The survival rate of Lanyu Scops Owls Otus elegans botelensis

Few species of owls have been well studied in the wild and estimates of sur vival rates are available only for a few species in the temperate region. T his paper reports the adult annual and monthly survival estimates of the La nyu Scops Owl Otus elegans botelensis, a subtropical Asian species, based o n a 13-year study of a colour-marked population. The estimated seasonal sur vival pattern was relatively stable, with an indication of lower survival d uring May-June, the time of egg-laying and chick-rearing. Female survival i n this species was consistently higher than male survival by an estimated 7 %, which may have resulted from differential costs in reproduction. Annual survival rates during 1986-96 showed no significant differences between yea rs. Based on a model with constant survival and annual variation in recaptu re rate, average annual survival for all birds was estimated as 75%, which is higher than expected given the small body weight of the Lanyu Scops Owl. This survival and the stable monthly survival pattern are discussed in lig ht of the mild subtropical conditions of Lanyu Island.