Monitoring the Population of the Endangered Lanyu Scops Owl (Otus elegans botolensis)

The Lanyu scops owl is an endangered species found only on Lanyu Island off Taiwan. There were no studies of this species prior to this project. Triangulation of owl vocalizations was used as the primary method of population census between 198S and 1988. Banding and sighting records provided supplementary population data. Since 1989, tape-recorded play-back has been used to stimulate responses of owls during population censuses. The population of the Lanyu scops owl appears to have been stable though still vulnerable through the last five years. Owls inhabiting peripheral areas lack the social interactions of those in the core areas. It is still unknown whether social interactions are significant to the survival of the species. An effort was made to monitor the productivity and mortality of the species, as well as the dispersal and movement pattern of the young and the adults. Many aspects of their movement patterns are only partially known. The survival of the two sexes appears to be different, which may reflect differential pressures imposed by their social system. Habitat destruction and human persecution are the two main external pressures on the species. Human disturbance is especially high at the peripheral sites, resulting in those breeding pairs contributing no young to the population.