Diets of Owls and Feral Cats in Hawaii

The feral house cat (Felis catus), Hawaiian Short-eared Owl or Pueo (Asio
flammeus sandwichensis), and Common Barn Owl (Tyto alba) are important
predators of birds and introduced rodents in Hawai'i. Cat scats from the
island of Hawai'i (n=87), Pueo pellets from Hawai'i, Kaua'i, and Kaho'olawe
(n=36), and Barn Owl pellets from Hawai'i, O'ahu and Kaho'olawe (n=301) were
examined to determine the incidence of rodent, bird and insect remains in the
diets of these predators. Rodents were the main prey of cats, Pueo, and Barn
Owls, but the incidence of bird remains in diets of all three predator species
was high relative to studies conducted elsewhere in the world.

Geographic Description:
All cat scats were collected in dry mamane (Sophora chrysophylla)-naio
(Myoporum sandwichensis) forests on the western and eastern slopes of Mauna Kea
above 2,000 m elevation. Pueo pellets were collected in dry forests on Mauna
Kea (n=13), from Kaumana Gulch on Kaho'olawe (n=21), and from the Alakai Swamp
on Kaua'i (n=2). Barn Owl pellets were collected at roosts and nests at
Kakalau Forest National Wildlife Refuge on Hawai'i (n=207), near the Pu'u La'au
cabin on Mauna Kea (n= 73), on O'ahu (n=19), at Ahupi Beach on Kaho'olawe
(n=1). Acumulations of Barn Owl pellets were found below roosting sites,
whereas single Pueo pellets were found below tall trees or on open ground
(Mauna Kea), or on cliff faces on Kaho'olawe. On Kaua'i, Pueo pellets were
found in an open bog near the remains of a recent Pacific Golden Plover kill.
1.5.2 Bounding Rectangle Coordinates

Methodology:
Determined predator diets from analysis of 87 cat scats, 36 Pueo pellets,
and
301 Barn Owl pellets. All cat scats were collected in dry mamane-naio forests.
Size, appearance, and consistency were used to determine the source of scats
and pellets. Cat scats were smaller than pellets and had tapered ends with
fewer bones distributed through them. Pueo pellets were smaller than Barn Owl
pellets and had a uniformly cylindrical shape. They fit Mikkola's (1983)
description as "elongated, roughly cylindrical dark gray and formed from a
tightly-massed conglomeration of fur or feathers with a central core of mammal
and bird bones."