2000), setting the stage for colonization of invasive species, while studies show that over-browsing within rare maritime holly forests, characterized by the American holly, leads to a change in species composition in which the American holly is replaced by stands of black cherry (Forrester, Leopold, & Underwood, 2006). This alteration is brought about when deer consume nearly all small saplings and vegetation below six feet, leaving a distinctive “browse line” in their wake, which marks the height of vegetation that deer can reach when on their hind legs (“Deer facts,” 2012). The end result is a forest floor devoid of ground cover that deer find palatable. As mature trees die and light gaps open, seedlings of light-tolerant species sprout up, effectively creating an altered state ecosystem (Holmes et al., 2008). Over-browsing of ground cover results in extirpation of sensitive forbs, such as species like Solomon’s Seal (Fletcher et al., as cited by Forrester et al., 2006), and others from the Trillium genus (Augustine & Frelich, 1998). Results of deer exclosure studies indicate that such forbs are slow to recover from over-browsing, often resulting in little or no regeneration (Forrester et al., 2006). 2 Impact on Other Organisms Over-browsing extends beyond tree composition, however, at the expense of other wildlife who depend upon native vegetation (Rossell, Patch, & Salmons, 2007). Nesting birds, for example, are negatively impacted by the removal of critical ground cover (Sterba, 2005). A decline of intermediate canopy-nesting songbirds has been linked to high deer densities with the threshold deer density number existing between 7.9 and 14.9 deer per square kilometer (deCalesta, 1994). Over-browsing also causes shifts in bird species in response to changing vegetation; these shifts are reversible with decreases in deer density (McShea & Rappole, 2000). Deer densities of 20 to 38 deer per square mile have been found to be the threshold for which deer negatively impact forest bird communities within northeastern Pennsylvania (“White-tailed deer management plan,” 2006). Forest Response to Deer Removal Reductions in deer population have mixed results on vegetation regeneration. The synergistic effects of over-browsing, habitat fragmentation, and invasive species are altering the landscape, creating forests consisting primarily of vegetation unpalatable to deer (Holmes et al., 2008). The remaining disturbance-tolerant species, such as the pawpaw (Asimina triloba), American beech (Fagiis grantifolia), and jewelweed (Impatiends capensis), may act to prevent growth of browsesensitive species (Scholl, 2004). Over-browsing is also negatively impacting economically important hardwood species upon which the Pennsylvania timber industry depends are being negatively impacted (McClenahen & Hutnik, as cited by Stromayer, & Warren, 1997). Many studies have concluded that over-browsing by white-tailed deer has resulted in an alternative stable ecosystem that replaces the normal succession usually observed in eastern United States deciduous forests (Stromayer & Warren, 1997), and results in recruitment failure when over-browsing occurs after clear cutting or some other canopy disturbance (Tremblay, Huot, & Potvin, 2007). The altered state is evidence of a system whose normal checks and balances are not functioning properly (Caughley, as cited by Stromayer & Warren, 1997). An alarming pattern present in the literature is that despite deer removal, many forests fail to regenerate as expected. Although ground cover increases following white tailed deer removal, recovery is limited to browse-tolerant species and diversity remained lower than expected (Forrester et al., 2006). Reversal of this trend will only be possible through careful management reforestation of native trees (Holmes et al., 2007). Maintaining a mixed forest whose composition includes oak trees is vital for biodiversity; numerous organisms such as the black bear, mice, and birds rely on its acorns (Roberson, 2007). Although he decline of the economically-important oak is not due to over consumption of acorns by deer (Haas & Heske, 2005), but rather to over-browsing of young oak saplings, a reduction in oak trees will mean fewer acorns, a staple crop of numerous birds as well as the black bear, who depend on the acorns fat to get them through the winter (Roberson, 2007). Deer in the Suburbs Without predation, hunting, or seasonal malnutrition (Piccolo, 2010) to keep deer populations in check, over-browsing by whitetails has spilled into suburban backyards of the northeastern United States. Excess deer numbers in suburban areas result in deer damage that includes destruction of ornamental plants, vehicular collisions involving deer (Green, Askins, & West, 3 1997), and increased rates of Lyme disease (“Reduce deer population,” 2004). Suburban deer populations pose a difficult challenge for wildlife managers (Hanback & Blumig, 1993) since traditional approaches to managing deer, such as recreational hunting, are often rejected by suburbanites who enjoy seeing deer in their neighborhood (Decker, & Gavin, 1987; Campbell, Laseter, Ford, Miller, & Euler 2004). Valley Forge National Park The detrimental effect of a whitetail population existing beyond its carrying capacity can be easily witnessed at Valley Forge