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At least 91 records · Page 5Linked to original sources
USGS2020

Spatial ecology of closely-related taxa: The case of the little shearwater complex in the North Atlantic Ocean

Seabirds inhabiting vast water masses provide numerous examples where opposing phenomena, such as natal and breeding philopatry vs. vagility have dug cryptic taxonomic boundaries among closely related taxa. The taxonomy of little shearwaters of the North Atlantic Ocean (Little–Audubon’s shearwater complex, Puffinus assimilis – lherminieri ) still remains unclear, and complementary information on non-breeding distributions and at-sea behaviour becomes essential to unravel divergent local adaptations to specific habitats. Using miniaturized light-level geolocators from seven study areas in the North Atlantic, we evaluate the spatial and habitat segregation, estimate the timing of their key life-cycle events and describe the at-sea behaviour of three taxa of these little shearwaters year-round to distinguish ecological patterns and specializations that could ultimately unravel potential lineage divergences. We also assess morphometric data from birds that were breeding at each study area to further discuss potential adaptations to specific habitats. Our results show that, while birds from different taxa segregated in space and habitats, they share ecological plasticity, similar annual phenology and diel foraging behaviour. These ecological inconsistencies, while defining the evolutionary stressors faced by these taxa, do not suggest the existence of three Evolutionary Significant Units. However, they confirm the recent evolutionary divergence among the three little shearwaters of the North Atlantic.

Zoological Journal of the Linnean Society↗
USGS1993

Population structure, body mass, activity, and orientation of an aquatic snake ( Seminatrix pygaea ) during a drought

The snout – vent length, tail length, weight, sex, activity, and orientation of a population of swamp snakes ( Seminatrix pygaea ) in north – central Florida were recorded from 1985 through 1990. A small temporary pond was monitored for 1343 days, using a drift fence – pitfall trap sampling regime. I captured 123 different snakes, plus 45 recaptures. Juveniles comprised 89% of the snakes at the pond. Females were generally longer and weighed more than males, although regression analysis showed no differences between the sexes in the relationship of length versus wet body mass. Males had longer tails than females. The sex ratio of snakes with a snout – vent length of more than 150 mm was 1:1. Activity occurred throughout the year but peaked during summer. Hydroperiod and weather conditions did not appear to influence snake activity. During the latter years of the study, a regional drought that began in the mid-1980s became quite severe. However, drought had little direct effect on overland migration or body condition but caused snakes to leave or to shorten the amount of time they spent within the pond basin. Snakes immigrated and emigrated nonrandomly; orientation was directed to and from the nearest large water body. Certain temporary ponds may comprise developmental habitat for Seminatrix pygaea . The dynamic wet – dry climatic cycles in southeastern North America may lead to the formation of metapopulations in some aquatic snakes.

Canadian Journal of Zoology↗
USGS2019

Tools to understand seasonality in health: quantification of microbe loads and analyses of compositional ecoimmunological data reveal complex patterns in Mojave Desert Tortoise (Gopherus agassizii) populations

Using data from six wild Mojave Desert Tortoise ( Gopherus agassizii (Cooper, 1861)) populations, we quantified seasonal differences in immune system measurements and microbial load in the respiratory tract, pertinent to this species’ susceptibility to upper respiratory tract disease. We quantified bacteria-killing activity of blood plasma and differential leukocyte counts to detect trends in temporal variation in immune function. We used centered log-ratio (clr) transformations of leukocyte counts and stress that such transformations are necessary for compositional data. We tested animals for the potential pathogen Pasteurella testudinis Snipes and Biberstein, 1982 with a newly created quantitative polymerase chain reaction (qPCR) assay, as well as for the known respiratory pathogens Mycoplasma agassizii Brown et al., 2001 and Mycoplasma testudineum Brown et al., 2004. We found very little disease and suggest that P. testudinis is a prevalent, commensal microbe in these Mojave Desert Tortoise populations, and its quantification may be a tool to study natural fluctuations in microbe levels in Mojave Desert Tortoise respiratory tracts. Our analyses showed that both the potential for inflammatory responses and microbe levels are highest in the spring for healthy Mojave Desert Tortoises, when lymphocyte levels are lowest. The genetic and statistical tools that we used are easily applicable to other wildlife systems and provide the necessary data to quantify species-wide trends in health and test hypotheses pertinent to host–microbe dynamics.

