Radiographic Evaluation of Perching-joint Angles in Cockatiels (Nymphicus hollandicus), Hispaniolan Amazon Parrots (Amazona ventralis), and Barred Owls (Strix varia)

2009 ◽  
Vol 23 (2) ◽  
pp. 91-100 ◽  
Author(s):  
Glen Bonin ◽  
Susanne K. Lauer ◽  
David Sanchez-Migallon Guzman ◽  
Javier Nevarez ◽  
Thomas N. Tully ◽  
...  
Keyword(s):  
Radiographic Evaluation ◽  
Joint Angles ◽  
Strix Varia ◽  
Nymphicus Hollandicus ◽  
Barred Owls

scholarly journals Using Detection Dogs to Conduct Simultaneous Surveys of Northern Spotted (Strix occidentalis caurina) and Barred Owls (Strix varia)

PLoS ONE ◽  
2012 ◽  
Vol 7 (8) ◽  
pp. e42892 ◽  
Author(s):  
Samuel K. Wasser ◽  
Lisa S. Hayward ◽  
Jennifer Hartman ◽  
Rebecca K. Booth ◽  
Kristin Broms ◽  
...  
Keyword(s):  
Strix Occidentalis ◽  
Strix Varia ◽  
Strix Occidentalis Caurina ◽  
Barred Owls

scholarly journals Does The Presence of Barred Owls Suppress the Calling Behavior of Spotted Owls?

The Condor ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 760-769 ◽  
Author(s):  
Michelle L. Crozier ◽  
Mark E. Seamans ◽  
R. J. GutiÉRrez ◽  
Peter J. Loschl ◽  
Robert B. Horn ◽  
...  
Keyword(s):  
Calling Behavior ◽  
Field Observations ◽  
Spotted Owl ◽  
Strix Occidentalis ◽  
Response Data ◽  
Strix Varia ◽  
Spotted Owls ◽  
Strix Occidentalis Caurina ◽  
Northern Spotted Owls ◽  
Barred Owls

Abstract Abstract Barred Owls (Strix varia) have expanded their range throughout the ranges of Northern (Strix occidentalis caurina) and California Spotted Owls (S. o. occidentalis). Field observations have suggested that Barred Owls may be behaviorally dominant to Spotted Owls. Therefore, we conducted a test of behavioral dominance by assessing responsiveness of Spotted Owls to conspecific calls when they were in the simulated presence (i.e., imitation of Barred Owl vocalizations) of a Barred Owl. We hypothesized that Spotted Owls would be less likely to respond to conspecific calls in areas where Barred Owls were common. We used a binary 2 × 2 crossover experimental design to examine male Spotted Owl responses at 10 territories randomly selected within two study areas that differed in abundance of Barred Owls. We also conducted a quasi experiment at four study areas using response data from any Spotted Owl (male or female) detected following exposure to Barred Owl calls. We inferred from the crossover experiment that the simulated presence of a Barred Owl might negatively affect Spotted Owl responsiveness. Both subspecies of Spotted Owl responded less to Spotted Owl calls after exposure to Barred Owl calls, Northern Spotted Owls responded less frequently in areas having higher numbers of Barred Owls, and California Spotted Owls responded less frequently than Northern Spotted Owls overall.

scholarly journals Are Barred Owls Displacing Spotted Owls?

The Condor ◽  
2003 ◽  
Vol 105 (1) ◽  
pp. 45-53 ◽  
Author(s):  
Elizabeth G. Kelly ◽  
Eric D. Forsman ◽  
Robert G. Anthony
Keyword(s):  
Pacific Northwest ◽  
Current Status ◽  
Spotted Owl ◽  
Strix Occidentalis ◽  
Strix Varia ◽  
The Pacific ◽  
Spotted Owls ◽  
Before And After ◽  
Strix Occidentalis Caurina ◽  
Barred Owls