National Park. Valley Forge, home to the Continental Army and George Washington during the winter of 1977-1778, consists of 3500 acres situated in Montgomery County, Pennsylvania; an affluent and densely populated suburb of Philadelphia. Although its main mission is to protect a historical area and to educate the public regarding the area’s history, the size of Valley Forge National Park makes it a significant island for biodiversity within an otherwise overly developed and fragmented area (“Valley Forge,” 2007; “Animals,” 2006). A glance at the wood line at Valley Forge reveals the distinctive browse line created by overbrowsing. This line first became apparent in the mid-1990s and coincides with increasing reports of Lyme disease (“White-tailed deer management plan,” 2006). Previous to that, a deer study conducted in 1983 revealed a population of approximately 165-185 animals; a population that was within its carrying capacity as indicated by the excellent habitat condition (Leong & Decker, 2007). Over the last two decades, however, the population has swelled (Lovallo & Tzilkowski, as cited by “White-tailed deer,” 2006). The deer at VFNP present a unique management challenge; hunting is not allowed at national parks, and the deer contained within are managed by the National Park Service rather than the Pennsylvania Game Commission. In response to the need to obtain an accurate estimate of the park’s white-tail deer population and understand their movements, 105 deer were involved in a mark and recapture study which utilized radio telemetry starting in 1997 (“White-tailed deer management plan,” 2006). Understanding deer movement informed park officials about habitat use and effectiveness of proposed management techniques. Findings indicated that 88% of the females stayed within 400 feet of the park boundary and limited their home range to .46 square miles (“White-tailed deer management plan,” 2006). Beginning in 1992, the effect of browsing on long-term vegetation was monitored using (30) 2 meter by 2 meter randomly fenced plots partnered with unfenced plots. Data was collected during four different years over a decade beginning with the year 1993. Findings indicated that unfenced areas contain primarily browse-resistant plants and non-native species, while fenced plots yielded three times the tree seedling density as unfenced plots. Red oak seedlings survived only within fenced areas, and no seedlings of any species between 20 and 59 inches were found in the unfenced plots (Heister et al., as cited by “White-tailed deer management plan,” 2006). The conclusion was that browsing will prevent forest regeneration and decrease habitat quality for lower canopy and ground nesting birds (“White-tailed deer management plan,” 2006). Based on this information, park biologists made the decision to reduce deer numbers within the park, ultimately deciding to employ federal sharp shooters to cull the herd in order to allow adequate tree regeneration of 8,079 seedlings per acre (“Briefing statement,” 2009). 4 VFNP is currently in the second year of a four year lethal reduction phase in which the goal is to reduce the deer population from an estimated 241 deer per square mile (approximately 1277 deer) to somewhere between 31 and 35 deer square mile. This will bring deer numbers to the165185 range; the same number of deer that existed in the park in 1983. Numbers will be reduced through a combination of sharpshooting and capture and euthanasia. Last fall, federal sharpshooters using night vision goggles and high-powered rifles to reduce the deer population by 600; over 18,000 pounds of meat were donated to local shelters. A further reduction of an additional 500 deer is planned for the winter of 2011-12 (“Valley Forge Park officials call,” 2011). Park managers plan to keep the deer within the target range using female birth control if an acceptable one becomes available once four years of lethal control have occurred (“White tailed deer management,” 2006). Employing lethal methods to decrease deer populations is one that has been practiced in other national parks. In 1995, Gettysburg National Military Park decided to use federal sharpshooters to cull deer whose voracious appetite for crops and woods were destroying the historical aura recreated within the park (O’Connell, 1995), although culling was halted for 18 months when an injunction was filed by animal rights activists (Kratzke, 2011). The Grand Teton National Park and other places have resulted in similar controversial hunts involving elk populations whose numbers had outgrown carrying capacity (“National Park Service strives,” 2011). PUBLIC OPINION Arriving at the decision to cull the herd via sharpshooters was not easy given the demographics of the surrounding area since suburbanites are often unfamiliar with hunting or the role that it plays in keeping deer populations in check, and typically prefer non-lethal methods such as transportation and contraceptives (Green, et al., 1997). Viewpoints represented by animal rights groups can make management issues a challenge, and therefore many park managers are fearful of lawsuits (Leong & Decker, as cited by Stewart et al., 2007). Since careful facilitation in which stakeholders are involved is crucial to the process (Shedd, 2000), prior to making the decision to use