Most organisms face the problem of foraging and maintaining growth while avoiding predators. Typical animal responses to predator exposure include reduced feeding, elevated metabolism, and altered development rate, all of which can be beneficial in the presence of predators but detrimental in their absence. How then do animals balance growth and predator avoidance? In a series of field and greenhouse experiments, we document that the tobacco hornworm caterpillar, Manduca sexta, reduced feeding by 30-40% owing to the risk of predation by stink bugs, but developed more rapidly and gained the same mass as unthreatened caterpillars. Assimilation efficiency, extraction of nitrogen from food, and percent body lipid content all increased during the initial phase (1-3 d) of predation risk, indicating that enhanced nutritional physiology allows caterpillars to compensate when threatened. However, we report physiological costs of predation risk, including altered body composition (decreased glycogen) and reductions in assimilation efficiency later in development. Our findings indicate that hornworm caterpillars use temporally dynamic compensatory mechanisms that ameliorate the trade-off between predator avoidance and growth in the short term, deferring costs to a period when they are less vulnerable to predation.antipredator behavior | nonconsumptive effects | predator-prey interactions | phenotypic plasticity F eeding is dangerous (1, 2). For many animals, reduced feeding is a common response to the watchful eyes of predators that exploit movement as a primary prey location cue (3, 4). In addition, metabolic rate typically increases in response to predation risk (5), potentially exacerbating the costs of reduced food intake. Organisms respond to predation risk and the corresponding food limitation through phenotypically plastic responses, including behavioral, physiological, and developmental changes (6-9). The integration of these factors to ameliorate the impacts of predator exposure has been little studied, however, especially over development during periods of chronic predation risk (10).After a period of food limitation and associated decreased growth (11, 12), many organisms increase growth through compensatory responses (13-15). Compensation after starvation can be achieved via increased consumption, increased metabolic or digestive efficiency, or altered developmental rate when food becomes available (16). Because predation risk is an important natural phenomenon that constrains foraging and induces physiological stress, compensatory mechanisms may be especially important in this context. Nonetheless, compensatory responses to predation risk, and their behavioral, physiological, and developmental underpinnings, are not well understood (17). Much of the research on responses to predator exposure has focused on behavioral changes in resource selection, where generalist foragers, such as elk and grasshoppers, switch habitat and diet use in the presence of predators (18,19). Little is known about physiological respon...