Desert mule deer (Odocoileus hemionus eremicus) densities in central Arizona are below historic levels, likely due to neonatal mortality influencing desert mule deer population dynamics. However, no direct assessments have been made into causes and timing of neonatal mortalities in central Arizona. The objectives of our study were to determine the causes and timing of mortalities of desert mule deer fawns, estimate the annual survival rate of adult females and fawns, and quantify predator effects on fawn survival. In 2007 and 2008 we captured 52 adult female desert mule deer and equipped pregnant females with vaginal implant transmitters to aid in capturing fawns. We performed survival analyses using Program MARK and compared competing models with Akaike's information criterion. We captured 44 desert mule deer fawns; summer survival was 0.432 (95% CI = 0.292–0.584) and annual fawn survival was 0.071 (95% CI = 0.013–0.303). Predation accounted for 64% of fawn mortality. Probability of fawn survival was lowest in the first 2 weeks postparturition. Most (50 of 51) adult females of breeding age were pregnant and adult female survival was 0.858 (95% CI = 0.766–0.961). High predation rates and timing of predation on mule deer fawns were important factors influencing deer densities in central Arizona.

Biocontrol of tamarisk in the southwestern United States, in the form of species belonging to the genus Diorhabda, has been the subject of much research in the past few years in terms of efficacy and impact to native wildlife. This study documents the northern tamarisk beetle's (Diorhabda carinulata) arrival to the Las Vegas Wash in southern Nevada, and its impact on two other nonnative phytophagous invertebrate species that also feed on tamarisk. Our research indicates a negative correlation between the arrival of the northern tamarisk beetle and a population of tamarisk leafhoppers (Opsius stactogalus). There was no significant influence on a population of the splendid tamarisk weevil (Coniatus splendidulus). The arrival of the northern tamarisk beetle resulted in substantial defoliation of tamarisk whereas the two other species had minimal impacts on tamarisk foliage.

We describe a new species of cricetid rodent based on isolated molars recovered from the early Pliocene (early Blancan) Chapala Formation, Jalisco, Mexico. Compared with other named species of the genus, the new species is characterized by its large size, M1 with the median mure connected to the protocone; m1 with (1) a wide and strongly bilobed procingulum, (2) an ectolophid and ectostylid, and (3) a well-developed mesolophid on m1, but a short mesolophid in m2 not extending to the lingual cingulum. A preliminary phylogenetic analysis places the new species with other Postcopemys species from southwestern North America and with Jacobsomys dailyi. The new species comprises the second fossil record of the genus Postcopemys in Mexico and the southernmost record of the genus in North America. We refer the recently named J. dailyi to the genus Postcopemys.

We studied the responses of Desert Ironwood trees (Olneya tesota), located in desert washes of the Sonoran Desert in California, to a reduction in overland water flow. We hypothesized that trees with access to overland water runoff would have different morphological and ecophysiological responses than trees that did not. We studied responses including branch growth, water potentials, leaf carbon isotope ratios, leaf mass per area, flower production, seed production, and tree population densities. Only branch growth and predawn water potentials were found to be significantly different between treatments. Predawn water potentials indicated seasonally increased water stress in trees without access to overland water runoff. Trees with access to overland water runoff also responded with increased branch growth. The lack of differences between treatments observed for all other morphological and ecophysiological responses may indicate that environmental conditions, especially water availability, were similar in both treatments during the production of these structures.

We documented puma (Puma concolor) and jaguar (Panthera onca) prey consumption in northeastern Sonora, Mexico, by investigating global positioning system cluster sites (n = 220), and conducting molecular analyses of scat (n = 116) collected between 2011 and 2013. We used camera trap data (n = 8,976 camera days) to estimate relative abundances of pumas and jaguars. Deer (Odocoileus virginianus) was the most frequent prey for puma found at kill sites (67%) and identified from scat (74%), although based on relative numbers of prey consumed, deer represented 45% and lagomorphs 20% of the proportion of all individuals eaten. A variety of small prey (weighing <15 kg) comprised the majority (52%) of the jaguar kill sites. From prey found at kill sites, jaguars killed calves (Bos taurus) at a lower frequency than previously reported, whereas pumas preyed on calves at a higher frequency than previously reported in the same area. In our study area, jaguars preyed on calves at approximately the same rate as pumas (jaguars 3.7 calves per year, pumas 4.9 calves per year). Calculated predation rates were limited only to collared animals within our study area and therefore should not be considered applicable to all pumas and jaguars in Sonora.