lethal methods, interviews were held to determine the public opinion regarding the deer situation. Interviewees consistently expressed a positive response to viewing deer within the park (Leong & Decker, 2007). Of those interviewed, known stakeholders understood the complexities of deer management issues best; other interviewees were frequently of the opinion that deer did not need to be managed (“White-tailed deer management plan,” 2006). In accordance with the National Environmental Policy Act, park officials prepared an Environmental Impact Statement and outlined four scenarios for controlling the deer population (Kozlowski, 2011). Park officials involved the public extensively through the use of a website, brochures, public meetings, and numerous briefings to local organizations (“Briefing statement,” 2009). Ultimately, it was decided to target the deer population to 31 to 35 per square mile, a number that can be adjusted given the rate of forest regeneration (“Briefing statement,” 2009). The plan is to initially decrease the population over a period of four years, and then use reproductive control if an acceptable one becomes available; lack of an effective contraceptive 5 would mean that lethal control would continue to occur (“Briefing statement,” 2009). The decision to use lethal methods was one of cost-effectiveness (Stewart, 2007), as other alternatives examined proved too expensive or inefficient. Despite the effort to involve the public, the citizen group CARE, Compassion for Animals (“Care is fighting,” 2009), attempted to halt the deer reduction plan, refuting its effectiveness and claiming that the park’s coyote population was capable of keeping the deer under control, a sentiment was not backed by park officials (“Briefing statement,” 2009). Alternatives Park officials examined a number several management including translocation of the animals, fencing the park, sterilizing the male deer, fencing the entire park, hazing the deer from the park, public hunting, supplemental feeding, translocation, predator reintroduction, the use of repellants, and poisons. The options were rejected on the basis of ineffectiveness, cost, human safety, or difficulty (“White-tailed deer management plan,” 2006). Other alternatives were seriously examined prior to the decision to use lethal methods. The first was to take no action and allow predators to maintain the population. This was ultimately rejected because studies indicate that coyotes are ineffective at effectively controlling deer (Kozlowski, 2011). Since immunocontraception is the most widely used non-lethal population control method and has the best potential for use in urban environments (Blumstein, 2011), the use of contraceptives was also critically examined as studies have shown that the whitetail’s high site fidelity make it a viable method of population control because immigration is unlikely to increase local populations. Furthermore, habituated deer, such as the deer at VFNP, are relatively easy to dart. Ultimately, the use of contraceptives was rejected due to difficulties such as distinguishing treated and untreated females, the necessity of treating deer one year with follow-up treatment the next year and the difficulty in developing a viable delivery method since contraceptive-laced baits can be harmful to other wildlife or even to humans who consume deer who have fed upon contraceptive bait (Rutberg et al., 2004; Hanback & Blumig, 1993). Educating the public regarding the issues associated with contraceptives is important; the public often does not understand the cost of this method or the difficulties of effective application (Green, 1997). A third option examined was to fence the park; this option would not address issues with overbrowsing and was rejected due to the high cost associated with installing, monitoring, and maintaining an 8 feet fence for the 3500 acre park (Blumstein, 2011). Additionally, public access to the park would be impacted and fencing would destroy to historical image that the park projects (Blumstein, 2011). The Role of Education People in the suburbs often view deer as valued wildlife, often choosing to feed deer which is a problem for a number of reasons (McCullough; McNay; as cited by Leong, & Decker, 2007). Deer quickly become habituated and the carrying capacity artificially increases, leading to habitat degradation (Green et al., 1997). Although the deer at VFNP were not fed by local people (Leong, & Decker, 2007), educating people about the issues with feeding deer is an important 6 role in keeping deer populations in check. It is currently legal to feed deer in PA up to 30 days prior to hunting season, although the Game Commission discourages it (“Please don’t feed the deer,” n.d.) Many residents do not realize the harm they are doing by feeding deer (Chunko, 2010) or that they could cause a deer’s death through acidosis, a condition in which the pH level falls dramatically and the animal dies of shock shortly after consuming corn (“PGC wildlife veterinarian,” 2012). The use of lethal methods to control suburban deer populations is both controversial and political due to animal rights groups who feel deer need protection (Girard; Curtis; Decker & Richmond, as cited by Green et al., 1997). Since the public plays an important role in managing suburban