Reproducción y observación de grupos de nutria (Lutra lutra L.) en el norte de España

Resum

Breeding and group observation in the Otter (Lutra lutra L.) in northem Spain
The size of otter litters in northem Spain was studied through direct observation of females with cubs or tracks. On average, 1.72 cubs / female (S.D. = 0.83; range 1-4; n = 18). Litters with one or two cubs represented about the 88.8%. 2.0 embryos / female (S.D. = 0.82; n = 4). Parturition occurred throughout the year. However, in northeastern Spain, breeding appeared to be seasonal, with parturitions principally between May and September. The average number of otter in observations was 1.16 (S.D. = 0.52; range 1-5; n = 110 observations), being a 25.0 % of individuals in groups. Without considenng cubs and mothers the average size was 1.08 (S.D. = 0.30; range 1-3; n = 103 observations). Average size of groups (two or more otters) was 2.29 (S.D. = 0.83; range 2-5; n = 14).