Association of Weather and Nest-Site Structure with Reproductive Success in California Spotted Owls

North, Malcolm P.; Steger, George N.; Denton, Renee G.; Eberlein, Gary E.; Munton, Tom; Johnson, Kenneth S.

doi:10.2307/3802750

Cited by 41 publications

(39 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We adopted the above tree size classes because they are commonly used by foresters (Blakesley et al., ; Verner et al., ), although the large old trees used by owls for nesting are typically larger than 61 cm dbh (e.g., mean 157 cm dbh; North et al., ). Median QMD in the >61 cm dbh size class was 75.5 cm and reached a maximum of 279 cm (Fig.…”

Section: Methodsmentioning

confidence: 99%

Declining old‐forest species as a legacy of large trees lost

Jones

Keane

Gutiérrez

et al. 2017

Diversity and Distributions

View full text Add to dashboard Cite

Aim Global declines in large old trees from selective logging have degraded old‐forest ecosystems, which could lead to delayed declines or losses of old‐forest‐associated wildlife populations (i.e., extinction debt). We applied the declining population paradigm and explored potential evidence for extinction debt in an old‐forest dependent species across landscapes with different histories of large tree logging. Location Montane forests of the Sierra Nevada, California, USA. Methods We tested hypotheses about the influence of forest structure on territory extinction dynamics of the spotted owl (Strix occidentalis) using detection/non‐detection data from 1993 to 2011 across two land tenures: national forests, which experienced extensive large tree logging over the past century, and national parks, which did not. Results Large tree/high canopy cover forest was the best predictor of extinction rates and explained 26%–77% of model deviance. Owl territories with more large tree/high canopy cover forest had lower extinction rates, and this forest type was ~4 times more prevalent within owl territories in national parks (truexfalse¯ = 19% of territory) than national forests (truexfalse¯ = 4% of territory). As such, predicted extinction probability for an average owl territory was ~2.5 times greater in national forests than national parks, where occupancy was declining (truenormalλfalse¯false^<1) and stable (truenormalλfalse¯false^=1), respectively. Large tree/high canopy cover forest remained consistently low, but did not decline, during the study period on national forests while owl declines were ongoing—an observation consistent with an extinction debt. Main conclusions In identifying a linkage between large trees and spotted owl dynamics at a regional scale, we provide evidence suggesting past logging of large old trees may have contributed to contemporary declines in an old‐forest species. Strengthening protections for remaining large old trees and promoting their recruitment in the future will be critical for biodiversity conservation in the world's forests.

show abstract

Section: Methodsmentioning

confidence: 99%

Declining old‐forest species as a legacy of large trees lost

Jones

Keane

Gutiérrez

et al. 2017

Diversity and Distributions

View full text Add to dashboard Cite

show abstract

“…The possible additional function of thermal insulation proposed for dense canopy cover in temperate or boreal areas (Galeotti et al . 2000, Henrioux 2002; see also North et al . 2000) could be less important in warmer Mediterranean climates.…”

Section: Discussionmentioning

confidence: 99%

Landscape and anti‐predation determinants of nest‐site selection, nest distribution and productivity in a Mediterranean population of Long‐eared Owls Asio otus

Rodrı́guez

Garcı́a

Cervera³

et al. 2006

Ibis

View full text Add to dashboard Cite

Nest predation is an important determinant of owl breeding success. We studied Long‐eared Owl Asio otus productivity and attributes of nest‐sites at the microhabitat and landscape scales in a Mediterranean locality over an 8‐year period. We examined the effect on nest location and productivity of protective cover in concealing the nest from aerial and terrestrial predators. A dense cover of ivy and tree‐foliage at canopy level favoured nest location but not productivity. By contrast, high shrub cover beneath the nest was selected by Owls and was positively related to both the site reoccupancy rate and the overall number of young fledged. Pre‐fledging Owls use the ground, where they are exposed to terrestrial predators, which are much more abundant in the study area than are aerial predators. Our results therefore support the hypothesis that Owls adapt nest‐site choice to local sources of predation risk. As reported elsewhere, Long‐eared Owls in our study area showed restricted territoriality and nested in clusters. As active nest‐sites during the same breeding season were more than 1 km apart on average, and their productivity was never greater for clustered nests than for more isolated nests, nest aggregation could not be interpreted as a case of facultative colonial breeding, which has been reported for this species in other areas. Neither landscape variables indicative of the availability of foraging areas nor structural attributes that protect young from predators explained the remarkable scarcity of nests in half of the study area. Unmeasured factors such as human disturbance could explain the pattern of distribution of Long‐eared Owl nests.

show abstract

“…However, foliage from banner limbs may provide additional overhead protection from precipitation, or radiative heat loss. Spotted owls had higher reproductive success when using nest sites that had an above-nest foliage volume >4300 m 3/ 0.05 ha [31]. Precipitation that wets the eggs could reduce hatching success because of a reduction in eggshell conductance of O 2 and CO 2 [25], or increased heat loss due to the effects of latent heat loss [35], [39].…”

Section: Discussionmentioning

confidence: 99%

Potential Influences of Climate and Nest Structure on Spotted Owl Reproductive Success: A Biophysical Approach

et al. 2012

View full text Add to dashboard Cite

Many bird species do not make their own nests; therefore, selection of existing sites that provide adequate microclimates is critical. This is particularly true for owls in north temperate climates that often nest early in the year when inclement weather is common. Spotted owls use three main types of nest structures, each of which are structurally distinct and may provide varying levels of protection to the eggs or young. We tested the hypothesis that spotted owl nest configuration influences nest microclimate using both experimental and observational data. We used a wind tunnel to estimate the convective heat transfer coefficient (hc) of eggs in 25 potential nest configurations that mimicked 2 nest types (top-cavity and platform nests), at 3 different wind speeds. We then used the estimates of hc in a biophysical heat transfer model to estimate how long it would take unattended eggs to cool from incubation temperature (∼36°C) to physiological zero temperature (PZT; ∼26°C) under natural environmental conditions. Our results indicated that the structural configuration of nests influences the cooling time of the eggs inside those nests, and hence, influences the nest microclimate. Estimates of time to PZT ranged from 10.6 minutes to 33.3 minutes. Nest configurations that were most similar to platform nests always had the fastest egg cooling times, suggesting that platform nests were the least protective of those nests we tested. Our field data coupled with our experimental results suggested that nest choice is important for the reproductive success of owls during years of inclement weather or in regions characterized by inclement weather during the nesting season.

show abstract

Association of Weather and Nest-Site Structure with Reproductive Success in California Spotted Owls

Cited by 41 publications

References 0 publications

Declining old‐forest species as a legacy of large trees lost

Declining old‐forest species as a legacy of large trees lost

Landscape and anti‐predation determinants of nest‐site selection, nest distribution and productivity in a Mediterranean population of Long‐eared Owls Asio otus

Potential Influences of Climate and Nest Structure on Spotted Owl Reproductive Success: A Biophysical Approach

Contact Info

Product

Resources

About