The Influence of Winter Social Behavior on the Habitat Selection and Reproductive Success of the Black-billed Magpie

This study examined the influence of winter social behavior, particularly dominance relationships, on the subsequent nesting habitat selection and reproductive success of Black-billed Magpies (Pica ~ hudsonia) on 2 areas in northern Utah. Hierarchical cluster analysis ordinated the habitats available to breeding birds and Chi-square and Bonferoni-z statistics were used to determine those habitat types the magpies seemed to prefer. Social status was determined by observing color-banded birds engaged in agonistic encounters at winter bait stations. Social dominance was evaluated by% dyads won, not by total % victories. Relationships between winter social status of magpies and their subsequent breeding habitat use and reproductive performance was tested by Kenda 11 \u27s Tau. Winter foraging flocks were comprised primarily of juvenile (1st year) birds while adults tended to remain as isolates or in pairs. Social status within flocks was correlated with age and sex; males dominated females and juvenile males dominated adult males. This was caused by differences in the social organization of adults and juveniles which created asymmetric views of winter food resources between male age classes. Breeding territories were densely packed in all habitats with a mean size of 0.5 ha. Date of clutch initiation was significantly correlated with clutch size and number of fledglings, with earlier nests more successful. Juveniles occupied marginal habitats and produced fewer offspring than adults. Within a dominance hierarchy of juvenile males, no significant differences in reproductive variables were detected except date of clutch initiation and weight of nestlings. Nestlings of dominant parents fledged earlier and were heavier than those of subordinates, which should increase post-fledging survival. This study has documented, for the first time in a free-living population, relationships between characteristics of nestlings and their future dominance status. Two characteristics, fledging date and rank (by weight) in the brood, were correlated with future winter dominance of juvenile males. The dominance status of male magpies is associated with many factors related to relative fitness, with hereditary components moderated by environmental and social factors

Saving sage-grouse from the trees: A proactive solution to reducing a key threat to a candidate species

Conservation investment in management of at-risk species can be less costly than a delay-and-repair approach implemented after species receive legal protection. The United States Endangered Species Act candidate species designation represents an opportunity to implement proactive management to avoid future listing. Such efforts require substantial investments, and the challenge becomes one of optimization of limited conservation funds to maximize return. Focusing on conifer encroachment threats to greater sage-grouse (Centrocercus urophasianus), we demonstrated an approach that links species demographics with attributes of conservation threats to inform targeting of investments. We mapped conifer stand characteristics using spatial wavelet analysis, and modeled lek activity as a function of conifer-related and additional lek site covariates using random forests. We applied modeling results to identify leks of high management potential and to estimate management costs. Results suggest sage-grouse incur population-level impacts at very low levels of encroachment, and leks were less likely to be active where smaller trees were dispersed. We estimated costs of prevention (treating active leks in jeopardy) and restoration (treating inactive leks with recolonization potential) management across the study area (2.5 million ha) at a total of US$17.5 million, which is within the scope of landscape-level conservation already implemented. An annual investment of US$8.75 million can potentially address encroachment issues near all known Oregon leks within the next decade. Investments in proactive conservation with public and private landowners can increase ecosystem health to benefit species conservation and sustainable land uses, replace top-down regulatory approaches, and prevent conservation reliance of at-risk species.Keywords: Conifer encroachment, Spatial wavelet analysis, Sage-Grouse Initiative, Random forest models, Ecological economics, Juniperus occidentalis, Proactive managementKeywords: Conifer encroachment, Spatial wavelet analysis, Sage-Grouse Initiative, Random forest models, Ecological economics, Juniperus occidentalis, Proactive managemen

Response of a Sage Grouse Breeding Population to Fire in Southeastern Idaho

Prescribed burning is a common method to eliminate sagebrush (Artemisia spp.) and has been suggested as a tool to enhance the habitat of sage grouse (Centrocercus urophasianus). Effects of this practice on sage grouse have not been evaluated rigorously. We studied effects of prescribed fire on lek (traditional breeding display areas) attendance by male sage grouse occupying low-precipitation (\u3c26 cm) sagebrush habitats in south- eastern Idaho from 1986 through 1994. During the preburn period (1986-89), average declines for male attendance were 48% and 46% for treatment and control leks, respectively. Lek counts were similar for treatment and control leks during the preburn years (G-test, 0.25\u3eP\u3e0.10). During the postburn period (1990-94), male attendance at treatment leks declined 90% and control leks declined 63%. Although declines were similar between treatment and control leks during the preburn period, postburn declines were greater for treatment than control leks (0.0

Timing of Vegetation Sampling at Greater Sage-Grouse Nests

Habitat management guidelines for greater sage-grouse, Centrocercus urophasianus, have been formulated, in part, based on studies of nest site selection. However, these guidelines may not represent conditions when the female initiates nesting because sampling occurs posthatch (> 30 days after nest initiation) to avoid disturbing incubating females. In 2002, we investigated differences in 22 habitat variables at initiation and hatch. Sampling was at 30 randomly selected active nests marked in 2001. There was no significant difference in structural or cover data (P > 0.05). Grass height and percent grass cover differed (P < 0.05) based on timing of sampling. Grass heights at the nest bowl and at 1 m from the edge of the nest bowl were 10 and 9 cm at initiation and 16 and 13 cm at hatch, respectively. Percent grass cover increased from 4% to 6% cover from initiation to hatch. Sampling occurred in a dry year; differences in grass heights and percent cover may be more pronounced in years of normal precipitation. Preliminary results indicated current habitat sampling techniques conducted posthatching adequately described selection of structural components of shrub height, visual obstruction, and percent cover of shrubs, bare ground, litter, and forbs at the nest site at initiation. Data need to be verified for other study areas and under different climatic conditions.  The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 2020Legacy DOIs that must be preserved: 10.2458/azu_rangelands_v58i5_rees

Effects of Prescribed Fire on Movements of Female Sage Grouse from Breeding to Summer Ranges

Volume: 109Start Page: 82End Page: 9