No description available.

No description available.

No description available.

No description available.

No description available.

The middle Cambrian (Drumian) Rockslide Formation is a deeper-water succession of mixed carbonates and siliciclastics. At the Ravens Throat River location it hosts a Burgess Shale-type (BST) deposit. The BST units are found in two separate 1m thick horizons of green-coloured calcareous mudstone and contain a biota similar to that of the Wheeler and Marjum formations of Utah, and to some extent the Burgess Shale itself. The biota is low in diversity and preserves mainly robust soft-tissue parts. The lithologically heterogeneous composition of the formation (shale, dolomite, lime mudstone, sandstone, mudstone) and absence of metamorphism offer an opportunity to analyze the depositional environment and taphonomy of this deeper water unit. Geochemical analysis including, trace elements, organic carbon, biomarker, and synchrotron were attempted and yielded varying results. Trace element ratios, particularly V/Sc, indicate low oxygenation of the bottom waters during the deposition of the fossil-bearing interval. These results differ from most other BST deposits, which suggest that oxygenated bottom waters were maintained throughout sedimentation. In addition, organic matter in the sediments and δ13Corg values suggest the presence of benthic microbial mats. Silver is concentrated mostly in nm to μm-sized particles in the fossilifereous calcareous mudstone, suggesting elevated levels in the depositional environment. Organic films and the evidence for hyoliths feeding on them suggest an in situ preservation of the biota, perhaps from sudden and short anoxic events and quick burial under either microbial mats or the muddy sediment. This is also supported by the presence of only very rare trace fossils.

Field work to determine possible causes of variation in avian social behavior in a nonbreeding community of 42 species was undertaken during two winter seasons in oak-juniper woodland of the Santa Rita mountains of southern Arizona. Transect observations are used to calculate monthly densities, frequency of social foraging, and size and composition of social groups for all species. Additional data taken to quantify the foraging logistics of 22 species includes foraging substrate, time spent at a foraging station, and distance travelled between foraging stations. These data are used to generate indices of logistic similarity and interspecific association for species pairs in order to test the hypothesis that species which are similar in their foraging logistics are more likely to associate than those which are not. Causes of solitary behavior and variation in intraspecific social behavior are also examined. Exclusively solitary foraging behavior is strongly associated with species that use sparse, unpredictable prey too small to share. These species, referred to as "extensive foragers," appear to be constrained from both intraspecific and interspecific association by being logistic mismatches with all but their closest competitors, with which the potential for interference competition is high. Evidence is presented to refute the hypothesis that solitary behavior is due to low vulnerability to predators. Species which are intraspecifically solitary tend to use evenly distributed resources, and gregarious species use patchy and abundant resources. Exceptions are most frequent among permanent residents, which may continue to maintain social and spacing systems used in the breeding season. Among gregarious species, permanent residents are more likely to maintain stable group sizes than winter residents. A correlation exists between similarity of foraging logistics and likelihood of interspecific association, but it is subject to considerable variance. Causes of this variance include the tendency of transient migrants not to associate with other species, and the tendency of certain species to form temporary associations, regardless of logistic similarities. Why some species form temporary ("opportunistic") associations while others do not remains unclear.

No description available.

A forest inventory was made by a two-man team in the Emory oak (Quercus emoryi) woodlands, near the Huachuca Mountains, in southeastern Arizona. Two plot sizes, 1/10th, and 1/25th hectare, and three basal area factors, 2, 4 and 6 (square meters per hectare) were used. Tree tally time was recorded, but the travelling time between plots was not recorded. Total number of trees, total basal area, and total volume of trees per hectare were measured, summarized, and analyzed. Significant differences were noted between plot sampling and point sampling. Results suggested that with plot sampling, 1/25th hectare plot was more efficient than 1/10th hectare plot for all measures of forest densities. With point sampling, basal area factor 6 had the highest relative sampling efficiency in terms of trees per hectare. Basal area factor 2 had the highest relative sampling efficiency in terms of basal area and volume per hectare. From this information, more efficient forest inventories of the Emory oak woodlands can be designed.

No description available.