Abstract Barred Owls (Strix varia) have expanded their range into the Pacific Northwest, and anecdotal evidence suggests that they may be displacing the federally threatened Northern Spotted Owl (Strix occidentalis caurina). Our objectives were to describe the current status of Barred Owls in Oregon and compare occupancy of Spotted Owls in historic Spotted Owl territories before and after Barred Owls were first detected in those territories. Between 1974 and 1998, we estimated that 706 different Barred Owl territories were located in Oregon. From 1989–1998 an average of 60 new Barred Owl territories were located in Oregon each year. In Spotted Owl demographic study areas in Oregon and Washington, Barred Owl detections increased at Spotted Owl territories from 1987–1999. Occupancy of Spotted Owl territories declined after Barred Owls were detected within 0.80 km of the territory center. When Barred Owls were detected 0.81–2.40 km from Spotted Owl territory centers, occupancy of Spotted Owls was only marginally less than at territories without Barred Owls. This suggests that the frequency and intensity of interactions between the two species is negatively associated with distance between them. Our results suggest that land managers and regulatory agencies should regard Barred Owls as a threat to Spotted Owls, particularly if Barred Owls continue to increase in number as they have during the past 25 years. ¿Está Strix varia Desplazando a Strix occidentalis caurina? Resumen. Desde su expansión hacia el Pacífico Noroeste, existe evidencia anecdótica de que Strix varia podría estar desplazando a S. occidentalis caurina. Nuestros objetivos fueron describir el estatus actual de S. varia en Oregon y comparar la ocurrencia de S. occidentalis caurina en sus territorios históricos antes y después de que S. varia se detectó por primera vez en dichos territorios. Entre 1974 y 1998, estimamos que se confirmaron 706 territorios diferentes de S. varia en Oregon. Entre 1989 y 1998, se localizaron en promedio 60 nuevos territorios de S. varia anualmente. En áreas con estudios demográficos de S. occidentalis caurina en Oregon y Washington, las detecciones de S. varia en territorios de S. occidentalis caurina se incrementaron entre 1987 y 1999. En comparación con territorios sin S. varia, la ocupación de territorios de S. occidentalis caurina disminuyó luego de que se detectaron individuos de S. varia a menos de 0.80 km del centro del territorio. Cuando se detectaron individuos de S. varia entre 0.81 y 2.40 km del centro de los territorios, la ocupación de éstos fue sólo marginalmente menor que en territorios sin S. varia. Esto sugiere que la frecuencia e intensidad de la interacción entre las dos especies está asociada con la distancia entre ellas. Nuestros resultados sugieren que las autoridades ambientales y de regulación deben considerar a S. varia como una amenaza para S. occidentalis caurina, particularmente si los números de S. varia se siguen incrementando como en los últimos 25 años.

Trichomonosis due to Trichomonas gallinae infection in barn owls (Tyto alba) and barred owls (Strix varia) from the eastern United States

2019 ◽  
Vol 16 ◽  
pp. 100281
Author(s):  
Kevin D. Niedringhaus ◽  
Holly J. Burchfield ◽  
Elizabeth J. Elsmo ◽  
Christopher A. Cleveland ◽  
Heather Fenton ◽  
...  
Keyword(s):  
United States ◽  
Eastern United States ◽  
Tyto Alba ◽  
Trichomonas Gallinae ◽  
Strix Varia ◽  
Barn Owls ◽  
Barred Owls

A synopsis of suggested approaches to address potential competitive interactions between Barred Owls (Strix varia) and Spotted Owls (S. occidentalis)

2007 ◽  
Vol 9 (6) ◽  
pp. 679-691 ◽  
Author(s):  
Joseph B. Buchanan ◽  
R. J. Gutiérrez ◽  
Robert G. Anthony ◽  
Tim Cullinan ◽  
Lowell V. Diller ◽  
...  
Keyword(s):  
Competitive Interactions ◽  
Strix Varia ◽  
Spotted Owls ◽  
Barred Owls

scholarly journals Home Range Attributes and Habitat Selection of Barred Owls and Spotted Owls in an Area of Sympatry

The Condor ◽  
2007 ◽  
Vol 109 (4) ◽  
pp. 750-768 ◽  
Author(s):  
Thomas E. Hamer ◽  
Eric D. Forsman ◽  
Elizabeth M. Glenn
Keyword(s):  
Habitat Selection ◽  
Home Range ◽  
Breeding Season ◽  
Home Range Size ◽  
Negative Slope ◽  
Home Ranges ◽  
Strix Varia ◽  
Spotted Owls ◽  
Barred Owls ◽  
Selection Of

Abstract We compared home range areas and habitat selection of radio-marked Spotted Owls (Strix occidentalis) and Barred Owls (Strix varia) in an area of sympatry in the northern Cascade Range of Washington in 1986–1989. On average, home ranges of Spotted Owls were 3–4 times larger than ranges of Barred Owls, and there was little overlap of home ranges during the breeding season. Ranges of both species tended to expand during winter. Home range size of both species was negatively correlated with the amount of old forest, but the negative slope of the regression was much steeper for Spotted Owls than for Barred Owls. For both species, home ranges of individual owls typically had high overlap among seasons and years, indicating high site fidelity. Barred Owls generally occupied home ranges at lower elevations than Spotted Owls (mean  =  386 ± 27 m vs. 750 ± 68 m). Both species tended to use old forests more than expected, but Spotted Owls tended to use other cover types less than expected, whereas Barred Owls used most other cover types in proportion to their availability. We suggest that Spotted Owls may use larger ranges than Barred Owls because they prey selectively on a few species of nocturnal mammals, whereas Barred Owls forage more evenly across a broad range of prey types, including diurnal and aquatic species. The low overlap of Barred Owl and Spotted Owl home ranges suggests that territorial Barred Owls exclude Spotted Owls from their territories, at least during the breeding season, thus reducing the amount of habitat available to Spotted Owls.

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