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At least 973 records · Page 54Linked to original sources
USGS2009

Structural changes in vegetation coincident with annual grass invasion negatively impacts sprint velocity of small vertebrates

Sagebrush ecosystems in the intermountain west of the United States are being threatened by conversion to the non-native grass, cheatgrass ( Bromus tectorum ). The dramatic shift in the physical structure of vegetation coincident with cheatgrass invasion likely has negative impacts on animal communities, yet these structural impacts have not been well-studied. In a previous study, dense cheatgrass stems reduced sprint velocity for the flattened, wide-bodied desert horned lizard ( Phrynosoma platyrhinos ). Here, we asked if a decrease in sprint velocity due to cheatgrass impediment can be generalized to the suite of small vertebrates inhabiting the sagebrush ecosystems of western Utah. We evaluated sprint performance of the common rodent ( n = 3) and lizard ( n = 4) species on two raceway types, cheatgrass and no-cheatgrass, and hypothesized that body size, body shape, and form of movement are important factors influencing sprint velocity through dense cheatgrass stems. All species showed significant reductions in speed on cheatgrass versus no-cheatgrass raceways, with percent reduction greatest for larger, wider, or hopping organisms compared to smaller, more slender, or running organisms. Of concern, surveys for rodents and lizards at our study areas support a common pattern: lower abundances of small vertebrates, as well as a loss of rodent species richness, in areas infested with cheatgrass compared to intact, native sagebrush communities. By extension, we expect a negative impact on animal communities in other semi-arid regions experiencing dramatic shifts in vegetation structure upon invasion by non-native grasses that are capable of forming dense stands in the interspaces of native desert plants [e.g., Sonoran desert invaded by buffelgrass ( Pennisetum ciliare )].

Utah↗
USGS2011

Customizing a rangefinder for community-based wildlife conservation initiatives

Population size of many threatened and endangered species is relatively unknown because estimating animal abundance in remote parts of the world, without access to aircraft for surveying vast areas, is a scientific challenge with few proposed solutions. One option is to enlist local community members and train them in data collection for large line transect or point count surveys, but financial and sometimes technological constraints prevent access to the necessary equipment and training for accurately quantifying distance measurements. Such measurements are paramount for generating reliable estimates of animal density. This problem was overcome in a survey of Asiatic wild ass ( Equus hemionus ) in the Great Gobi B Strictly Protected Area, Mongolia, by converting an inexpensive optical sporting rangefinder into a species-specific rangefinder with visual-based categorical labels. Accuracy trials concluded 96.86% of 350 distance measures matched those from a laser rangefinder. This simple customized optic subsequently allowed for a large group of minimally-trained observers to simultaneously record quantitative measures of distance, despite language, education, and skill differences among the diverse group. The large community-based effort actively engaged local residents in species conservation by including them as the foundation for collecting scientific data.

Great Gobi B Strictly Protected Area↗
USGS2011

Reproductive endocrine disruption in smallmouth bass ( Micropterus dolomieu ) in the Potomac River basin: spatial and temporal comparisons of biological effects

A high prevalence of intersex or testicular oocytes (TO) in male smallmouth bass within the Potomac River drainage has raised concerns as to the health of the river. Studies were conducted to document biomarker responses both temporally and spatially to better understand the influence of normal physiological cycles, as well as water quality and land-use influences. Smallmouth bass were collected over a 2-year period from three tributaries of the Potomac River: the Shenandoah River, the South Branch Potomac and Conococheague Creek, and an out-of-basin reference site on the Gauley River. The prevalence of TO varied seasonally with the lowest prevalence observed in July, post-spawn. Reproductive maturity and/or lack of spawning the previous spring, as well as land-use practices such as application of manure and pesticides, may influence the seasonal observations. Annual, seasonal, and site differences were also observed in the percentage of males with measurable concentrations of plasma vitellogenin, mean concentration of plasma vitellogenin in females, and plasma concentrations of 17β-estradiol and testosterone in both sexes. Bass collected in the South Branch Potomac (moderate to high prevalence of TO) had less sperm per testes mass with a lower percentage of those sperm being motile when compared to those from the Gauley River (low prevalence of TO). An inverse relationship was noted between TO severity and sperm motility. An association between TO severity and wastewater treatment plant flow, percent of agriculture, total number of animal feeding operations, the number of poultry houses, and animal density within the catchment was observed.

