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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.

Texas quail populations have declined over the past few decades. While habitat loss has been identified as the primary cause, it has been speculated that pathogens may also play a role in this decline. To help address this, we collected scaled quail, Callipepla squamata, Gambel's quail, Callipepla gambelii, and Montezuma quail, Cyrtonyx montezumae, from across the Trans-Pecos ecoregion of Texas via hunter-harvest. Quail samples were then necropsied to document pathogens not previously recorded in the host species. Pathogens were submitted to the Texas A&M University Veterinary Medicine Diagnostic Lab (TVMDL), where parasite identification and histopathological analyses were conducted. From this, we identified several parasites that had never been documented in the quails of the Trans-Pecos ecoregion of Texas. This study was the first to document Mycobacterium sp. and Sarcocystis sp. in scaled quail, Subulura sp. and Physaloptera sp. in Montezuma quail, and Oxyspirura petrowi and Aulonocephalus pennula in a Texas Gambel's quail.

The Loggerhead Shrike (Lanius ludovicianus) is a facultative grassland songbird that preys on various species; its generalist diet includes arthropods, reptiles, birds, and mammals. It is distinguished by its peculiar behavior of impaling its prey. The Loggerhead Shrike is an efficient predator known to hunt birds more than twice its size. In January 2016, in Valle Colombia Ranch in northern Coahuila, Mexico, we documented 2 Loggerhead Shrikes preying on Scaled Quails (Callipepla squamata). We first observed a Loggerhead Shrike feeding on the ground on a recently depredated, headless Scaled Quail and subsequently discovered the quail's right wing impaled on a honey mesquite (Neltuma glandulosa). During the second event, we witnessed the successful predation attack of a different Loggerhead Shrike on a Scaled Quail. These are the first records of the Scaled Quail as part of the Loggerhead Shrike's diet. Being almost 4 times the mean weight of the Loggerhead Shrike, the Scaled Quail is the largest recorded prey for this species. As attacking prey this large is considered unusual behavior, we suggest it was due to limited prey availability given a below-mean rainfall year and extremely low temperatures during that winter. El verdugo americano (Lanius ludovicianus) es un ave facultativa de pastizal con una dieta generalista que se alimenta de diversas especies, incluyendo artrópodos, reptiles, aves y mamíferos. Se distingue por su peculiar comportamiento de empalar a sus presas. El verdugo americano es un depredador eficiente que se sabe que caza aves de más del doble de su tamaño. En enero de 2016, en el Rancho Valle Colombia, en el norte de Coahuila, México, documentamos dos verdugos americanos depredando codornices escamosas (Callipepla squamata). Primero observamos a un verdugo americano alimentándose en el suelo de una codorniz sin cabeza recientemente cazada y subsecuentemente descubrimos su ala derecha empalada en un mezquite (Neltuma glandulosa). En el segundo evento, presenciamos el ataque exitoso y muerte de una codorniz escamosa por un verdugo americano diferente. Estos son los primeros registros de la codorniz escamosa como parte de la dieta del verdugo americano. Con casi cuatro veces la media del peso del verdugo americano, la codorniz escamosa es la presa registrada más grande confirmada para esta especie. Dado que atacar presas tan grandes se considera un comportamiento inusual, sugerimos que se debió a una disponibilidad limitada de presas debido a una precipitación pluvial por debajo de la media y temperaturas extremadamente bajas durante ese invierno. Palabras clave: aves de pastizal, codorniz escamosa, depredación, Desierto Chihuahuense, dieta invernal.

Ambiguity in sexually dimorphic characteristics can lead to inaccurate sex determination in some species. One such species is the scaled quail (Callipepla squamata). We collected DNA samples from scaled quail and compared the genetically confirmed biological sex to the sex assigned in the field. Sexing accuracy was significantly lower in the early-fall months (September-October) than in other months, coinciding with the annual molt. Accuracy tended to be higher for females than males and higher for adults than juveniles. Our results indicate that established field methods for sexing scaled quail are fairly accurate but may be unreliable during the early fall, before the annual molt is complete. Even when the early-fall months are excluded, disparities in sexing accuracy between females and males might bias reported sex ratios for this species.

