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1. Landscape-level toxicant exposure mediates infection impacts on wildlife populations

   https://doi.org/10.1098/rsbl.2020.0559  

   Sánchez, Cecilia A.; Altizer, Sonia; Hall, Richard J. (November 2020, Biology Letters)

   null (Ed.)

   Anthropogenic landscape modification such as urbanization can expose wildlife to toxicants, with profound behavioural and health effects. Toxicant exposure can alter the local transmission of wildlife diseases by reducing survival or altering immune defence. However, predicting the impacts of pathogens on wildlife across their ranges is complicated by heterogeneity in toxicant exposure across the landscape, especially if toxicants alter wildlife movement from toxicant-contaminated to uncontaminated habitats. We developed a mechanistic model to explore how toxicant effects on host health and movement propensity influence range-wide pathogen transmission, and zoonotic exposure risk, as an increasing fraction of the landscape is toxicant-contaminated. When toxicant-contaminated habitat is scarce on the landscape, costs to movement and survival from toxicant exposure can trap infected animals in contaminated habitat and reduce landscape-level transmission. Increasing the proportion of contaminated habitat causes host population declines from combined effects of toxicants and infection. The onset of host declines precedes an increase in the density of infected hosts in contaminated habitat and thus may serve as an early warning of increasing potential for zoonotic spillover in urbanizing landscapes. These results highlight how sublethal effects of toxicants can determine pathogen impacts on wildlife populations that may not manifest until landscape contamination is widespread. 

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2. Seascape heterogeneity and predictability drive movement strategy selection in estuarine predators

   https://doi.org/10.1111/1365-2656.70164  

   Eggenberger, Cody W; Viadero, Natasha; Santos, Rolando; Papastamatiou, Yannis; Price, Rene; Strazisar, Theresa; Madden, Christopher; Rehage, Jennifer (October 2025, Journal of Animal Ecology)

   Abstract Animal movement strategies, or suites of correlated traits reflecting how individuals respond to their environment, are often shaped by spatiotemporal heterogeneity and predictability in physicochemical conditions, resources or risk.While movement strategies have been well studied in terrestrial animals using high‐resolution satellite telemetry, our understanding of how seascape heterogeneity influences movement strategies in aquatic systems remains limited due to technological constraints.We used a non‐gridded passive acoustic telemetry array to identify and classify movement strategies of Common Snook (Centropomus undecimalis) and Atlantic Tarpon (Megalops atlanticus) within two estuarine systems in Everglades National Park, Florida. We then evaluated how seasonal heterogeneity and environmental predictability influenced movement strategy selection.Using a suite of movement metrics, we identified three statistically distinct movement strategies that varied in movement frequency, home range size and site fidelity. Fish in more homogeneous environments tended to adopt strategies involving frequent movements, larger home ranges and shorter stays in a given location. In contrast, increased seascape heterogeneity was associated with movement strategies characterized by less frequent movements, smaller home ranges and longer residence times. We also found species‐level differences in strategy use, with the predictability of dissolved oxygen, salinity and turbidity emerging as key environmental drivers of movement strategy selection.These results demonstrate that seascape heterogeneity and predictability strongly influence the emergence and selection of movement strategies in estuarine predators. Our findings provide a novel approach for identifying movement strategies in aquatic systems using passive acoustic telemetry and highlight the broader importance of seascape complexity in shaping animal behaviour and predicting responses to environmental change. 