Maryl↗
USGS2009

Relationship between body condition of American alligators and water depth in the Everglades, Florida

Feeding opportunities of American alligators (Alligator mississippiensis) in freshwater wetlands in south Florida are closely linked to hydrologic conditions. In the Everglades, seasonally and annually fluctuating surface water levels affect populations of aquatic organisms that alligators consume. Since prey becomes more concentrated when water depth decreases, we hypothesized an inverse relationship between body condition and water depth in the Everglades. On average, condition of adult alligators in the dry season was significantly higher than in the wet season, but this was not the case for juveniles/subadults. The correlation between body condition and measured water depth at capture locations was weak; however, there was a significant negative correlation between the condition and predicted water depth prior to capture for all animals except for spring juveniles/subadults which had a weak positive condition-water depth relationship. Overall, a relatively strong inverse correlation occurred at 10-49 days prior to the capture day, suggesting that current body condition of alligators may depend on feeding opportunities during that period. Fitted regression of body condition on water depth (mean depth of 10 days when condition-water depth correlation was greatest) resulted in a significantly negative slope, except for spring adult females and spring juveniles/subadults for which slopes were not significantly different from zero. Our results imply that water management practices may be critical for alligators in the Everglades since water depth can affect animal condition in a relatively short period of time.

Hydrobiologia↗
USGS2014

Reduced population variance in strontium isotope values informs domesticated turkey use at Chaco Canyon, New Mexico, USA

Traditionally strontium isotopes (87Sr/86Sr) have been used as a sourcing tool in numerous archaeological artifact classes. The research presented here demonstrates that 87Sr/86Srbioapatite ratios also can be used at a population level to investigate the presence of domesticated animals and methods of management. The proposed methodology combines ecology, isotope geochemistry, and behavioral ecology to assess the presence and nature of turkey (Meleagris gallopavo) domestication. This case study utilizes 87Sr/86Srbioapatite ratios from teeth and bones of archaeological turkey, deer (Odocoileus sp.), lagomorph (Lepus sp. and Sylvilagus sp.), and prairie-dog (Cynomys sp.) from Chaco Canyon, New Mexico, U.S.A. (ca. A.D. 800 – 1250). Wild deer and turkey from the southwestern U.S.A. have much larger home ranges and dispersal behaviors (measured in kilometers) when compared to lagomorphs and prairie dogs (measured in meters). Hunted deer and wild turkey from archaeological contexts at Chaco Canyon are expected to have a higher variance in their 87Sr/86Srbioapatite ratios, when compared to small range taxa (lagomorphs and prairie dogs). Contrary to this expectation, 87Sr/86Srbioapatite values of turkey bones from Chacoan assemblages have a much lower variance than deer and are similar to that of smaller mammals. The sampled turkey values show variability most similar to lagomorphs and prairie dogs, suggesting the turkeys from Chaco Canyon were consuming a uniform diet and/or were constrained within a limited home range, indicating at least proto-domestication. The population approach has wide applicability for evaluating the presence and nature of domestication when combined with paleoecology and behavioral ecology in a variety of animals and environments.

New Mexico↗
USGS2019

Connectivity of mule deer (Odocoileus hemionus) populations in southern California: A genetic survey of a mobile ungulate in a highly fragmented urban landscape

Urbanization is a substantial force shaping the genetic and demographic structure of natural populations. Urban development and major highways can limit animal movements, and thus gene flow, even in highly mobile species. Characterizing varying species responses to human activity and fragmentation is important for maintaining genetic continuity in wild animals and for preserving biodiversity. As one of the only common and wide-ranging large wild herbivores in much of urban North America, deer play an important ecological role in urban ecosystems, yet the genetic impacts of development on deer are not well known.

Landscape Ecology↗
USGS2012

The discourses of incidents: Cougars on Mt. Elden and in Sabino Canyon, Arizona

Incidents are relatively short periods of intensified discourse that arise from public responses to symbolically important actions by public officials, and an important part of the conflict that increasingly surrounds state wildlife management in the West. In an effort to better understand incidents as a facet of this conflict, we analyzed the discourses of two incidents in Arizona that were precipitated by the intended removal of cougars by managers in response to public safety concerns. We used newspaper content, 1999–2007, to elucidate seminal patterns of public discourses and discourse coalitions as well as differences in discursive focus between incident periods and background periods. Cougars were mentioned in newspaper articles 13–33 times more often during incidents compared with background periods. State wildlife agency commissioners and hunters were part of a discourse coalition that advocated killing cougars to solve problems, blamed cougars and those who promoted the animals’ intrinsic value and sought to retain power to define and solve cougar-related problems. Personnel from affected state and federal agencies expressed a similar discourse. Environmentalists, animal protection activists, and some elected officials were of a coalition that defined “the problem” primarily in terms of people’s behaviors, including behaviors associated with current institutional arrangements. This discourse advocated decentralizing power over cougar management. The discourses reflected different preferences for the allocations of power and use of lethal versus non-lethal methods, which aligned with apparent core beliefs and participants’ enfranchisement or disenfranchisement by current state-level management power arrangements.

