We examined the incubation pattern of yellow-legged gulls Lar us michahellis at a colony in the Balearic Archipelago. Incubating gulls were captured at the nest at different times of day. We found that, on average, males attend the nest less than females. Male or female attendance had a marked diurnal pattern: males seem to show a progressive increase in the probability of incubation until the central part of the day, which then declines during the evening hours (following a quadratic model). This pattern remained unaltered during the years that followed the closure of the local open-air landfill site, which represented the main food resource of this population. Our results suggest that the sex-related diurnal pattern of nest attendance during incubation is skewed towards females and is unrelated to food resources.