The Importance of Riparian Old-Growth Forest for Fish Owls

ABSTRACT: Despite its status as an endangered species, conservation efforts for the Blakiston's Fish Owl (Ketupa blakistoni) in Russia are limited, partly because habitat use by these rare owls is poorly known. Therefore, we identified nesting and foraging habitat characteristics of Blakiston's Fish Owls in Primorye, Russia from 2006-2011. We sampled habitat at 14 nest sites, 12 nest stand sites, and 13 random sites; we also sampled rivers at 14 used and 14 available sites within Fish Owl home ranges across our 20,213 square km study area . Large, old trees and riparian old-growth forest were the primary discriminating characteristics at nest and foraging sites, respectively. Large trees were likely used as nest sites because they are capable of supporting the bird's large body size. Large trees are also important because they are the primary source of large woody debris in rivers, which creates suitable habitat for salmon, the owl's primary prey. Based on habitat characteristics, nest sites were correctly classified from random sites 74% (Kappa = 0.48) of the time, nest stands from random sites 56% (Kappa = 0.12) of the time, and used from available foraging sites 68% (Kappa = 0.36) of the time. The management and conservation of old forests is essential for conservation of this species because they are central to their nesting and foraging ecology.

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