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At least 325 records · Page 18Linked to original sources

USGS1991

Reproductive vulnerability: Parental attendance around hatching in roseate (Sterna dougallii) and common (S. hirundo) terns

Presence of one or both members of a pair at the nest site during the incubation and early chick stage reduces reproductive losses due to predation and weather stresses. The authors monitored the presence of pair members by the temporary removal of one member of several pairs of Roseate (Sterna dougallii ) and Common (Sterna hirundo ) Terns at nests at Cedar Beach, New York, to determine if vulnerability varies by reproductive stage, to compare species differences that might partially account for declines in Roseate Tern populations, and to examine their response to trapping. There were significant differences between species in the time to return to the nest following an initial disturbance, and Roseate Terns that were trapped and released took longer to return to the nest and resume incubating than did Common Terns. The nests of Roseate Terns were vulnerable (neither adult in attendance) for longer time than were the nests of Common Terns.

Condor↗

USGS1992

Reproductive ecology of Emperor Geese: Survival of adult females

Life history theory predicts a decrease in survival with increased reproductive effort of individuals. This relationship, however, is highly variable among and within species. I studied the nesting success and survival of adult female Emperor Geese during 1982-1986 and found no direct evidence that differential reproductive effort as measured by the number of eggs laid or hatching success had a significant negative effect on survival to the next breeding season. Incubated clutch size, hatched clutch size, number of parasitic eggs, nest initiation date, hatch date, and mass at hatch were not related to subsequent survival. Of the factors I examined, only an attempt to nest the previous season was related to survival of a female. I suggest that the higher probability of survival among non-nesting adult female Emperor Geese was primarily related to hunting pressure on the nesting area between spring and fall migration. The probability of survival was increased for females with larger clutches, suggesting a positive relationship between brood size and survival.

Alaska↗

USGS1988

Reproductive effects of nest-marking studies in an American white pelican colony

In 1981 and 1982 we studied the reproductive success of American White Pelicans in the Klamath Basin of northern California. We observed that reproductive success at one colony became reduced in 1981 when we entered that colony to collect eggs for chemical analysis and to mark nests for an assessment of nesting success. Those pelicans produced only 0.5 Y/N contrasted to pelicans nesting at an undisturbed colony that produced about 1.2 Y/N. No colonies were entered in 1982 and both produced about 1.1 Y/N. We concluded that our activities reduced the success of that one disturbed colony. We suggest that the sample-egg technique should not be used in American White Pelican colonies, in-colony activities should be very limited, and researchers in bird colonies should attempt more often to assess the effects of their own activiites

Colonial Waterbirds↗

USGS1997

Reproduction of black-crowned night-herons related to predation and contaminants in Oregon and Washington, USA

We studied reproductive characteristics of Black-crowned Night-Herons ( Nycticorax nycticorax ) at four colonies in south central Washington and one colony in north central Oregon in 1991. Nest success, adjusted using the Mayfield method, was significantly different between colonies and ranged from 12-84% to hatching and 12-73% to 14 days post-hatching. The mean number of young surviving to 14 days of age in each colony ranged from 0.47-1.94 per nesting female (includes recycling efforts that involve laying more than one clutch). They were marked intercolony differences in clutch size and incidence of recycling. Predation (primarily avian) was a major factor that adversely affected nest success in three colonies and was relatively unimportant in two colonies. Residues of DDE, total polychlorinated biphenyls, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and other compounds in eggs were generally low and apparently had little influence on reproductive success at any of the colonies. Mean eggshell thinning ranged from 7-1 1 % in comparison to a pre-1947 norm for eggs measured in museum collections. Cytochrome P450 enzyme (EROD, PROD, and BROD) induction in livers of pipped embryos by colony ranged from low to average in comparison with other colonies throughout the U.S. Average EROD and BROD activities were highest at Sand Dune Island and were lowest at Potholes Reservoir which was designated the reference colony. In relation to our study of three of the five colonies in the early 1980s, residues of DDE and several related compounds appeared to decline, nest predation rates increased, and nest success decreased at all three colonies.

Oregon, Washington↗

USGS1989

Growth and fat-body cycles in feral populations of the African clawed frog, Xenopus laevis (Pipidae), in California with comments on reproduction

Feral populations of the African clawed frog ( Xenopus laevis ) exist in several areas of southern California. By following the first cohort of progeny produced by African clawed frogs at a recently colonized site, data on the growth rates and age at first maturity were obtained in field conditions. Females reached maturity at an earlier age than males, grew faster than males, and attained body lengths up to 25% larger than males. Larger females were capable of producing larger numbers of eggs than small females and, therefore, had greater reproductive potential. The relatively stable ambient temperatures of southern California contributed to the possibility of reproduction of clawed frogs during all but the coolest periods of the year. Cycles detected in the mass of fatbodies suggested that nutrients were mobilized from fat prior to and during ovulation. The amount of fat in females varies widely, but fat in males tended to accumulate as the males grew during the study period.

