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Desert mule deer (Odocoileus hemionus eremicus) in central Arizona declined from 11 deer/km2 in the early 1960s to 2 deer/km2 in 2006. We had the opportunity to examine the causes of desert mule deer population fluctuations in Arizona from 1960 to 2006 by contrasting deer density, body condition, productivity, and diet quality inside and outside of the 259-ha Walnut Canyon Predator Proof Enclosure (WCPPE) on the Three Bar Wildlife Area (TBWA) in central Arizona. Mule deer inside the enclosure increased from 11/km2 in 1997 to 32 deer/km2 in 2004 while mule deer outside the enclosure in the TBWA remained between 1 and 5 deer/km2 during the same time. There was no difference in body mass and number of fetuses (in utero) between mule deer inside and outside the enclosure. However, there was evidence of mule deer in better body condition inside the enclosure compared to mule deer outside the enclosure. Mule deer inside the enclosure consumed a diet higher in energy than mule deer outside the enclosure. There were no differences in plant species diversity or composition inside and outside the enclosure. Current mule deer densities in the study area are below what the environment is capable of maintaining, and a history of higher mule deer densities inside WCPPE over 40 y has not resulted in measurable impacts on the highly diverse plant communities of TBWA. Observed differences in diet quality of mule deer may be related to trade-offs incurred through predation risk, where mule deer inside the enclosure are maximizing their energy intake without the burden of predator avoidance and vigilance. Our study provided evidence that current mule deer densities in central Arizona are below what the environment is capable of sustaining.
One of the most useful strategies for biological conservation is the creation of protected natural areas. In addition, periodic updates of management plans are necessary to modify or improve the information and make it accessible to future research. Banco Chinchorro Biosphere Reserve is a protected atoll situated 31 km eastward from the southern coast of Quintana Roo, Mexico. A management plan published in 2000 contains a list of reptiles inhabiting the four islands of the atoll, but concerns about errors contained on the list necessitated updates and corrections. Herein, we clarify and update this list and present new life-history data for some species. We used four approaches to improve the list: interviews with staff, fishermen, and professional visitors; literature review; scientific collections; and field work conducted from 2011 to 2013. Thirteen species (1 crocodilian, 4 marine turtles, 2 iguanas, 2 geckos, 2 anoles, 1 whiptail lizard, and 1 snake) were observed in comparison to 14 species previously recorded in the management plan. Of the 13 species currently noted, 9 (69%) species appear in the International Union for Conservation of Nature Red List (7 with a threatened status), 7 (54%) are in Convention on International Trade in Endangered Species of Wild Fauna and Flora Appendices, and 9 (69%) are protected by Mexican law. One invasive species (Anolis sagrei) seems to have adapted and found its niche; whereas another (Hemidactylus frenatus) represents a threat for another species (Aristelliger georgensis), and efforts to eradicate it are strongly recommended. Banco Chinchorro is the only site in Mexico where Anolis allisoni is present. It also hosts the most distant and isolated population of the parthenogenetic lizard Aspidoscelis maslini from the mainland. After this study, we promoted the inclusion of both species in the Mexican protected species list based on ecological and distribution information. Finally, we discuss considering the reptiles of the reserve as Evolutionarily Significant Units.
Little information is available regarding the distribution of the endangered black-capped vireo (Vireo atricapilla) on its wintering grounds along the Pacific slope of mainland Mexico. We surveyed 62 sites from October 2011 to January 2012 to identify previously undocumented wintering locations for the black-capped vireo. We located 66 individuals at 31 sites (47%) in seven states, including Michoacán, Guerrero, and Oaxaca, where there have been few surveys for black-capped vireos. Vireos occupied sites between 12 and 1,328 m, with slopes ≤23°. We detected vireos at 67% of dry forest and 17% of pine-oak (Pinus-Quercus) forest survey sites. Occupied locations were commonly characterized as deciduous, semideciduous, or agricultural lands and other disturbed areas. We found no evidence of latitudinal segregation in this species on its wintering grounds. These observations contribute to our understanding of the distribution and ecology of wintering black-capped vireos.
Wild pigs (Sus scrofa) are an invasive species that can negatively impact arid environments. Their invasiveness mainly stems from two aspects of their behavior: diet and reproductive ability. We examined the stomach contents (n = 89) and reproductive tracts (n = 78) taken from wild pigs from June 1996 to October 1998 in the Rolling Plains of Texas. Pigs showed variation in forage categories among seasons. Agricultural crops were used with high frequency in all seasons. Farrowing peaked between December and February, with an average fetal litter size of 4.75 ± 2.67. Older and larger sows tended to have larger litters, but sows as young as 8 months of age were reproductive. We recommend limiting pig access to agricultural crops when possible and trapping when pigs are most nutrient stressed (summer). Control efforts should be most effective immediately preceding the farrowing peak and focused on females >8 months of age.
