Pulsed resource subsidies can have profound effects on recipient communities. The effects of resource pulses are often mediated by increases in the density of consumer populations. Here we investigate several mechanisms linking experimental pulses of seaweed deposition to population-level responses in the brown anole Anolis sagrei. Subsidized lizards grew approximately 30% faster than lizards in seaweed-removal plots, but there was no effect of seaweed subsidies on survival or body condition. Breeding is strongly seasonal in A. sagrei, resulting in a limited reproductive window of opportunity. Accelerated growth allows subsidized females to reach sexual maturity earlier and thereby exploit more of this window, which is projected to double fecundity in their first year of life. These results show how changes in an individual trait can translate pulses of resource input into reproductive output. Further, they highlight the importance of seasonal timing in mechanistically linking individual-, population- and community-level responses to pulsed resource subsidies.