California↗

USGS1985

Snowpack and variation in reproductive ecology of a montane ground-nesting passerine, Junco hyemalis

Effects of snow depth and rate of snowmelt on reproduction of a montane ground-nesting passerine were examined in a 5-year study of Dark-eyed Juncos Junco hyemalis in northern Utah, USA. Distribution of clucth sizes differed significantly among years. Although most clutches contained four eggs, 3-egg clutches, due primarily to second nestings, were more common during a year of early snowmelt and 5-egg clutches were most common during two years of late snowmelt. Average clutch size was lowest in an early snowmelt year and average clutch size and date at which meadows became snow-free were significantly positively correlated. Average hatching date of 4-egg clutches was also significantly positively correlated with date at which meadows became snow-free demonstrating that most birds tracked the pattern of snowmelt. Early snowmelt may allow more pairs to attempt second nesting, but late-lying snow causes breeding to be delayed, allowing time for only one nesting attempt. During this delay, female juncos continue to feed and some may gain enough reserves to produce larger clutches, accounting for the increase in average clutch size in years of late snowmelt. Three female juncos examined in June 1982, a period of late snowmelt, had significantly more lipid reserves than did six males collected at the same time, suggesting that females are not physiologically stressed while awaiting snowmelt. By tracking snowmelt patterns, juncos synchronize production of young with peak summer insect abundance and potentially decrease risk of predation. Snow depth and rate of snowmelt are thus proximate environmental factors that may influence the reproductive ecology of ground-nesting passerines.

Utah↗

USGS1975

Some nutritional aspects of reproduction in prairie nesting pintails

The nutritional significance of invertebrate foods in the diet of breeding hen waterfowl during the period of egg formation is discussed. Proximate, elemental, and amino acid analyses of the principal foods consumed by hen pintails ( Anas acut ) during the nesting season indicate the animal foods selected are rich sources of protein and calcium, whereas plant foods tested were low in protein, particularly in the essential amino acids lysine and methionine. Calcium content in major plant foods was far below needs considered adequate for egg production. Studies with penned, hand-reared pintails indicated the inadequacy of wheat as the dietary staple during breeding. Egg production among pairs on the control diet differed significantly from that of the wheat plus oystershell (P < 0.05) and wheat (P < 0.01) diets. Pairs fed wheat during the breeding period experienced nearly complete reproductive failure. The poor reproductive response among hens on the diet of wheat plus oystershell suggested that calcium availability was not the only factor limiting productivity.

Journal of Wildlife Management↗

USGS2000

Effect of hibernation and reproductive status on body mass and condition of coastal brown bears

We investigated the effect of hibernation and reproductive status on changes in body mass and composition of adult female brown bears (Ursus arctos) on the Kenai Peninsula, Alaska. This information is fundamental to understanding nutritional ecology of wild brown bear populations. Six adult females handled in the fall and following spring (paired samples) lost 73 ± 22 kg (x̄ ± SD; 32 ± 10%) of fall body mass over 208 ± 19 days. Of this mass loss, 56 ± 22% (55 ± 22 kg) was lipid and 44 ± 22% (43 ± 21 kg) was lean body mass. Catabolism of lipid stores accounted for 88.4 ± 8.1% of the body energy used to meet maintenance demands. Overwinter differences in body composition of adult females assessed only once in either the fall (n = 21) or spring (n = 32) were similar to those of paired samples. Relative fatness of bears entering the den was positively related to the contribution of fat (%) to body mass (P < 0.01) and body energy (P < 0.01) losses during hibernation. Thus, relative fatness at the onset of fasting influences the relative proportion of lipid stores and lean body mass catabolized to meet protein and energy demands during hibernation. In the spring, lone females had greater body and lean masses than females with cubs of the year or yearlings. Lipid content was greatest in lone females in the fall. Studies using body mass and composition as indices of population health should consider season or reproductive class.