Arizona↗
USGS2017

Changes in habitat availability for multiple life stages of diamondback terrapins (Malaclemys terrapin) in Chesapeake Bay in response to sea level rise

Global sea level rise (SLR) will significantly alter coastal landscapes through inundation and erosion of lowlying areas. Animals that display area fidelity and rely on fringing coastal habitats during multiple life stages, such as diamondback terrapins (Malaclemys terrapin Schoepff 1793), are likely to be particularly vulnerable to SLR-induced changes. We used a combination of empirical nest survey data and results from a regional SLR model to explore the long-term availability of known nesting locations and the modeled availability of fringing coastal habitats under multiple SLR scenarios for diamondback terrapin in the MD portion of Chesapeake Bay and the MD coastal bays. All SLR scenarios projected the rapid inundation of historically used nesting locations of diamondback terrapins with 25%–55% loss within the next 10 years and over 80% loss by the end of the century. Model trajectories of habitat losses or gains depended on habitat type and location. A key foraging habitat, brackish marsh, was projected to decline 6%–94%, with projections varying spatially and among scenarios. Despite predicted losses of extant beach habitats, future gains in beach habitat due to erosion and overwash were projected to reach 40%–600%. These results demonstrate the potential vulnerability of diamondback terrapins to SLR in Chesapeake Bay and underscore the possibility of compounding negative effects of SLR on animals whose habitat requirements differ among life stages. More broadly, this study highlights the vulnerability of species dependent on fringing coastal habitats and emphasizes the need for a long-term perspective for coastal development in the face of SLR.

Chesapeake Bay↗
USGS2014

Hidden Markov model for dependent mark loss and survival estimation

Mark-recapture estimators assume no loss of marks to provide unbiased estimates of population parameters. We describe a hidden Markov model (HMM) framework that integrates a mark loss model with a Cormack–Jolly–Seber model for survival estimation. Mark loss can be estimated with single-marked animals as long as a sub-sample of animals has a permanent mark. Double-marking provides an estimate of mark loss assuming independence but dependence can be modeled with a permanently marked sub-sample. We use a log-linear approach to include covariates for mark loss and dependence which is more flexible than existing published methods for integrated models. The HMM approach is demonstrated with a dataset of black bears ( Ursus americanus ) with two ear tags and a subset of which were permanently marked with tattoos. The data were analyzed with and without the tattoo. Dropping the tattoos resulted in estimates of survival that were reduced by 0.005–0.035 due to tag loss dependence that could not be modeled. We also analyzed the data with and without the tattoo using a single tag. By not using.

Journal of Agricultural, Biological, and Environme↗
USGS1993

Snaring to control feral pigs sus scrofa in a remote Hawaiian rain forest

Feral pig Sus scrofa control in Kipahulu Valley, a remote rain forest in Haleakala National Park, Maui, Hawaiian Islands, has been achieved with snares over a 45-month period. Initial pig densities in fenced management units of 6·2 km 2 and 7·8 km 2 were estimated at 6 animals/km 2 and 14·3 animals/km 2 for the two units, based on population reconstruction from animals killed and aged. During the 45 months of the study, 1978 snares were set, and 1·6 million snare nights were logged. Snare density reached 96/km 2 and 200/km 2 for the two management units by the end of the study. A mean effort of 43 worker hours/pig was used to remove 53 pigs from the upper management unit, and a mean of 7 worker hours/pig to remove 175 animals from the more densely populated lower unit. Pig activity monitoring along transects provided a good measure of control effectiveness until densities of about 1 pig/km 2 were achieved, after which transects became less useful than scouting for determining pig activity.

Hawai'i↗
USGS2017

Late-Pleistocene and Holocene remains of Hysterocarpus traski (Tule Perch) from Clear Lake, California, and inferred Holocene temperature fluctuations

The remains of scales of Hysterocarpus traski Gibbons (Tule perch) were found throughout a 27.44-m core from Clear Lake. Most scales occurred between the mud surface and deposits approximately 11,000 years old. Changes in growth rates of the animals were examined by measuring scale annuli and applying an empirically established regression of fish length on scale radius. The data indicate a pattern of accelerating growth rates, reaching a peak between ⋍4000 and 2800 BP. After ⋍2800 BP, growth rates decline markedly. Because the growth rates of these animals are essentially dependent on temperature, the changes observed in the patterns of growth probably reflect changes in climate in the northern Coast Range. The general pattern of inferred temperature increase during the early and middle Holocene, ending between ⋍4000 and 2800 BP, is consistent with evidence from tree-line studies and palynology indicating higher temperatures in parts of the western United States during this period.