Canadian Journal of Zoology↗
USGS2025

Harmless tags or hazardous ads? Investigating the potential for ear tags to increase predation on neonatal ungulates

Studies involving individually marked animals provide insights predicated on the assumption marked individuals are accurate models of their unmarked counterparts. Taxa-specific and marker-specific examinations are needed to determine if marked animals are suitable models for the parameter(s) being measured. Our objective was to determine if brightly colored ear tags influenced the probability of predation for neonatal ungulates. We captured 94 neonatal pronghorn (Antilocapra americana (Ord, 1815)), fitted each neonate with a tracking collar, and attached a yellow ear tag to 49 (52.1%) of the captured neonates. We monitored the survival of each neonate during 2023–2024 in Oklahoma, USA. Predation was the leading cause of mortality during our monitoring period and accounted for 29 (82.9%) of the 35 mortalities with a known cause. Coyotes (Canis latrans Say, 1823) were the predominant predator of neonatal pronghorn in our study area. Presence of a yellow ear tag seemingly did not influence the probability of predation, even though coyotes can distinguish yellow objects from most natural backgrounds. A larger sample size may be needed to validate our results, but neonatal ungulates with an ear tag appear to be accurate models of neonatal ungulates without an ear tag when examining predation risk.

Oklahoma↗
USGS2003

Breeding ecology of Horned Puffins ( Fratercula corniculata ) in Alaska: annual variation and effects of El Niño

Both within and among seabird species, different aspects of breeding biology may respond to changes in prey availability in distinct ways, and the identification of species-specific breeding parameters that are sensitive to food availability is useful for monitoring purposes. We present data from a 5-year study (1995–1999) of the breeding ecology of Horned Puffins ( Fratercula corniculata ) in Alaska. The El Niño – Southern Oscillation event of 1997–1998 provided an opportunity to examine the sensitivity of various breeding parameters to a reduction in prey availability caused by the anomalous oceanographic conditions of 1998. Horned Puffins were able to maintain high fledging success (83–97%) over the 5 years of the study, despite the poor local feeding conditions in 1998. The rate of increase in chick mass was lowest in 1998, and evidence suggests that chicks also fledged at the youngest ages in that year. The impacts of reduced food availability on growth varied among body structures, suggesting differential allocation of energy and nutrients. There was no variation among years in either chick diet or the mass of food loads delivered by adults. We suggest that rates of chick growth, specifically mass increase, may be a good parameter to measure for use in monitoring Horned Puffins.

Canadian Journal of Zoology↗
USGS2001

Effective population size and genetic structure of a Piute ground squirrel (Spermophilus mollis) population

Piute ground squirrels ( Spermophilus mollis ) are distributed continuously in habitat dominated by native shrubs and perennial grasses in the Snake River Birds of Prey National Conservation Area in Idaho, U.S.A. This habitat is being fragmented and replaced by exotic annual plants, changing it to a wildfire-dominated system that provides poor habitat for ground squirrels. To assess potential effects of this fragmentation on ground squirrel populations, we combined an estimate of effective population size ( N e ) based upon a demographic study with a population genetic analysis. The study area included three subpopulations separated from each other by 8–13 km. The ratio of effective population size to census number ( N e / N ) was 0.57. Combining N e / N with dispersal distances from a radio-tracking study, we calculated that neighborhood size was 62.2 ha, which included between 204 and 480 individuals. Our population genetic analysis (based on randomly amplified polymorphic DNA (RAPD) and microsatellite markers) showed relatively low levels of genetic differentiation (Q populations 0.07–0.10) between subpopulations and no inbreeding within subpopulations ( f = 0.0003). These estimates of population subdivision translate into an effective migration rate ( N e m ) of 2.3–3.3 per year, which represents a high level of gene flow. Invasion by exotics will reduce the overall productivity of the habitat, and will lead to isolation among subpopulations if favorable habitat patches become isolated.

Canadian Journal of Zoology↗
USGS1999

Regurgitative food transfer among wild wolves

Few studies of monogamous canids have addressed regurgitation in the context of extended parental care and alloparental care within family groups. We studied food transfer by regurgitation in a pack of wolves on Ellesmere Island, North West Territories, Canada, during 6 summers from 1988 through 1996. All adult wolves, including yearlings and a post-reproductive female, regurgitated food. Although individuals regurgitated up to five times per bout, the overall ratio of regurgitations per bout was 1.5. Pups were more likely to receive regurgitations (81%) than the breeding female (14%) or auxiliaries (6%). The breeding male regurgitated mostly to the breeding female and pups, and the breeding female regurgitated primarily to pups. The relative effort of the breeding female was correlated with litter size (Kendall's τ = 0.93, P = 0.01).