We analyzed the metacommunity structure of volant and nonvolant small-mammal assemblages along the San Pedro-Mezquital River to provide insights on its role as a biological corridor connecting the eastern and western versants of the Sierra Madre Occidental. Because the river bed descends from 1,800 m to sea level, and from arid to tropical environments, we expected high species turnover and significant relationships of species composition with the vegetation and elevation. Different metacommunity structures were identified for volant (Gleasonian) and nonvolant (quasi-Gleasonian) mammals; i.e., species along the gradient replace each other, but replacement is not by groups but rather species respond idiosyncratically to local environment. We found no significant relationship between species composition and vegetation or elevation, likely because mammals that would otherwise be confined to one vegetation type can occur here in more than one, probably tracking specific resources along the elevation–vegetation gradient. Results support the hypothesis that it is not species richness in itself that accounts for the high biodiversity in Mexico but rather the high environmental heterogeneity that in turn produces high species turnover rates at relatively low scales.
We report the use and evaluation of various techniques to locate, identify, and observe our target species, the collared lizard (Crotaphytus collaris), while refuged inside rock crevices. We tested the use of radiotelemetry, visual observation via an articulating borescope, remote monitoring of passive integrated transponder tags implanted into subjects as they entered and left refuges, and the measurement of body temperatures of subjects inside refuges. The combined set of techniques provides reliable results and has the potential to uncover novel behavior and social interactions of occupants of otherwise inaccessible refuges or burrows for a host of wild animals.
While highway underpasses and culverts are often identified in conservation planning as wildlife corridors, their success at facilitating connectivity in deserts has rarely been tested. We evaluated wildlife use of seven, pre-existing highway underpass structures and four associated canyon sites over 29 mo to identify spatial and temporal wildlife use patterns and to assess factors that may constrain wildlife use, particularly for native carnivore species. Our results indicate that a wide diversity of wildlife species utilize the underpass structures including rodents, lagomorphs, deer, and carnivores. Structural attributes of the underpasses have a minor influence on use by most observed species, although structural characteristics and human activity both contributed to determining bobcat (Lynx rufus) usage. Wildlife and human diel patterns differed between the underpass sites and their associated canyons. We suggest that providing a range of underpass structures to support use by a diversity of wildlife, as well as development or modification of underpasses to minimize human disturbance, will enhance landscape connectivity in desert systems.
Ephemeral streams in the southwestern United States have unpredictable, short, torrential flows during extreme weather, and their aquatic biology is poorly studied. During the 2006 monsoon, we sampled aquatic communities at 14 ephemeral stream sites within the Santa Cruz River, Arizona, and Río Puerco, New Mexico, watersheds following a monsoon-related thunderstorm and continuing daily until flows and pools dried. With the 86 taxa of macroinvertebrates that we collected, these sites host a modest community, although presence was limited by drying. Macroinvertebrate taxa richness was not associated with duration of water presence, and biomass was greater in sites with less water available. We collected more taxa in ephemeral reaches of interrupted streams than in truly ephemeral streams. Drought-resistant/resilient species traits were well represented. Vertebrates colonized these ephemeral stream reaches quickly; however, native fish species used ephemeral reaches as corridors between perennial reaches while nonnative fish were unable to do so, and amphibians sometimes completed the aquatic portion of their life cycle in the receding waters. This study provides the first data on aquatic organisms in ephemeral streams immediately after monsoon thunderstorms in the southwestern United States.
Freshwater drum (Aplodinotus grunniens) are native to wide, slow, meandering rivers of North America. Drastic habitat changes along with the expansion of metropolitan areas may have an impact on the growth rates or population structure of this species. To characterize these populations, we collected freshwater drum (n = 83) during the months of June and July 2013, using hook and line methods. We used analysis of variance to compare age, physical measurements, and volume of prey items consumed by fish, among sample sites. We used analysis of covariance to examine differences in growth among sample sites and sexes. Although we observed no significant variations in growth rates, there were differences in weight, relative weight, and prey among sites. Invasive Corbicula fluminea and Dreissena polymorpha were found in the guts of many drum and comprised all identifiable bivalve shells found in this study.
Studies that examine frugivore assemblages have traditionally relied on focal tree observations. However, this method presents disadvantages in that few tree individuals can be monitored simultaneously and not for periods of 24 hours per day. We deployed camera traps in the canopy of Oreopanax echinops trees to evaluate the method's potential use in frugivory studies. We detected 12 frugivore–omnivore species at monitored trees. We recorded two nocturnal species (Potos flavus and an unidentified rodent) that would have been overlooked in a focal tree study and two threatened bird species (Oreophasis derbianus and Penelopina nigra) that feed regularly on O. echinops fruits. Our study shows that camera trapping in the canopy can increase the number of frugivores identified as well as those that may not be detected in a traditional focal tree observation study.
