# Abundance, Diet and Foraging of Galápagos Barn Owls (Tyto furcata punctatissima)

## TL;DR

This study examines the diet, foraging behavior, and threats to Galápagos barn owls on Santa Cruz Island, highlighting their role in controlling rodents and the need for conservation.

## Contribution

The study provides new data on the foraging behavior and diet of Galápagos barn owls using data loggers, a method not previously applied to this subspecies.

## Key findings

- Galápagos barn owls forage in small areas and primarily consume rodents, providing ecosystem services by controlling invasive species.
- Foraging behavior includes resting periods that make up nearly 56% of the time spent away from day roosts.
- The owls face increasing threats from human activities, including road accidents, poisoning, and intentional killing.

## Abstract

Barn owls are one of two owl subspecies that inhabit the Galápagos Islands. Since data on these birds have been lacking since the 1980s, we initiated a project in 2016 to study the abundance, prey, and foraging behavior of barn owls on Santa Cruz, the island with the largest human population in the archipelago. We observed barn owls both in agriculture-dominated and remote, natural areas. The observed foraging areas of Galápagos barn owls were much smaller than those observed in Europe or Argentina. The diet of the Galápagos barn owls consisted of ~89% rats and mice and ~10% arthropods. Bird bones were detected in 1% of the pellets. Barn owls provide ecosystem services by controlling invasive rodents. Threats to barn owls come from car traffic, poisoning, and intentional harm by humans who believe owls hunt chickens or symbolize misfortune or death. Galápagos barn owls are listed as endangered and warrant increased protection due to the ecosystem services they provide and the anthropogenic threats they face. A management plan and an education program could improve the status of the barn owl in this unique world-famous heritage site.

We studied Galápagos barn owls on Santa Cruz Island in the Galápagos Archipelago. We collected and analyzed pellets to determine diet composition. Barn-owl diet consisted—in terms of biomass—of ~89% rodents and ~10% insects. Bird remains occurred in 1% of the pellets. Foraging was studied with data loggers, a method not previously applied to the study of Galápagos barn owls. Owls rested during the day in natural and human-built roosts such as lava holes, trees, or huts. Night-time foraging was characterized by periods during which the bird moved and periods during which the bird stayed within one place, with the latter amounting to ~56% of the time away from the day roost. Birds began foraging shortly after sunset and returned to their day roost before sunrise. The duration of foraging was approximately 11 h per night. Foraging areas were small (median value: 0.28 km2). Although our data demonstrate a continued presence of the subspecies, we regard the situation for this subspecies as labile, as multiple threats, such as road kills, poisoning, and intentional killing by farmers, have increased recently, and suggest the development of a management plan to improve its conservation.