Canadian Journal of Zoology↗
USGS1998

Relationship between deer mouse population parameters and dieldrin contamination in the Rocky Mountain Arsenal National Wildlife Refuge

A small-mammal capture-recapture study was conducted in the Rocky Mountain Arsenal National Wildlife Refuge to quantify the effects of soil contamination with dieldrin on demographic parameters of deer mouse (Peromyscus maniculatus) populations. Increased dieldrin concentrations were significantly associated with larger deer mouse populations, although the size of populations on contaminated sites decreased during the study. The most parsimonious model for estimating survival rates was one in which survival was a decreasing function of dieldrin concentration. A significantly higher proportion of female deer mice in the populations residing on the more highly contaminated sites exhibited signs of reproductive activity. Development of genetic resistance in P. maniculatus to chronic chemical exposure is suggested as a possible mechanism responsible for the species' observed dominance and relatively high densities on contaminated sites. Under the additional stress of unfavorable environmental conditions, however, these populations may suffer disproportionately greater mortality. The design and analytical methods presented offer a rigorous statistical approach to assessing the effects of environmental contamination on small mammals at the population level.

Canadian Journal of Zoology↗
USGS2009

Using time-dependent models to investigate body condition and growth rate of the giant gartersnake

Identifying links between phenotypic attributes and fitness is a primary goal of reproductive ecology. Differences in within-year patterns of body condition between sexes of gartersnakes in relation to reproduction and growth are not fully understood. We conducted an 11-year field study of body condition and growth rate of the giant gartersnake Thamnophis gigas across 13 study areas in the Central Valley of California, USA. We developed a priori mixed effects models of body condition index (BCI), which included covariates of time, sex and snout-vent length and reported the best-approximating models using an information theoretic approach. Also, we developed models of growth rate index (GRI) using covariates of sex and periods based on reproductive behavior. The largest difference in BCI between sexes, as predicted by a non-linear (cubic) time model, occurred during the mating period when female body condition (0.014??0.001 se) was substantially greater than males (-0.027??0.002 se). Males likely allocated energy to search for mates, while females likely stored energy for embryonic development. We also provided evidence that males use more body energy reserves than females during hibernation, perhaps because of different body temperatures between sexes. We found GRI of male snakes was substantially lower during the mating period than during a non-mating period, which indicated that a trade-off existed between searching for mates and growth. These findings contribute to our understanding of snake ecology in a Mediterranean climate. ?? 2009 The Zoological Society of London.

Journal of Zoology↗
USGS1989

Avian community response to small-scale habitat disturbance in Maine

The effects of small clearcuts (1 - 8 ha) on avian communities in the forest of eastern Maine were studied using point counts during spring 1978 - 1981. Surveys were conducted in uncut (control) and clear-cut (treatment) plots in three stand types: conifer, hardwood, and mixed growth. We used a mark-recapture model and its associated jackknife species richness estimator (N), as an indicator of avian community structure. Increases in estimated richness (N) and Shannon - Weaver diversity (H') were noted in the treated hardwood and mixed growth, but not in the conifer stands. Seventeen avian species increased in relative abundance, whereas two species declined. Stand treatment was associated with important changes in bird species composition. Increased habitat patchiness and the creation of forest edge are hypothesized as causes for the greater estimates of richness and diversity.

Maine↗
USGS1994

New records of Ergasilus (Copepoda: Ergasilidae) in the Laurentian Great Lakes, including a lakewide review of records and host associations

Ergasilus nerkae was found infecting ninespine stickleback (Pungitius pungitius) in lakes Huron, Michigan, and Superior and threespine stickleback (Gasterosteus aculeatus) and round whitefish (Prosopium cylindraceum) in Lake Huron. Based upon the literature and study of archived material, we propose that E. nerkae is enzootic to the Great Lakes and that ninespine stickleback are a preferred host in Lake Huron. Prevalence of E. nerkae on ninespine stickleback increased from 17% in June to 68% in September, but mean intensity remained light. Prevalence and mean intensity increased with host length. Ergasilus luciopercarum is also reported on lake trout (Salvelinus namaycush) and largemouth bass (Micropterus salmoides) for the first time. Host-parasite records of Ergasilus spp. in North America are reviewed, biology and taxonomy are summarized, and a checklist of Great Lakes host-parasite-locality records is provided. At present, eight species of Ergasilus are known to infect 42 Great Lakes fish species.

