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Aim: A conspicuous climatic and biogeographical transition occurs at 40?45� N in western North America. This pivot point marks a north?south opposition of wet and dry conditions at interannual and decadal time-scales, as well as the northern and southern limits of many dominant western plant species. Palaeoecologists have yet to focus on past climatic and biotic shifts along this transition, in part because it requires comparisons across dissimilar records [i.e. pollen from lacustrine sediments to the north and plant macrofossils from woodrat (Neotoma) middens to the south]. To overcome these limitations, we are extending the woodrat-midden record northward into the lowlands of the central Rocky Mountains. Published...
The global mean surface temperature increased 0.85°C during the period 1880 – 2012. Some climate models predict an additional warming of up 2 to 4 ◦ C over the next 100 years for the primary breeding grounds for North American ducks. Such an increase has been predicted to reduce mid - continent breeding duck populations by >70%. Managing continental duck populations in the face of climate change requires understanding how waterfowl have responded to historical spatio - temporal climatic variation. However, such responses to climate may be obscured by how ducks respond to variation in land cover. We estimated effects of climate on settlement patterns of breeding ducks in the Prairie - Parkland Region (PPR), boreal...
Advancements in ancient DNA analyses now permit comparative molecular and morphological studies of extinct animal dung commonly preserved in caves of semiarid regions. These new techniques are showcased using a unique dung deposit preserved in a late glacial vizcacha (Lagidium sp.) midden from a limestone cave in southwestern Argentina (38.5° S). Phylogenetic analyses of the mitochondrial DNA show that the dung originated from a small ground sloth species not yet represented by skeletal material in the region, and not closely related to any of the four previously sequenced extinct and extant sloth species. Analyses of pollen and plant cuticles, as well as analyses of the chloroplast DNA, show that the Cuchillo Curá...
Survival or extinction of an endangered species is inherently stochastic. We develop statistical methods for estimating quantities related to growth rates and extinction probabilities from time series data on the abundance of a single population. The statistical methods are based on a stochastic model of exponential growth arising from the biological theory of age or stagestructured populations. The model incorporates the socalled environmental type of stochastic fluctuations and yields a lognormal probability distribution of population abundance. Calculation of maximum likelihood estimates of the two unknown parameters in this model reduces to performing a simple linear regression. We describe techniques for rigorously...
Fishery biologists are increasingly recognizing the importance of considering the dynamic nature of streams when developing streamflow policies. Such approaches require information on how flow regimes influence the physical environment and how those factors, in turn, affect species-specific demographic rates. A more cost-effective alternative could be the use of dynamic occupancy models to predict how species are likely to respond to changes in flow. To appraise the efficacy of this approach, we evaluated relative support for hypothesized effects of seasonal streamflow components, stream channel characteristics, and fish species traits on local extinction, colonization, and recruitment (meta-demographic rates) of...
Aim: A conspicuous climatic and biogeographical transition occurs at 40–45° N in western North America. This pivot point marks a north–south opposition of wet and dry conditions at interannual and decadal time-scales, as well as the northern and southern limits of many dominant western plant species. Palaeoecologists have yet to focus on past climatic and biotic shifts along this transition, in part because it requires comparisons across dissimilar records [i.e. pollen from lacustrine sediments to the north and plant macrofossils from woodrat (Neotoma) middens to the south]. To overcome these limitations, we are extending the woodrat-midden record northward into the lowlands of the central Rocky Mountains.
Like many other species, cutthroat trout (Oncorhynchus clarki) have declined substantially relative to historic conditions, and many existing populations are isolated. To inform conservation and restoration efforts for stream-resident cutthroat trout, I built a stage-structured stochastic simulation model to explore the dynamics of populations in isolation or connected by immigration. Relatively small increases in carrying capacity substantially reduced extinction risk in small, isolated populations. In the sensitivity matrix, the two most important elements affecting population growth rate were the survival of subadults that became reproductively mature the next year and the survival of young-of-the-year fish....
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These data are CSV files comprised of a heading and tables from Appendix 1 and Appendix 2 in the accompanying paper. The tables show the sampling dates and locations for the coachwhip (Masticophis flagellum) and striped racer (Masticophis lateralis) in pit-fall arrays (Fisher et al. 2008) monitored in southern California from 1995-2000. GPS data are shown in decimal degrees and were collected in the field using the WGS84 datum system. Elevation is in meters. Columns in the tables include a site ID number assigned to each site name, the year and calendar dates each site was sampled, number of arrays, number of sampling days, number of sampling occasions, and whether or not each of the target species were detected...
Conclusions:Habitat fragmentation results in demographic changes in plant populations associated wtih increased extinction risk.Thresholds/Learnings:Trillium populations in forest remnants within 65m of forest clear-cut edges have almost no recruitment of young plants
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The long decline of the eastern migratory population of monarch butterflies (Danaus plexippus) appears to have abated in recent years and the population now persists at a much-reduced abundance. Stochastic variation in abundance typical of monarch butterflies, and other insects, places this population at heightened risk of quasi-extinction, a level of abundance below which recovery of the migratory behavior is uncertain. These data and results provide insight into the near-term status and trajectory of the eastern migratory population of monarch butterflies. Within the stationarymonarchdata.csv, overwinter[ha] are annual monarch butterfly overwinter area occupied estimates as provided by World Wildlife Fund-Mexico...
    map background search result map search result map Masticophis occupancy in southern California, 1995-2000 Eastern migratory monarch butterfly population estimates and associated early warning signals (2006-2022) Masticophis occupancy in southern California, 1995-2000 Eastern migratory monarch butterfly population estimates and associated early warning signals (2006-2022)