About

John Orrock is the principal investigator (PI) of the Orrock Lab at the University of Wisconsin–Madison. The lab focuses on ecological interactions at the intersection of spatial ecology, global change, and behavioral ecology. The research conducted under his leadership aims to understand how these ecological factors interact and influence each other in natural systems. The Orrock Lab is part of the Department of Integrative Biology at UW–Madison, and John Orrock can be contacted via email at jorrock@wisc.edu for further information or inquiries related to his research and lab activities.

Research topics

• Geography
• Ecology
• Environmental science
• Biology
• Cartography
• Meteorology
• Agroforestry
• Demography
• Zoology
• Environmental resource management

Selected publications

• Environmental variability affects individual variation in activity onset at large geographic scales

  Behavioral Ecology · 2026-01-22 · 1 citations

  articleSenior author

  Abstract Timing is an essential component of the phenotype, influencing individual fitness and shaping ecological interactions. Although variation in the timing of activity can be substantial, the degree to which this variation stems from within-individual variation vs. among-individual variation is poorly understood and represents a key knowledge gap with distinct ecological and evolutionary implications. Within-individual variation in timing may allow individuals to adjust to unfamiliar or shifting cues, while consistent among-individual variation in timing may lead to maladaptive behavior in novel conditions (eg, light pollution or novel predators). We estimated activity onset from 821 captures of 254 individual white-footed mice, Peromyscus leucopus, across the upper Midwest, Northeast, Mid-Atlantic, and southern Appalachia regions of the United States. In each locale, we quantified the total phenotypic variation in activity onset and partitioned this into its within- and among-individual components. We then examined whether environmental factors, such as variable climate or habitat structure, influenced these components of variation. We found that within-individual variation in timing consistently exceeded among-individual variation, and individuals from populations at cooler, drier sites with seasonal fluctuations in precipitation and temperature exhibited more within-individual behavioral variation than mice at warmer, wetter sites with less seasonal change. Neither within- nor among- individual variation was significantly associated with habitat structure heterogeneity. Our results reveal that most variation in timing across this species’ range derives from within-individual variation and suggests that individuals may have the capacity to adjust the timing of activity onset in response to local conditions.

  PublisherDOI

• Woody seeds and seedlings are unresponsive to herbivore kairomones

  AoB Plants · 2026-02-25

  articleOpen access

  Abstract Herbivory is particularly threatening to young plants that lack the resources needed to survive an attack. Seeds and seedlings should thus benefit greatly from using pre-attack cues to induce defence before damage. Locomotion mucus from slugs, generalist herbivores that consume young plants, has been shown to speed germination, slow growth, and increase both chemical defences and resistance to herbivores in several herbaceous plants. Whether woody species exhibit similar responses has not been tested. Arion subfuscus, an invasive slug in the eastern USA, is a major herbivore of young sugar maples (Acer saccharum); we explored the effect of its locomotion mucus on Ac. saccharum seeds and seedlings. We exposed sugar maple seeds and seedlings to mucus and measured germination speed and rate, seed susceptibility to slugs, seedling emergence, growth, chemical defences, and foliar susceptibility to Lymantria dispar and Ar. subfuscus. Contrary to our expectations and previous findings with herbaceous species, we found that mucus had no effect on these performance or resistance traits. Habituation to repeated cue exposure or the limited coevolutionary history between Ac. saccharum and Ar. subfuscus could be the reason for the lack of an observed response by the plants. Further studies should investigate the effects of kairomones using a short-term cue exposure procedure or by using a woody plant species and native slug herbivore with a coevolutionary history. Understanding how woody plants respond to kairomones would provide insight into the risk and defence strategies used by long-lived species in crucial early life stages.

