Effects of Gunnison Sage-Grouse habitat treatment efforts on associated avifauna and vegetation structure

Conservation efforts over the last 20 years for the Gunnison Sage-Grouse (Centrocercus minimus) have involved extensive habitat manipulations done predominantly to improve brood rearing habitat for the grouse. However, the effects of Gunnison Sage-Grouse habitat treatments on sympatric avifauna and responses of vegetation to manipulations are rarely measured, and if they are, it is immediately following treatment implementation. This study examined the concept of umbrella species management by retrospectively comparing density and occupancy of eight sagebrush associated songbird species and six measures of vegetation in treated and control sites. Our results suggested that songbird densities and occupancy changed for birds at the extreme ends of their association with sagebrush and varied with fine-scale habitat structure. We found Brewer’s Sparrows (Spizella breweri) decreased in density on treated sites and Vesper Sparrows (Pooecetes gramineus) increased. Occupancy estimation revealed that Brewer’s Sparrows and Green-tailed Towhees (Pipilo chlorurus) occupied significantly fewer treated points whereas Vesper Sparrows occupied significantly more. Vegetation comparisons between treated and control areas found shrub cover to be 26% lower in treated sites. Lower shrub cover in treated areas may explain the differences in occupancy and densities of the species sampled based on known habitat needs. The fine-scale analysis showed a negative relationship to forb height and cover for the Sage Sparrow (Amphispiza belli) indicating, from vegetation measures showing grass and forb cover during a good precipitation year covered significantly more area in the treatment than the control sites, that Sage Sparrows may also not respond favorably to Gunnison Sage-Grouse habitat treatments. While the concept of an umbrella species is appealing, evidence from this study suggests that conservation efforts aimed at the Gunnison Sage-Grouse may not be particularly effective for conserving other sagebrush obligate species of concern. This is probably due to Gunnison Sage-Grouse habitat management being focused on the improvement of brood rearing habitat which reduces sagebrush cover and promotes development of understory forbs and grasses

The Effects of Special Mule Deer Buck Regulations on Mule Deer Populations and Harvest

We evaluated the effects of 3 restrictive season types on mule deer population and harvest characteristics in 41 Montana hunting districts (HDs). Using a mixed-effects, before-after-control-impact modeling framework, we analyzed 6 harvest and hunter use response variables, and 4 population response variables. Buck : doe ratios increased by 0.42 bucks:100 does and 0.33 bucks :100 does per year, following changes to a shortened season and limited permits, respectively. We found no significant change in buck : doe ratios in unlimited permit HDs. All restrictive season types resulted in declines in hunter numbers and days. HDs with no restrictions, with limited permits and with unlimited permits also showed a downward annual trend in hunter numbers. In shortened season HDs, a significant loss in hunter numbers was followed by a slow return of hunters back to those HDs. Limited permit HDs had a statistically greater proportion of bucks with ?4 points on at least one antler, a lower number of bucks harvested annually, and a smaller total number of ?4 point bucks harvested than in HDs with no buck restrictions. For those same 3 response variables, unlimited and shortened season HDs were not different than HDs without restrictions. In all three restricted regulation HDs there was an annual increase in the observed spring fawn : adult ratios even though the general trend was for a decreasing fawn : adult ratio of 0.83 fawns:100 adults per year in HDs with no restrictions

Dates, Caries, and Early Tooth Loss During the Iron Age of Oman

Eine Ernährung aus fermentierbaren Kohlenhydraten ist bekannterweise hoch kariogen, besonders im Falle von zuckerhaltigem Essen wie zum Beispiel Datteln. Diese Ernährung ist bei der späteisenzeitlichen Samad-zeitlichen Bevölkerung Omans zu beobachten. 32 Erwachsene und 5 Jugendliche dienten für diese Studie als Erhebung. Vorzeitiger Zahnverlust war in allen Fällen nachweisbar

Testing factors influencing identification rates of similar species during abundance surveys

Most abundance estimation methods assume that all sampled individuals are identified correctly. In practice, this assumption may be difficult to meet and can bias abundance estimates, especially when morphologically similar species overlap in range. Over the past 2 decades, Kittlitz\u27s Murrelet (Brachyramphus brevirostris) populations appear to have declined across parts of their Alaskan range, where they co-occur with the Marbled Murrelet (B. marmoratus). Recently, the reliability of Kittlitz\u27s Murrelet declines have been questioned due to variability and uncertainty in species identification between the 2 species. We conduced a field experiment to quantify misidentification and partial identification (identification to genus [Brachyramphus] level only) of Kittlitz\u27s and Marbled murrelets during abundance surveys, and to evaluate the relative impacts of environmental and observational factors on misidentification and partial identification. We applied these results to previously collected survey data to measure the potential bias of abundance estimates resulting from varying identification rates. Overall, the misidentification rate during our field experiment was -0.036 + 0.004 (SE), with observer experience best explaining the variation. Abundance estimates adjusted for misidentification reflected little bias. The overall partial identification rate was much higher than the misidentification rate (0.211 + 0.007 SE). Partial identification rates increased in choppy sea states, with greater observation distances, and when murrelets exhibited diving behavior; rates decreased with increased observer experience and when murrelets exhibited flushing behavior. Because observer experience was an important driver of both misidentification and partial identification, we stress the importance of conducting rigorous observer training before and during surveys to increase confidence in species identification and precision in abundance estimates. the methods developed in this study could be modified for any at-sea survey scenario to measure identification rates and the factors influencing these rates. Results may reveal important relationships for adjusting survey protocolors to increase confidence in species identification and thereby to increase the precision of abundance estimates

Monitoring Low Density Avian Populations: An Example using Mountain Plovers

Declines in avian populations highlight a need for rigorous, broad-scale monitoring pro-grams to document trends in avian populations that occur in low densities across expansive landscapes. Accounting for the spatial variation and variation in detection probability inherent to monitoring programs is thought to be effort-intensive and time-consuming. We determined the feasibility of the analytical method developed by Royle and Nichols (2003), which uses presence-absence (detection-non-detection) field data, to estimate abundance of Mountain Plovers (Charadrius montanus) per sampling unit in agricultural fields, grassland, and prairie dog habitat in eastern Colorado. Field methods were easy to implement and results suggest that the analytical method provides valuable insight into population patterning among habitats. Mountain Plover abundance was highest in prairie dog habitat, slightly lower in agricultural fields, and substantially lower in grassland. These results provided valuable insight to focus future research into Mountain Plover ecology and conservation