About

Krysten Schuler is an Associate Research Professor at the Cornell University College of Veterinary Medicine, working within the Department of Public & Ecosystem Health and affiliated with the Cornell Wildlife Health Lab and the Cornell Center for Wildlife Conservation in Ithaca, NY. Her research focuses on infectious and parasitic diseases of free-ranging terrestrial wildlife, with particular expertise in Chronic Wasting Disease surveillance and response, disease risk assessment, geographic epidemiology, and wildlife health database integration. She is actively involved in wildlife health education and contributes to understanding disease dynamics in wildlife populations. Schuler holds a Ph.D. in Biological Sciences with a specialization in Wildlife Sciences from South Dakota State University, a Master’s degree in Wildlife and Fisheries Ecology from Oklahoma State University, and a Bachelor’s degree in Biological Sciences from the University of Notre Dame. Her professional experience includes roles as a Wildlife Disease Ecologist at Cornell’s Animal Health Diagnostic Center, a Senior Extension Associate at Cornell, and a Wildlife Disease Ecologist for the U.S. Geological Survey’s National Wildlife Health Center. Throughout her career, she has received numerous awards, including the Wildlife Society Fellows Award, the Outstanding Professional award from the New York State Chapter of The Wildlife Society, and recognition from the National Deer Association. Her work has contributed significantly to wildlife disease ecology, epidemiology, and conservation efforts.

Research topics

• Ecology
• Biology
• Demography
• Genetics
• Zoology
• Medicine
• Geography
• Pathology
• Environmental science
• Physical therapy
• Virology
• Gerontology

Selected publications

• HEALTH STATUS AND DRIVERS OF ENDOPARASITE INFECTION IN A LOW-DENSITY MOOSE (ALCES ALCES) POPULATION

  Journal of Wildlife Diseases · 2026-04-20

  articleSenior author

  At their southern range limits in North America, moose (Alces alces) experience increased overlap with white-tailed deer (Odocoileus virginianus) and associated parasites through shared habitat use. Moose persist at low densities in New York state, USA, and are incidental hosts to multiple pathogenic endoparasites. Understanding the contributions of endoparasitism to moose morbidity and mortality requires investigation into their health status and drivers of parasite infection. We summarized health data from 60 live-captured and 191 opportunistically necropsied moose (spanning 2000-23) and used generalized linear modeling to assess the determinants of moose infection by giant liver fluke (Fascioloides magna) and meningeal worm (Parelaphostrongylus tenuis). Despite 98% of live moose having good or excellent body condition, 75% were potentially infected with at least one internal parasite species. Hematologic analyses of live moose indicated elevated eosinophil and lymphocyte counts. Infestations with winter tick (Dermacentor albipictus) were common on live-captured New York moose (74%), although intensities were considerably lower than on moose in neighboring states. Necropsied moose were commonly infected with F. magna and P. tenuis, but most often succumbed to trauma from vehicle collisions. Density of white-tailed deer, definitive host to both endoparasites, was the primary driver of P. tenuis infection in moose. For F. magna, moose age and sampling year were positively associated, whereas deer density and road density were negatively associated with moose infection probability. Limiting deer densities in core moose areas may help reduce the risk of P. tenuis infection, and targeted management efforts could promote resilience of small moose populations to multiple parasites.

  PublisherDOI

• Exploring management options for moose at their southern range limits considering growing disease risk

  Ecological Solutions and Evidence · 2026-04-01

  articleOpen access

  Abstract Populations of cold‐adapted species are increasingly vulnerable along their lower latitude range limits due to shifting environmental conditions, biotic interactions and anthropogenic pressures. Managing these populations is particularly challenging because of complex ecological dynamics, conflicting stakeholder interests and decision‐making under uncertainty. We explored population growth ( λ ) of moose ( Alces alces ) under different hypothetical management scenarios, simulating combinations of five hypothetical harvest levels with three levels of disease impact. Facing current disease limitations, the population could support multiple levels of conservative harvest. We projected increased λ across all harvest scenarios when overlap with white‐tailed deer ( Odocoileus virginianus ) was hypothetically reduced and disease mortality in moose minimized. However, under elevated levels of disease‐caused mortality, projections indicated declines across all harvest scenarios. We further observed that changes in adult fecundity and calf survival could alter harvest decisions when λ < 1. Practical implication . While moose population trajectories may remain stable under current conditions, management of white‐tailed deer that reduces moose exposure to lethal parasites may provide the greatest utility in sustaining moose in New York given the potential for increased disease. Continued monitoring of population size, growth and disease prevalence would inform sustainable moose harvest levels that balance social and ecological management considerations.

