We monitored the persistence of a remnant population of pronghorn (Antilocapra americana) near Hillside, AZ, over an 11-year period from May 2008 through December 21, 2019. Originally consisting of three bucks, two does, and one female yearling, the last pregnant doe was seen March 13, 2014, and the last fawn was seen on November 10, 2014. Only one buck was seen after June 17, 2014, and no males after July 7, 2018. The last pronghorn seen were three does on a follow-up survey April 3, 2021. Although the possibility exists of animals immigrating or emigrating from the 78 km² study area, we did not document such behavior during our study. With no overt attempts at management the population doubled, before losing four animals following a May 2014 Palmer Drought Severity Index (PDSI) of -4.09. The persistence of this population through 2021 is attributed to low adult mortality and a greater recruitment of females than males. The low percentage of available habitat utilized suggests an adequate carrying capacity. The disappearance of this population is attributed to inbreeding depression and low recruitment due to genetic bottle-necking. The Hillside population was too small and too isolated to survive without periodic translocations. Although we frequently observed coyotes during our surveys, predation was not considered the principal factor in the population's demise.

More than 60 years of survey and hunt data indicate declining trends in Arizona's desert cottontail (Sylvilagus audubonii) populations. Survey numbers, hunter participation, harvests, and hunt success for this species after 1990 are considerably less than prior to the 1980s. Summer surveys conducted in the 1950s and repeated in 2019 and 2020 showed that populations were not uniform and related to winter precipitation amounts (r²=0.71, p=0.07). Although one population in 2020 was at an historic low, others were as robust as in the 1950s. Although declines in hunter numbers may be due to sociological factors, the reasons for declining trends in cottontail survey numbers and hunt success are more difficult to evaluate. Precipitation amounts and temperature data suggest that population declines might have been caused by increased mortality due to climate change, increases in predator populations, and/or the presence of disease.

Semi-desert grasslands in the southwestern United States have undergone significant ecological changes as a result of anthropogenic activities beginning in the 1800s. As efforts to restore semi-desert grasslands continue, importance should be placed on understanding the habitat requirements of species, and their relationships with other plants and animals. We examined habitat characteristics of antelope jackrabbits (Lepus alleni Mearns 1890) at Buenos Aires National Wildlife Refuge in south-central Arizona. We examined antelope jackrabbit habitat in relation to endangered Pima pineapple cacti (Coryphantha scheeri Kuntz var. robustispina Schott) and available freshwater sources. Dominant vegetation type and cover were measured at 247 points in antelope jackrabbit home ranges between October 2015 and December 2015. Additionally, we documented the proximity of antelope jackrabbit locations to Pima pineapple cacti and available water sources to determine whether antelope jackrabbits have a spatial relationship with this endangered cactus or water availability.Antelope jackrabbits did not select for habitat based on the vegetation characteristics we measured, proximity to Pima pineapple cacti or based on water availability (P > 0.05).Some jackrabbit species have indicated habitat structure preferences, and while antelope jackrabbits are most commonly associated with tropic-subtropic savannas, our study did not show that antelope jackrabbits select for specific vegetation types or a specific vegetation density, nor native grasses over non-native grasses. Antelope jackrabbits may encounter and eat Pima pineapple cactus opportunistically, as opposed to selecting habitat where Pima pineapple cactus occur. Additionally, antelope jackrabbits did not choose habitat based on the location of freshwater sources which may be because they do not need to drink water to survive and instead get their water needs from their food. Little information exists on how antelope jackrabbits select habitat. This study concluded that there is no relation between vegetation factors previously thought to influence antelope jackrabbit habitat selection and habitat use. Future studies based on larger-scale variables, like topography or predator pressure, may help in understanding the factors that influence how this species uses man-altered landscapes.

We summarize >80 accounts of jaguars killed and/or photographed in Arizona during a 160-year period. These accounts include 13 previously unrecorded animals and six contemporary photographic records. The period with most records occurred between 1900 and 1920. Occurrences ranged from Sonoran desertscrub < 1000 m ASL to mixed confer forest at 2,134 m ASL. Every county in Arizona save four had jaguar records and distribution of records indicate a north by northwest movement along montane corridors from the southeastern quarter of the state northwest to the Grand Canyon. Three counties bordering Sonora yielded numerous records over protracted periods, namely Santa Cruz, Cochise, and Pima Counties. The distribution, number of occurrences and records of females and sub-adults before 1920 suggest some animals may have been breeding residents.