  PublisherOA PDFDOI

• Correction: Herbivore cues and plant damage-associated compounds jointly alter seed germination and seedling herbivory

  Oecologia · 2026-02-01

  articleOpen access
  PublisherOA PDFDOI

• Congeneric Rodents Differ in Immune Gene Expression: Implications for Host Competence for Tick‐Borne Pathogens

  Journal of Experimental Zoology Part A Ecological and Integrative Physiology · 2025-01-27 · 1 citations

  articleOpen access

  Mice in the genus Peromyscus are abundant and geographically widespread in North America, serving as reservoirs for zoonotic pathogens, including Borrelia burgdorferi (B. burgdorferi), the causative agent of Lyme disease, transmitted by Ixodes scapularis ticks. While the white-footed mouse (Peromyscus leucopus (P. leucopus)) is the primary reservoir in the United States, the deer mouse (P. maniculatus), an ecologically similar congener, rarely transmits the pathogen to biting ticks. Understanding the factors that allow these similar species to serve as a poor and competent reservoir is critical for understanding tick-borne disease ecology and epidemiology, especially as climate change expands the habitats where ticks can transmit pathogens. Our study investigated immunological differences between these rodent species. Specifically, we compared the expression of six immune genes (i.e., TLR-2, IFN-γ, IL-6, IL-10, GATA-3, TGF-β) broadly involved in bacterial recognition, elimination, and/or pathology mitigation in ear biopsies collected by the National Ecological Observatory Network (NEON) as part of their routine surveillance. A principal components analysis indicated that immune gene expression in both species varied in two dimensions: TLR2, IFN-γ, IL-6, and IL-10 (comprising PC1) and TGF-β and GATA3 (comprising PC2) expression tended to covary within individuals. However, when we analyzed expression differences of each gene singly between species, P. maniculatus expressed more TLR2, IL-6, and IL-10 but less IFN-γ and GATA3 than P. leucopus. This immune profile could partly explain why P. leucopus is a better reservoir for bacterial pathogens such as B. burgdorferi.

  PublisherOA PDFDOI

• Deer Vigilance and Movement Behavior Are Affected by Edge Density and Connectivity

  Ethology · 2025-05-19 · 3 citations

  articleOpen accessSenior authorCorresponding

  ABSTRACT Animal behavior is an important component of individual, population, and community responses to anthropogenic habitat alteration. For example, antipredator behavior (e.g., vigilance) and animal movement behavior may both be important behavioral responses to the increased density of habitat edges and changes in patch connectivity that characterize highly modified habitats. Importantly, edge density and connectivity might interact, and this interaction is likely to mediate animal behavior: linear, edge‐rich landscape features often provide structural connectivity between patches, but the functional connectedness of patches for animal use could depend upon how edge density modifies animal vigilance and movement. Using remote cameras in large‐scale experimental landscapes that manipulate edge density (high‐ vs. low‐density edges) and patch connectivity (isolated or connected patches), we examined the effects of edge density and connectivity on the antipredator behavior and movement behavior of white‐tailed deer ( Odocoileus virginianus ). Deer vigilance was 1.38 times greater near high‐density edges compared to low‐density edges, regardless of whether patches were connected or isolated. Deer were also more likely to move parallel to connected high‐density edges than all other edge types, suggesting that connectivity promotes movement along high‐density edges. These results suggest that increases in edge density that accompany human fragmentation of existing habitats may give rise to large‐scale changes in the antipredator behavior of deer. These results also suggest that conservation strategies that simultaneously manipulate edge density and connectivity (i.e., habitat corridors) may have multiple effects on different aspects of deer behavior: linear habitat corridors were areas of high vigilance, but also areas where deer movement behavior implied increased movement along the habitat edge.

