Time filter

Source Type

Toppenish, Washington, United States

Kozma J.M.,Yakama Nation | Kroll A.J.,Weyerhaeuser Company
Condor | Year: 2010

We examined the association of temporal and spatial factors with nest survival of Western Bluebirds (Sialia mexicana) nesting in tree cavities in ponderosa pine (Pinus ponderosa) forests along the east slope of the Cascade Mountains, Washington. All study areas were managed for timber production through planned harvests or postfire salvage logging. Bluebirds laid a mean clutch of 5.3 ± 0.1 (SE) eggs (n = 131), and successful nests fledged an average of 4.5 ± 0.2 young (n = 85). Using a model-selection framework, we found that nest survival was a function of clutch size and treatment and that there was a quadratic effect of nest age. Daily survival rates decreased after the onset of incubation, then increased through the nestling period, and were higher for clutches with ≥5 eggs and in stands that were burned and salvaged. Survivorship over the entire period for clutches (n = 131 nests) with ≤4, 5, and ≥6 eggs was 0.39 (95% CI: 0.11, 0.65), 0.61 (95% CI: 0.34, 0.80), and 0.71 (95% CI: 0.46, 0.85), respectively. Vegetation variables associated with nest sites did not significantly affect nest survival. Predation accounted for the most nest failures (34% of nests). We suggest that parental defense of nests accounts for the quadratic effect of nest age, with adult bluebirds defending nests more aggressively as nestlings approach fledging, and that bluebirds laying larger clutches are older, more experienced birds, resulting in greater nest survival. © The Cooper Ornithological Society 2010.

Kozma J.M.,Yakama Nation | Kroll A.J.,Weyerhaeuser Company
Condor | Year: 2012

Woodpeckers are particularly susceptible to habitat changes resulting from forest management because of their reliance on trees and snags for nesting and foraging. However, the influence of habitat variables on the reproductive success of woodpeckers has received less attention than it has in other avian taxonomic groups. We estimated nest-survival rates for the White-headed Woodpecker (Picoides albolarvatus), Hairy Woodpecker (P. villosus), and Northern Flicker (Colaptes auratus) in managed ponderosa pine (Pinus ponderosa) forests along the eastern slope of the Cascade Range in Washington, 2005-2010. Using a model-selection framework, we found that the most supported models included terms for a quadratic effect of date and habitat type for the Hairy Woodpecker, a negative effect of percent shrub cover for the White-headed Woodpecker, and a negative linear effect of date and habitat type, a negative linear effect of snag density, and a positive linear effect of tree density for the flicker. Survival rates over the entire cycle (laying + incubation + nestling stages) were 0.51 in unburned stands and 0.41 in burned stands for the Hairy Woodpecker, 0.70 for the White-headed Woodpecker, and 0.41 in unburned stands and 0.80 in burned stands for the flicker. In both habitats of our study survival rates of Hairy Woodpecker nests are lower than those reported in other studies, while those of White-headed Woodpecker nests are comparable to those reported in other areas of that species' range. © The Cooper Ornithological Society 2012.

Lorenz T.J.,University of Idaho | Lorenz T.J.,U.S. Department of Agriculture | Vierling K.T.,University of Idaho | Kozma J.M.,Yakama Nation | And 2 more authors.
Journal of Wildlife Management | Year: 2015

