Geology topics

Dave P. Onorato

Publications and source records attributed to Dave P. Onorato.

3 recordsLinked to original sources

USGS2025

If you build it, will they come? Assessing the response of tiger populations to elevated conservation efforts in lowland Nepal

Thirteen countries within the distributional range of tigers adopted the St. Petersburg Declaration in 2010, committing to double their tiger populations by 2022. As a signatory to this document, Nepal elevated its tiger conservation efforts soon after the declaration was adopted. Using capture-mark-recapture (CMR) analyses of tiger survey data (2013–2022), we assessed the response of tiger populations to enhanced conservation measures in Banke and Bardia national parks (NP) in western lowland of Nepal. In Bardia NP, estimated tiger numbers increased from 49 in 2013 to 122 in 2022, and estimated population density increased from 3.39 in 2013 to 8.47 tigers/100 km 2 in 2022). Female survival rate was consistently higher than male, with 87.06 % during 2013–2018 and 89.08 % during 2018–2022, compared to 72.9 % and 76.6 % for males in the respective periods. Additionally, the female population grew at a faster rate (6–7 % per year vs. ∼ 2 % per year for males). In Banke NP, tiger abundance increased from 3 to 22 between 2013 and 2022, and population density increased from 0.34 to 2.42/100 km 2 over the same period. The remarkable 7-fold increase in tiger abundance within the Banke NP was facilitated by high male and female survival rates (≥ 90 % per year), as well as high recruitment rates (0.27 individual −1 year −1 ) from 2013 to 2018, leading to a robust (18–20 %) annual population growth rate. Tigers were recolonizing Banke NP at the beginning of this study, and the area offered ample space and a recovering prey base. This facilitated the recruitment of dispersers from the larger population in Bardia NP and allowed survival to be high by eliminating mortality due to density-dependent intra-specific aggression. Our results not only suggest that Nepal has met or exceeded its commitment to the St. Petersburg Declaration in Banke and Bardia NPs, but they highlight the ability of certain tiger populations to respond quickly and positively to enhanced conservation measures given suitable habitat and a healthy prey base.

Banke National Park, Bardia National Park↗

USGS2022

Pleistocene–Holocene vicariance, not Anthropocene landscape change, explains the genetic structure of American black bear (Ursus americanus) populations in the American Southwest and northern Mexico

The phylogeography of the American black bear ( Ursus americanus ) is characterized by isolation into glacial refugia, followed by population expansion and genetic admixture. Anthropogenic activities, including overharvest, habitat loss, and transportation infrastructure, have also influenced their landscape genetic structure. We describe the genetic structure of the American black bear in the American Southwest and northern Mexico and investigate how prehistoric and contemporary forces shaped genetic structure and influenced gene flow. Using a suite of microsatellites and a sample of 550 bears, we identified 14 subpopulations organized hierarchically following the distribution of ecoregions and mountain ranges containing black bear habitat. The pattern of subdivision we observed is more likely a product of postglacial habitat fragmentation during the Pleistocene and Holocene, rather than a consequence of contemporary anthropogenic barriers to movement during the Anthropocene. We used linear mixed-effects models to quantify the relationship between landscape resistance and genetic distance among individuals, which indicated that both isolation by resistance and geographic distance govern gene flow. Gene flow was highest among subpopulations occupying large tracts of contiguous habitat, was reduced among subpopulations in the Madrean Sky Island Archipelago, where montane habitat exists within a lowland matrix of arid lands, and was essentially nonexistent between two isolated subpopulations. We found significant asymmetric gene flow supporting the hypothesis that bears expanded northward from a Pleistocene refugium located in the American Southwest and northern Mexico and that major highways were not yet affecting gene flow. The potential vulnerability of the species to climate change, transportation infrastructure, and the US–Mexico border wall highlights conservation challenges and opportunities for binational collaboration.

Arizona, New Mexico, Utah, Wyoming↗

USGS2015

Is there a single best estimator? selection of home range estimators using area- under- the-curve

Background Global positioning system (GPS) technology for monitoring home range and movements of wildlife has resulted in prohibitively large sample sizes of locations for traditional estimators of home range. We used area-under-the-curve to explore the fit of 8 estimators of home range to data collected with both GPS and concurrent very high frequency (VHF) technology on a terrestrial mammal, the Florida panther Puma concolor coryi , to evaluate recently developed and traditional estimators. Results Area-under-the-curve was the highest for Florida panthers equipped with Global Positioning System (GPS) technology compared to VHF technology. For our study animal, estimators of home range that incorporated a temporal component to estimation performed better than traditional first- and second-generation estimators. Conclusions Comparisons of fit of home range contours with locations collected would suggest that use of VHF technology is not as accurate as GPS technology to estimate size of home range for large mammals. Estimators of home range collected with GPS technology performed better than those estimated with VHF technology regardless of estimator used. Furthermore, estimators that incorporate a temporal component (third-generation estimators) appeared to be the most reliable regardless of whether kernel-based or Brownian bridge-based algorithms were used and in comparison to first- and second-generation estimators. We defined third-generation estimators of home range as any estimator that incorporates time, space, animal-specific parameters, and habitat. Such estimators would include movement-based kernel density, Brownian bridge movement models, and dynamic Brownian bridge movement models among others that have yet to be evaluated.

Florida↗