Journal of Wildlife Management↗

USGS2021

Efficacy of manipulating reproduction of common ravens to conserve sensitive prey species: Three case studies

Expansion of human enterprise across western North America has resulted in an increase in availability of anthropogenic resource subsidies for generalist species. This has led to increases in generalists’ population numbers across landscapes that were previously less suitable for their current demographic rates. Of particular concern are growing populations of common ravens ( Corvus corax ; ravens), because predation by ravens is linked to population declines of sensitive species. Ecosystem managers seek management options for mitigating the adverse effects of raven predation where unsustainable predator–prey conflicts exist. We present 3 case studies examining how manipulating reproductive success of ravens influences demographic rates of 2 sensitive prey species. Two case studies examine impacts of removing raven nests or oiling raven eggs on nest survival of greater sage-grouse ( Centrocercus urophasianus ; sage-grouse) within Wyoming and the Great Basin of California and Nevada, USA, respectively. The third case study uses Mojave desert tortoise ( Gopherus agassizii ; tortoise) decoys to examine effects of oiling raven eggs on depredation rates of juvenile tortoises in the Mojave Desert in California. Initial trial years from all 3 case studies were consistent in finding improved vital rates associated with the application of strategies for reducing reproductive success of ravens. Specifically, removal of raven nests resulted in increased nest survival of sage-grouse within treatment areas where predation by ravens was the primary cause of nest failure. In addition, nest survival of sage-grouse and survival of juvenile tortoise decoys was higher following a treatment of oiling the eggs of ravens in their nests at 2 sites within the Great Basin and 4 tortoise conservation areas in the Mojave Desert in California. Along with specialized technologies that can make techniques such as egg-oiling more feasible, these findings support these management practices as important tools for managing ravens, especially in areas where breeding ravens have negative impacts on sensitive prey species.

California, Nevada, Wyoming↗

USGS2019

The effects of seasonal temperature and photoperiod manipulation on reproduction in the eastern elliptio Elliptio complanata

The eastern elliptio Elliptio complanata is a species of freshwater mussel common to streams and rivers of the Atlantic Coast. Egg fertilization, larval brooding, and glochidial release are reported to occur within a period of several weeks during early to midsummer. In this study, mussels were exposed to manipulated photoperiod and water temperatures to prolong the availability of glochidia for use in artificial propagation and research. Brooding mussels were collected from Pine Creek, Tioga County, PA, in late December and were housed in groups subjected to one of four environmental treatments: natural temperature and photoperiod, 6-wk delay in natural conditions, 12-wk delay in natural conditions, and natural temperature and photoperiod with a winter low of 10°C. Reproductive activity was monitored for 1 y. Mussels subjected to natural conditions released mature glochidia between 16°C and 19°C with a photoperiod of 15 h of light. Temperature and photoperiod delays of 6 and 12 wk delayed reproduction proportional to the treatment, and constant 10°C winter low temperatures slightly shifted the timing of glochidial release. Survival during the study was high (96%–100%). Data indicate that the seasonal availability of E. complanata glochidia can be extended 3-fold using photoperiod and temperature manipulation.

Journal of Shellfish Research↗

USGS2007

Reproductive biology of the brown tree snake, Boiga irregularis (Reptilia: Colubridae), during colonization of Guam and comparison with that in their native range

Since their introduction to Guam shortly after World War II, brown tree snakes, Boiga irregularis (Merrem), have seriously impacted the biota and human population of the island. Understanding the biology of this exotic species will likely be important to the success of control programs. We compared the reproductive biology of 782 B. irregularis caught on Guam during the 1980s with results from published studies of native-range populations. Average and maximum sizes of mature snakes on Guam were larger than those from Australian populations. The majority of female brown tree snakes matured at snoutvent lengths (SVLs) of 910-1,025 mm, and most males matured at SVLs of 940-1,030 mm. on Guam. Based on growth rates from the early 1990s on Guam, sexual maturity is estimated to occur during a snake's third or fourth year. Only one female (0.3%) in our data set had oviductal eggs. Clutch size was estimated at 4.3 (SD = 2.2), based on large vitellogenic ovarian follicle (???30 mm in length) and oviductal egg counts. Unlike their Australian counterparts, the Guam population reproduced year-round. Our data offer insights into the likely reproductive patterns of brown tree snakes should they infest other islands in the Pacific region. ?? 2007 by University of Hawai'i Press. All rights reserved.

Pacific Science↗

USGS1971

Aerial photographic reproductions

Geological Survey vertical aerial photography is obtained primarily for topographic and geologic mapping. Reproductions from this photography are usually satisfactory for general use. Because reproductions are not stocked, but are custom processed for each order, they cannot be returned for credit or refund .

