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We evaluated differential predation pressure on the lizard Sceloporus grammicus at 3 sampling sites along a high-mountain gradient, using 3 methods of assessment: attacks on plasticine lizard models, frequency of lizard tail autotomy, and estimation of the richness of potential predators. We placed a total of 720 lizard models at each sampling site (2600, 3100, and 4150 m asl) on 6 d during the reproductive season and on 6 d during the nonreproductive season. Each day we placed 60 models (n = 30 for each sex, with each sex having 10 each of 3 gular color morphotypes [gray, yellow, and orange]) at lizards' previously observed basking sites. Additionally, we conducted 20 mark-recapture sampling visits at each site from 2014 to 2019 to determine the number of individuals with tail autotomy; we also made observations to estimate the richness of potential predators and supplemented our observations with information from the available literature. We expected (1) an inverse effect of altitude on predation pressure due to a possible decrease in the richness of potential predators with altitude, and (2) differential predation pressure according to sex and gular morphotype due to differential behavioral and morphological conspicuity. Our findings support a decrease in predation pressure with altitude according to our 3 methods of assessment. However, we did not find evidence for an effect of sex or color of gular morphotype on predation pressure, neither from the number of attacks on the plasticine models nor from the frequency of tail autotomy. Lower predation with increasing altitude could be due to the following combined effects: lower richness of predators, lower visibility of lizards because of less contrast of their bodies with the substrate, and reduced locomotor, foraging, and social movements due to thermal restriction.
In addition to its resident Golden Eagles (Aquila chrysaetos), the Southern Great Plains of North America receives an influx of migrant Golden Eagles each winter. However, little current or quantitative information is available regarding eagle presence or the species' land cover associations across the region. During the winters of 2014/2015 and 2015/2016, we surveyed Golden Eagles along 51 approximately 55-km-long road survey transects within a 136,800-km2 area of the Southern Great Plains of eastern New Mexico and the panhandles of Texas and Oklahoma. Our goal was to estimate the winter density of Golden Eagles in the region and to evaluate their land cover associations. Detections were low, with an estimated regional winter density of 0.31 eagles per 100 km2. We found that Golden Eagles were detected in rangeland cover types in greater proportion, and in agricultural and other land cover types in lesser proportion, to their availability. Our results provide regulatory agencies with data that may facilitate better-informed decision making for eagle conservation in the region.
Habitat destruction, hydrologic alteration, and nonnative species introductions have greatly altered the composition of North American stream fish assemblages. In the western United States, intermediate-elevation transition-zone stream reaches––those located between higher-elevation mountain and lower-elevation plains areas––historically supported native fish assemblages that included sensitive species and peripheral or isolated populations of more widespread taxa. We compiled historical records and conducted sampling to examine changes to the fish assemblage in the transition-zone reach of South Boulder Creek, Colorado, USA. Because human development of transition zones altered stream and riparian ecosystems prior to sampling, we developed a historical timeline of human activities to formulate hypotheses regarding factors that influenced fish assemblage change through time. Native fish species richness declined by 60% from the likely historical assemblage, and we hypothesize that widespread alteration of stream and riparian habitat in the mid-1800s caused a first wave of species losses, especially taxa with specific habitat or life history requirements. The remaining coolwater native fishes dominated through the mid-1990s, but more recently, the coldwater-tolerant, nonnative Brown Trout Salmo trutta has greatly expanded and is implicated in additional native species loss. Possible management actions to restore native fish assemblages in transition-zone streams include the following: increasing habitat diversity, particularly off-channel backwaters suited to lentic-adapted native fishes; providing refuges from predators or reducing predator abundance; restoring sinuosity to straightened reaches to improve channel function; improving stream connectivity via installation of fish passages; reintroducing beaver or installing beaver dam analogs; provisioning of suitable flow; and eventually, identifying native stocks for reintroduction. Management of other western United States transition-zone stream reaches may benefit from these insights, especially if conservation of the locally distinct native fish assemblages and their scarce habitat is a priority in the face of rapid human population growth and expanding invasive species.
The use of DNA from fecal samples can allow for a better understanding of the ecology of a species without capturing and handling the animals. This is particularly useful for cryptic and elusive animals, such as bats. Being able to identify critical habitat, such as maternity roosts, for bat species in areas where they depend on abandoned mines that could be slated for closure is necessary to enact appropriate protections for such roosts. In particular, Corynorhinus townsendii commonly uses abandoned mines for maternity roosts. Further, maternity roosts are difficult to identify through visual surveys when only one or a few surveys are performed before mine closures. We have developed a method for identification of C. townsendii maternity roosts that uses fecal DNA extracted from fresh guano collected from plastic sheeting placed at a mine entrance. We provide a multiplex PCR assay to amplify a control region fragment found only in C. townsendii, as well as a Y-linked protein (DBY) to detect male C. townsendii DNA. The purpose of this study was to identify a temporal shift in the presence of male C. townsendii bats, which can be useful to identify a maternity roost. This method allows for noninvasive identification of critical habitat for this species and reduces the effort and safety risk of entering mines on the part of biologists.