Canadian Journal of Zoology↗
USGS2015

Hypoxia tolerance of introduced Nile perch: Implications for survival of indigenous fishes in the Lake Victoria basin

The introduction of predatory Nile perch ( Lates niloticus ) into the Lake Victoria basin coincided with a dramatic decline in fish diversity. However, remnant populations of indigenous fishes persist in lagoons and satellite lakes separated from the main lakes by extensive areas of swamp, while other indigenous species find refuge in ecotonal areas at edges of marginal swamps in the main lakes. Low-oxygen conditions in these wetlands may physiologically stress Nile perch and therefore minimize its interaction with prey species. This study examined the low-oxygen tolerance of Nile perch collected from Lake Nabugabo, Uganda, by documenting behavioural and physiological strategies that relate to oxygen uptake. In response to hypoxia, Nile perch used aquatic surface respiration (ASR) at the air–water interface, ventilating their gills with water from the surface. However, several lines of evidence suggest that Nile perch in Lake Nabugabo are inefficient at ASR and relatively intolerant of low oxygen conditions. These include high thresholds for ASR relative to other indigenous fishes of the Lake Victoria basin, no decrease in gill ventilation rate with the onset of ASR, a faster time to loss of equilibrium in hypoxic conditions than other species from the region, and a high critical oxygen tension (24 mm Hg).

Lake Victoria, Lake Victoria Basin↗
USGS1991

Trends in North American small mammals found in common barn-owl (Tyto alba) dietary studies

Data on mammals were compiled from published studies of common barn-owl (Tyto alba) pellets. Mammalian composition of pellet samples was analyzed within geographic regions in regard to year, mean annual precipitation, latitude, and number of individual mammals in the sample. Percentages of individuals in pellets that were shrews increased whereas the percentages of rodents decreased with greater mean annual precipitation, especially in northern and western areas of North America. From the 1920s through 1980s, in northern and eastern areas the percentage of species that was shrews decreased, and in northern and central areas the percentage of individuals that was murid rats and mice increased. Human alterations of habitats during these seven decades are postulated to have caused changes in available small mammals, leading to changes in the barn-owl diet.

Canadian Journal of Zoology↗
USGS2002

α1-Antitrypsin polymorphism and systematics of eastern North American wolves

We used data on the polymorphic status of α 1 -antitrypsin (α 1 AT) to study the relationship of Minnesota wolves to the gray wolf ( Canis lupus ), which was thought to have evolved in Eurasia, and to red wolves ( Canis rufus ) and coyotes ( Canis latrans ), which putatively evolved in North America. Recent evidence had indicated that Minnesota wolves might be more closely related to red wolves and coyotes. Samples from wild-caught Minnesota wolves and from captive wolves, at least some of which originated in Alaska and western Canada, were similarly polymorphic for α 1 AT, whereas coyote and red wolf samples were all monomorphic. Our findings, in conjunction with earlier results, are consistent with the Minnesota wolf being a gray wolf of Eurasian origin or possibly a hybrid between the gray wolf of Eurasian origin and the proposed North American wolf.

Canadian Journal of Zoology↗
USGS2001

Myrmecophagy by Yellowstone grizzly bears

I used data collected during a study of radio-marked grizzly bears ( Ursus arctos horribilis ) in the Yellowstone region from 1977 to 1992 to investigate myrmecophagy by this population. Although generally not an important source of energy for the bears (averaging <5% of fecal volume at peak consumption), ants may have been an important source of protein during midsummer and were heavily consumed during some years. Myrmecophagy was most common annually when known high-quality foods were scarce, as well as during the warmest months of the study, when regional average temperatures exceeded 12–15°C. Bears tended to select large ants (>8 mm long) nested in logs over small ants ( 6 mm long) nested under stones. Optimal conditions for consumption of ants occurred on the warmest sites with ample substrate suitable for ant nests. For ants in mounds, this occurred at low elevations at non-forested sites. For ants in logs, this occurred at low elevations or on southerly aspects where there was abundant, large-diameter, well-decomposed woody debris under an open forest canopy. Grizzly bears selected moderately decomposed logs 4–5 dm in diameter at midpoint. Ants will likely become a more important food for Yellowstone's grizzly bears as currently important foods decline, owing to disease and warming of the regional climate.

