USGS Science⌕ Search

USGS · 5223819

Of elephants and blind men: Deer management in the U.S. National Parks

Abstract

Overabundant populations of white-tailed deer ( Odocoileus virginianus ) are becoming common in the eastern United States. Faced with burgeoning deer populations in eastern parks, the National Park Service (NPS) formulated policy based on its long experience with ungulate management in western parks. That the NPS failed to find a management solution acceptable to its many constituencies was inevitable. Like blind men touching different parts of an elephant and disagreeing about its form, those engaged in the debate about deer management in parks are viewing different parts of the ecological system. None has seen the entire system, and consequently, there is neither common agreement on the nature of the problem nor on the solutions. We explore the quandary of deer management in eastern parks by addressing three questions: (1) Can the National Park Service reconcile its management goals with those of its neighbors? (2) Can thresholds be identified for determining when to intervene in natural processes? (3) Is there a scientific foundation for proceeding with effective management of deer? We argue that reconciling the NPS management with that of state conservation agencies is not possible because management policy guides these agencies in opposite directions: the NPS is charged with limiting human impact on ecological processes, and state agencies are charged with exerting human control over population abundance. Questions about thresholds and a scientific basis for management arise from concern that irrupting deer populations are a manifestation of disrupted natural processes. Several population growth paradigms are at the heart of this ecological question. The science provides no consensus about which of these paradigms are appropriate to deer in eastern ecosystems. Thus, it is premature to expect science to identify if or when natural processes have been disrupted. While the NPS cannot effectively achieve its goals without better science, neither can it wait for science to fully understand the dynamics of plant–herbivore interactions. The best hope for resolving both the biological and political dilemmas surrounding deer management is through an adaptive management approach.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

W.F. Porter, H. Brian Underwood. 1999. Of elephants and blind men: Deer management in the U.S. National Parks. https://doi.org/10.1890/1051-0761(1999)009%5B0003%3Aoeabmd%5D2.0.co%3B2

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

Malady in motion: Chronic wasting disease effects on host movement

Pathogens can have significant impacts on host movement and behavior with consequences for ongoing transmission. For example, chronic wasting disease (CWD) causes severe nutritional deficiencies and neurologic changes, which may alter white-tailed deer ( Odocoileus virginianus ) movement and subsequent transmission risk. Our objectives were to test for changes in movement and habitat selection in deer affected by CWD, and determine the timing of any changes we observed. We leveraged comprehensive movement and mortality data from a large study of free-ranging deer in southwest Wisconsin, a region with high prevalence of CWD. We used necropsy data to identify end stage CWD cases with movement data leading up to death ( n = 44), and sex-, date-, and age-matched test-negative controls. Using GPS collar data, we identified extra-home range excursions and tested for differences in excursion rates, distances, and durations between cases and controls. We evaluated movement characteristics (e.g., movement rates, weekly range sizes) and habitat selection for the two groups, using change point analysis to determine when behavior changes occurred during disease progression. Excursion distances were reduced for CWD cases but were otherwise largely unaffected by infection status. However, CWD cases moved at slower rates and maintained smaller ranges than controls. Habitat selection varied minimally between cases and controls, though CWD cases had an increased preference for proximity to forest edges. While changes in case movement rates and range sizes were detected at or before 6 months prior to death, other movement and habitat selection changes appeared about 2 months prior to death. In addition, CWD cases were frequently in good body condition even within 6 months prior to death, implying that clinically apparent changes occur very late in the disease progression. Our results suggest the occurrence of subclinical and clinical phases of infection, beginning around 6 and 2 months prior to death, respectively. Public communication may therefore benefit from emphasizing that CWD-infected deer are infectious long before they appear sick. Further, because most movement changes occur for very short periods relative to the infectious period of CWD, typical healthy deer movement is likely adequate for representing transmission dynamics for surveillance and management planning.

Wisconsin↗

Improving predictions of insect harassment for barren-ground caribou in the Arctic

Many populations of barren-ground caribou ( Rangifer tarandus ) have declined or are declining, which is concerning given their ecological role in Arctic ecosystems and their societal role in northern communities. Insect harassment is an important driver of the behavior, energetics, and demographic rates of caribou, and yet, due to challenges in predicting harassment, there is limited understanding of how it is responding to changing Arctic conditions. We investigated environmental correlates of mosquito (Culicidae) and oestrid fly (Oestridae) harassment for the Porcupine caribou herd, with the aim of improving our ability to predict harassment. We collected field observations of mosquito activity and used video collars to detect oestrid fly activity across the summer range, which spans the Alaska–Yukon border. Additionally, we documented the composition of harassing insects collected in malaise traps using DNA metabarcoding. We developed predictive mosquito and oestrid fly harassment models using remotely sensed variables relevant to the insects' biology within a nonlinear modeling framework. We then used the top mosquito and oestrid fly models to hindcast predictions of harassment during 1950–2024 and investigate long-term changes in severity and phenology. The top mosquito harassment model included wind speed, temperature, days since snowmelt, precipitation, topographic position, and soil moisture. The top oestrid fly harassment model included temperature, cumulative growing degree days, and time of day. Harassment of both insects was limited at low temperatures (<10°C), with mosquitoes being additionally limited at high temperatures (>22°C) and wind speeds (>7 m/s). The phenology of mosquito and oestrid fly harassment exhibited curvilinear trends across the summer, peaking in midsummer based on the number of days since snowmelt and cumulative growing degree days, respectively. Mosquito harassment also increased with greater soil moisture, precipitation, and at lower relative elevations. Hindcasting indicated that insect harassment notably intensified and advanced over time. Intensifying harassment could decrease caribou foraging opportunities and body condition, and advancing harassment is likely to increasingly overlap with the calving season when calves are most vulnerable. Our results highlight climate-driven changes in insect harassment and provide improved indices for predicting harassment in the Arctic for future applications.

Alaska↗

Application of close-kin mark–recapture to an American black bear population using harvest samples

Close-kin mark–recapture (CKMR) offers a promising alternative to traditional mark–recapture methods for estimating wildlife population parameters. CKMR estimates demographic parameters by identifying genetic relationships between individuals, effectively “recapturing” parental genotypes through their offspring's genetic profiles. One key advantage of CKMR over traditional methods is the ability to estimate abundance without recapture, facilitating the use of lethally collected biological samples. Here, we present an application of CKMR to a terrestrial species using samples collected from harvested individuals. We analyzed genetic data from 1767 American black bears ( Ursus americanus ) harvested over two consecutive years in Michigan's Upper Peninsula. Using Genotyping-in-Thousands by sequencing (GT-seq), we identified parent-offspring pairs and developed sex-specific models tailored to black bear reproductive biology and management strategies. Female population estimates aligned with our expectations, based on prior knowledge of the population. In contrast, male population estimates deviated from expectations, potentially due to an unmodeled combination of factors pertaining to male reproductive biology and sampling bias. Our study not only demonstrates the viability of using harvest-based CKMR for monitoring of terrestrial wildlife populations, but also highlights the need for careful model specification. By providing a novel method to estimate demographic parameters and population size, CKMR using harvest samples can inform management decisions and harvest quotas. This approach leverages existing management practices involving collection of genetic samples, such as mandatory harvest registrations and health monitoring programs. Our findings contribute to the growing body of CKMR applications and expand its use to terrestrial species management.

Michigan↗