A central tenet in evolutionary biology is that populations adapt to their environment with every
generation through the process of natural selection. In long-lived species such as gulls (Larus spp.),
environmental changes may however also occur at timescales much shorter than generations,
which is the timeframe over which evolution acts. Individuals should therefore benefit from being
able to (partly) adjust their physiology or behaviour to environmental changes throughout their
lifetime. Such adjustments are nevertheless believed to be costly in terms of time or energy, and
may thus jeopardize an organism’s reproduction or survival. Individuals must therefore benefit
when they are able to assess the reliability of environmental cues and the extent to which current
adjustment costs may be offset by future benefits. Yet, current ecological theory generally
assumes that individuals exhibit a constant degree of plasticity throughout their lifetime, tracking
environmental changes to the best of their ability, irrespective of the entailed costs. In this project,
I will elaborate further on this theory by assessing to what extent two co-occuring gull species
adjust their foraging strategies throughout their lifetime in response to (a)biotic environmental
cues, how such plasticity in foraging niche use may trade off with other life-history traits, and how
individual differences in niche plasticity may therefore persist over evolutionary timescales.