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Background: Despite decades of epidemiological theory making relatively simple assumptions about host movements, it is increasingly clear that non-random movements drastically affect disease transmission. To better predict transmission risk, theory is needed that quantifies the contributions of both fine-scale host space use and non-independent, correlated host movements to epidemiological dynamics., Methods: We developed and applied new theory that quantifies relative contributions of fine-scale space use and non-independent host movements to spatio-temporal transmission risk. Our theory decomposes pairwise spatio-temporal transmission risk into two components: (i) spatial overlap of hosts-a classic metric of spatial transmission risk - and (ii) pairwise correlations in space use - a component of transmission risk that is almost universally ignored. Using analytical results, simulations, and empirical movement data, we ask: under what ecological and epidemiological conditions do non-independent movements substantially alter spatio-temporal transmission risk compared to spatial overlap?, Results: Using theory and simulation, we found that for directly transmitted pathogens even weak pairwise correlations in space use among hosts can increase contact and transmission risk by orders of magnitude compared to independent host movements. In contrast, non-independent movements had reduced importance for transmission risk for indirectly transmitted pathogens. Furthermore, we found that if the scale of pathogen transmission is smaller than the scale where host social decisions occur, host movements can be highly correlated but this correlation matters little for transmission. We applied our theory to GPS movement data from white-tailed deer (Odocoileus virginianus). Our approach predicted highly seasonally varying contributions of the spatial and social drivers of transmission risk - with social interactions augmenting transmission risk between hosts by greater than a factor of 10 in some cases, despite similar degrees of spatial overlap. Moreover, social interactions could lead to a distinct shift in the predicted locations of transmission hotspots, compared to joint space use., Conclusions: Our theory provides clear expectations for when non-independent movements alter spatio-temporal transmission risk, showing that correlated movements can reshape epidemiological landscapes, creating transmission hotspots whose magnitude and location are not necessarily predictable from spatial overlap., Competing Interests: Declarations. Ethics approval and consent to participate: Deer capture was performed under the IACUC permit # 2850-1021 issued by the University of Tennessee. Consent for publication: Not applicable Competing interests: The authors declare that they have no Conflict of interest., (© 2025. The Author(s).)

Management of large herbivores often involves increasing availability of forages sufficient in nutrient density to allow animals to meet dietary demands. Nutritional carrying capacity (NCC) models commonly are used to compare plant communities and management strategies, but failure to use the most limiting nutrient could result in overestimating NCC. Moreover, the relationship between limiting nutrients often is not considered, which may influence the utility of NCC models based on a single nutrient, especially when herbivores must simultaneously meet multiple constraints. We examined crude protein and phosphorus concentrations in 131 plant species commonly eaten by white-tailed deer (Odocoileus virginianus) to determine whether they would meet a minimum 14% crude protein and 0.3% phosphorus constraint for a lactating female. Crude protein and phosphorus demands were met in 43.9% and 18.8% of sampled forages, respectively. Concentrations of crude protein and phosphorus were greatest in young forb tissue, with an average of 18.6% crude protein and 0.28% phosphorus. Protein and phosphorus concentrations were positively correlated, but not all plants which met protein requirements simultaneously provided sufficient phosphorus. We created NCC models using crude protein and phosphorus and documented phosphorus tended to be more limiting, but variation existed among sites. Given that limiting nutrients may vary spatiotemporally, focusing conservation efforts on providing a diversity of plants, particularly to include forbs that simultaneously meet multiple nutritional demands, is likely the most practical management approach., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025 Elsevier Ltd. All rights reserved.)