Seed predation can significantly reduce the reproductive success of individual plants and their populations. The consequences of seed predation often are most pronounced for rare plant species, in which loss of seeds can have a disproportionate effect on populations. The present study examined the effects of seed predation by Owyhee harvester ants (Pogonomyrmex salinus) on seed survivorship in slickspot peppergrass (Lepidium papilliferum), a rare mustard endemic to sagebrush-steppe habitat in southwestern Idaho. Within sagebrush-steppe, L. papilliferum is restricted to microsites known as “slick spots”—shallow depressions of soil characterized by distinct clay layers and surface water retention that is higher than that of surrounding areas. Harvester ants frequently nest in L. papilliferum habitat and readily consume the plant's seeds. We conducted a controlled field experiment at a population of L. papilliferum in 2012 to quantify seed loss to individual plants as a result of seed predation by harvester ants. Across 20 slick spots, plants exposed to harvester ants experienced a median reduction in seed survivorship of 89.2% (interquartile range, 69.3% to 93.9%) relative to plants in the same slick spot that were matched for size and shielded from ants. The proportion of seeds that plants lost to seed predation was more variable and significantly lower in slick spots with >150 plants than in those with fewer plants, suggesting that a threshold to the number of seeds that can be collected and consumed by ants may occur within the natural range of plant densities found in slick spots. Our results suggest that slick spots supporting large numbers of L. papilliferum in a given year may be buffered from the effects of predation, whereas those with relatively few plants are particularly vulnerable to high levels of seed loss to harvester ants.
I made six extensive collections of black fly larvae at the Little Blackfoot River (LBFR) in western Montana at roughly 2-week intervals from 25 March to 2 June 2019 to describe larval size-class frequencies and cytogenetic diversity of the first spring generation. Frequencies of seven size classes, pupae, and pupal exuviae are given, though no larvae with egg bursters (first-instar larvae) were observed. Therefore, the earliest instars were missed. Sex chromosomes of 562 larvae of this first generation were compared to those of 1260 other larvae previously analyzed from 10 dates (2003 to 2012) to determine whether sex chromosome frequencies differed over time. The fifth and sixth size classes, those having white gill histoblasts, possess the best polytene chromosomes for analysis. The LBFR is a very diverse site having four sibling species and nine cytotypes present. However, the sibling species Simulium brevicercum (IIL-st/st) and S. arcticum s. s. (IIL-3 st/i) are most abundant, comprising 64.6% of the 2019 samples and 62.0% of the yearly samples. Simulium arcticum s. s. is abundant in early spring (2019), while S. brevicercum is rare. As the 2019 spring progresses, however, S. brevicercum becomes abundant, while S. arcticum s. s. becomes less frequent. This trend is not seen in the analysis of yearly samples, suggesting that single collections and analyses may not be accurate. In both the 2019 and yearly analyses, male larvae predominate early while female larvae eventually predominate in late spring, although only slightly. All taxa except S. brevicercum and S. arcticum IIL-10 are not significantly different from year to year. The proportions of these two taxa for the year 2019 were close to the overall average of both types; thus, 2019 was not an anomalous year.
Remnant wood found above the present-day altitudinal limit of trees provides a record of treeline shifts in response to past variations in climate. 14C dating and wood identification of remnant trees from Windy Ridge, a ridgeline in the northwestern Uinta Mountains of northeastern Utah, show treeline ∼100 m higher than today between ∼730 and 500 calibrated 14C years before present (cal yr BP; ∼1220–1450 CE). This treeline shift coincides with the Medieval Climatic Anomaly (MCA), suggesting that warm temperatures allowed limber pine (Pinus flexilis) and Engelmann spruce (Picea engelmannii) to establish above the current treeline during that interval. However, 2 of the remnant trees (limber pine and Douglas-fir [Pseudotsuga menziesii]) date to ∼175 cal yr BP (∼1775 CE), well after the end of the MCA and beginning of the Little Ice Age. This may indicate that some trees that established during the MCA were able to persist for centuries under colder conditions. Comparison of the Windy Ridge 14C dates with those of remnant trees from elsewhere in the western United States suggests that the timing of, and controls on, past treeline dynamics varied across the region.