White-headed woodpeckers (Picoides albolarvatus) are important cavity excavators that recently have become the focus of much research because of concerns over population declines. Past studies have focused on nest site selection and survival but information is needed on factors influencing their space use when away from the nest. We examined space use by white-headed woodpeckers during the nesting (May-Jul) and post-nesting (Jul-Oct) periods and compared the role of environmental factors (e.g., landcover) and socio-demographic factors (e.g., age, breeding success) in home range size and selection of location. Average size of 99% kernel home ranges was 125 ha (SD ± 59 ha; n = 19) in the nesting period and 137 ha (SD ± 70 ha; n = 30) in the post-nesting period. Minimum convex polygons were generally comparable to or smaller than ranges reported from previous radio-telemetry studies with this species. Although bird weight and age best explained variation in home range size compared to other factors, neither parameter estimate was significant in our models. Thus, even though weight and age were the most-supported factors in our analysis, home range size was largely influenced by factors that we did not measure. We found that most woodpeckers selected home ranges within forest patches that had undergone a recent disturbance; these areas included forests that had recently been burned with prescribed fire by the United States Forest Service (82%) or subject to disease (16%). Most burned patches in our study were small (approx. 4.8 ha) and occurred within otherwise live forest but had nearly complete mortality of adult trees. We suggest that recent forest disturbances, especially mixed-severity prescribed burns, may have been selected by white-headed woodpeckers because they created snags for nesting and future studies should explore this hypothesis. Because home range size was variable and not linked with productivity, it should not be used as an indication of habitat quality without more detailed studies on causal factors that affect space use in this species. © Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Lorenz T.J.,University of Idaho | Vierling K.T.,University of Idaho | Kozma J.M.,Yakama Nation | Millard J.E.,U.S. Department of Agriculture
Forest Ecology and Management | Year: 2016

Information on the foraging ecology of animals is important for conservation and management, particularly for keystone species whose presence affects ecosystem health. We examined foraging by an at-risk cavity excavator, the white-headed woodpecker (Picoides albolarvatus). The foraging needs of this species are used to inform management of ponderosa pine (Pinus ponderosa) forests in some areas of western North America. Past observational studies indicated that white-headed woodpeckers forage predominately on cones and trunks of large-diameter (>68cm) pines in old-growth stands, although habitat selection while foraging has not been formally examined. We used radio telemetry to track forage substrate use among 37 adult, breeding woodpeckers for 176h (10,576min) in forest stands that had been recently thinned and/or burned with prescribed fire. We used discrete choice models to examine forage site selection and multinomial regression to examine consequences of foraging on nest productivity. Woodpeckers foraged on more than ten individual substrates and switched substrates seasonally, presumably to take advantage of prey availability. Dead wood and fir foliage were used commonly in the nesting period (86% and 68% of foraging, respectively), whereas pine foliage and trunk foraging dominated in the fledgling (66% of foraging) and post-fledgling periods (73% of foraging). Average size of used trees was 49cm (±20cm) and pine cones were rarely used (4% of foraging). During the nesting period, substrate use (χ2=1.49, df=4, P=0.83) and distances traveled from nests for foraging did not affect productivity (F(3,16)=0.61, P=0.62), which was high even for birds with the longest (2.1km) and shortest (0.39km) maximum forage distances. Habitats selected for foraging matched substrate use, and woodpeckers selected areas with low basal areas of live trees in the nesting period, but high basal areas in the post-nesting period. The variable foraging that we observed suggests that white-headed woodpeckers are plastic in their foraging in managed forests, and this plasticity has no negative consequences for productivity. © 2015.

I compared characteristics of sites of Western Bluebird (Sialia mexicana) nests in natural tree cavities in burned and unburned logged ponderosa pine (Pinus ponderosa) forests along the east slope of the Cascade Range of Washington, 2003-2008 and 2010. Tree density and percent debris cover (litter and large woody debris) were greater at nest sites in unburned stands because fire kills live trees and consumes woody debris, and they were the only characteristics in which nest sites in burned and unburned forests differed. In burned stands cavities were oriented primarily east, whereas in unburned stands they were oriented randomly. East-facing cavities may be thermally advantageous early in the day, keeping eggs warmer when the incubating female is away foraging. Most snags containing bluebird nest cavities (73%) were advanced in decay and had broken tops. Of the cavities whose original excavator was known, 27% were excavated by the Hairy Woodpecker (Picoides villosus), 12% by the White-headed Woodpecker (P. albolarvatus), and 5% by the Northern Flicker (Colaptes auratus). Only one nest was located in a non-excavated cavity. Of the 38 second nests, 76% were in the same cavity as the first, even though 38% of these first attempts were unsuccessful, suggesting that suitable cavities are limiting. My results suggest that bluebirds use similar nest sites in burned and unburned ponderosa pine stands and that abandoned woodpecker cavities are critical to the Western Bluebird in these managed forests.

Discover hidden collaborations