Quail populations in the United States have been declining for several decades, and the role that parasites may be playing in this decline is not well understood. The goal of this study was to document novel parasites that inhabited the scaled quail, Callipepla squamata, of the Trans-Pecos ecoregion of Texas. To do this, quail were collected by hunter-harvest, night-netting, and funnel-trapping and were necropsied in the laboratory to determine the parasites they hosted. After analyzing 386 birds, we identified Dispharynx sp. in one of the samples. This specimen is the first to be officially documented in scaled quail.

The primary driver of nest failure for terrestrial birds is depredation, especially for ground-nesting species that are vulnerable to a diverse guild of predators. However, descriptions of how complex predator–prey interactions happen, and ultimately lead to nest failures, are scarce. Herein, we provide observations collected from cameras stationed at nest sites as part of a larger study on Northern Bobwhite (Colinus virginianus) and Scaled Quail (Callipepla squamata) nesting behavior in the Oklahoma Panhandle during 2016. We observed 2 multi-episode (i.e., multiple predator visits) diurnal nest depredation events at a nest of each species. In both instances, repeated nest depredation by hispid cotton rats (Sigmodon hispidus) as well as 2 different snake species resulted in nest abandonment. We observed that cotton rats routinely visited nest sites (up to 11 times in 1 diurnal period), and often entered the nest during off bouts (64% of off bouts) of the incubating females. By detailing interspecific interactions involved in nest depredation, we provide a glimpse into the complexity of the nesting ecology of ground-dwelling birds. These observations further reinforce the potential pitfalls of categorizing nest depredation events without camera data.

The Northern bobwhite quail (Colinus virginianus) is a popular game bird that has been experiencing a well-documented decline throughout Texas since the 1960s. While much of this decline has been attributed to habitat loss and fragmentation, recent studies have identified other factors that may also contribute to decreasing quail populations. Parasites, in particular, have become increasingly recognized as possible stressors of quail, and some species, particularly the eyeworm (Oxyspirura petrowi) and cecal worm (Aulonocephalus pennula) are highly prevalent in Texas quails. Eyeworm infection has also been documented in some passerines, suggesting helminth infection may be shared between bird species. However, the lack of comprehensive helminth surveys has rendered the extent of shared infection between quail and passerines in the ecoregion unclear. Thus, helminth surveys were conducted on bobwhite, scaled quail (Callipepla squamata), Northern mockingbirds (Mimus polyglottos), curve-billed thrashers (Toxistoma curvirostre), and Northern cardinals (Cardinalis cardinalis) to contribute data to existing parasitological gaps for birds in the Rolling Plains ecoregion of Texas. Birds were trapped across 3 counties in the Texas Rolling Plains from March to October 2019. Necropsies were conducted on 54 individuals (36 quail and 18 passerines), and extracted helminths were microscopically identified. Nematode, cestode, and acanthocephalan helminths representing at least 10 helminth species were found. Specifically, A. pennula and O. petrowi had the highest prevalence, and O. petrowi was documented in all of the study species. This research adds to the body of knowledge regarding parasitic infections in quail and passerines of the Rolling Plains ecoregion and highlights the potential consequences of shared infection of eyeworms among these bird species.

