Breeding of the Little Tern <i>Sternula albifrons</i> in the Atlantic plains of Morocco (Province of Benslimane)

The breeding of the Little Tern has been the subject of a ten-year monitoring project from 2009 to 2018 on part of the Atlantic coast of Morocco. The aim was to identify elements of the biology and ecology of Little Terns breeding in a habitat of limited area and heavily frequented and disturbed by predators and humans. The breeding cycle was studied from the arrival of the first migrants to pair formation, nest sitting, egg-laying, brooding and hatching. Nesting success was calculated and analysed over the study period, including factors leading to breeding failure. Systematic field studies revealed that nests were predominantly concentrated on a large islet (88.6%), which becomes inaccessible to land-based predators and people at high tide. The islet's basins, sand and pebble arenas, and sandstone mounds provided suitable nesting sites. Analysis of individual broods revealed that most clutches were laid in May, averaging 2.2 eggs per nest. The incubation period was 16–23 days and hatching success was approximately 49.8%. The primary causes of hatching failure (50.2%) included human disturbance, unfavourable weather and predation. Reproductive success was positively influenced by the territorial, gregarious and defensive behaviour of the adult Little Terns, the selection of optimal nest sites, the availability of limestone pavements with hiding places for the chicks, and the presence of other nesting individuals to assist in territorial defence. Conversely, breeding success was negatively affected by disturbance from predators, such as gulls and stray or domestic dogs, and by various human-related activities.