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3. What’s in a resource gradient? Comparing alternative cues for foraging in dynamic environments via movement, perception, and memory

   https://doi.org/10.1007/s12080-022-00542-0  

   Fagan, William F.; Saborio, Cole; Hoffman, Tyler D.; Gurarie, Eliezer; Cantrell, Robert Stephen; Cosner, Chris (September 2022, Theoretical Ecology)

   Abstract Consumers must track and acquire resources in complex landscapes. Much discussion has focused on the concept of a ‘resource gradient’ and the mechanisms by which consumers can take advantage of such gradients as they navigate their landscapes in search of resources. However, the concept of tracking resource gradients means different things in different contexts. Here, we take a synthetic approach and consider six different definitions of what it means to search for resources based on density or gradients in density. These include scenarios where consumers change their movement behavior based on the density of conspecifics, on the density of resources, and on spatial or temporal gradients in resources. We also consider scenarios involving non-local perception and a form of memory. Using a continuous space, continuous time model that allows consumers to switch between resource-tracking and random motion, we investigate the relative performance of these six different strategies. Consumers’ success in matching the spatiotemporal distributions of their resources differs starkly across the six scenarios. Movement strategies based on perception and response to temporal (rather than spatial) resource gradients afforded consumers with the best opportunities to match resource distributions. All scenarios would allow for optimization of resource-matching in terms of the underlying parameters, providing opportunities for evolutionary adaptation, and links back to classical studies of foraging ecology. 

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4. What’s in a resource gradient? Comparing alternative cues for foraging in dynamic environments via movement, perception, and memory.

   https://doi.org/10.1007/s12080-022-00542-0  

   Fagan, W. F.; Saborio, C.; . Hoffman, T.; Gurarie, E.; Cantrell, R. S.; Cosner, C. (January 2022, Theoretical ecology)

   Consumers must track and acquire resources in complex landscapes. Much discussion has focused on the concept of a ‘resource gradient’ and the mechanisms by which consumers can take advantage of such gradients as they navigate their landscapes in search of resources. However, the concept of tracking resource gradients means different things in different contexts. Here, we take a synthetic approach and consider six different definitions of what it means to search for resources based on density or gradients in density. These include scenarios where consumers change their movement behavior based on the density of conspecifics, on the density of resources, and on spatial or temporal gradients in resources. We also consider scenarios involving non-local perception and a form of memory. Using a continuous space, continuous time model that allows consumers to switch between resource-tracking and random motion, we investigate the relative performance of these six different strategies. Consumers’ success in matching the spatiotemporal distributions of their resources differs starkly across the six scenarios. Movement strategies based on perception and response to temporal (rather than spatial) resource gradients afforded consumers with the best opportunities to match resource distributions. All scenarios would allow for optimization of resource-matching in terms of the underlying parameters, providing opportunities for evolutionary adaptation, and links back to classical studies of foraging ecology. 

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5. Small scale, elevation- and environmental-related differences in life history strategies in a temperate resident songbird

   https://doi.org/10.1098/rsos.241777  

   Sonnenberg, Benjamin R; Branch, Carrie L; Pitera, Angela M; Heinen, Virginia K; Whitenack, Lauren E; Welklin, Joseph F; Pravosudov, Vladimir V (April 2025, Royal Society Open Science)

   Environmental drivers of within-population reproductive patterns are often hypothesized to lead to reproductive strategies tuned to local conditions. Organisms adjust energy allocation between survival and reproduction based on experience, age, lifespan and resource availability. Variation in these energetic investments can be described as different demographic tactics which are expected to optimize the fitness of local populations. These ideas are largely supported by both empirical and model-based studies but research identifying specific strategies and their corresponding environmental drivers within wild populations remains rare. Using 12 years of data, we investigated reproductive investment strategies in a relatively short-lived resident songbird, the mountain chickadee (Poecile gambeli), at two elevations that differ in environmental harshness in the North American Sierra Nevada mountains. Challenging winter environments at high elevations impose strong selection pressure on survival-related traits (e.g. specialized spatial cognition associated with food caching) and significantly shorten the length of the reproductive window. Here, we show that chickadees at a higher elevation lay smaller clutches (ca0.41 fewer eggs) and produce fewer (ca0.25 fewer nestlings) but larger offspring (ca0.4 g heavier) compared to lower elevation residents. Due to the harsher and less predictable environmental conditions at higher elevations, this investment strategy in this resident species likely leads to the production of offspring with greater chances of survival. Overall, our results show that within-species differences in life history strategies may evolve over a small spatial scale along strong environmental gradients. 

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