Non-native grasses are frequently sown in the southwestern United States for livestock forage and erosion control. These grasses often spread from areas where they are planted and replace native grasses and forbs. We tested the hypothesis that chestnut-bellied scaled quail (Callipepla squamata castanogastris) avoid locations dominated by non-native grasses. We trapped scaled quail at 5 different sites in southern Texas, USA, and located quail fitted with necklace-style transmitters 3 times/week during 2013–2014. We manually delineated plant communities using aerial maps and on-the-ground knowledge of the study sites. We examined second-order (home-range scale) selection by comparing proportion of the areas of plant communities within 62 scaled quail home ranges (used) paired with random home ranges (available). We examined third-order (within-home-range scale) selection by comparing the composition of bird location (used) and random (available) points based on proportion of points within plant communities. For both home-range scale and within-home-range scale analyses, we used non-parametric multivariate analysis of variance with 9,999 random permutations. We examined fourth-order (organism-centered) selection by measuring vegetation variables at used and available locations and then estimating the relative probability of use of vegetation variables and by estimating continuous selection functions for variables that were influential in determining relative probability of use. Buffelgrass (Pennisetum ciliare) and Old World bluestems (Bothriochloa spp., Dichanthium annulatum and other Dichanthium spp.) comprised 99% (95% CI = 98–100%, n = 143 sites where non-native plants occurred) of the non-native grasses in our study areas. Scaled quail avoided non-native and riparian plant communities at the home-range and within-home-range scales of selection. At the organism-centered scale of selection, odds of use by scaled quail decreased 28% for every 10% increase in non-native grass cover and increased 12% for every 10% increase in shrub canopy cover. Scaled quail avoided locations with >10% canopy cover of non-native grasses. Based on avoidance at 3 scales of selection, dominance of buffelgrass and Old World bluestems degrades habitat for scaled quail. Spread and sowing of non-native grasses and brush clearing may be partly responsible for declines in scaled quail populations.

Northern bobwhite (Colinus virginianus) and scaled quail (Callipepla squamata) have experienced chronic declines within the Rolling Plains ecoregion of Texas. Parasitic infection, which has long been dismissed as a problem in quail, has not been studied thoroughly until recently. A total of 219 northern bobwhite and 101 scaled quail from Mitchell County, Texas were captured and donated from 2014 to 2015, and examined for eyeworm (Oxyspirura petrowi) and caecal worm (Aulonocephalus pennula) infections. In 2014, bobwhites averaged 19.6 ± 1.8 eyeworms and 98.6 ± 8.2 caecal worms, and 23.5 ± 2.1 eyeworms and 129.9 ± 10.7 caecal worms in 2015. Scaled quail averaged 4.8 ± 1.0 eyeworms and 50 ± 6.8 caecal worms in 2014, and 5.7 ± 1.3 eyeworms and 38.1 ± 7.1 caecal worms in 2015. This study expands the knowledge of parasitic infection in quail inhabiting the Rolling Plains of Texas. A significant difference was documented in O. petrowi infection between species but there was no significant difference in A. pennula between quail species. No significant difference was detected in parasite infection between the sexes of both northern bobwhite and scaled quail. This study also documented the highest reported O. petrowi infection in both species of quail. Additional research is needed on the life history and infection dynamics of O. petrowi and A. pennula infections to determine if there are individual- and/or population-level implications due to parasitic infection.

Predator visitation to acclimatization or soft-release pens containing captive translocated animals has the potential to cause sub-lethal effects or physical injury that could influence post-release survival and establishment. No previous study has examined potential interactions between captive and resident animals during pre-release holding periods. We monitored seven holding pens containing wild-caught northern bobwhite Colinus virginianus or scaled quail Callipepla squamata in the Rolling Plains Ecoregion of Texas, USA, using remote camera systems. Our objectives were to determine if resident predator species and conspecifics visited holding pens, and to characterize visits by species, frequency, duration and behaviour. We recorded visitation to holding pens by four potential predator species. Although most visits by mammalian predators were short in duration, northern raccoons Procyon lotor were observed spending extended periods of time at holding pens. We also recorded resident scaled quail and northern bobwhite quail visiting holding pens containing conspecifics. We recommend that future studies using a soft-release technique in which captive animals are held at the release site consider the potential impacts of predator visitation to holding pens, and methods to mitigate those impacts.