Recreational activities in nature have increased considerably in recent decades. Human disturbance may trigger similar trade-offs in birds that the natural risk of predation generates on productivity through parental investment decisions. To estimate how the impact of human presence affects breeding birds on Mediterranean beaches, the behaviour of incubating Kentish PloversCharadrius alexandrinuswas studied in relation to the approach of people, vehicles and dogs. Observational data were collected and control experiments were performed with a standardized stimulus. The response variability of birds in the decision to flush from the nest was studied depending on the type of beach user, the location of the disturbance event and thermal stress. Walkers, when accompanied by dogs, flushed plovers 93.8% of the time when walking through dunes and 80.0% of the time when walking on paths, whereas pedestrians alone flushed plovers 47.6% of the time when in dunes and only 12.9% of the time when on paths. Lone dogs triggered a flushing response 100% of the time when they roamed the dunes and 50% on the shore. The number of users in each disturbance event did not affect the flushing behaviour. Nest return times were shorter on disturbed beaches, suggesting habituation to the human disturbance stimulus. The ambient temperature for the nests in which plovers flushed was lower and nest return time decreased proportionally with ambient temperature, both suggesting that habituation to the human disturbance stimulus encourages relaxation of the trade-off between escape behaviour to avoid predation risk and the effects of thermal stress on unattended eggs. Females flushed more frequently (57.1%) than males (32.0%), suggesting that they may perceive risk differently. Establishing buffers between nesting areas and people may help birds habituate to the predictable and non-lethal stimulus of human presence, facilitating coexistence between conservation and recreation.