Causes of admission of little owl (Athene noctua) at a wildlife rehabilitation centre in Catalonia (Spain) from 1995 to 2010

This retrospective study analyzes the causes of morbidity of little owl (Athene noctua) admitted to the Wildlife Rehabilitation Centre of Torreferrussa from 1995 to 2010. A total of 1,427 little owls were included in the study, with an average of 89 cases per year (range: 73-116). As regards the sex category, 80.7% animals (1,152/1,427) were classified as undetermined gender, 9.1% (130/1,427) were sexed as females and 10.2% (145/1,427) as males. The overall age distribution according to the calendar year showed that 66.6% (951/1,427) of birds were '1st calendar year and 16.6% (237/1,427) were '> 1 calendar year'. Age could not be determined in 16.7% of birds. Primary causes of admission were orphaned young (53.2%), unknown trauma (24.7%), impact with motor vehicles (5.6%), other cause (5.5%), undetermined (3.7%), illegally captive (2.1%), natural diseases (2.1%), and gunshot (1.1%). Within the breeding season the frequency of admissions due to traumas -unknown trauma (x 2 = 147.108; p < 0.001)- and impact with motor vehicles (x 2 = 28.528; p < 0.001) and other cause (x 2 = 11.420; p = 0.003) were the most important causes. In winter, admissions were mainly related to unknown trauma and gunshot. Over the fifteen years we observed a significant increase in the orphaned young category. © 2011 Museu de Ciències Naturals de Barcelona.