Burrowing Owl Diet at a Migratory Stopover Site and Wintering Ground on Southeast Farallon Island, California

Chandler, Sara Lee; Tietz, James R.; Bradley, Russell W.; Trulio, Lynne

doi:10.3356/jrr-16-00006.1

Cited by 7 publications

(14 citation statements)

References 57 publications

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“…There are no abundant insect prey on the South Farallon islands, which accords with Chandler et al. 's () finding that, overall, insects formed less than 1% of the diet biomass of burrowing owls. Nor are there reptile or amphibian prey available to owls.…”

Section: Discussionsupporting

confidence: 86%

“…As shown by Chandler et al. () and here, owls appear to prefer house mice as prey, but turn to depredating storm petrels when mouse abundance has dropped severely. This prey‐switching behavior has been observed to adversely impact seabirds as well as mammalian prey on islands (Roemer et al.…”

Section: Discussionsupporting

confidence: 73%

“…Thus, storm petrels, which are nocturnal at the colony, as are the foraging owls, become a major prey item for the owls in the late winter and spring (Chandler et al. , Mills ).…”

Section: Introductionmentioning

confidence: 99%

“…Rather, mice have an indirect impact on storm petrels through the hyper-predation of burrowing owls. On SEFI, owls subsist almost entirely on a diet of mice in fall and early winter (Chandler et al 2016, Mills 2016. However, as the mouse population crashes in early winter, overwintering owls switch from a diet dominated by mice in December to one dominated by storm petrels in February, with the January diet displaying a mixture of the two prey species (Chandler et al 2016).…”

Section: Introductionmentioning

confidence: 99%

“…On SEFI, owls subsist almost entirely on a diet of mice in fall and early winter (Chandler et al 2016, Mills 2016. However, as the mouse population crashes in early winter, overwintering owls switch from a diet dominated by mice in December to one dominated by storm petrels in February, with the January diet displaying a mixture of the two prey species (Chandler et al 2016). Thus, storm petrels, which are nocturnal at the colony, as are the foraging owls, become a major prey item for the owls in the late winter and spring (Chandler et al 2016, Mills 2016.…”

Section: Introductionmentioning

confidence: 99%

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Evaluating population impacts of predation by owls on storm petrels in relation to proposed island mouse eradication

et al. 2019

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We quantify the expected demographic benefit to a seabird of conservation concern, the ashy storm‐petrel Oceanodroma homochroa, from the proposed eradication of introduced house mice Mus musculus on the South Farallon Islands, California. A key objective of the eradication is to reduce storm petrel predation by burrowing owls Athene cunicularia, which stopover on the island during their fall migration. Mouse trapping and field surveys of both owls and depredated storm petrel carcasses conducted during 2000–2012 reveal a strongly seasonal, inter‐related pattern among the three species: When owls arrive during the fall, mice are super‐abundant and the overwhelming choice of prey for those owls that remain. In the winter, the mouse population crashes just as storm petrels begin to arrive in large numbers; owls that remain on the island switch to preying upon storm petrels until May, when they depart to breed. Capture–recapture analyses of storm petrels showed (1) annual adult survival was inversely related to owl abundance, especially during January–April, and (2) storm petrels demonstrated a declining trend in abundance 2006–2012. The latter was associated with low rates of adult survival, high abundance of overwintering burrowing owls, and high incidence of depredated storm petrels. To evaluate projected impacts to storm petrels of a change in owl predation, we developed a Leslie matrix model, incorporating environmental stochasticity. We modeled future storm petrel population trajectories, allowing for different levels of owl‐mediated predation. Our results suggest that a reduction in owl abundance, a projected consequence of the elimination of mice, has the potential to substantially reduce overall storm petrel mortality, thereby reducing storm petrel declines and increasing the likelihood of stable trends in the future. While long‐term benefits to storm petrels of mouse eradication are apparent, the risk of increased predation due to prey‐switching by owls also needs to be addressed. This study highlights uncertainty of outcomes, which must be considered in evaluating management impacts. This study demonstrates the value of concurrent, continuous, long‐term datasets in providing a quantitative basis for management to aid the conservation of species of concern.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionsupporting

confidence: 73%

“…Thus, storm petrels, which are nocturnal at the colony, as are the foraging owls, become a major prey item for the owls in the late winter and spring (Chandler et al. , Mills ).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Evaluating population impacts of predation by owls on storm petrels in relation to proposed island mouse eradication

et al. 2019

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Population Dynamics and Resource Availability Drive Seasonal Shifts in the Consumptive and Competitive Impacts of Introduced House Mice (Mus musculus) on an Island Ecosystem

Polito

Robinson

Warzybok

et al. 2022

Preprint

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Background. House mice (Mus musculus) are widespread and invasive on many islands where they can have both direct and indirect ecological impacts on native ecological communities. Given their opportunistic, omnivorous nature the consumptive and competitive impacts of house mice on islands have the potential to vary over time in concert with resource availability and mouse population dynamics. Methods. We examined the ecological niche of invasive house mice on Southeast Farallon Island, California, USA using a combination of mouse trapping, food resource surveys, and stable isotope analysis to better understand their trophic interactions with native flora and fauna. Results. We found that plants were the important resource for house mice during the spring months when vegetation is abundant and mouse populations are low. However, plants decline in dietary importance throughout the summer and fall as mouse populations increase, and seabird and insect resources become relatively more available and consumed by house mice. Mouse abundance peaks and other resource availability are low in the fall months when the isotopic niches of house mice and salamanders overlap significantly indicating the potential for competition, most likely for insect prey. Discussion. These results indicate how seasonal shifts in both the mouse abundance and resource availability are key factors that mediate the consumptive and competitive impacts of introduced house mice on this island ecosystem.

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Future Directions in Conservation Research on Petrels and Shearwaters

Arcos²,

et al. 2019

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Shearwaters and petrels (hereafter petrels) are highly adapted seabirds that occur across all the world's oceans. Petrels are a threatened seabird group comprising 124 species. They have bet-hedging life histories typified by extended chick rearing periods, low fecundity, high adult survival, strong philopatry, monogamy and long-term mate fidelity and are thus vulnerable to change. Anthropogenic alterations on land and at sea have led to a poor conservation status of many petrels with 52 (42%) threatened

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Burrowing Owl Diet at a Migratory Stopover Site and Wintering Ground on Southeast Farallon Island, California

Cited by 7 publications

References 57 publications

Evaluating population impacts of predation by owls on storm petrels in relation to proposed island mouse eradication

Evaluating population impacts of predation by owls on storm petrels in relation to proposed island mouse eradication

Population Dynamics and Resource Availability Drive Seasonal Shifts in the Consumptive and Competitive Impacts of Introduced House Mice (Mus musculus) on an Island Ecosystem

Future Directions in Conservation Research on Petrels and Shearwaters

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