Report↗

USGS2007

Organic Chemical Concentrations and Reproductive Biomarkers in Common Carp (Cyprinus carpio) Collected from Two Areas in Lake Mead, Nevada, May 1999-May 2000

The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, National Park Service, Bureau of Reclamation, and Nevada Department of Wildlife, collected and assessed data to determine the general health and reproductive status of common carp (Cyprinus carpio) at two study areas in Lake Mead, Nevada, during May 1999-May 2000. These data will form the basis of interpretations and provide a comparison for continuing studies on the health of the ecosystem in Lake Mead. One study area, Las Vegas Bay, is in the western part of Lake Mead. Las Vegas Bay receives inflows from Las Vegas Wash, which is predominantly tertiary-treated wastewater effluent, and to a lesser extent stormwater runoff from Las Vegas, Henderson, and other nearby communities, and from ground water underlying Las Vegas Valley. The other study area, Overton Arm, is in the northern extent of Lake Mead. Overton Arm receives inflow from the Virgin and Muddy Rivers, which historically are not influenced by wastewater effluent. Both sexes of common carp were collected bimonthly for 12 months using boat-mounted electrofishing gear (a direct electric current is used to temporarily immobilize fish for capture) to determine their health and reproductive status and any relation between these factors and environmental contaminants. This report presents fish tissue chemistry, organic chemical compound concentrations, and biomarker data for 83 male common carp collected from Las Vegas Bay, similar organic chemistry results for 15 male common carp, and similar biomarker measures for 80 male common carp collected from Overton Arm. Tissue chemistry results also are presented for 16 female common carp and biomarker measures for 79 female common carp collected from Las Vegas Bay, and tissue chemistry results for 15 female common carp and biomarker measures for 81 female common carp collected from Overton Arm. Thirty-three organic chemical compounds plus total concentrations for four groups of compounds (chlordanes, polychlorinated biphenyls [PCBs], brominated diphenyl ethers [BDEs], and triclosans) were analyzed from extracts of whole-body tissue using gas chromatography/mass spectrometry in male common carp from Las Vegas Bay during May 1999 through May 2000. All 33 compounds were detected in at least one sample of whole-body tissue from male common carp collected in Las Vegas Bay. In Overton Arm, 37 organic compounds plus total concentrations of three groups of compounds (PCBs, BDEs, and triclosans) were analyzed in male common carp where 20 (54 percent) of the compounds were detected. Sixteen of the 33 compounds detected in male common carp from Las Vegas Bay and 10 compounds detected in males from Overton Arm have the potential to disrupt the endocrine system in fish in Lake Mead. During May and June 1999, the mean concentration of all organic compounds detected in male common carp was 670 micrograms per kilogram from Las Vegas Bay and 109 micrograms per kilogram from Overton Arm. Twenty-seven organic compounds plus total PCBs were analyzed from extracts of whole-body tissue in female common carp collected in Las Vegas Bay and Overton Arm during May 1999. Twenty-four (86 percent) of these compounds were detected in at least one sample of whole-body tissue from female common carp collected from Las Vegas Bay while 10 (36 percent) chemical compounds were detected in female common carp from Overton Arm during that same period. Median concentrations of all chemical compounds were higher in female common carp from Las Vegas Bay compared to those collected from Overton Arm except Dacthal (DCPA), which was similar between sites. Biomarker measures obtained for male and female common carp include gonadosomatic index (percentage of gonad weight to total body weight), plasma vitellogenin (a phospholipid protein normally produced by female common carp and other oviparous fish), and condition factor [body weight/(fork length)3]. Biomarker measures for male c

Data Series↗

USGS2014

Atrazine reduces reproduction in fathead minnow ( Pimephales promelas ): raw data report

The herbicide, atrazine, routinely is observed in surface and groundwaters, particularly in the “corn belt” region, a high-use area of the United States. Atrazine has demonstrated effects on reproduction in mammals and amphibians, but the characterization of endocrine-related effects in fish has received only limited attention. Peak concentrations of atrazine in surface water of streams from these agricultural areas coincide with annual spawning events of native fishes. Consequently, there was an unacceptable level of uncertainty in our understanding of the risks associated with the periods of greatest atrazine exposure and greatest vulnerability of certain species of fishes. For this reason, a study of the effects of atrazine on fathead minnow reproduction was undertaken (Tillitt and others, 2010). This report provides the raw data from that study.

