Shrubsteppe Bird Response to Habitat and Landscape Variables in Eastern Washington, U.S.A.

Abstract: The landscape of the intermountain west has changed dramatically in the last 150 years, particularly in the state of Washington, where over half the native shrubsteppe ecosystem has been converted to agricultural lands, resulting in a fragmented landscape with few extensive tracts of shrubsteppe. We examined the historical and current distribution of shrubsteppe on different soil types in eastern Washington, and we censused bird communities at 78 sites in shrubsteppe from 1991 to 1993. We compared abundance of species among soil types and range conditions and developed models of species occurrence using site-specific vegetation and landscape variables. The pattern of shrubsteppe conversion has resulted in a disproportionate loss of deep soil communities. Eight bird species showed strong relationships with soil type and three with range condition. These associations likely resulted from the influence of soil type and range history on the vegetation of these communities. Brewer's Sparrows (  Spizella breweri ) and Sage Sparrows ( Amphispiza belli ) reached their highest abundances in deep, loamy soils, whereas Loggerhead Shrikes (   Lanius ludovicianus ) were most abundant in deep, sandy soils. Sage Sparrows occurred more frequently in landscapes dominated by shrubsteppe, indicating a negative relationship with fragmentation. Our results suggest that fragmentation of shrubsteppe and the pattern of agricultural conversion among soil types have had detrimental effects on numerous shrubsteppe species. The landscape for species with an affinity for deep, loamy soil communities has changed considerably more than the overall loss of shrubsteppe would indicate. Conservation practices that emphasize retention of shrubsteppe communities on deep soils and that reduce further fragmentation will be critical to the maintenance of avian biological diversity in this system.     

Focus of Attention at Work and Leader-Follower Relationships

Three different studies examine moderating effects of focus of attention at work on leader-follower relationships, using the typology developed by Howell, Dorfman, and Kerr (1986). Survey data were collected from over 1300 subjects. Results indicate that: (1) high focus on the supervisor while at work enhances leader behaviour-subordinate satisfaction and behaviour relationships, (2) high focus on off-job factors while at work enhances leader behaviour-subordinate satisfaction relationships, and (3) high focus on off-job factors while at work weakens leader behaviour-subordinate behaviour relationships. Theoretical implications for the study of organizational behaviour are discussed, as well as practical issues for enhancing leader behaviour effectiveness in work organizations.     

Light at night reduces digestive efficiency of developing birds: an experiment with king quail

The Science of Nature - Gravity is very important for many organisms, including web-building spiders. Probably the best approach to study the relevance of gravity on organisms is to bring them to...     

The costs and benefits of cooperation between the Australian lycaenid butterfly,Jalmenus evagoras,and its attendant ants

Summary The larvae and pupae of the Australian lycaenid butterfly, Jalmenus evagoras associate mutualistically with ants in the genus Iridomyrmex. Four ant exclusion experiments in three field sites demonstrated that predation and parasitism of J. evagoras are so intense that individuals deprived of their attendant ants are unlikely to survive. Larvae and pupae of J. evagoras aggregate, and the mean number of attendant ants per individual increases with larval age and decreases with group size. Field observations showed that young larvae could gain more attendant ants per individual by joining the average size group of about 4 larvae than by foraging alone. Aggregation behaviour is influenced by ant attendance: young larvae and pupating fifth instars aggregated significantly more often on plants with ants than on plants where ants had been excluded. In return for tending and protecting the larvae, ants were rewarded by food secretions that can amount to as much as 409 mg dry biomass from a single host plant containing 62 larvae and pupae of J. evagoras over a 24 h period. Larval development in the laboratory lasted approximately a month, and larvae that were tended by ants developed almost 5 days faster than larvae that were not tended. However, tended individuals, particularly females, pupated at a significantly lower weight than their untended counterparts, and the adults that eclosed from these pupae were also lighter and smaller. On average, pupae that were tended by ants lost 25% more weight than untended pupae, and in contrast with larvae, they took longer to eclose than pupae that were not tended. These experimental results are discussed in terms of costs and benefits of association for both partners, and of aggregation for the lycaenids.     

Application of a risk assessment based approach to designing ambient air quality monitoring networks for evaluating non-cancer health impacts

An ambient air quality monitoring network has been establishedusing risk assessment techniques to evaluate adverse health effects from exposures to airborne contaminants. The risk assessment method was compared to traditional methods of establishing air quality monitoring networks: identifying maximumconcentration impacts or maximum total population. Results suggest that the health risk method best predicted the locationof adverse, non-carcinogenic respiratory illnesses during the evaluation period. Spearman Rank Correlation Coefficient, r _s, values obtained using the risk assessment method werestatistically greater than the values obtained using theconcentration and population methods. The concentration methodwas the least accurate predictor of adverse effects.     

Integrated resource assessment and sustainable land use

Decision makers and planners in resource sectors recognize, at least in theory, the multiple uses of land, reflecting possible choices and options for society, and the need to evaluate the economic, social, and environmental implications of these choices. As such, the need for integrated resource management is now widely accepted in resource planning. This article contributes to the understanding of sustainable resource development through a specific case study. An integrated analytical system is developed and applied to the Peace River Region, British Columbia, Canada, to examine the impacts of a wide range of land-use options and policies upon the achievement of multiple resource use goals. The results indicate that an integrated approach in land resource analysis is not only possible but a necessary step in the move to develop procedures for assisting public decision makers in integrating the diverse functions of the land resource base and to revise demands or develop alternative strategies in order to move society closer to sustainable outcomes.