Wyoming↗
USGS2019

Rapid adoption of nestboxes by Prothonotary Warblers (Protonotaria citrea) in mesic deciduous forest

Breeding territory selection in Prothonotary Warblers ( Protonotaria citrea (Boddaert, 1783)) is thought to hinge on standing water, with a strong preference for low-lying areas prone to seasonal flooding. However, we have observed this species nesting in much drier areas than previously reported. We recently initiated a study of the Carolina Wren ( Thryothorus ludovicianus (Latham, 1790)) using wooden nest boxes, and nearly 60% of all nests produced in these boxes during the initial study year were produced by Prothonotary Warblers, despite this species being absent from our field site during the year preceding nest-box availability. Most nests were produced in dense, closed-canopy forest with a thick shrub layer >100 m from any water body. There was no difference in the mean distance from water between nests of the Prothonotary Warbler and those of the Carolina Wren, a habitat generalist that does not nest over water. We then observed a 60% increase in the number of Prothonotary Warbler nests the following year, along with significant increases in breeding productivity. Although they nested on sites that they are not thought to prefer, our observations suggest that Prothonotary Warblers may nest in drier areas than usual if appropriate nest cavities are provided.

Canadian Journal of Zoology↗
USGS1991

Mitochondrial and nuclear genetic relationships of deer ( Odocoileus spp.) in western North America

Odocoileus hemionus (mule deer and black-tailed deer) and Odocoileus virginanus (white-tailed deer) are sympatric in western North America and are characterized by distinct morphology, behavior, and allozyme allele frequencies. However, there is discordance among nuclear and mitochondrial genetic relationships, as mule deer ( O . h . hemionus ) and white-tailed deer have similar mitochondrial DNA (mtDNA) which is very different from that of black-tailed deer ( O . h . columbianus , O . h . sitkensis ). I expanded previous studies to clarify the genetic relationships of these groups by determining mtDNA haplotype and allozyme genotypes for 667 deer from several locations in northwestern North America. Different mtDNA haplotypes in mule deer, black-tailed deer, and white-tailed deer indicate that mitochondrial gene flow is restricted. Allozyme allele frequencies indicate that there is also restriction of nuclear gene flow between O . virginianus and O . hemionus , and to a lesser extent between mule deer and black-tailed deer. There is a low level of introgressive hybridization of mtDNA from mule deer and black-tailed deer into white-tailed deer populations and considerable interbreeding of mule deer and black-tailed deer in a contact zone. The discordance of mitochondrial and nuclear genomes is apparent only if mtDNA sequence divergences, and not haplotype frequencies, are considered.

Canadian Journal of Zoology↗
USGS1995

Survival rates of radio-collared female polar bears and their dependent young

Polar bears are hunted throughout most of their range. In addition to hunting, polar bears of the Beaufort Sea region are exposed to mineral and hydrocarbon extraction and related human activities such as shipping, road building, and seismic testing. As human populations increase and demands for polar bears and other arctic resources escalate, reliable estimates of survivorship of polar bears are needed to predict and manage the impacts of those activities. We used the Kaplan-Meier model to estimate annual survival (with 95% confidence intervals) for radio-collared female polar bears and their dependent young that were followed during a 12-year study in the Alaskan Beaufort Sea. Survival of adult female polar bears was higher than had been previously thought: S = 0.969 (range 0.952-0.983). If human-caused mortalities were deleted, the computed survival rate was 0.996 (0.990-1.002). Survival of young from den exit to weaning was 0.676 (0.634-0.701). Survival during the second year of life, 0.860 (0.751-0.903), was substantially higher than during the first year, 0.651 (0.610-0.675). Shooting by local hunters accounted for 85% of the documented deaths of adult female polar bears. Conversely, 90% of documented losses of young were independent of litter size (P = 0.36), indicating that parental investment in single cubs was not different from investment in litters of two or more. Precise estimates of the survival of independent juveniles and adult males still need to be developed.

Canadian Journal of Zoology↗