Abstract : The use of drones to census nesting seabirds is well established, but far less is known about the possibility of using them for the estimation of reproductive success. In particular, very few studies dealt so far with birds nesting in saltmarshes, a type of nesting habitats which poses several problems — such as logistical constraints due to the tidal cycle or damages to halophytic vegetation caused by trampling — when the traditional method, i.e., field surveys, is adopted. The present study aimed to compare the effectiveness and safety of drone-conducted monitoring of hatching success with the usual ground surveys on black-headed gulls (Chroicocephalus ridibundus) breeding on marsh islands in the Lagoon of Venice (NE Italy). Fieldwork was performed throughout the breeding seasons of 2017–2019. Each year, one colony of black-headed gull was studied, and it was visited weekly for 4 weeks after laying to compare the relative effectiveness and safety for the monitored birds using both methods, i.e., ground vs. drone counts. No significant differences were found in the number of both eggs and hatchings (n = 543) per nest between the two methods. The average coefficient of agreement between the methods was high for all comparisons. Overall, 224.2 min were spent on censusing the three colonies by the traditional approach vs. 30.6 min by the drone method (− 86.4%). An additional 92.6 min were needed for the drone approach to process recorded videos. The mean time spent measuring the hatching success of the three colonies with a drone was far less, about 84.6% less, than that with the traditional approach. No apparent negative effects of drone flights on nesting pairs, clutches, or chicks were observed. Drone use allowed the effective, rapid, affordable, and safe measurement of black-headed gull breeding success in marsh islands.