Temperature influences resource use by chestnut‐bellied scaled quail

Abstract

Animals use physiological and behavioral adaptations to maintain constant body temperatures when environmental temperatures are outside of their thermoneutral zone. We define the temperature suitability bounds as the range of temperatures above and below which animals avoid locations because of unfavorable thermal conditions. Temperatures outside the temperature suitability bounds may trigger behavioral responses such as movement to cooler locations. We tested the hypothesis that temperature during late April to August influences resource selection using chestnut‐bellied scaled quail (Callipepla squamata castanogastris) as our study species. We estimated temperature suitability bounds for scaled quail and tested the prediction that ground surface temperature is a better predictor of habitat space use than black globe temperature. We compared models containing ground surface temperature and woody vegetation structure variables to test the hypothesis that including woody vegetation variables improves prediction of relative probability of use. We trapped scaled quail at five different locations in southern Texas. We located quail fitted with necklace‐style transmitters three times/week during 2013–2014. We measured ground surface and black globe temperatures at locations used by scaled quail and at random locations. We estimated percent canopy cover of cacti, subshrubs, and woody plants using 20 × 50 cm Daubenmire frames at each used and random location. We also estimated height and vertical obstruction of woody vegetation. Temperature suitability bounds of scaled were 24–43°C for the ground surface and 23–39°C for black globes. Ground surface temperature was a better predictor of relative probability of use than black globe temperature. Ground surface temperature during the warmest time of day (early afternoon, 13:30–17:29) decreased with increasing vertical obstruction after accounting for the influence of other structural variables. The best model for predicting relative probability of use by scaled quail during the warmest time of day included ground surface temperature and vertical obstruction. Use of microsites where vegetation structure is conducive to cooler temperatures is an important driver of resource selection by scaled quail during the warmest time of day in southern Texas, but availability of thermal refugia appears to be limited.

Temporal and scalar variations affect resource use of northern bobwhite broods

“…Authors characterizing temperatures by bobwhite in the literature commonly report estimates of operative temperature by using temperature loggers fixed inside black, steel spheres (Carroll et al., 2015, 2016, 2018; Kline et al., 2019; Olsen et al., 2018). Operative temperatures represent the temperature experienced by an animal by accounting for solar radiation and convection.…”

Non‐native grasses reduce scaled quail habitat

“…Vertical obstruction, or vertical cover of woody vegetation, was associated with reduced ground surface temperatures during early afternoon on our study sites (Kline et al 2019). Kline et al (2019) reported that vertical cover influenced relative probability of selection by scaled quail more strongly than shrub canopy cover. Shrubs are also important to scaled quail for nesting.…”

“…Scaled quail in Oklahoma and New Mexico, USA, likewise selected locations with overhead cover and a sparse herbaceous understory (Schemnitz , Campbell et al ). In addition to a more open understory, shrubs provide other resources such as protection from predators (Schemnitz ) and more moderate temperatures (Guthery et al , ; Kline et al ). Vertical obstruction, or vertical cover of woody vegetation, was associated with reduced ground surface temperatures during early afternoon on our study sites (Kline et al ).…”

“…In addition to a more open understory, shrubs provide other resources such as protection from predators (Schemnitz ) and more moderate temperatures (Guthery et al , ; Kline et al ). Vertical obstruction, or vertical cover of woody vegetation, was associated with reduced ground surface temperatures during early afternoon on our study sites (Kline et al ). Kline et al () reported that vertical cover influenced relative probability of selection by scaled quail more strongly than shrub canopy cover.…”