We observed white-winged doves (Zenaida asiatica asiatica) feeding on Chinese tallow (Triadica sebifera) seeds in south Texas. We noted two types of foraging behavior from October through January during 2013–2015. We observed white-winged doves either plucking seeds directly from the branches or cooperatively feeding by one dove shaking a branch, allowing loose seeds to fall to the ground to be consumed by other doves. This is the first recorded occurrence of apparent collaborative foraging behavior between white-winged doves on the ground and individuals in the treetops.

A State-threatened White Sands pupfish (Cyprinodon tularosa) was captured by a fishing spider (genus Dolomedes) in a spring on White Sands Missile Range, New Mexico. Before it was able to consume its prey, a predaceous diving beetle (Cybister fimbriolatus) stole the pupfish from the spider's grasp. Depredation of pupfish by these two invertebrates has not previously been documented to our knowledge. Although it is likely not a significant mortality source for pupfish populations, the pupfish is nonetheless a potential food source for Dolomedes and C. fimbriolatus.

We document the occurrence of a black hawk-eagle (Spizaetus tyrannus) in tropical rain forest in the Los Tuxtlas Biosphere Reserve, Veracruz, Mexico, based on two sequence fragments of mitochondrial genes—cytochrome c oxidase I (DNA barcode) and nicotinamide adenine dinucleotide dehydrogenase 2—taken from a feather recovered from the field. This record is significant because it documents the occurrence of the species in an area with few reliable reports of its occurrence and illustrates the use of genetic identification to confirm the presence of a species in an area. Given that the black hawk-eagle is considered endangered in Mexico, the presence of this species in a natural area is important information relative to conservation efforts.

Close relatives of the small genera Cualac (one species) and Floridichthys (two species) in the family Cyprinodontidae show sexual differences in chromosome number, with females having 2n = 48 and males having 2n = 47 with a large Y chromosome representing chromosomal fusion. However, karyotypic analysis of both sexes in F. carpio and C. tesselatus revealed the typical cyprinodontid karyotype, with 2n = 48, one normal-sized metacentric to submetacentric chromosome pair, and a graded series of 23 acrocentric or subtelocentric pairs. The phylogenetic pattern suggests that sexually dimorphic karyotypes have arisen independently on two separate occasions in a group that otherwise shows unusually high stability in chromosome morphology.

During May of 2015, I observed two separate instances of Mexican jays (Aphelocoma wollweberi) preying on small brown bats in the Chiricahua Mountains of southeastern Arizona. On one occasion I observed a jay carrying, and then eating, a bat in a tree, whereas for the second record I observed a jay strike a bat out of the air as it was flying low to the ground. This is the first published record of Mexican jays preying on or interacting with bats.

The endangered Pecos gambusia (Gambusia nobilis) is known to aggregate around spawning pairs of the endangered Leon Springs pupfish (Cyprinodon bovinus). We documented the behavior of both species, and the reproductive success of C. bovinus, following exposure to controlled numbers of G. nobilis. We found higher densities of G. nobilis around spawning pupfish compared to nonspawning pairs yet there was an absence of a negative density-dependent effect on C. bovinus reproductive success. Gambusia nobilis density showed no effect on spawning behavior yet interference by G. nobilis might reduce the time male C. bovinus spend pursuing females and eliciting spawning behavior.

We inferred the diet and habitat preferences of three individuals of the dwarf pronghorn Capromeryx mexicana from Cedral, Mexico, using stable isotope analysis and the mesowear method. Both approaches showed that the individuals were C₃/C₄ mixed feeders which inhabited open forest. These results differ from previous hypotheses that suggested this species only fed on grasses and lived in grasslands.

Fluctuating asymmetry—small random deviations from perfect bilateral symmetry—is commonly used as an indicator of environmental stress. I used the extent of fluctuating asymmetry in leaves to evaluate the degree to which heavy metal contamination has an observable phenotypic effect on the developmental stability of Rhus glabra (Anacardiaceae), the smooth sumac. Sumac from a deserted mining site near Picher, Oklahoma, displayed significantly greater size-corrected unsigned fluctuating asymmetry than that of sumac from a control site near Tulsa, Oklahoma. These results suggest that heavy metal contamination has a significant effect on the stability of developmental processes in R. glabra and suggest that fluctuating asymmetry may be used as an indicator of environmental pollution.