Considerable attention has been paid to perennial aridland rivers due to their disproportionate importance both ecologically and socially within aridlands. The Verde River Basin (VRB) is a large aridland watershed in central-northern Arizona. The river is subject to variable surface flow inputs, but its baseflow is sourced from springs. We investigated trends in increasing summer temperature and reduced June baseflow beginning in 1990 and continuing through the present. We discuss the potential impacts on the 965 reported springs in the watershed.

Springs of the VRB support a wide array of flora and fauna. Early summer dry-season flows are almost entirely derived from springs making the aquatic species of the VRB almost entirely springs-dependent. VRB baseflow was increasing prior to 1990, with a change in trend that coincides with a change in air temperature. Declining snowpack and infiltration, coupled with warming temperatures since 1990 have reduced baseflow basin-wide through reduced groundwater supply, with likely impacts to springs ecosystems, especially springs fed by “younger” groundwater that is most vulnerable to reduction in aquifer recharge. The empirical results of this study indicate a trend of warming temperature correlated to diminishing groundwater dependent resources; supporting recent hydrological and climate projections for the American Southwest.

The thermal stability of capsaicin and dihydrocapsaicin were investigated by conducting cooking tests where temperature and duration varied. These results were used to calculate the half-life of capsaicin at different temperatures and to obtain sufficient data to describe all the variables in the Arrhenius equation between 100°C and 210°C. In addition, the degradation of capsaicinoids appeared to followed first order kinetics. Degradation rates also increased at higher temperatures as expected. The unknown variables in the Arrhenius equation of frequency factor (A) and activation energy (E_a) were determined for both capsaicin and dihydrocapsaicin. The frequency factor for capsaicin and dihydrocapsaicin were 2.60×10⁹and 1.25×10⁹, respectively. The activation energy for capsaicin and dihydrocapsaicin were 87.2 kJ/mol and 84.0 kJ/mol, respectively. Pepper samples cooked in water had longer half-lives than dry pepper powder, which suggests hydrolysis was not a significant degradation mechanism. These results estimated that less than 30% capsaicinoid degradation occurred in nine typical cooking scenarios.

The upper elevation limit of Cylindropuntia acanthocarpa is often reported as either 1,200 or 1,300 m, despite the type locality being at 1,465 m. We provide 31 herbarium records from over 1,300 m elevation, 23 personal iNaturalist photographic records from 1,700-1,900 m, and evidence that the upper limit of C. acanthocarpa may be 2,000 m.

Stocking of rare native fishes for conservation purposes is a common practice in the southwestern United States. Monitoring typically occurs after hatchery-reared fish are released to assess post-stocking movement and survival. We conducted a two-year study, in which tow-barge electrofishing and portable, flat-bed passive integrated transponder (PIT) antennas were used to monitor PIT-tagged, hatchery-reared roundtail chub (Gila robusta) following release into the upper Verde River in Arizona. Specifically, our study aimed to compare the performance of PIT antennas and electrofishing in detecting PIT tagged fish released in a small desert river and to examine the behavioral response of hatchery-reared roundtail chub after stocking. In both years, more fish were detected by antenna arrays (84%) than by electrofishing (30%). roundtail chub were significantly more likely to be detected by antennas than electrofishing each year; however, when antenna data were evaluated only during the few days in which electrofishing took place, there was no significant difference (Year 1, p=0.1784; Year 2, p=0.6295) in detection between gear types for the same time interval, suggesting that electrofishing and antennas are equally likely to detect fish during 48-72 hour time frames. Within 72 hours of release, antennas detected 100% of fish that moved upstream and 93.8% of fish that moved downstream from the stocking location. Overall, less than half (45.6% in Year 1; 41.1% in Year 2) of the stocked roundtail chub were detected using both methods in both years. Utilization of both active capture gear (electrofishing) and passive gear (antennae) had advantages over monitoring with a single method. PIT antennae can be especially useful for managers who lack the personnel or time to implement more intensive methods of capture but want to monitor post-stocking movement and survival of stocked fish.