  PublisherOA PDFDOI

• Promoting acorn survival using capsaicin seed coatings is strengthened by the removal of invasive shrubs

  Restoration Ecology · 2025-03-21 · 1 citations

  articleOpen accessSenior author

  Promoting regeneration of native trees, like Quercus spp., is a priority for land managers given the ecological and economic importance of oak woodlands. Although direct seeding may promote recruitment of Quercus spp., the effectiveness of direct seeding may be greatly reduced in environments where the activity of granivorous rodents is high. Importantly, the activity of granivorous rodents may be highest in environments where oak restoration is most desired, such as habitats invaded by non‐native woody shrubs. Implementing chemical deterrents to granivory should promote direct seeding success; yet it is essential to understand if those deterrents are effective in challenging restoration situations (e.g. areas with dense invasive shrub cover). Moreover, it is important to determine whether chemicals that deter granivory have undesired effects on beneficial ecological interactions, such as animal‐mediated seed dispersal. We used multi‐field site experiments in shrub‐invaded and shrub‐cleared forest plots to compare the removal and dispersal of Quercus rubra acorns with seed coats treated with a pepper‐based capsaicin extract versus acorns treated with control solutions (i.e. water and ethanol). Seed removal was quantified for 37 days, and seed survival and dispersal were quantified by relocating nail‐tagged acorns after 8 weeks. We found that capsaicin‐treated seeds had a significantly higher probability of survival compared to seeds treated with control solutions; the presence of the invasive shrub Rhamnus cathartica increased post‐dispersal seed consumption regardless of seed‐coat treatment; capsaicin did not affect acorn dispersal distance; and the concentration of capsaicin coatings on acorns declined over time in the field.

  PublisherOA PDFDOI

• Phylogenetics of Channel Island Deer Mice Based on the Cytochrome B Gene Sheds Light on Multiple Colonization Events and Supports Current Taxonomy

  Western North American Naturalist · 2025-07-15

  article

  El complejo de especies Peromyscus maniculatus es un grupo diverso de América del Norte que comprende varios linajes de amplia distribución, así como formas endémicas insulares, incluidos los ratones ciervo de las Islas del Canal (Channel Islands). En este estudio se analizan secuencias completas del gen mitocondrial citocromo b de 75 ratones provenientes de las ocho Islas del Canal de California, con el objetivo de comprender mejor sus orígenes y analizar, por primera vez, la posición filogenética de los ratones ciervo insulares en un contexto más amplio del grupo de especies P. maniculatus. Recuperamos un clado, con buen soporte, de P. gambelii (Baird 1858) que incluye ratones de las Islas del Canal del Norte (Anacapa, Santa Cruz, Santa Rosa y San Miguel), así como de las islas Santa Bárbara y San Nicolás. Los patrones resultantes de estructura genética indican procesos biogeográficos naturales en las Islas del Canal del Norte y sugieren una posible translocación hacia la isla San Nicolás a través de las rutas comerciales de los Chumash. Es notable que las islas Santa Catalina y San Clemente podrían representar colonizaciones independientes a partir de este clado de seis islas, mostrando señales de conectividad entre sí y con el continente. La recuperación de clados de ratones insulares no anidados, divergentes entre un 0.98% y un 1.08% del clado continental central de P. gambelii, resulta sorprendente dada su supuesta reciente historia evolutiva (∼11,000 años) en las Islas del Canal, según la evidencia arqueológica. Proponemos que los genomas mitocondriales de la mayoría de los ratones ciervo de las Islas del Canal podrían haberse originado a partir de un haplogrupo continental antiguo y actualmente escaso de P. gambelii, que también podría haber colonizado otras islas de California. Nuestros resultados también corroboran la asignación de todas las subespecies a P. gambelii, según la taxonomía más reciente propuesta, aunque esta clasificación sigue siendo un área de investigación activa y sin consenso.

  PublisherDOI

• Environmental variability affects flexibility in activity onset at large geographic scales