Thermopsis divaricarpa (Fabaceae) is a common wildflower in the montane zone of the Colorado Rocky Mountains, but its reproductive ecology is still largely unknown. Montane meadows are recognized for their relatively high species richness and important ecosystem services. Thus, knowledge of the reproductive ecology of T. divaricarpa is useful when assessing community-level responses to climate change in the montane zone of the Rockies. We investigated the phenology, breeding system, and pollination of this species in the southern Rocky Mountains of Colorado. Our results suggest that T. divaricarpa flowers from early June to mid-July, exhibits a facultative xenogamous breeding system, and may be pollinated by bumble bees. Pollen grains of T. divaricarpa are singular, ellipsoidal, and tricolpate. Beetles consume floral tissue, but their role as pollinators is questionable.
Excavations at Persistence Cave (Black Hills, SD), produced a large sample of Quaternary microfauna including a diverse assemblage of arvicoline rodents. Identifiable lower first molars (n = 367) include specimens referred to heather vole (Phenacomys sp.), muskrat (Ondatra sp.), southern bog lemming (Synaptomys cooperi), red-backed vole (Myodes sp.), sagebrush vole (Lemmiscus curtatus), prairie vole (Microtus ochrogaster), and a form of meadow vole (Microtus sp.). Direct radiocarbon dating of specimens of Lemmiscus curtatus is consistent with previous records from the Nelson–Wittenberg Site and indicates that sagebrush voles inhabited the southern Black Hills roughly 40,000 yr BP. Direct ages for Myodes sp. and Microtus ochrogaster taxa are consistent with previously published data from Don's Gooseberry Pit, supporting previous interpretations of faunal turnover in the late Pleistocene/early Holocene. Collectively, the radiocarbon record suggests that deposition of fossils of arvicoline rodents at Persistence Cave occurred over a restricted period of time beginning approximately 40,000 yr BP. This period of deposition was followed by a depositional hiatus that included the Last Glacial Maximum, and deposition was reinitiated near the terminal Pleistocene.
Fire is an important ecosystem process that can impact local amphibian communities and breeding behaviors. Riparian gallery forests of the American Southwest are an important habitat for amphibians that breed in river channels, wetlands, and pools within the floodplain. High-intensity fires are rare in these riparian forests, and there is no information on how amphibians respond to fire in this system. We documented the presence and reproductive attempts of Couch's spadefoot (Scaphiopus couchii) in the San Pedro River following a high-intensity wildfire in riparian gallery forest. These observations are the first recorded breeding events of Couch's spadefoot in recently burned habitat and one of the first documented breeding events of this species in a perennial river. Our findings suggest that Couch's spadefoot can breed in burned habitat and may also suggest that the species selects perennial streams for breeding following wildfire.
Little information on the making or use of tents by bats is available for Mexico, although tent-making phyllostomids are common and abundant throughout the Mexican tropics. I report the use of tents by Dermanura phaeotis in northern Nayarit, México, in the northern portion of the species' distribution. One bat was found roosting in a boat-apical tent located in a banana (Musa paradisiaca) grove surrounded by tropical semideciduous forest. Other fronds in the same grove were similarly modified as tents.
We analyzed 47 scats of neotropical otter (Lontra longicaudis annectens), collected along the Necaxa River in Central Mexico, using the Willis flotation technique with a 48% saturated saline solution. Along with plant material, we found the endoparasites Oxyuris equi, Ascaris sp., and Strongylus equinus, among others. Our results indicate that otters in the Necaxa River have a parasite load that needs further analysis, particularly because 2 of the parasite species are associated with human activity.
Endangered black-footed ferrets (BFFs, Mustela nigripes) specialize on prairie dogs (Cynomys spp.) for prey and use prairie dog burrows for shelter. In the wild, female BFFs produce 2–3 kits on average. Litters of 6 have been observed. At the Conata Basin, South Dakota, we observed an adult female BFF, named F05–183, with 7 kits. Data on space use by neighboring female BFFs suggest that F05–183 produced all 7 kits; alternative explanations are discussed. To our knowledge, this is the largest recorded litter count for wild-born BFFs.
We present the first known case of aspergillosis found in a wild, augmented Greater Sage-Grouse (Centrocercus urophasianus) population. This case was not directly associated with the sage-grouse translocations and is the first documented in wild sage-grouse populations since the mid-1900s. Aspergillosis is a fungal infection of the lungs caused by an inoculation of Aspergillus spp. spores. Wild birds that are infected by the pathogen's spores die from the resulting infection. We hypothesize that the Aspergillus spp. spores were propagated either in mesic nesting conditions or in residual damp mulch piles created from sagebrush (Artemisia spp.) habitat restoration projects and that these spores infected the individual within several days of inhalation. This case may have conservation implications for small, augmented, or reintroduced avian populations, especially those of conservation concern where concurrent habitat restoration projects and other conservation actions may create conditions conducive to the propagation of Aspergillus spp. spores and enhance the risk of sage-grouse inoculation.