California↗
USGS1990

Determination and occurrence of AHH-active polychlorinated biphenyls, 2,3,7,8-tetrachloro-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in Lake Michigan sediment and biota. The question of their relative toxicological significance

An analytical procedure has been developed for the determination of the 18 PCB congeners which are inducers of methylcholanthrene-like mixed function oxidase activity in animals and include the most toxic PCBs. Determinations of the toxic PCB congeners in samples of eggs of predatory fish and piscivorous birds of the Great Lakes and in Aroclor mixtures demonstrate that the apparent toxic potency of PCB residues in these samples is dominated by two congeners, 3,3′,4,4′,5- and 2,3,3′,4,4′-pentachlorobiphenyl. Furthermore, the analyses demonstrate that the potential toxicity of PCB residues can increase 5 to 10 fold as they reach upper levels of aquatic food chains and most often exceed the potential toxicity of chlorinated dibenzodioxins and furans in higher animals even in environments highly contaminated by the latter compounds.

Chemosphere↗
USGS1992

Anomalous abundances of deep-sea fauna on a rocky bottom exposed to strong currents

Unusually high abundances of sponges and gorgonian corals, covering as much as 25% of the bottom, occur at depths greater than 3.5 km on the Blake Spur, a rocky cliff-dominated feature on the western Atlantic continental margin. This is the first report of such high abundances of megafauna from a non-hydrothermal or otherwise chemosynthetically enriched site in abyssal depths. Animal densities at other steep rocky sites at similar depths are usually lower by more than an order of magnitude. The deep slope of the Blake Spur is exposed to the vigorous Western Boundary Undercurrent, with local flow speeds that may exceed 100 cm s-1. Currents can control this anomalous animal abundance by removing sediments and by enhancing fluxes, rather than concentrations, of food particles to the dominant suspension feeders. ?? 1992.

Deep Sea Research Part A, Oceanographic Research P↗
USGS1996

Kangaroo rat bone compared to white rat bone after short-term disuse and exercise

Kangaroo rats ( Dipodomys ordii ) were used to study the effects of confinement on mechanical properties of bone with a long range objective of proposing an alternative to the white rat model for the study of disuse osteoporosis. Kangaroo rats exhibit bipedal locomotion, which subjects their limbs to substantial accelerative forces in addition to the normal stress of weight bearing. We subjected groups of kangaroo rats and white rats ( Rattus norvegicus ) to one of two confinement treatments or to an exercise regime; animals were exercised at a rate calculated to replicate their (respective) daily exercise patterns. White laboratory rats were used as the comparison because they are currently the accepted model used in the study of disuse osteoporosis. After 6 weeks of treatment, rats were killed and the long bones of their hind limbs were tested mechanically and examined for histomorphometric changes. We found that kangaroo rats held in confinement had less ash content in their hind limbs than exercised kangaroo rats. In general, treated kangaroo rats showed morphometric and mechanical bone deterioration compared to controls and exercised kangaroo rats appeared to have slightly “stronger” bones than confined animals. White rats exhibited no significant differences between treatments. These preliminary results suggest that kangaroo rats may be an effective model in the study of disuse osteoporosis.

Comparative Biochemistry and Physiology, Part A: P↗
USGS2017

Turtles: Freshwater

With their iconic shells, turtles are morphologically distinct in being the only extant or extinct vertebrate animals to have their shoulders and hips inside their rib cages. By the time an asteroid hit the earth 65.5 million years ago, causing the extinction of dinosaurs, turtles were already an ancient lineage that was 70% through their evolutionary history to date. The remarkable evolutionary success of turtles over 220 million years is due to a combination of both conservative and effective life history traits and an essentially unchanging morphology that withstood the test of time. However, the life history traits of many species make them particularly susceptible to overharvest and habitat destruction in the modern world, and a majority of the world’s species face serious conservation challenges with several extinctions documented in modern times. The global plight of turtles is underscored by the fact that the percentage of imperiled species exceeds that of even the critically endangered primates. Freshwater turtles, with over 260 recognized species, have become a focus on a worldwide scale for many conservation issues. This article is a synthesis of a diverse body of information on the general biology of freshwater turtles, with particular emphasis on the extensive research on ecology, life history, and behavior that has been accomplished in the last half century. Much of the research has been applicable to the aforementioned conservation challenges. The studies presented include a combination of laboratory and field experiments and observational studies on this intriguing group of animals.

