Do Some Northern Goshawk Nest Areas Consistently Fledge More Young Than Others?

McClaren, Erica L.; Kennedy, Patricia L.; Dewey, Sarah R.

doi:10.1650/0010-5422(2002)104[0343:dsngna]2.0.co;2

Cited by 17 publications

(18 citation statements)

References 23 publications

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“…In contrast to the above results, McClaren et al (2002) found that the number of young fledged did not show significant spatial variation across 3 study areas (Vancouver Island, B.C., Jemez Mountains, N.M., and Uinta Mountains, Ut. ), suggesting that habitat is not an important determinant of reproductive success.…”

Section: Occupancy and Productivity Related To Landscape Habitat Featcontrasting

confidence: 94%

A review of northern goshawk habitat selection in the home range and implications for forest management in the western United States

Greenwald¹,

Crocker-Bedford

Broberg

et al. 2005

Wildlife Society Bulletin

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We reviewed all North American radiotelemetry studies of within-home-range habitat selection by northern goshawks (Accipiter gentilis) and all studies relating territory occupancy and productivity to landscape habitat features. Goshawks selected habitats in the home range with structural characteristics of mature to old-growth forests, such as large trees and high canopy closure. We documented selection of these structures in a number of forest types, including ponderosa pine (Pinus ponderosa), mixed conifer, lodgepole pine (P. contorta), temperate rainforest, upland hardwood, and boreal forest, suggesting that goshawks are selecting forests for their structure rather than for species composition. Goshawks did not select stands with the greatest prey abundance. Selection for natural openings, edges, and stand diversity was inconclusive. Habitat selection patterns suggest that current goshawk management plans in the western United States may be inadequate.

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Section: Occupancy and Productivity Related To Landscape Habitat Featcontrasting

confidence: 94%

A review of northern goshawk habitat selection in the home range and implications for forest management in the western United States

Greenwald¹,

Crocker-Bedford

Broberg

et al. 2005

Wildlife Society Bulletin

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“…θ denotes either probability of occupancy or reproductive output. Variable acronyms are defined in Table 1. et al , McClaren et al 2002, and the rest of the variables as fixed effects. To control for annual variation, year was also considered as a fixed effect.…”

Section: Data Analysis and Model Selectionmentioning

confidence: 99%

Factors influencing territorial occupancy and reproductive output in the Booted Eagle Hieraaetus pennatus

Martínez

Pagán

Calvo

2006

Ibis

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During a 7‐year research project in a forested area of southeastern Spain, we studied territorial occupancy and reproductive success in a Booted Eagle Hieraaetus pennatus population. We monitored 65 territories, gathering information on 406 occupancy events and 229 breeding attempts, including those of two potential competitors, the Northern Goshawk Accipiter gentilis and the Common Buzzard Buteo buteo. Generalized linear mixed models were used to explain occupancy and productivity, by evaluating the relative contribution of three different types of variables (habitat, competition and past events) and considering territory as a random effect. We examined a set of a priori hypothesized models, together with a number of additional models, and selected the best models following an information‐theoretic approach. Our best models related territorial occupancy and productivity to previous breeding success (the fledging of one or two young), which appeared to be the most important factor determining the probability of reoccupation and the reproductive output in the subsequent year. The best occupation model revealed that the probabilities of occupancy were also conditioned by a competition variable (intraspecific nearest‐neighbour distance) and two habitat variables (the location of the nest on the valley slope and the distance to the nearest forest track). Unlike the best occupation model, however, the selected model for reproductive output did not incorporate any competition variable besides previous breeding success, but included another two habitat variables (the effects of trunk height and NNE orientation).

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“…If intrinsic habitat quality is important during settlement, then the density of adult individuals and habitat quality should be correlated across the landscape. However, in human-modified landscapes, the ability to recognize site quality or utilize high quality sites may be hampered if the cues used for selecting habitats are corrupted (McClaren et al 2002;Battin 2004;Bock and Jones 2004). Furthermore, when individuals use environmental cues and the settlement patterns follow IDD or IPD, an ecological trap may occur if high numbers of individuals are forced to aggregate in low quality sites (Van Horne 1983).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution and settlement strategies in willow ptarmigan

et al. 2014

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In heterogeneous landscapes individuals select among several habitat patches. The fitness rewards of these choices are assumed to play an important role in the distribution of individuals across landscapes. Individuals can either use environmental cues to directly assess the quality of breeding sites, or rely on social cues to guide the settlement decision. We estimated the density of adult birds and per capita reproductive success of willow ptarmigan over 5-15 years in 42 survey areas, nested within 5 spatially separated populations in south-central Norway. Our aims were to (1) examine spatial and temporal patterns of variation in densities of adult birds (i.e., the breeding densities) and reproductive success (juveniles/pair) measured in autumn and (2) evaluate which habitat distribution model best described the distribution of willow ptarmigan across heterogeneous mountain landscapes. Variation in density of adult birds was primarily attributable to variation between survey areas which could arise from spatial heterogeneity in adult survival or as a consequence of spacing behavior of juveniles during the settlement stage. In contrast, reproductive success was more variable between years and did not vary consistently between survey areas once year effects were accounted for. The lack of any relationship between the density of adult birds and reproductive success supported the predictions of an ideal free distribution (IFD), implying that within years, the mean reproductive success was approximately equal across survey areas. However, analysis based on Taylor's power law (i.e., the relationship between logarithms of spatial variance and mean density of adult birds) suggested that aggregation was stronger than expected under IFD. This implies that the relative change in density of adult birds was larger in areas with high mean densities than in areas with low densities. The exact mechanisms causing this statistical pattern are unclear, but based on the breeding biology of willow ptarmigan we suggest that yearlings are attracted to areas of high densities during the settlement period in spring. Our study was conducted during a period of low overall density and we suggest that this pattern might be particular to such situations. This implies that the presence of conspecifics might represent a cue signaling high adult survival and thus high habitat quality.

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Do Some Northern Goshawk Nest Areas Consistently Fledge More Young Than Others?

Cited by 17 publications

References 23 publications

A review of northern goshawk habitat selection in the home range and implications for forest management in the western United States

A review of northern goshawk habitat selection in the home range and implications for forest management in the western United States

Factors influencing territorial occupancy and reproductive output in the Booted Eagle Hieraaetus pennatus

Spatial distribution and settlement strategies in willow ptarmigan

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