Geology topics

Clay T. Nichols

Publications and source records attributed to Clay T. Nichols.

4 recordsLinked to original sources

USGS2025

Maintenance of genetic diversity despite population fluctuations in the lesser prairie-chicken (Tympanuchus pallidicinctus)

Assessments of genetic diversity, structure, history, and effective population size ( N e ) are critical for the conservation of imperiled populations. The lesser prairie-chicken ( Tympanuchus pallidicinctus ) has experienced declines due to habitat loss, degradation, and fragmentation in addition to substantial population fluctuations with unknown effects on genetic diversity. Our objectives were to: (i) compare genetic diversity across three temporally discrete sampling periods (2002, 2007-2010, and 2013-2014) that are characterized by low or high population abundance; (ii) examine genetic diversity at lek and lek cluster spatial scales; (ii) identify potential bottlenecks and characterize genetic structure and relatedness; and (iii) estimate the regional N e . We analyzed 194 samples across the shinnery oak prairie region of eastern New Mexico and western Texas using 13 microsatellite loci. Mean heterozygosity, allelic richness, and inbreeding coefficient were not significantly different between discrete sampling periods, suggesting that this population has maintained its genetic diversity across the sampled population fluctuations. We did not detect genetic structure using multiple Bayesian clustering approaches. Furthermore, there was no support for recent genetic bottlenecks, and we estimated that the N e ranged from 229.5 ( p crit = 0.05, 95% CIs = 121.2-1023.1) to 349.1 ( p crit = 0.02, 95% CIs = 176.4-2895.2) during our final sampling period (2013-2014). Although we provide evidence for gene flow within this region, continued habitat loss and fragmentation that leads to population declines and isolation could increase the risk of genetic consequences. Continued monitoring of genetic diversity and increasing available habitat that supports robust populations of lesser prairie-chickens may improve the likelihood of the species' persistence.

New Mexico, Texas↗

USGS2018

Temporal variation in breeding season survival and cause-specific mortality of lesser prairie-chickens

The lesser prairie-chicken Tympanuchus pallidicinctus has experienced significant declines in distribution and abundance since the early 1900s. A severe and prolonged drought from 2009 to 2013 resulted in further declines in population numbers and despite improved environmental and habitat conditions since 2013, populations of lesser prairie chickens have shown little improvement. To investigate whether breeding season survival of lesser prairie-chickens in eastern New Mexico could be driving this response, we developed the following objectives: 1) estimate male and female breeding-season survival; 2) determine whether male and female survival varies temporally among lekking, nesting, and brood-rearing periods; and 3) determine cause-specific mortality during the breeding season. We captured and radiocollared 76 lesser prairie-chickens (50 male, 26 female) during spring of 2014 and 2015 and estimated their survival throughout the breeding season (15 March–31 August). Male survival was nearly double that of females in both years (0.79–0.81 and 0.38–0.45, respectively). Males had similar survival across all periods (lekking, postlekking, late summer: 0.89–0.95). Females had the greatest period-specific survival during lekking and brood rearing (0.87 ± 0.08 and 0.85 ± 0.10, respectively) relative to the nesting period (0.58 ± 0.11). Mammalian predation was the primary cause of mortality in both years. Our results indicate that in New Mexico 1) lesser prairie-chicken breeding season survival was consistent with geographically similar studies, 2) females have lower survival during the nesting period, and 3) female lesser prairie-chicken survival was lower than male survival regardless of time period. Management actions that provide and protect high-quality nesting habitat may help ensure that female survival is maximized during the nesting period.

New Mexico↗

USGS2017

A projection of lesser prairie chicken ( Tympanuchus pallidicinctus ) populations range-wide

We built a population viability analysis (PVA) model to predict future population status of the lesser prairie-chicken ( Tympanuchus pallidicinctus , LEPC) in four ecoregions across the species’ range. The model results will be used in the U.S. Fish and Wildlife Service's (FWS) Species Status Assessment (SSA) for the LEPC. Our stochastic projection model combined demographic rate estimates from previously published literature with demographic rate estimates that integrate the influence of climate conditions. This LEPC PVA projects declining populations with estimated population growth rates well below 1 in each ecoregion regardless of habitat or climate change. These results are consistent with estimates of LEPC population growth rates derived from other demographic process models. Although the absolute magnitude of the decline is unlikely to be as low as modeling tools indicate, several different lines of evidence suggest LEPC populations are declining.

Colorado, Kansas, New Mexico, Oklahoma, Texas↗

USGS2017

Impacts of mesquite distribution on seasonal space use of lesser prairie-chickens

Loss of native grasslands by anthropogenic disturbances has reduced availability and connectivity of habitat for many grassland species. A primary threat to contiguous grasslands is the encroachment of woody vegetation, which is spurred by disturbances that take on many forms from energy development, fire suppression, and grazing. These disturbances are exacerbated by natural- and human-driven cycles of changes in climate punctuated by drought and desertification conditions. Encroachment of honey mesquite (Prosopis glandulosa) into the prairies of southeastern New Mexico has potentially limited habitat for numerous grassland species, including lesser prairie-chickens (Tympanuchus pallidicinctus) . To determine the magnitude of impacts of distribution of mesquite and how lesser prairie-chickens respond to mesquite presence on the landscape in southeastern New Mexico, we evaluated seasonal space use of lesser prairie-chickens in the breeding and nonbreeding seasons. We derived several remotely sensed spatial metrics to characterize the distribution of mesquite. We then used these data to create population-level resource utilization functions and predict intensity of use of lesser prairie-chickens across our study area. Home ranges were smaller in the breeding season compared with the nonbreeding season; however, habitat use was similar across seasons. During both seasons, lesser prairie-chickens used areas closer to leks and largely avoided areas with mesquite. Relative to the breeding season, during the nonbreeding season habitat use suggested a marginal increase in mesquite within areas of low intensity of use, yet aversion to mesquite was strong in areas of medium to high intensity of use. To our knowledge, our study is the first to demonstrate a negative behavioral response by lesser prairie-chickens to woody encroachment in native grasslands. To mitigate one of the possible limiting factors for lesser prairie-chickens, we suggest future conservation strategies be employed by land managersto reduce mesquite abundance in the southern portion of their current range.

New Mexico↗