  PublisherDOI

• Environmental contaminants assessment for frequently harvested migratory waterfowl in the Northeast Atlantic flyway

  The Science of The Total Environment · 2025-01-15 · 2 citations

  articleOpen accessSenior authorCorresponding

  Waterfowl serve as indicators of ecosystem health and represent a pathway of contaminant exposure for hunters who consume them. In the northeast Atlantic Flyway, data on baseline contaminant loads in waterfowl are lacking. We assessed five species of commonly harvested (and consumed) waterfowl for mercury, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and per- and polyfluoroalkyl substances (PFAS). We found that Canada geese (Branta canadensis) and wood ducks (Aix sponsa) had lower contaminant burdens than mallards (Anas platyrhynchos), American green-winged teal (Anas carolinensis), and American black ducks (Anas rubripes). Regardless of species, all samples contained detectable levels of PCBs and at least one OCP and PFAS. Mercury and OCPs posed limited non-cancer risks to human consumers who follow current waterfowl consumption advisories. Based on a probabilistic risk assessment, lower consumption rates were required to reduce risks from PCBs compared to other contaminants. Protective human consumption advisories depend in part on the level of allowable cancer risk and whether contaminants were considered toxicologically to act individually or collectively. Accordingly, revisions to consumption advisories to protect public hunter health given these new data hinge upon risk management decisions. These data can be used to update waterfowl consumption advisories in the northeast Atlantic Flyway and inform future research into the health effects of legacy and contemporary contaminants on the sustainability of waterfowl populations.

  PublisherDOI

• A “hazard model” using risk-weighted surveillance for first detection of chronic wasting disease

  Preventive Veterinary Medicine · 2025-06-20 · 1 citations

  articleOpen access1st authorCorresponding

  Surveillance for emerging diseases can be enhanced through incorporation of risks and hazards to identify areas on the landscape with higher likelihoods of disease introduction and spread while increasing confidence that samples are collected from locations and animals with the highest probability of disease detection. A primary example of this situation is wildlife surveillance programs for chronic wasting disease (CWD) in free-ranging white-tailed deer (Odocoileus virginianus) in jurisdictions where it is not yet known to exist. But knowledge gaps in areas that lack sufficient disease testing and the nonexistence of data depicting disease introduction risks have impeded the ability to detect disease at the earliest intrusion into wild herds. We developed a novel method to conduct wildlife disease surveillance by considering how disease introduction likelihood may increase in the presence of risk factors, such as certain human activities and dense deer populations. In the absence of empirical risk data, we solicited perceptions from subject matter experts to develop a risk assessment (survey) characterizing the likelihood of disease introduction from anthropogenic activities. We overlaid these summarized perceptions with independent harvest data on the demographic attributes of wild cervid herds. We further incorporated previously published surveillance weights representing the differential disease information gained by testing each age/sex segment of deer. We applied the resulting surveillance design ('Hazard Model') in New York during the 2013-2014 hunting season and in Tennessee during the 2018-2019 hunting season. In both states, the Hazard Model suggested that counties with large deer populations, high-risk cervid businesses, or those in close proximity to infections in neighboring states were at greatest risk for introduction of CWD and therefore should be sampled with the greatest intensity. After a brief outbreak of CWD in New York in 2005, wildlife officials in New York did not re-discover CWD in their state, while officials in Tennessee discovered their first case of CWD within four months. The Hazard Model was developed with logistics and constraints as primary considerations, so implementation is sufficiently flexible to accommodate specific operational needs of the wildlife agency.

  PublisherDOI

• Development of High‐Throughput Genomic Resources to Inform White‐Tailed Deer Population and Disease Management

  Molecular Ecology Resources · 2025-11-26 · 1 citations

  articleOpen access

  White-tailed deer (Odocoileus virginianus) are the most abundant and widespread cervid in North America. Genetic data are used as a tool to monitor populations and make management decisions for this game species. However, the development and use of genomic tools that can generate a set of markers suitable for longitudinal genomic data collection, whether for management purposes or to study the demographic and evolutionary processes of widely distributed species, have been challenging. This is mainly due to the cost required to fully implement and interpret the data produced. Here, we generated whole genome resequencing data for 44 free-ranging deer from three regions in their central and eastern North American range and identified over 89 million single nucleotide polymorphisms (SNPs). We used a subset of these SNPs to develop two nested SNP tools, a high-density array (702,183 SNPs) and a medium-density array (72,723 SNPs) to support deer and chronic wasting disease (CWD) management and research. SNPs were selected to ensure an even distribution across scaffolds of the reference genome and include SNPs associated with CWD susceptibility. Using genotyping results for 469 deer from 15 states in the US and Mexico generated by the high-density array and 1335 deer from 18 states generated by the medium-density array, we assessed genotyping success across different populations and explored some insights into population structure. These genomic tools offer a standard set of markers that will enable researchers and managers to address important questions related to white-tailed deer and CWD management. Our SNP arrays also offer the opportunity to examine aspects of white-tailed deer ecology and evolutionary history that were previously difficult to address.

