The Barred Owl in British Columbia

Grant, James

doi:10.2307/3536439

Cited by 30 publications

(19 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Barred Owl was historically widely distributed across south-central and southeastern parts of Canada, down through the eastern half of the United States, all the way to an isolated population in Mexico. Over the last century, researchers have noted an expansion of its geographic range (Grant 1966, Shea 1974, Wright and Hayward 1998, Holt et al 2001, Priestley 2004, Gutie´rrez et al 2007, Livezey 2009a. Barred Owls were first documented in northwestern Oregon in 1974 (Taylor and Forsman 1976) and have spread through Oregon, reaching Northern California by 1981 (Dark et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Neighborhood and habitat effects on vital rates: expansion of the Barred Owl in the Oregon Coast Ranges

Yackulic

Reid

Davis

et al. 2012

Ecology

144

View full text Add to dashboard Cite

In this paper, we modify dynamic occupancy models developed for detection-nondetection data to allow for the dependence of local vital rates on neighborhood occupancy, where neighborhood is defined very flexibly. Such dependence of occupancy dynamics on the status of a relevant neighborhood is pervasive, yet frequently ignored. Our framework permits joint inference about the importance of neighborhood effects and habitat covariates in determining colonization and extinction rates. Our specific motivation is the recent expansion of the Barred Owl (Strix varia) in western Oregon, USA, over the period 1990-2010. Because the focal period was one of dramatic range expansion and local population increase, the use of models that incorporate regional occupancy (sources of colonists) as determinants of dynamic rate parameters is especially appropriate. We began our analysis of 21 years of Barred Owl presence/nondetection data in the Tyee Density Study Area (TDSA) by testing a suite of six models that varied only in the covariates included in the modeling of detection probability. We then tested whether models that used regional occupancy as a covariate for colonization and extinction outperformed models with constant or year-specific colonization or extinction rates. Finally we tested whether habitat covariates improved the AIC of our models, focusing on which habitat covariates performed best, and whether the signs of habitat effects are consistent with a priori hypotheses. We conclude that all covariates used to model detection probability lead to improved AIC, that regional occupancy influences colonization and extinction rates, and that habitat plays an important role in determining extinction and colonization rates. As occupancy increases from low levels toward equilibrium, colonization increases and extinction decreases, presumably because there are more and more dispersing juveniles. While both rates are affected, colonization increases more than extinction decreases. Colonization is higher and extinction is lower in survey polygons with more riparian forest. The effects of riparian forest on extinction rates are greater than on colonization rates. Model results have implications for management of the invading Barred Owl, both through habitat alteration and removal.

show abstract

Section: Introductionmentioning

confidence: 99%

Neighborhood and habitat effects on vital rates: expansion of the Barred Owl in the Oregon Coast Ranges

Yackulic

Reid

Davis

et al. 2012

Ecology

144

View full text Add to dashboard Cite

show abstract

“…To better illustrate invasion dynamics of barred owls throughout western North America, we provide observations in 20‐year increments, beginning in 1910 through 1959 shown on panel A, demonstrating the advance of barred owls into the delineated ranges of northern, California, and Mexican spotted owls. A) 1910–1959, data points from Grant (), Boxall and Stepney (), Holt et al (), and Livezey (); B) 1910–1979, additional data points from Grant (), Reichard (), Rogers (), Taylor and Forsman (), Sharp (), Holt et al (), Livezey (), and eBird (); C) 1910–1999, additional data points from Evens and LeValley (), Harrington‐Tweit and Mattocks (), Sharp (), Dark et al (), Hamer et al (), Kelly (), Anthony et al (), Livezey (), Keane (), and eBird (); and D) 1910–2018, additional data points from Anthony et al (), Steger et al (), Jennings et al (), Keane (), and eBird ().…”

Section: Methodsmentioning

confidence: 99%

Review of the effects of barred owls on spotted owls

Long

Wolfe

2019

J Wildl Manag

View full text Add to dashboard Cite

Barred owls (Strix varia) are forest‐dwelling owls, native to eastern North America, with populations that expanded westward into the range of the spotted owl (Strix occidentalis). Barred owls exert an overwhelmingly negative influence on spotted owls, thereby threatening spotted owl population viability where the species co‐occur. In this review, we provide an overview of the barred owl's range expansion and detail and synthesize previously published literature on spotted and barred owls within the range of the spotted owl as related to potential future outcomes for the northern spotted owl (S. o. caurina). We include research on diet, habitat use and selection, effects of barred owls on spotted owl demography and behavior, hybridization with spotted owls, parasites, contemporary management, and future research needs for spotted owl populations given continued barred owl expansion throughout western North America. Our literature review and synthesis should provide managers with the information necessary to develop strategies that mitigate deleterious effects of barred owls at local and landscape scales. © 2019 The Wildlife Society.

show abstract

“…However, the recent expansion of the barred owl into the spotted owl's range in the Pacific Northwest deserves special attention. This expansion was first documented in the early 1960s, when the birds began moving into southeastern British Columbia (Grant, 1966). Shortly thereafter the first records for Washington (in 1965) and Oregon (in 1974) were obtained (Taylor and Forsman, 1976;Rohweder, 1978).…”

Section: Evolutionary Relationships and Conservation Statusmentioning

confidence: 97%