I experimentally examined in Bidens aristosa whether extent of flower symmetry affected pollination by insects. Flowers that were treated to increase asymmetry were visited by significantly fewer pollinators than control flowers. Flowers that remained symmetrical after manipulation showed no change in pollinators relative to the controls. These results suggest that insect pollinators have a preference for symmetrical flowers, and that radially symmetric flowers are better at attracting pollinators than their asymmetric counterparts.
We report the first record of the Pseudomyrmecinae subfamily of ants in Oklahoma. Eleven species have been recorded from the Nearctic region, primarily in southern or coastal areas. This collection increases the known distribution northward into the central United States for one of those species, Pseudomyrmex pallidus.
We used fixed videography to record the natural ambush foraging behavior of northern Pacific rattlesnakes (Crotalus oreganus) in central coastal California. We captured approximately 2,000 h of snake behavior over two field seasons. During this time we recorded two occurrences of an unusual behavior which has only been reported twice previously: after selecting sites at which to ambush prey, two different snakes used their anterior bodies to move vegetation away from their strike path. Both individuals used similar stereotyped behavior, forcibly jerking their head and neck upward in a rapid movement. The head jerks were either preceded or followed by head-scanning and lateral head movements. These observations suggest that hunting rattlesnakes may be able to anticipate future events and use past experiences to solve current problems. This report adds to the growing literature on reptile intelligence.
Louse flies (Diptera: Hippoboscidae) are vectors of several blood-borne pathogens of wild birds, such as parasites of the genera Trypanosoma and Haemoproteus. We captured birds during the dry (March–April) and rainy (June–July) seasons in 2013 and 2014 using mist nets at five sites with different land-use types (urban and suburban forests, cattle ranch, shade coffee plantation, and well-preserved montane cloud forest). We thoroughly examined plumage of each captured bird to search for dipteran macroectoparasites. We used PCR to screen for haemosporidian parasites that could infect bird hosts parasitized by hippoboscids. The birds Chlorospingus flavopectus (prevalence: 0.6%, n = 150), Basileuterus rufifrons (1.8%, n = 56), and Sayornis nigricans (50%, n = 2) are first-time host records for the louse fly Ornithoctona fusciventris (Diptera: Hippoboscidae). We found a positive infection by Plasmodium/Haemoproteus parasites in C. flavopectus. This fly family includes many species that are vectors of bird pathogens; this has important implications for wild and domestic animal health.
The bobcat (Lynx rufus) is typically described as an obligatory predator that infrequently scavenges and displays a strong preference for fresh prey. Scavenging behavior of the species has rarely been directly observed or documented and instead has been generally inferred from stomach content analysis. We observed a female bobcat and cub scavenging domestic pig (Sus scrofa) carcasses for a total of seven consecutive days during a carrion utilization study in central Oklahoma. These observations suggest that bobcats will readily exploit fresh carrion when under the caloric demands of rearing young. Bobcats possibly play an overlooked role in the guild of carrion recyclers in suburban and semirural ecosystems subjected to human encroachment.
Capture and transportation of wild rodents is needed to supply study animals for laboratory or enclosure studies and for translocation of threatened and endangered species. Stress of captured rodents must be minimized to maximize survival. Methods to limit stress include minimizing capture and transportation durations, providing sufficiently sized housing with adequate nesting materials and foods, and ensuring that animals are maintained in comfortable environmental conditions. We utilized these techniques to capture and transport California voles (Microtus californicus) and pocket gophers (Thomomys bottae) from California to Colorado to determine their rate of survival during this process. We captured pocket gophers through live-trapping; burrow excavation substantially reduced capture and holding times for voles. All 50 voles and 88 of 91 pocket gophers were still alive and in good condition 2 weeks postarrival. The techniques and materials described should provide a useful framework for other wild rodents as well.
The known distribution of Baiomys taylori taylori is limited to Texas, Oklahoma, New Mexico, and Mexico. Baiomys t. taylori is reported for the first time from Louisiana, from the northwestern portion of the state.
We used a motion-triggered camera to document and qualify the nature of interspecific interactions between elk (Cervus elaphus) and feral horses (Equus caballus) at an isolated, natural water source in Mesa Verde National Park, Colorado. The camera was active for at least 110 of 145 potential trap-nights between 24 April 2012 and 16 September 2012. Elk and horse interactions were observed 51 times, and elk were averted from accessing water 42 times (82%). Feral horses exhibited dominant behavior over native elk during the driest time of the year (May–June), often preventing acquisition of water by elk.
We developed a new method for deploying a passive integrated transponder (PIT) with a flexible antenna cable hung as a serpentine curtain at a cave entrance. This fly-through method increased PIT tag detections of nectar-feeding bats (Phyllostomidae) that appeared to pass undetected via other PIT tag antenna configurations.