Ecological interactions at the intersection of spatial ecology, global change, and behavioral ecology.


Trophic dynamics and animal behavior in urban vs. rural forests.  Recent work suggests that the nature of ecological interactions may differ in urban areas compared to rural ones.  We are interested in whether differences in the behavior and abundance of small mammals in urban vs. rural forests leads to changes in granivory and recruitment of important understory plant and canopy-tree species.  This work was recently funded by USDA and is a collaboration with Dr. Brian Connolly (Gonzaga University) and explicitly includes facets of our invasive species research:  we are coupling invasive shrub removal with experimental seed additions in forests that differ in their proximity to urban areas so that we can develop a comprehensive roadmap for maximizing diversity and viability of Midwestern forests.

Linking animal behavior with climatic variation to understand large-scale patterns in tick-borne zoonotic disease.  Tick-borne zoonotic diseases, such as Lyme disease, affect hundreds of thousands of people in the U.S. each year.  As such, understanding the ecological factors that lead to hotspots or coldspots of infected animals and ticks is essential for understanding human disease risk.  We are collaborating with Marty Martin (University of South Florida) on an NSF-funded project to postdoctoral position to understand how shifts in animal behavior and immunity drive contact between rodent hosts and tick vectors that fuel spread of the pathogen associated with Lyme disease.  Using a novel method to measure rodent activity timing (Orrock and Connolly 2015) and large-scale data collected via collaboration with the National Ecological Observatory Network (NEON), this project will quantify variation in Borrelia burgdorferi competence in two rodent species across 8 NEON sites over 3 years.

Invasive plants modify species interactions. Many non-native plant species supplement predation refuge and/or food resources for native animals, which may lead to apparent competition between invasive and native plants (Orrock et al. 2015, Bartowitz and Orrock 2016). New work in the lab is particularly focused on how the extended leaf phenology of invasive shrubs during spring and fall lead to particularly strong shifts in small-mammal activity timing (Guiden and Orrock 2019) and space use (Guiden and Orrock 2017).

Climatic variation shapes species interactions. Deep snow provides both plants and animals with a critical refuge from natural enemies and cold winter air temperatures. As the climate warms, snowfall is decreasing in northern temperate forests across the world, yet the consequences of winter climate change remains poorly understood for many trophic interactions. Recent work from our lab highlights how extreme-cold temperatures associated with reduced snow depth can amplify plant-consumer interactions (Connolly et al. 2017, Guiden et al. 2018), but that the consequences of reduced snow vary based on factors such as canopy composition or small-mammal community (Guiden et al. 2019).  Moreover, we have found that snow cover can change the timing of animal activity, such that typically nocturnal mice become diurnal under snow (Guiden and Orrock 2020).

Climate and predation interact to shape disease transmission. Predation risk drives variation in prey behavior (Connolly and Orrock 2018), even after predators have been absent for many years (Orrock and Fletcher 2014). Predators may therefore shape prey responses to extreme climate events, as well as the diseases transmitted by prey. We are currently collecting ecological, behavioral, and molecular data to study the response of deer mice (Peromyscus maniculatus) populations and Sin Nombre Virus transmission to extreme drought in the California Channel Islands (Orrock et al. 2021). We predict that the rate at which mouse populations and disease prevalence recover from bottom-up limitation may depend on the predator community each island.

Past and present human disturbances interact to determine contemporary species interactions. Roughly half of the earth’s land has been used for agriculture over the past three decades. Even after agricultural land abandonment, the legacies of past agricultural land use can persist for centuries, and the outcomes of contemporary management activities can be contingent upon these legacies.  We are investigating how changes in habitat structure, driven by past and present disturbances, modify animal behavior and species interactions (i.e., predator-prey and plant-consumer interactions) to generate predictable outcomes for plant recruitment and persistence. Research in our lab has found that past and present disturbances interact to affect herbivore anti-predator behavior (Bartel and Orrock 2021), community composition (Hahn and Orrock 2015), plant-herbivore interactions (Hahn and Orrock 2015a, 2015b, 2016), and seed-granivore interactions (Stuhler and Orrock 2016; Bartel and Orrock 2020).

The ecological and evolutionary consequences of attack risk. The risk of being attacked and consumed is a common dilemma faced by plants and animals. We use theory and experiments to understand how risk of attack modifies strategies that plants and animals use to defend themselves, and how risk-mediated changes in behavior lead to changes in interactions. For example, our work has demonstrated that risk of predators and disease shapes phenotypic and molecular variation in mice (Orrock et al. 2021)  and that plants eavesdrop on cues of their herbivores (Orrock et al. 2018), leading to changes in defense that affect multiple herbivore species and also promote cannibalism (Orrock et al. 2017). By considering how the common theme of being consumed affects nearly all organisms, this work has led to new insights into the evolution of maternal effects (Sheriff et al. 2018 and 2020; Donelan et al. 2020), as well as helped reconcile unanswered questions and pose exciting new hypotheses in the context of plant defense (Orrock et al. 2015; Karban et al. 2016; Karban & Orrock 2018; Raffa et al. 2020).

Climate and land use impacts on plant communities. Understanding geographic variation in the forces that limit plant establishment, persistence, and spread is relevant for addressing many contemporary issues in ecology, such as the restoration of degraded communities, the success of biological invasions, and the persistence of populations and species amidst climate change. In collaboration with Lars Brudvig (MSU), Ellen Damschen (UW-Madison), Joan Walker (USFS), Joe Veldman (Iowa State University) and Brett Mattingly (Eastern Connecticut Univ.), we conducted an experimental manipulation of restoration strategies for understory plant communities in longleaf pine savannas that span climatic and land use gradients at 108 sites in three states: North Carolina, South Carolina, and Georgia. This work illustrated the importance of land use and restoration strategies in structuring plant communities (e.g., Brudvig et al. 20201, Brudvig et al. 2013, Veldman et al. 2012, Veldman et al. 2014, Mattingly and Orrock 2013, Mattingly et al. 2015). We are currently evaluating the interplay of land use, climate, restoration strategies and species’ traits on each species ability to establish, persist and disperse.

Conservation corridors, animal behavior, and plant-consumer interactions. Wildlife reserve designs implement conservation corridors to reduce the negative effects of habitat fragmentation on biodiversity; however, resulting changes in patch geometry after corridors are built may have unappreciated effects on the foraging behavior of animal species sensitive to habitat edges and connectivity. These modifications to animal behavior and plant-animal interactions could generate large-scale patterns in plant populations consumed or dispersed by animals. Using experimental landscapes created as part of a multi-university NSF-funded collaboration (i.e., the Corridor Project), we are examining how habitat connectivity and geometry modify granivory and seed dispersal by small mammals, anti-predator behavior of large herbivores (i.e., deer), and habitat use by mesopredators. Work in the lab with our collaborators has shown that corridors modify rodent foraging behavior (Orrock and Danielson 2005, Brinkerhoff et al. 2005) and seed-granivore interactions (Orrock and Danielson 2003, Orrock and Damschen 2005), affecting landscape-level plant abundances (Orrock et al. 2006).