Souad Narsis, Abdessalam Grira, Mohammed-Laid Ouakid and Moussa Houhamdi
Abstract
The monitoring of the Ferruginous Duck (Aythyanyroca) in Tonga Lake (El Kala National Park) was conducted from September 2016 until August 2017. This diving duck listed as a Near Threatened Species (IUCN Red List, 2017) is a regular breeder in this Lake. The evolution of the duck number showed a maximum of 128 individuals during the winter season, 970 individuals during the breeding season and 1050 individuals composed mainly of chicks and juveniles in the post-breeding period. This Anatidae prefers to nest in clumps of Typha angustifolia with a rate of 74 % compare to the tufts of Phragmites australis and tree trunks Alnus glutinosa. In general, the date of the beginning of the laying is estimated to wards the end of April, the nests contain on average 11 eggs with a maximum of 16 eggs. The monitoring of bio-metric parameters of the nests exposes us very variable measurement, an external diameter 25.8 cm[18-35.5] internal diameter 16.46 cm[12.5-22], a depth of 9.44 cm[4.5-17], nests elevation regarding to the water around 11.75 cm[4-20] and a mean inter-nest distance of 5 cm[1.75-22.84].