  PublisherOA PDFDOI

• Parasite‐Mediated Competition Limits Dominant Cervid Competitor

  Ecology Letters · 2025-06-01 · 3 citations

  articleOpen access

  Species interactions structure ecological communities through direct and indirect pathways with ecosystem-wide implications. Despite mounting interest in the importance of indirect interactions, empirical evidence remains limited. Here, we demonstrate the critical role of parasite-mediated competition in driving community outcomes in a multi-species system of conservation and management concern. We leveraged 2 years of detection/non-detection data of moose (Alces alces) and white-tailed deer (Odocoileus virginianus) and parasite loads in faecal samples within a hierarchical abundance-mediated interaction model to test hypotheses regarding interactions between these cervids and their shared parasites (Parelaphostrongylus tenuis, Fascioloides magna). We demonstrate that moose occupancy was limited by parasite-mediated competition, with no evidence of population-level effects of direct competitive interactions between moose and white-tailed deer. Such evidence of the importance of indirect interactions and resulting community outcomes is critical for species conservation and managing range contractions due to increasing pressures from habitat loss, disease and climate change.

  PublisherOA PDFDOI

• Spatiotemporal drivers of rodenticide exposure in a mammalian forest carnivore

  The Science of The Total Environment · 2025-05-14

  articleOpen accessSenior author

  Anticoagulant rodenticide (AR) use carries a risk to wild carnivores via secondary consumption of toxic prey, specifically via coagulopathy which can result in morbidity or mortality. Though proximity to urban development often correlates with increased exposure in non-target wildlife, outdoor use of AR products in more rural settings can also contribute to secondary exposures, though point sources are difficult to identify. For fishers (Pekania pennanti), we suspected that alternate-year pulsed resources (e.g., mast seeding), known to drive irruptions in small mammal abundance in densely forested systems, would influence AR exposure, especially where human densities are high. We further suspected AR exposure might increase over time independent of the masting and that fisher age and sex would influence AR exposure given differential patterns of space use. We quantified AR exposure in legally harvested fishers (n = 338) sampled across a gradient of forest coverage across New York State between 2018 and 2020. We detected between 1 and 5 AR compounds in 83 % of sampled fishers, with the rate of detection of at least one compound increasing by approximately 8 % per year. We modeled the total number of compounds detected and the probability of exposure to each of the three most-detected compounds as a function of fisher sex, age, and spatial covariates. Adult fishers (3-4 years-old) and males had the highest exposure. The odds of exposure to bromadiolone increased 4 % for a unit increase in the previous year beech seed production relative to the long-term mean-equal to 2.6× the long-term average, an impact that appears small relative to the high background rate of exposure owing to the apparently ubiquitous use of ARs across the landscape. A better understanding of patterns of AR use, as well as how these patterns interact with ecological processes, will be important to mitigate exposure of non-target wildlife.

  PublisherDOI

• Author response for "Parasite-Mediated Competition Limits Dominant Cervid Competitor"

  2025-05-05

  peer-review
  PublisherDOI

• Author response for "Exploring management options for moose at their southern range limits considering growing disease risk"

  2025-12-20

  peer-review
  PublisherDOI

• Management Agencies can Leverage Animal Social Structure for Wildlife Disease Surveillance

  Journal of Wildlife Diseases · 2025-05-16 · 1 citations

  articleSenior author

  Wildlife agencies are tasked with sustaining healthy wildlife populations. Advances in understanding health in wildlife, are, however, suppressed by issues with surveillance. Cost and logistical complexity are leading reasons why ideal surveillance implementation is often infeasible. A particularly important issue in surveillance is the sample size necessary to declare a local wildlife population (or social group) disease free. More precisely, how many animals must we sample to conclude with high confidence that prevalence of an infectious disease is below a specified threshold? Here we show that the answer to this question hinges on the ease of transmission between animals, a factor not considered in standard sample-size formulas. When disease statuses of animals in a local population are positively correlated, such as when a species forms social groups, the sample size requirement needed to declare freedom from disease is substantially lower relative to sample sizes suggested by existing hypergeometric and binomial models. Local wildlife populations or social groups must satisfy key properties for scientists to leverage this saving, but a reduction in cost arising in such a scenario is a welcome win in surveillance implementation.

  PublisherDOI

Frequent coauthors

• Nicholas Hollingshead

  Cornell University

  66 shared

• María J. Forzán

  Long Island University

  56 shared

• David B. Needle

  University of New Hampshire

  54 shared

• Edward J. Dubovi

  53 shared

• Julie C. Ellis

  University of Pennsylvania

  52 shared

• Patrick Tate

  New Hampshire Fish and Game Department

  50 shared

• Chris Bernier

  Vermont Fish & Wildlife Department

  50 shared

• Rebecca P. Wilkes

  49 shared

Education

• PhD, Natural Resources

  South Dakota State University

  2006

• MS, Wildlife and Fisheries Ecology

  Oklahoma State University

  2002

• BS

  University of Notre Dame

  1998

Awards & honors

• Outstanding Professional, The New York State Chapter of The…
• National Deer Association’s Professional Deer Manager of the…
• The Wildlife Society Fellows Award (2021)
• Certificate of Appreciation, WHISPers Partner Work Team, U.S…
• Honorary Member, The Society of Phi Zeta, Honor Society of V…