New data on the nesting sites selection and breeding success of three bird species in the riparian vegetation of Northwest African rivers

Many avian species partition feeding and breeding resources to avoid competition for nesting and food elements. This competition frequently leads to the segregation of space and time use among cohabiting species. The breeding requirements of coexisting species and drivers of segregation are poorly understood in passerine birds. In this study, we monitored nesting habitats, nest placement, and breeding success among two passerine birds, Hippolais polyglotta and Turdus merula, and the Columbidae species Streptopelia turtur arenicola, in rivers of the upper Moulouya (Morocco) Mountains to examine the levels of habitat partitioning, success rates, and governing factors during the breeding season. We recorded the nests, nesting sites, nest placements, and success rates of the studied species along three rivers during 2017 and 2019. Our results revealed important breeding activity in the studied birds, with 420 nests of H. polyglotta and 88 nests of T. merula, compared to 99 nests of S. t. arenicola. Nest niches were segregated between passerines and Columbidae and within passerines. Nesting sites were segregated along sections of rivers except for nests of H. polyglotta, which were shared between upstream and intermediate zones. Nest substrates were partially segregated among the three species; nests of H. polyglotta and S. t. arenicola were commonly constructed on Crataegus monogyna and Rosa canina substrates, while nests of T. merula were on Salix sp. Similarly, vertical placements of nests were segregated among birds. Breeding success rates differed among birds (94.44% in T. merula, 87.88% in H. polyglotta, and 55.56% in S. t. arenicola) due to human and natural factors. Finally, this study confirmed the first breeding case of H. polyglotta on the southern slope of the Mediterranean and provided new insight into nest niches in cohabiting passerines and Columbidae species cobred in riparian vegetation in Morocco and the entire region of North Africa. However, future investigations are required to understand the main reasons behind the selection of nesting habitats for passerine species, particularly in farmlands.