Data Series↗

USGS2007

Ovule-bearing reproductive organs of the glossopterid seed ferns from the Late Permian of the Beardmore Glacier region, Antarctica

The Glossopteridales are an extinct group of seed ferns that dominated Gondwana during the Permian. The strap-shaped leaves of Glossopteris are widespread and provided early evidence of continental drift, but reproductive organs of this group have remained enigmatic since they were first described in the 1950s. Based on compression- impression fossils, there are at least two basic types of ovulate (seed-bearing) organs. In one form, numerous ovules are borne on the surface of a leaf-like megasporophyll (e.g., Plumsteadia, Dictyopteridium), while the second type consists of stalked, apparently uniovulate cupules borne on a branching system (e.g., Lidgettonia). More than 30 genera of seed- bearing organs have been described, many based on compressions or, more commonly, impression fossils, in which it is often impossible to discern the three-dimensional morphology or attachment of these structures. Both morphological types have now been found in permineralized peat from Skaar Ridge, central Transantarctic Mountains (CTM), and provide some of the first anatomical detail of the diversity of reproductive organs of Glossopteris. The multiovulate organ is small (6 mm wide), with ovules borne on the upper (adaxial) surface; the uniovulate structure consists of four stalked cupules, each containing a single ovule about 2 mm long. These two forms provide important information about the diversity of the glossopterids and their status as a natural group of seed plants.

Open-File Report↗

USGS2011

Biological dimensions of tern management-a case study of the least tern in Sonora, Mexico, and a comparative analysis of reproductive investment in terns

Least terns (Sternula antillarum) are threatened by rapid human development on the northern coast of Sonora, Mexico. Terns are bellwethers for changes along the world's coastlines, as their coastal breeding habitat is vulnerable to flooding and development. We conducted targeted ground and aerial surveys for least tern colonies along 160 kilometers of coast, and document our findings on colony sizes at nine sites over 3 years in the first portion of this report. Like many taxa, terns lay larger clutches at higher latitudes. In the second portion of this report, we evaluate least tern breeding lifespan, food availability, and nest predation as potential ecological reasons behind this differing clutch-size pattern. After correcting for phylogenetic relationships, we found that food availability, not breeding lifespan or nest predation rate, was related to reproductive investment across 46 species and populations of terns. We conclude that coastal development may have a greater impact on nesting terns in tropical regions as compared to temperate breeding locations, because global oceanic patterns of decreased food availability reduce reproductive investment in the tropics.

Open-File Report↗

USGS2010

Ecological requirements for pallid sturgeon reproduction and recruitment in the Lower Missouri River: Annual report 2009

The Comprehensive Sturgeon Research Project is a multiyear, multiagency collaborative research framework developed to provide information to support pallid sturgeon recovery and Missouri River management decisions. The general Comprehensive Sturgeon Research Project strategy is to integrate field and laboratory studies of sturgeon reproductive ecology, habitat requirements, and physiology to produce a predictive understanding of sturgeon population dynamics. The project scope of work is developed annually with cooperating research partners and in collaboration with the U.S. Army Corps of Engineers, Missouri River Recovery-Integrated Science Program. The research consists of several interdependent and complementary research tasks engaging multiple disciplines that primarily address spawning as a probable limiting factor in reproduction and survival of the pallid sturgeon. The research is multifaceted and is designed to provide information needed for management decisions impacting habitat restoration, flow modification, and pallid sturgeon population augmentation on the Missouri River, and throughout the range of the species. Research activities and progress towards understanding of the species are reported to the U.S. Army Corps of Engineers annually. This annual report details the research effort and progress made by Comprehensive Sturgeon Research Project during 2009.

Open-File Report↗

USGS2014

Ecological requirements for pallid sturgeon reproduction and recruitment in the Missouri River: annual report 2011

The Comprehensive Sturgeon Research Project is a multiyear, multiagency collaborative research framework developed to provide information to support pallid sturgeon recovery and Missouri River management decisions. The project strategy integrates field and laboratory studies of sturgeon reproductive ecology, early life history, habitat requirements, and physiology. The project scope of work is developed annually with cooperating research partners and in collaboration with the U.S. Army Corps of Engineers, Missouri River Recovery—Integrated Science Program. The research consists of several interdependent and complementary tasks that engage multiple disciplines. The research tasks in the 2011 scope of work emphasized understanding of reproductive migrations and spawning of adult sturgeon, and hatch and drift of larvae. These tasks were addressed in three hydrologically and geomorphologically distinct parts of the Missouri River Basin: the Lower Missouri River downstream from Gavins Point Dam, the Upper Missouri River downstream from Fort Peck Dam and including downstream reaches of the Milk River, and the Lower Yellowstone River. The research is designed to inform management decisions related to channel re-engineering, flow modification, and pallid sturgeon population augmentation on the Missouri River, and throughout the range of the species. Research and progress made through this project are reported to the U.S. Army Corps of Engineers annually. This annual report details the research effort and progress made by the Comprehensive Sturgeon Research Project during 2011.

Missouri River↗