  Open MIND · 2025-10-13

  datasetSenior author

  Timing is an essential component of the phenotype, influencing organism fitness and fundamentally shaping ecological interactions. Although variation in the timing of activity can be substantial, the degree to which this variation stems from behavioral flexibility (within-individual variation) vs. consistent behavioral differences (among-individual variation) is poorly understood and represents a key knowledge gap as these have different ecological and evolutionary implications. Whereas flexibility in timing may be advantageous in novel circumstances, individuals could also make mistakes. Alternatively, consistent among-individual differences in timing may lead certain individuals to exhibit maladaptive behavior when confronting novel conditions (e.g., light pollution or novel predators). We estimated activity onset from 1050 captures of 483 individual white-footed mice, Peromyscus leucopus, across the upper Midwest, Northeast, Mid-Atlantic, and southern Appalachia regions of the United States. In each locale, we quantified the total phenotypic variation in activity onset and partitioned this into its within- and among-individual components. We then examined whether mice at locations experiencing more variable climate or residing in more structurally variable habitats exhibited differences in within- or among-individual variation in timing. We found that timing flexibility was always greater than consistency, and individuals from populations at cooler, drier sites with variable seasonal precipitation and temperature were more flexible than mice at warmer, wetter sites with less seasonal change in precipitation and temperature. Behavioral flexibility was not significantly associated with habitat structure heterogeneity. Our results reveal that most variation in timing across the range of this species derives from within-individual variation.

  DOI

• Herbivore cues and plant damage-associated-compounds jointly alter seed germination and seedling herbivory

  Research Square · 2025-07-22

  preprintOpen access
  PublisherOA PDFDOI

• Freeze–thaw events differently affect survival of seeds of two native and two invasive woody species

  Canadian Journal of Forest Research · 2025-01-01

  articleOpen access1st authorCorresponding

  Current and projected changes in climatic conditions (e.g., increased freeze–thaw events) may have detrimental effects on the survival of seeds that are essential for plant regeneration in forest ecosystems. We conducted a factorial experiment manipulating thermal regime (daily freeze–thaw event vs. a constant-freeze treatment) and fungicide application to examine how freeze–thaw events affect seed survival of two native tree species ( Pinus strobus and Acer saccharum) and two invasive shrub species ( Lonicera maackii and Rhamnus cathartica). Pinus strobus seeds exhibited increased survival after freeze–thaw treatment, while A. saccharum survival was uniformly low and unaffected by freeze–thaw treatment. Freeze–thaw treatment significantly reduced survival of seeds of R. cathartica and L. maackii. Fungicide led to significantly higher survival only for L. maackii, and only when exposed to the freeze–thaw treatment. Our study highlights how recruitment of some invasive woody shrub species, but not two native tree species, may be significantly reduced by increased climatic variability.

  PublisherDOI

Recent grants

• RAPID: Linking population dynamics and behavior to understand how wildfire modifies the prevalence of zoonotic disease

  NSF · $133k · 2020–2022

• RAPID: Do extreme climatic events and predator diversity interact to shape the biogeography of disease?

  NSF · $84k · 2014–2018

• DISSERTATION RESEARCH: Disentangling the roles of neighboring plant density and palatability in providing associational defense against herbivory within different habitat types

  NSF · $20k · 2014–2015

• Collaborative Research: Landscape connectivity and the movement ecology of plant and animal communities

  NSF · $65k · 2011–2015

• IMAGINE Collaborative Research: Linking individual variation in immunity and behavior to landscape patterns in disease risk using the National Ecological Observatory Network (NEON)

  NSF · $787k · 2021–2027

Frequent coauthors

• Ellen I. Damschen

  University of Wisconsin–Madison

  60 shared

• Douglas J. Levey

  U.S. National Science Foundation

  43 shared

• Nick M. Haddad

  Michigan State University

  41 shared

• Joshua J. Tewksbury

  Smithsonian Tropical Research Institute

  37 shared

• B. Connolly

  Gonzaga University

  27 shared

• Lars A. Brudvig

  Michigan State University

  26 shared

• Evan L. Preisser

  University of Rhode Island

  22 shared

• Suzanne M. Prober

  Commonwealth Scientific and Industrial Research Organisation

  22 shared

Labs

• Orrock LabPI

Education

• Ph.D., Ecology and Evolutionary Biology

  Iowa State University

  2004

• M.S., Biology

  Virginia Commonwealth University

  1999

• B.S., Biology

  Virginia Commonwealth University

  1995