Book chapter↗
USGS2021

Movement ecology

(Yackulic) At first glance, the decision to study movement in Galapagos tortoises seems curious. Given the slow speed of tortoises and tendency to forage and rest as they move, it seems implausible that tortoises would string their slow bursts of activity together to accomplish large-scale movements. Nonetheless, as early as 1815 (Porter 1815), visitors to Galapagos have noted the propensity for tortoises to walk long distances along well used trails, leading to seasonal changes in the distribution of tortoises on the various islands of the Archipelago. In recent years, advances in the technology used to track animals have led to a better understanding of movement and the diversity of movement strategies among many animal taxa. This chapter focuses on the application of these technologies to study of movement in Galapagos tortoises. Recent work has shown not only the diversity of movement strategies employed by Galapagos tortoises, but also illustrated how movement can both cause and be a consequence of interaction between reproductive and foraging ecologies of tortoises and the presence of strong environmental gradients. Understanding how critical unimpeded movement is to the persistence of Galapagos tortoises also informs efforts to maintain connectivity to, and suitable habitat within, tortoise range outside of protected areas.

Book chapter↗
USGS2024

Hepeviruses of aquatic organisms

Originally reported in California, the cutthroat trout virus (CTV) has now been isolated from nine species of salmonids in North America. Early work focused on the replication and physical characteristics of the virus, but 20 years later was determined to be most closely related to the hepatitis E virus. The small genome is positive-sense, single-stranded RNA similar to other members of the family Hepeviridae , which now contains its own genus Piscihepevirus with two distinct genotypes, CTV-1 and CTV-2. While CTV has not been associated with acute disease in fish, the virus could form persistently infected cell cultures that may aid research in treating hepatitis E-like viruses affecting humans or other animals. Interestingly, trout exposed to CTV were protected for about a month against subsequent exposure to the infectious hematopoietic necrosis virus. Replicating agents suspected to be CTV can be confirmed by polymerase chain reaction (PCR), quantitative PCR, and sequencing. Other unclassified hepeviruses detected in fish using viral metagenomics include Wenling fish hepevirus, Wenling moray eel hepevirus, Murray–Darling carp hepevirus, and eastern mosquitofish hepevirus. The family Hepeviridae has been placed in the order Hepevirales together with the family Matonaviridae (rubella virus), with member viruses having amino acid homology in the helicase and replicase regions of the nonstructural proteins. In addition, using next-generation sequencing, a hepe-like sequence was characterized in diseased giant freshwater prawn Macrobrachium rosenbergii and named Crustacea hepe-like virus 1. Thus the family Hepeviridae continues to expand among aquatic animal hosts.

Book chapter↗
USGS2007

Eutrophication study at the Panjiakou-Daheiting Reservoir system, northern Hebei Province, People's Republic of China: Chlorophyll-a model and sources of phosphorus and nitrogen

Concentrations, loads, and sources of nitrate and total phosphorus were investigated at the Panjiakou and Daheiting Reservoir system in northern Hebei Province, People's Republic of China. The Luan He River is the primary source of water to these reservoirs, and the upstream watershed has a mix of land uses including agriculture, forest, and one large urban center. The reservoirs have a primary use for storage of drinking water and partially supply Tianjin City with its annual needs. Secondary uses include flood control and aqua culture (fish cages). The response of the reservoir system from phosphorus input, with respect to chlorophyll- a production from algae, was fitted to a model of normalized phosphorus loading that regresses the average summer-time chlorophyll- a concentration to the average annual phosphorus concentration of the reservoir. Comparison of the normalized phosphorus loading and chlorophyll- a response of this system to other reservoirs throughout the world indicate a level of eutrophication that will require up to an approximate 5–10-fold decrease in annual phosphorus load to bring the system to a more acceptable level of algal productivity. Isotopes of nitrogen and oxygen in dissolved nitrate were measured from the headwater streams and at various locations along the major rivers that provide the majority of water to these reservoirs. Those isotopic measurements indicate that the sources of nitrate change from natural background in the rivers to animal manure and septic waste upstream of the reservoir. Although the isotopic measurements suggest that animal and septic wastes are a primary source of nutrients, measurements of the molar ratio of nitrogen to phosphorus are more indicative of row-cropping practices. Options for reduction of nutrient loads include changing the management practices of the aqua culture, installation of new sewage treatment systems in the large urbanized area of the upper watershed, and agricultural management practices that would reduce the loading of nutrients and soil erosion from that land use.

Agricultural Water Management↗