Research about California, Texas

USGS2023

Understanding fatality patterns and sex ratios of Brazilian free-tailed bats (Tadarida brasiliensis) at wind energy facilities in western California and Texas

Background Operation of wind turbines has resulted in collision fatalities for several bat species, and one proven method to reduce these fatalities is to limit wind turbine blade rotation ( i.e ., curtail turbines) when fatalities are expected to be highest. Implementation of curtailment can potentially be optimized by targeting times when females are most at risk, as the proportion of females limits the growth and stability of many bat populations. The Brazilian free-tailed bat ( Tadarida brasiliensis ) is the most common bat fatality at wind energy facilities in California and Texas, and yet there are few available data on the sex ratios of the carcasses that are found. Understanding the sex ratios of fatalities in California and Texas could aid in planning population conservation strategies such as informed curtailment. Methods We used PCR to determine the sex of bat carcasses collected from wind energy facilities during post-construction monitoring (PCM) studies in California and Texas. In California, we received samples from two locations within the Altamont Pass Wind Resource Area in Alameda County: Golden Hills (GH) ( n = 212) and Golden Hills North (GHN) ( n = 312). In Texas, we received samples from three wind energy facilities: Los Mirasoles (LM) (Hidalgo County and Starr County) ( n = 252), Los Vientos (LV) (Starr County) ( n = 568), and Wind Farm A (WFA) (San Patricio County and Bee County) ( n = 393). Results In California, the sex ratios of fatalities did not differ from 50:50, and the sex ratio remained stable over the survey years, but the seasonal timing of peak fatalities was inconsistent. In 2017 and 2018, fatalities peaked between September and October, whereas in 2019 and 2020 fatalities peaked between May and June. In Texas, sex ratios of fatalities varied between locations, with Los Vientos being female-skewed and Wind Farm A being male-skewed. The sex ratio of fatalities was also inconsistent over time. Lastly, for each location in Texas with multiple years studied, we observed a decrease in the proportion of female fatalities over time. Discussion We observed unexpected variation in the seasonal timing of peak fatalities in California and differences in the sex ratio of fatalities across time and facility location in Texas. In Texas, proximity to different roost types (bridge or cave) likely influenced the sex ratio of fatalities at wind energy facilities. Due to the inconsistencies in the timing of peak female fatalities, we were unable to determine an optimum curtailment period; however, there may be location-specific trends that warrant future investigation. More research should be done over the entirety of the bat active season to better understand these trends in Texas. In addition, standardization of PCM studies could assist future research efforts, enhance current monitoring efforts, and facilitate research on post-construction monitoring studies.

California, Texas↗

USGS2019

Performances of WorldView-3, Sentinel-2, and Landsat-8 data in mapping impervious surface

Many efforts have been made to map developed impervious surface from remotely sensed information in the last two decades. The U.S. Geological Survey (USGS) developed the National Land Cover Database (NLCD) to provide consistent land cover and change products for the Nation since 2001. Percent impervious surface area (ISA), one of the products in NLCD as a continuous field and estimated with Landsat imagery, represents the fraction of human-made impervious area in a 30 m resolution grid. ISA is used to map urban land cover types and extents for the United States. However, it is still a challenge to quantify highly heterogeneous features in many urban areas using remotely sensed data with spatial and spectral resolutions similar to Landsat and to determine the impacts of remotely sensed data characteristics on ISA mapping.

California, Texas↗

USGS1968

A Gemini mosaic along the thirty-second degree of latitude from Baja California to central Texas

A series of 39 overlapping photographs of the southwestern United States and adjacent areas of Mexico was obtained as part of an experiment of the Gemini IV mission. Twenty-four of these pictures plus one from the Gemini III and four from the Gemini V mission were used to construct a 1:1,000,000-scale, black and white, semi-controlled mosaic. This mosaic covers about 150,000 square miles and extends along the 32d parallel of north latitude from the Pacific Ocean to the 100th meridian in west-central Texas, and averages about 150 miles in width. Many of the individual rectified photographs can be enlarged to a scale of 1:250,000 with little or no loss of resolution; such enlargements will be of great value to earth resources studies. If the angle of tilt is more than 35 degrees, some detail in the background of the photograph is lost. The U. S. Geological Survey is currently conducting several small research projects in which this 1:1,000,000-scale mosaic and the individual photographs are the prime research tools.

California, Texas↗