Caddisflies within the genus Gumaga are generally considered shredders (i.e., consumers of leaf litter) or grazers (i.e., consumers of algae). We report on observations of Gumaga nigricula scavenging animal carcasses within and adjacent to isolated pools along intermittent reaches of Coyote Creek, Santa Clara County, California, USA. In particular, during the summer of 2018, we observed G. nigricula scavenging fish carcasses within isolated pools as well as bits of flesh from the bones of a black-tailed deer (Odocoileus hemionus columbianus) deposited on the stream bank. To the best of our knowledge, our observations represent the first published record of Gumaga spp. scavenging animal carcasses. Our observations also highlight how deteriorating conditions within isolated pools create a late-summer resource pulse for scavengers.
Jaguars (Panthera onca) suffer from the negative effects of roads, mostly significant habitat fragmentation and increased risk of mortality due to vehicle collisions. In Mexico records of jaguars killed on roads are scarce and mostly anecdotal. The Calakmul-Balam-Kú jaguar population is the most important jaguar population in Mexico, but it is threatened by an extensive road network in which Federal Highway 186 Escárcega–Chetumal (hereafter called Hwy. 186) serves as the main road in the region. As part of a study to determine the diversity and abundance of medium- and large-sized mammals around Hwy. 186, we set 47 camera traps during 2019 and obtained pictures of 2 male jaguars on both sides of the road, evidence that these animals were crossing the highway. Also, later in 2020 we found the road-killed carcass of one the jaguars that we had previously documented crossing the highway. These empirical observations occurred in areas where landscape models implemented as far back as 2010 had predicted jaguar crossing sites on Hwy. 186 and where wildlife-safe road-crossing infrastructure has been proposed but so far not installed.
We report, for the first time, visitation to the inflorescences of the endemic Agave cupreata by 2 marsupial species, Didelphis virginiana and Tlacuatzin canescens, in the state of Michoacán, western Mexico. These 2 species were recorded drinking the nectar of A. cupreata and transporting large amounts of pollen among the flowers. This agave is restricted to the mountainous slopes of the Balsas River basin in the states of Michoacán and Guerrero, and it constitutes the raw material for local production of a traditional beverage known as mezcal. In contrast to many other agaves that can propagate vegetatively, A. cupreata only reproduces sexually and has low self-fertilization capacity. Thus, the visits of the marsupials, while infrequent compared to those of bats and birds, could provide an important pollination service given the quantity of pollen that was moved and the duration of their visits. In addition, these 2 marsupial species are able to persist in transformed landscapes, raising the possibility that they could compensate for the loss of other vertebrate pollinators of A. cupreata that are more sensitive to habitat disruption.
We describe a case of brood parasitism of a Greater Sage-Grouse (Centrocercus urophasianus; hereafter, sage-grouse) nest by California Quail (Callipepla californica; hereafter, quail) in southwestern Idaho during 2019. We observed one quail egg in the parasitized nest; the egg partially hatched, but the chick was dead upon the final nest check. Of the 6 sage-grouse eggs in the nest, only 2 hatched, although the eggs contained chicks that appeared nearly completely developed. Identification of the quail chick was confirmed using mitochondrial DNA. Additional monitoring and documentation of this behavioral interaction is warranted to better understand its prevalence and any reproductive consequences for sage-grouse.
Human infrastructure, particularly highway infrastructure, has proven to be a hazard for the resilience of large felid populations throughout the world. The Yucatan Peninsula is no exception and is presently confronted with the establishment of the “Tren Maya,” a continental railway that will reshape the road network of the peninsula. We describe 12 successful crossings of a 4-lane highway on the peninsula by a female puma (Puma concolor) fitted with a GPS radio-transmitter. The median time between sequential locations was 24 h (range 8–56 h), and the average number of days between crossings was 4.33 (SD = 2.50). Felid behavior and movements in relation to roads may be influenced by reduced human mobility due to the COVID-19 pandemic lockdown. We identified a 3-km stretch of highway where the crossings occurred. We describe the characteristics of the area and recommend building wildlife passage structures appropriate for the site.
Two groups independently and seemingly simultaneously published the new combination of Pediomelum pariense, the Paria River breadroot. Both names were published in the second-quarter issues of separate journals in 1986. Same issue dates have led to confusion over which name takes precedence and is thus accepted. However, one issue was delayed in printing. Evidence is provided herein for acceptance of Pediomelum pariense (S.L. Welsh & N.D. Atwood) J.W. Grimes over Pediomelum pariense (S.L. Welsh & N.D. Atwood) S.L. Welsh & N.D. Atwood.