# Food Subsidy Effects on Host Foraging Behavior Shape Host–Macroparasite Infection Dynamics

## TL;DR

Food subsidies can change how animals forage, which affects how often they encounter parasites and how severe infections become.

## Contribution

The study shows how food subsidy distribution alters parasite encounter rates and infection dynamics through host foraging behavior.

## Key findings

- Homogenized food subsidies increase parasite abundance and reduce host population size.
- Patchy subsidies lower parasite encounter rates and infection impacts.
- Changes in foraging behavior due to subsidies strongly influence parasite transmission.

## Abstract

Anthropogenic food subsidies can have profound influences on wildlife behavior and health, including exposure to parasites. In many host–macroparasite systems, parasite exposure is tied to foraging behavior, but how different distributions of food subsidy shape macroparasite encounter and population‐level impacts is poorly understood. Here we modify a mathematical model of macroparasite transmission to explore how food subsidies could change parasite encounter rates and between‐host variation in parasite burdens, reflecting changes in host foraging and conspecific overlap. Hosts experience the highest average parasite abundance and associated reductions in population size when food subsidies increase and homogenize parasite encounter rates, for example when hosts center their home ranges on a point food source and overlap with many conspecifics. Conversely, hosts experience the lowest parasite abundance and impacts when subsidies result in lower and more heterogeneous parasite encounter rates, for example when multiple patchily distributed subsidies subdivide host populations and increase host commute times to food at the expense of time spent foraging. Even when resources affect other processes such as improving host immunity or fecundity, the overall effect of subsidies on infection is more strongly driven by changes in parasite encounter rates through altered foraging behavior. These patterns are robust to different effect sizes of resource subsidy on foraging and nonforaging parameters. Our findings demonstrate that resource‐driven shifts in host foraging behavior could play an integral role in determining infection dynamics for parasites with environmental (free‐living) infectious stages, with consequences for wildlife provisioning in recreational, conservation, and management contexts.

Wildlife behavioral responses to different distributions of food subsidies could shape encounter and infection intensity of environmentally transmitted parasites. Using a mathematical model, we show that the way in which food subsidy changes transmission rate and variation in parasite burdens (e.g., through changes in time spent foraging and variation in conspecific overlap) determines host and parasite abundance. Moreover, these behavioral responses to food subsidy typically outweigh other effects of food subsidy on immunity and host or parasite fitness, with implications for how food provisioning is managed across landscapes.