USGS Science⌕ Search

SEARCH · USGS Science

Results for “Reproduction”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 451 records · Page 25Linked to original sources
USGS2019

Reproductive biology of Grey-breasted Wood-Wren (Henicorhina leucophrys): A comparative study of tropical and temperate wrens

We provide a detailed breeding biology account for the Grey-breasted Wood-Wren ( Henicorhina leucophrys ) and a comparison of the reproductive life history of tropical and temperate wrens using literature data. We conducted this study at Yacambú National Park in Venezuela from 2002 to 2008. Clutch size was 1.99 (SE 0.01) and fresh egg mass was 2.35 g (0.02). Females incubated the eggs for 19.74 d (0.37), and nestlings left nests at 17.37 d (0.18). Nest attentiveness (percent time spent on the nest) increased across the incubation period while brooding attentiveness decreased as nestlings aged. Brooding effort began with similar attentiveness as at the end of incubation. Food provisioning rate and feeding rate per nestling increased as nestlings aged. Growth rates ( K ) based on mass, tarsus, and wing chord were relatively slow at 0.375, 0.246, and 0.257, respectively. The nesting season extended from mid-March to late June for 7 years and the average nesting season length was 64.5 d (3.68) with a median of May 4. Nest success was 22%. Nest predation was the cause of 77% of nest failures with a total daily predation rate of 0.030 (0.002). Results obtained from the literature demonstrated that tropical wrens averaged smaller clutch sizes and longer incubation periods than relatives in the temperate region.

Yacambú National Park↗
USGS2005

Effects of contaminant exposure on reproductive success of ospreys (Pandion haliaetus) nesting in Delaware River and Bay, USA

Despite serious water-quality problems and pollutant loading and retention, Delaware River and Bay(USA) provide important wildlife habitat. In 2002, we conducted a comprehensive evaluation of contaminant exposure and reproduction of ospreys ( Pandion haliaetus ) breeding in Delaware River and Bay. Sample eggs were collected from 39 nests and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury; a subset of 15 eggs was analyzed for perfluorinated compounds and polybrominated diphenyl ethers (PBDEs). The fate of each nest was monitored weekly. Concentrations of 10 organochlorine pesticides or metabolites, total PCBs, and several toxic PCB congeners were greater ( p < 0.05) in eggs collected between the Chesapeake and Delaware Canal (C and D Canal) and Trenton (Delaware River and northern Bay) compared to other sites. Concentrations of p,p ′-dichlorodiphenyldichloroethylene ( p,p ′-DDE; 0.785–3.84 μg/g wet wt) and total PCBs (5.50–14.5 μg/g wet wt) in eggs collected between the C and D Canal and Trenton were similar to levels recently found in the Chesapeake Bay. In all study segments, at least one young fledged from 66 to 75% of nests. Productivity for Delaware Inland Bays (reference area) and southern Delaware Bay was 1.17 and 1.42 fledglings/active nest, respectively; north of the C and D Canal, productivity was 1.00 fledgling/active nest, which is marginally adequate to maintain the population. Using these data, a logistic regression model found that contaminant concentrations ( p,p ′-DDE, heptachlor epoxide, chlordane and metabolites, and total PCBs) were predictive of hatching success. Several perfluorinated compounds and PBDEs were detected in eggs at concentrations approaching 1 μg/g wet weight. These findings provide evidence that contaminants continue to be a significant stressor on osprey productivity in the northern Delaware River and Bay.

Delaware, New Jersey, Pennsylvania,↗
USGS2007

Effects of methylmercury on reproduction in American kestrels

Sixty breeding pairs of captive American kestrels ( Falco sparverius ) were exposed to a range of sublethal dietary concentrations of mercury (Hg), in the form of methylmercuric chloride, and their subsequent reproduction was measured. Egg production, incubation performance, and the number and percent of eggs hatched decreased markedly between 3.3 and 4.6 mg/kg dry weight of Hg (1.2 and 1.7 mg/kg wet wt), in the diet. The number of fledglings and the percent of nestlings fledged were reduced markedly at 0.7 mg/kg dry weight (0.3 mg/kg wet wt) and declined further between 2 and 3.3 mg/kg dry weight (0.7 and 1.2 mg/kg wet wt). Dietary concentrations of ⩾ 4.6 mg/kg dry weight (1.7 mg/kg wet wt) were associated with total fledging failure. The estimated decline in fledged young per pair (24%, Bayesian regression) for kestrels consuming 0.7 mg/kg dry weight (0.3 mg/ kg wet wt) raises concerns about population maintenance in areas subject to high inputs of anthropogenic Hg. Mercury concentrations in 20 second-laid eggs collected from all groups were related to dietary concentrations of Hg, and the Hg concentrations in 19 of these eggs were related to eggs laid and young fledged. Concentrations of Hg in eggs from the highest diet group (5.9 mg/kg dry wt; 2.2 mg/kg wet wt) were higher than egg concentrations reported for either wild birds or for captive birds (nonraptors) fed dry commercial food containing 5 mg/kg methylmercury. Accumulation ratios of Hg from diets to eggs were higher than those reported for feeding studies with other species.

