Jesse M. Alston | Search USGS

USGS2026

Gambel’s quail (Callipepla gambelii) nest site selection and habitat use in Oracle Junction, Arizona

Gambel’s quail ( Callipepla gambelii ) is the most widespread, abundant, and heavily harvested species of game quail in Arizona. Gambel’s quail population dynamics in Arizona are strongly influenced by seasonal weather conditions. This is particularly relevant for Gambel’s quail management as drought conditions are expected to increase in Arizona, and this may exacerbate inter-annual variation in Gambel’s quail abundance and recruitment. The goal of this study is to provide information on Gambel’s quail population demographics, habitat use, and movement to inform land management decisions for Gambel’s quail in southeast Arizona in a way that mitigates the effect of drought. We used multiple trapping methods to capture Gambel’s quail from February–July 2024 and February–15 May 2025. We found noose mats (n = 57) to be more effective than drop traps (n=14) in capturing Gambel’s quail, with multiple types of walkin traps proving ineffective. We deployed 33 GPS backpack transmitters on female Gambel’s quail to monitor their movements and locate nests. We documented eight mortalities of tracked quail from apparent predation. Quail home range sizes ranged from 3 ha-100 ha (mean = 25 ha) in 2024 and from 7–57 ha (mean = 29 ha) in 2025. We identified four nest sites with 6-15 eggs and all nests were predated. We collected vegetation measurements at nest and brood sites and corresponding random points to examine nest and brood site selection although our small sample sizes limited our ability to make inferences about Gambel’s quail habitat selection.

Arizona↗

USGS2024

Climate, food and humans predict communities of mammals in the United States

Aim The assembly of species into communities and ecoregions is the result of interacting factors that affect plant and animal distribution and abundance at biogeographic scales. Here, we empirically derive ecoregions for mammals to test whether human disturbance has become more important than climate and habitat resources in structuring communities. Location Conterminous United States. Time Period 2010–2021. Major Taxa Studied Twenty-five species of mammals. Methods We analysed data from 25 mammal species recorded by camera traps at 6645 locations across the conterminous United States in a joint modelling framework to estimate relative abundance of each species. We then used a clustering analysis to describe 8 broad and 16 narrow mammal communities. Results Climate was the most important predictor of mammal abundance overall, while human population density and agriculture were less important, with mixed effects across species. Seed production by forests also predicted mammal abundance, especially hard-mast tree species. The mammal community maps are similar to those of plants, with an east–west split driven by different dominant species of deer and squirrels. Communities vary along gradients of temperature in the east and precipitation in the west. Most fine-scale mammal community boundaries aligned with established plant ecoregions and were distinguished by the presence of regional specialists or shifts in relative abundance of widespread species. Maps of potential ecosystem services provided by these communities suggest high herbivory in the Rocky Mountains and eastern forests, high invertebrate predation in the subtropical south and greater predation pressure on large vertebrates in the west. Main Conclusions Our results highlight the importance of climate to modern mammals and suggest that climate change will have strong impacts on these communities. Our new empirical approach to recognizing ecoregions has potential to be applied to expanded communities of mammals or other taxa.

Conterminous United States↗