Spatial, road geometric and biotic factors associated with Barn Owl mortality along an interstate highway

Abstract

Highway programmes typically focus on reducing vehicle collisions with large mammals because of economic or safety reasons, while overlooking the millions of birds that die annually from traffic. We studied wildlife–vehicle collisions along an interstate highway in southern Idaho, USA, with among the highest reported rates of American Barn Owl Tyto furcata road mortality. Carcass data from systematic and ad hoc surveys conducted in 2004–2006 and 2013–2015 were used to explore the extent to which spatial, road geometric and biotic factors explained Barn Owl–vehicle collisions. Barn Owls outnumbered all other identified vertebrate species of roadkill and represented > 25% of individuals and 73.6% of road‐killed birds. At a 1‐km highway segment scale, the number of dead Barn Owls decreased with increasing numbers of human structures, cumulative length of secondary roads near the highway and width of the highway median. The number of dead Barn Owls increased with higher commercial average annual daily traffic (CAADT), small mammal abundance index and grass rather than shrubs in the roadside verge. The small mammal abundance index was also greater in roadsides with grass vs. mixed shrubs, suggesting that Barn Owls may be attracted to grassy portions of the highway with more abundant small mammals for hunting prey. When assessed at a 3‐km highway segment scale, the number of dead Barn Owls again increased, with higher CAADT as well as with greater numbers of dairy farms. At a 5‐km scale, the number of dead Barn Owls increased with a greater percentage of cropland near the highway. Although human conversion of the environment from natural shrub‐steppe to irrigated agriculture in this region of Idaho has probably enhanced habitat for Barns Owls, it simultaneously has increased risk for owl–vehicle collisions where an interstate highway traverses the altered landscape. We review some approaches for highway mitigation and suggest that reducing wildlife–vehicle collisions involving Barn Owls may contribute to the persistence of this species.

Assessing patterns of barn owl Tyto alba occupancy from call broadcast surveys

“…2012, Belthoff et al 2015, Arnold et al 2018. Portions of our research also occurred in the Morley Nelson Snake River Birds of Prey National Conservation Area, where the Snake River canyon was one of the main geologic features.…”

“…here were also ~300 small to large dairy farms throughout the study area (Idaho Oice of the Administrative Rules Coordinator 2014), which likely increased owl prey and nesting/roosting sites because of associated food production/storage for livestock and farm buildings. he study area also contained a >150-km long stretch of Interstate-84, a major road where barn owl-vehicle collisions are documented (Boves and Belthof 2012, Belthof et al 2015, Arnold et al 2018. Portions of our research also occurred in the Morley Nelson Snake River Birds of Prey National Conservation Area, where the Snake River canyon was one of the main geologic features.…”

“…Barn owls appear to be particularly susceptible to vehicle collisions along roads, and owl-vehicle collisions are geographically quite widespread (Moore and Mangel 1996, Massemin et al 1998, Ramsden 2003, Grilo et al 2012, Bishop and Brogan 2013, Loss et al 2014, Belthof et al 2015. Mortality hotspots are often associated with agricultural landscapes and with high vehicle speeds and traic volume (Illner 1992, Ramsden 2003, Boves and Belthof 2012, Arnold et al 2018. Even though we included analysis of distance from major roads and cumulative road lengths within bufers surrounding point-count locations, owl occupancy was not associated with these variables in either season.…”

Flight Altitudes of Raptors in Southern Africa Highlight Vulnerability of Threatened Species to Wind Turbines

“…However, Barn Owls most often forage by quartering low (1.5-4.5 m; Marti et al, 2020) over open areas (König and Weick, 2008;Marti et al, 2020). This species is also a frequent victim of vehicle collision (Gomes et al, 2009;Boves and Belthoff, 2012;Arnold et al, 2019), reflecting their low-flying behavior. We were surprised that the Ovambo Sparrowhawk (Accipiter ovampensis), a relatively small woodland-dwelling accipiter (Ferguson-Lees and Christie, 2001), had the highest mode flight altitude.…”

Contribuição Para O Conhecimento Da Dieta De Corujas (Aves: Strigiformes) No Sul Do Brasil

“…As corujas são vítimas frequentes de atropelamentos (Novelli et al 1988, Carvalho et al 2014, Corrêa et al 2017) ao cruzarem rodovias (Bencke & Bencke 1999, Arnold et al 2019) ou ao tentarem se alimentar de carcaças de outros animais atropelados (Erritzoe et al 2003, Fischer et al 2018. A análise de conteúdos estomacais de aves atropeladas pode fornecer importantes informações sobre a composição de sua alimentação (Ramos et al 2011 (Triplehorn & Johnson 2011, Vieira et al 2015.…”