Geology topics

K. Shawn Smallwood

Publications and source records attributed to K. Shawn Smallwood.

3 recordsLinked to original sources

USGS2016

Avian fatalities at wind energy facilities in North America: A comparison of recent approaches

Three recent publications have estimated the number of birds killed each year by wind energy facilities at 2012 build-out levels in the United States. The 3 publications differ in scope, methodology, and resulting estimates. We compare and contrast characteristics of the approaches used in the publications. In addition, we describe decisions made in obtaining the estimates that were produced. Despite variation in the 3 approaches, resulting estimates were reasonably similar; about a quarter- to a half-million birds are killed per year by colliding with wind turbines.

Human-Wildlife Interactions↗

USGS1996

Scaling population density and spatial pattern for terrestrial, mammalian carnivores

A large part of ecological theory has been developed with the assumption that intra- and inter-specific patterns of density and spatial distribution can be consistently and reliably compared, and that these patterns have represented populations across nonstudied landscapes. These assumptions are erroneous. We found that log 10 population density estimates consistently decreased linearly with log 10 spatial extent of study areas for species of terrestrial Carnivora. The size of the study area accounted for most of the variation in population estimates, and study areas increased with the female body mass of the study species. But study sites consistently had higher densities than can be expected for nonstudy sites, regardless of the size of the study area, because study sites are typically chosen based on a priori knowledge of high density. Inter-specific comparisons of density and distribution might provide more insight into community organization after intra-specific density estimates have been scaled by the study areas, and related to the nonstudied landscapes within each species' geographic range.

Oecologia↗

USGS1996

Spatial scaling of allometry among terrestrial, mammalian carnivores

A regression slope of −0.75 between log 10 density and log 10 body mass is thought to express equivalence of energy conversion among species' populations of similar taxonomic and trophic status. Using larger sample sizes than the usual 1–3 density estimates per species, we estimated a regression slope of −0.71 for terrestrial mammalian carnivores. We investigated the sampling variation in this estimate, and those derived from smaller intra-specific subsets, using 1000-iteration bootstrap analyses to obtain 90% confidence intervals. As expected, these widened as random subsets were reduced in size, but always contained the postulated −0.75. However, log 10 density also declined as 3/4 of the log 10 spatial extent of study area, and study area accounted for virtually all of the variation in density that was previously thought due to body mass. We removed the effect of study area by using the species-specific regression models between density and study area to predict density at a common scale of 400 km 2 . These common-scale densities regressed against body mass with a slope of −0.16, but separated into body mass classes less than and greater than 11 kg, they produced slopes that were not significantly different from zero. We show that the allometry of density could be a case of circular logic, whereby body mass has influenced the investigator's choice of study area, and the resulting scale-dependent densities are related back to body mass. To test the allometry hypothesis, the effect of study area on density estimates needs to be removed. This requires conducting larger-scale studies of the smaller-bodied species so that all species compared are represented by an average study area that is near the common scale. Furthermore, study sites need to be selected and designed to represent more than the local detail in species' density.

Oecologia↗