Effects of barred owl (Strix varia) range expansion on Haemoproteus parasite assemblage dynamics and transmission in barred and northern spotted owls (Strix occidentalis caurina)

Lewicki, Krista E.; Huyvaert, Kathryn P.; Piaggio, Antoinette J.; Diller, Lowell V.; Franklin, Alan B.

doi:10.1007/s10530-014-0828-5

Cited by 11 publications

(11 citation statements)

References 41 publications

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“…The ability of northern spotted owls to adapt to increased interspecific competition and direct predation may also be limited by genetic constraints arising from severe decreases in population size in some parts of the subspecies’ range (Funk et al , Forsman et al ). In addition, comparisons of blood parasite loads among barred owls and northern spotted owls found that northern spotted owls have greater parasite diversity and probability of infection than sympatric barred owls (Lewicki et al ). These findings support the enemy release hypothesis (Torchin et al ), where hosts (barred owls) benefit from a loss of parasites in their invasive range.…”

Section: Hypothesized Effects Of Barred Owlsmentioning

confidence: 99%

Potential trophic cascades triggered by the barred owl range expansion

et al. 2016

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Recently, the barred owl (Strix varia) has expanded its range into the Pacific Northwest of the United States resulting in pronounced effects on the demography and behavior of the northern spotted owl (S. occidentalis caurina). The range expansion has brought together historically allopatric species, creating the potential for significant changes in the avian predator community with possible cascading effects on food-web dynamics. The adverse effects of the barred owl on the behavior and demography of the northern spotted owl are well-documented, but little is known about the immediate and long-term effects changes in the predator community may have on native species composition and ecosystem processes. Based on northern spotted owl and barred owl selection for diet and habitat resources, there is a potential for trophic cascades within the region's predator and prey communities, differing responses by their shared and unique prey species, and possible direct and indirect effects on ecosystem processes. We explored the possible ecological consequences of the barred owl range expansion to wildlife communities of the Pacific Northwest based on the theoretical underpinnings of predator-prey relationships, interspecific competition, intraguild predation, and potential cascading trophic interactions. Negative effects on fitness of northern spotted owls because of interspecific competition with barred owls are strong selection forces that may contribute to the regional extinction of the northern spotted owl. In addition, we posit that shared prey species and those uniquely consumed by barred owls, along with other competing native predators, may experience changes in behavior, abundance, and distribution as a result of increased rates of predation by rapidly expanding populations of barred owls.

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Section: Hypothesized Effects Of Barred Owlsmentioning

confidence: 99%

Potential trophic cascades triggered by the barred owl range expansion

et al. 2016

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“…While there is ample evidence for the acquisition of native parasites by invasive host species (step 1 of parasite spillback; e.g. Miller and Vincent 2006;Georgiev et al 2014;Sheath et al 2015;Lewicki et al 2015), there is little conclusive evidence for an actual amplification and/or spillback to native species (but see Hershberger et al 2010;Goedknegt et al 2016). Finally, as an alternative mechanism to parasite spillback, incompetent invasive host species can act as a sink by diluting the native parasite population and thereby reducing the disease risk for native species (transmission interference or parasite dilution; Thieltges et al 2009;Paterson et al 2011;Poulin et al 2011;Goedknegt et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Spillover but no spillback of two invasive parasitic copepods from invasive Pacific oysters (Crassostrea gigas) to native bivalve hosts

et al. 2016

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Invasive species can cause indirect effects on native biota by modifying parasite-host interactions and disease occurrence in native species. This study investigated the role of the invasive Pacific oyster (Crassostrea gigas) in potential spillover (co-introduced parasites infect native hosts) and spillback (native or established parasites infect invasive hosts and re-infect native hosts) scenarios of recently introduced (Mytilicola orientalis) and previously established (Mytilicola intestinalis) marine parasitic copepods in two regions in northern Europe, the Dutch Delta and the Wadden Sea. By examining 3416 individuals of 11 potential host species from sympatric host populations, we found that the recently introduced parasite M. orientalis does not only infect its principal host, the invasive Pacific oyster (prevalence at infected sites 2-43 %, mean intensity 4.1 ± 0.6 SE), but also native blue mussels (Mytilus edulis; 3-63 %, 2.1 ± 0.2), common cockles (Cerastoderma edule; 2-13 %, 1.2 ± 0.3) and Baltic tellins (Macoma balthica; 6-7 %, 1.0 ± 0), confirming a spillover effect. Spillback effects were not observed as the previously established M. intestinalis was exclusively found in blue mussels (prevalence at infected locations 3-72 %, mean intensity 2.4 ± 0.3 SE). The high frequency of M. orientalis spillover, in particular to native mussels, suggests that Pacific oysters may cause strong parasite-mediated indirect impacts on native bivalve populations.

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“…As a recent but closely related invader to the west coast, barred owls have the potential to bring novel, harmful pathogens and parasites from east coast populations, which could be transmitted to spotted owls and may be more lethal to the native species. As such, Lewicki et al () examined the Haemoproteus blood parasite assemblages of barred owls in their native and invasive ranges and in northern spotted owls. They reported that northern spotted owls had a slightly lower prevalence of Haemoproteus infection than both populations of barred owls, but mean infection intensity was almost 100 times greater than that of barred owls in the West.…”

Section: Resultsmentioning

confidence: 99%

Review of the effects of barred owls on spotted owls

Long

Wolfe

2019

J Wildl Manag

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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.

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Effects of barred owl (Strix varia) range expansion on Haemoproteus parasite assemblage dynamics and transmission in barred and northern spotted owls (Strix occidentalis caurina)

Abstract: Effects of barred owl (Strix varia) range expansion on Haemoproteus parasite assemblage dynamics and transmission in barred and northern spotted owls (Strix occidentalis caurina)" (2015).

Cited by 11 publications

References 41 publications

Potential trophic cascades triggered by the barred owl range expansion

Potential trophic cascades triggered by the barred owl range expansion

Spillover but no spillback of two invasive parasitic copepods from invasive Pacific oysters (Crassostrea gigas) to native bivalve hosts

Review of the effects of barred owls on spotted owls

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