populations, education must play a role in order to garner support for lethal management techniques (Decker & Gavin, 1987) and to inform the public about the costs and consequences of deer management (Green et al., 1997). Part of the public outrage over the lethal management techniques used at VFNP may be due to a lack of knowledge regarding management techniques. Although the decision to use lethal methods to control deer on at VFNP was undertaken with great angst, it is a decision that will surely be repeated in coming years as communities up and down the eastern seaboard come to terms with the controlling the once-threatened and now prolific whitetail in order to preserve deciduous forests for future generations. References Adams, K. (2010). QDMA in Pennsylvania: One year later. Retrieved from http://www.qdma.com/what-we-do/articles/herd-management/qdma-in-pennsylvania/ Animals. (2006). 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Gettysburg plans defy controversy: NPS contends with deer, land swap, and new museum. The Free Library. Retrieved from http://www.thefreelibrary.com/Gettysburg plans defy controversy: NPS contends with deer, land swap,...-a017534121 Opperman, J. J., & Merenlender, A. M. (2000). Deer herbivory as an ecological constraint to restoration of degraded riparian corridors. Restoration Ecology, 8, 41-47. doi:10.1046/j.1526100X.2000.80006.x Oyer, A. M., & Porter, W. F. (2004). Localized management of white-tailed deer in the central Adirondack mountains, New York. Journal of Wildlife Management, 68, 257-265. Doi:10.2193/0022-541X(2004)068[0257:LMOWDI]2.0.CO;2 Pennsylvania Game Commission. (n.d.). Please don’t feed the deer. Retrieved from http://www.portal.state.pa.us/portal/server.pt/community/deer/11949 PGC wildlife veterinarian to discuss hazards of illegal elk feeding. (January 10, 2012). The Outdoor Wire. http://www.theoutdoorwire.com/story/1326185322b2s80nams2v Piccolo, B. P., Van Deelen, T. R., Hollis-Etter, K. K., Etter, D. R., Warner, R. E., & Anchor, C. C. (2010). Behavior and survival of white-tailed deer neonates in two suburban forest preserves. Canadian Journal of Zoology, 88, 487-495. doi:10.1139/Z10-026 Roberson, M. A. (2007) Acorns: Masters of the Forest. Retrieved from http://nationalzoo.si.edu/Publications/Zoogoer/2007/4/acorns.cfm 9 Rossell Jr., C., Patch, S., & Salmons, S. (2007). Effects of deer browsing on native and nonnative vegetation in a mixed oak-beech forest on the Atlantic coastal plain. Northeastern Naturalist, 14, 61-72. Doi: 10.1656/1092-6194(2007)14[61:EODBON]2.0.CO;2 Royo, A. A., Stout, S. L., deCalesta, D. S., & Pierson, T. G. (2010). Restoring forest herb communities through landscape-level deer herd reductions: Is recovery limited by legacy effects? Biological Conservation, 143, 2425-2434. doi:10.1016/j.biocon.2010.05.020 Rutberg, A. T., Naugle, R. E., Thiele, L. A., Liu, I. K. M. (2004). Effects of immunocontraception on a suburban population of white-tailed deer Odocoileus virginianus. Biological Conservation, 116, 243-251. Doi: 10.1016/S0006-3207(03)00195-2 Scholl, R. (2004, June 13). Reduce deer population, reduce lyme disease. New York Times. Retrieved from http://www.nytimes.com/2004/06/13/nyregion/l-reduce-deer-population-reducelyme-disease-924946.html Shedd, W. (2000). Owls aren’t wise and bats aren’t blind. A naturalist’s debunks our favorite fallacies about wildlife. New York, NY: Three Rivers Press. Sterba, J. P. (2005). How deer are redesigning our forests. National Wildlife, 43(6), 16-18. Retrieved from http://connection.ebscohost.com/c/articles/18455425/how-deer-are-redesigningour-forests Stewart, C. M., Mcshea, W. J., & Piccolo, B. P. (2007). The impact of white-tailed deer on agricultural landscapes in 3 national historical parks in Maryland. Journal of Wildlife Management, 71, 1525-1530. doi:10.2193/2006-351 Stromayer, A. K, & Warren, R. J. (1997). Are overabundant deer herds in the eastern United States creating alternative stable states in forest plant communities? Wildlife Society Bulletin, 25(2), 227-234. Retrieved from http://www.jstor.org/stable/3783436 Suburban Whitetail Management of Northern Virginia. (2012). Deer facts. Retrieved from http://www.deerdamage.org/page/deer-facts Tremblay, J., Huot, J., & Potvin, F. (2007). Density-related effects of deer browsing on the regeneration dynamics of boreal forests. Journal of Applied Ecology, 44, 552-562. doi:10.1111/j.1365-2664.2007.01290.x U.S. Department of the Interior, National Park Service, Valley Forge National Park Service (2009). Briefing statement. Retrieved from http://www.nps.gov/vafo/parkmgmt/upload/VAFO_DEIS_BriefingStmt_2_27_09_final-2.pdf U.S. Department of the Interior, National Park Service, Valley Forge National Park Service (2006). White-tailed deer management plan / environmental impact statement final internal scoping report. Retrieved from 10 http://www.nps.gov/vafo/parkmgmt/upload/Final%20Internal%20deer%20Scoping%20Report.p df Valley Forge National Historical Park Information & History. (2007). Retrieved from http://www.valley.forge.national-park.com/info.htm Valley Forge Park officials call deer cull a success. (2011, April 1). Mainline Media News. Retrieved from http://mainlinemedianews.com/articles/2011/04/01/main_line_suburban_life/news/doc4d94cf679 9f78001603652.txt Appendix Include pictures 11