Ardeidae of the South-East Benin wetland (Ramsar site 1018): Phenology and indicator species of seasons and stations

Abstract

The wetland of South-East Benin is a potential site for migratory water birds. In order to study the phenology of bird species belonging to Ardeidae family, a monthly monitoring has been carried out between January 2015 and December 2016 in Nokoué Lake, Sô River, Porto-Novo lagoon, Ouémé River and old Lagoons. For birds observation and counting, technics based on transect and fix station were used. A total of 12 species were inventoried. Among them, Ixobrychus minutus, Ardeola ralloides, Ardea cinerea are sedentary and palearctic migratory, Nycticorax nycticorax is a palearctic migratory, Bubulcus ibis, Butorides striatus, Egretta intermedia are sedentary and intra-African migratory though Egretta garzetta, Ardea purpurea et Egretta alba are sedentary, intra-African migratory and palearctic migratory and Egretta ardesiaca, Egretta gularis are intra- African migratory. The specific richness varied significantly neither as a function of years nor in relation to months contrary to the abundance of the population.
Specifically, the time of arrival and departure differs from species to others. A positive and significant biserial correlation and indicator value were noticed among Ardea cinerea, Egretta intermedia, E. alba, Ardeola ralloides, E. garzetta, E. ardesiaca, A. purpurea, Butorides striatus are tied to Lake Nokoué station (NL) and are its indicator species. Thus, Nycticorax nycticorax is an indicator of Porto-Novo Lagoon (PL) and Bubulcus ibis that of the Ouémé River (OR). Indeed, E. alba, A. cinerea, A. purpurea, E. intermedia, B. ibis are indicators of the short dry season (SDS) while, Nycticorax nycticorax and Ardeola ralloides are indicators of the long dry season (LDS). No species correlate with the Sô River (SR) and the old lagoons (OL) and neither with the long rainy season (LRS) and the short rainy season (SRS). These last stations and seasons have no indicator species.