© 2019 Pueo Hui / Hawaiian Short-eared Owl Group.

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The Pueo Project

© Tom Kualii

The Pueo or Hawaiian Short-eared Owl (Asio flammeus sandwichensis), provides important ecosystem services, controlling population sizes of introduced rodents, and perhaps preying on other introduced and native species (Work and Hale 1996). Once common across the islands, and held as sacred in Hawaiian culture, the Hawaiian Short-eared Owl is now state-listed as Endangered on O'ahu (DLNR 2005). Short-eared Owl declines have also been observed in Europe and the North American Continent (Booms et al. 2014). Unfortunately, Short-eared Owls have received scant attention globally (Booms et al. 2014, Morales and Traba 2016).

Two characteristics that make this owl particularly vulnerable to disturbance are its reliance on intact grasslands, and its preference for a diet of small mammals (Wiggins et al. 2006). When environmental conditions result in a high density of prey items, Short-eared Owls breed at high densities. Conversely, in years when prey items are scarce owls either do not breed or move to other areas (Clark 1975, Johnson et al. 2013). Short-eared Owls also appear to have low or no site fidelity and vary movements between seasons and years, leading to challenges in monitoring population size (Booms et al. 2014). However, adults may roost communally outside of the breeding season (Keyes et al. 2016), and this may provide one means of assessing numbers.

Documentation is lacking for basic life history characteristics, perhaps due to difficulty in observing the species' well-concealed nests, and inconspicuous behavior from egg laying through fledging of young (Clark 1975, Wiggins et al. 2006, Booms et al. 2014). Most of the existing data come from studies on the North American continent, which show that short-eared owls lay eggs on the ground and prefer dry locations within open habitats such as grasslands, marshlands and dunes proximate to an adequate food base (Clark 1975).

Short-eared Owls prefer territories with wooden fence posts, rather than metal fence posts (Martinez et al. 1998, Keyes et al. 2016). Nest sites are surrounded by taller vegetation than occurs further away from nests at the same location, and are more likely to occur in patches of grass than in patches of herbs or bare ground (Keyes et al. 2016). At least one previous study suggests Short-eared Owls may be facultative colonial nesters, but this behavior may be driven by an aggregated food source or nest site availability, rather than social factors (Voous 1989, Keyes et al. 2016). Based on incredibly low site fidelity in Short-eared Owls breeding in North America, it is entirely possible that that owls hatched on one island may nest on a different island or may even migrate away from the Hawaiian Islands (Booms et al. 2014). Breeding success of mainland Short-eared Owls ranges from 2.1 — 3.2 per active nest (Clark 1975, Holt 1992, Keyes et al. 2016), with a high occurrence of depredation and mortality due to avian and mammalian predators, disease, as well as anthropogenic causes such as heavy machinery, car strikes, or barbed-wire fences (Lockie 1955, Clark 1975, Bluhm and Ward 1979, Holt 1992, Wiggins et al. 2006, Weir 2008, Keyes et al. 2016).

In this project we will address two research needs: (1) improve population monitoring; and (2) define habitats important to population stability. 

We hope to engage public participation in this scientific research. Citizen science can truly make a difference.
 

© Colin Capelle

Literature Cited

Bluhm, CK, EK Ward. 1979. Great Horned Owl predation on a Short-eared Owl. Condor 81:307-308.

Bonham, CD 1989. Measurements for terrestrial vegetation. John Wiley & Sons, Toronto, ON, Canada.

Booms, TL, GL Holroyd, MA Gahbauer, HE Trefry, DA Wiggins, DW Holt, JA Johnson, SB Lewis, MD Larson, LK Keyes, S Swengel. 2014. Assessing the status and conservation priorities of the Short-eared Owl in North America. Wildlife Management 78:772-778.

Clark, RJ. 1975. A field study of the Short-eared Owl, Asio flammeus (Pontoppidan), in North America. Wildlife Monographs 47:1-67.

Hawai'i Department of Land and Natural Resources. October 1,2005. DLNR Fact Sheet: Pueo or Hawaiian Short-eared Owl Asio flammeus sandwichensis In "Hawaii's Comprehensive Wildlife Conservation Strategy."

Holt, DW. 1992. Notes on Short-eared Owl, Asia flammeus, nest sites, reproduction, and territory sizes in coastal Massachusetts. Canadian Field-Naturalist 106:352-356.

Johnson, DH, SR Swengel, AB Swengel. 2013. Short-eared Owl (Asia flammeus) occurrence at Buena Vista Grassland, Wisconsin, during 1955-2011. Raptor Research 47:271-281.

Keyes, KL, MA Gahbauer, DM Bird. 2016. Aspects of the breeding ecology of Short-eared Owls (Asio flammeus) on Amherst and Wolfe Islands, Eastern Ontario. Raptor Research 50:121-124.

Lockie, JD. 1955. The breeding habits and food of Short-eared Owls after a vote plague. Bird Study 2:53—69.

Martinez, DR, RA Figueroa, CL Ocampo, FM Jaksic. 1998. Food habits and hunting ranges of Short-eared Owls (Asia flammeus) in agricultural landscapes of southern Chile. Raptor Research 32:111-115.

Morales, MB, J Traba. 2016. Prioritizing research in steppe bird conservation: a literature survey. Ardeola 63:137-150.

Price, MR, VA Lee, WK Hayes. 2011. Population status, habitat dependence, and reproductive ecology of Bahama Orioles: a critically endangered synanthropic species. Journal of Field Ornithology 82(4):366—378.

Work, WM, J Hale. 1996. Causes of owl mortality in Hawaii, 1992 to 1994. Journal of Wildlife Diseases 32:266-273.

Voous, KH. 1989. Owls of the northern hemisphere. Massachusetts Institute of Technology Press,Cambridge, MA, USA.

Weir, RD. 2008. Birds of the Kingston region, 2n d Ed. Kingston Field Naturalists, Kingston, ON, Canada.

Wiggins, DA, DW Holt, SM Leasure. 2006. Short-eared Owl (Asio flammeus). In A. Poole [Ed.], The birds of North America online. Cornell Lab of Ornithology, Ithaca, NY, USA. http://bna.birds.cornelLedu/bna/species/062.