Ecological determinants of species richness and abundance of endemic and threatened owls in the Andaman Islands, India

Doi: https://doi.org/10.13157/arla.66.1.2019.sc3

Authors: Santhanakrishnan BABU, Shanmugavel SURESHMARIMUTHU, Honnavalli Nagaraj KUMARA

E-mail: sanbabs@gmail.com

Published: Volume 66.1, January 2019. Pages 89-100.

Language: English

Keywords: Andaman Islands, conservation, endemics, habitat determinants, logging and Strigidae

Summary:

Factors that influence the distribution and abundance of the endemic and threatened owls of the Andaman Islands have not been assessed, in contrast to those affecting diurnal birds. Such studies would assist in prioritising habitats that have high conservation importance for owls. We evaluated the status and species composition of owls along c. 343km of the Andaman Trunk Road, employing one-time point counts between December 2013 and April 2015. We conducted spontaneous listening, broadcasting of conspecific calls and spotlight searches as survey protocols. The point-centred quarter method was used to evaluate the habitat at each count site. We recorded five owl species whose mean abundance was 2.09 owls/point. Species richness and abundance were greater in unlogged sites and deciduous forests. Habitat differences between owl species were noted according to land use, cover type and intensity of logging activity. However, these factors had no significant effect on the abundance of Oriental Scops-owl and Hume’s Boobook, but were significant  for Andaman Boobook and Andaman Scops-owl. Mean understory height, tree height and grass cover positively influenced the owl species richness and abundance. The Andaman Boobook and Andaman Scops-owl appeared stenotopic in habitat use and in contrast to the eurytopic Oriental Scops-owl and Hume’s Boobook. A review of the conservation status of Andaman Scops-owl and Andaman Boobook is suggested bearing in mind their low abundance, restricted distribution and less preference for altered habitats

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