Environmental Toxicology and Chemistry↗
USGS2008

Reproductive ecology of Actinonaias ligamentina (Bivalvia:Unionidae) in a regulated river

Factors affecting the reproductive success of freshwater mussels in lotic systems are poorly understood. Gravidity, fecundity, and fertilization success of Actinonaias ligamentina were examined at 4 sites along a 63-km reach of the Green River immediately below the Green River Dam, Kentucky. No gravid females were collected at the site closest to the dam, and the percentage of gravid females at downstream sites ranged from 20 to 36%. Not all females became gravid, despite the presence of early stages of ova in the gonadal fluid. This observation suggests that female A. ligamentina undergo a resting stage and, therefore, might not become gravid every year. Fecundity differed among sites and increased with distance from the dam. Fertilization rates ranged from 32 to 97% among sites and increased with distance from the dam. Fertilization rate was independent of local mussel density and position in the mussel bed. The high fertilization rates observed in the upstream portions of mussel beds indicate that freshwater mussel sperm have the ability to travel to distant females in lotic systems. Therefore, females are not necessarily dependent upon nearby males for fertilization. Successful fertilization of A. ligamentina at low mussel densities in the Green River suggests that natural recovery of rare endangered species might be possible if host fish and suitable conditions for juvenile survival and growth are present. ?? 2008 by The North American Benthological Society.

Journal of the North American Benthological Societ↗
USGS1963

Nesting ecology and reproductive rate of the red-winged blackbird in tidal marshes of the upper Chesapeake Bay region

The nesting ecology and reproductive rate of the polygynous red-winged blackbird, Agelaius phoeniceus, were studied in the tidal marshes of Maryland during the period of 1958 through 1961. Sixteen nesting colonies were located in six major marsh communities of the Eastern Shore and were visited approximately twice a week from late April to mid-August. The average clutch size for 537 clutches was 3.3 eggs, with a range of 2 to 5 eggs. The ratio of territorial males to nesting females was 1:1.9. There was direct evidence of double broods by four females. The average number of young produced was 4.2 per breeding female or 8.1 per breeding male. Nesting success for the total of 675 active nests was 57%, with a range from 38% to 69% in the colonies. Robust plants that held constant form throughout the nesting season supported 95% of the nests, and the success of these nests was 58%; in contrast, non-robust plants supported only 5% of the nests, and success of this group of nests was only 26%. Nesting success varied with height from ground: 45% for nests less than 2 feet from the ground, 55% for those 2 to 4 feet, and 62% for those more than 4 feet. Histories of 749 nests were summarized by stages: 749 newly built, 675 with eggs, 424 with nestlings, and 388 with fledging young.

Chesapeake Bay region↗
USGS1989

Aspects of the reproductive ecology and behavior of the tepui toads, genus Oreophrynella (Anura: Bufonidae)

We report direct development for toads of the bufonid genus Oreophrynella, endemic to the tepuis of the Guayanan Highlands. Tepui toads place few (9-13), large (-3 mm diameter) eggs in a single or communal terrestrial nest. One communal nest found on Kukenan-tepui contained 102 toads (70 males, 30 females, 2 hatchlings) and 321 eggs in clumps of 8-35. All viable clutches from Kukenan were attended by an adult. One clutch of 13 eggs from Ilu-tepui was without an attendant adult. Calls of Kukenan males consist of 9-16 partially pulsed notes given at a rate of 5-7 notes per second. Calls and notes were modulated and increased or decreased in frequency; dominant frequencies of the calls ranged between 2650-3650 Hz. Tepui toads are diurnal, rock dwellers with a slow, deliberate walking gait. An unusual balling and tumbling behavior and bright colored venter may be associated with predator avoidance in some populations. Remarkable parallels in reproductive ecology and behavior between Oreophynella and montane populations of the African bufonid Nectophrynoides are noted.

Copeia↗
USGS1985

Reproduction, mortality, and heavy metal concentrations in great blue herons from three colonies in Washington and Idaho

We collected eggs in nests, hatchlings and eggs with advanced embryos on the ground, and prefledgling young of Great Blue Herons (Ardea herodias) at three nesting colonies in Washington and Idaho. Intact fish were also collected on the ground at the Idaho colony. The Ft. Lewis colony near Puget Sound in Washington and the Lake Chatcolet colony in northern Idaho were located near areas extensively polluted with heavy metals from minning or smelting activities. The Hanford Reservation colony near Richland, Washington was located some distance from point sources of heavy metal pollution. Heavy metals in heron samples were generally low and were all below concentrations known to induce mortality or adversely affect reproductive success. The elevated copper in one of three prefledglings from Ft. Lewis paralleled that found in an occasional nestling of several species of birds in other studies; the significance of this relationship is unclear. Breeding herons apparently fed near their colonies in areas removed from the sites of heaviest contamination, but birds in the Lake Chatcolet colony were preying on fish containing as much as 6 mu-g/g lead.

Idaho, Washington↗
USGS1985

Reproduction and organochlorine contaminants in terns at San Diego Bay

In 1981, we studied Caspian Terns (Sterna caspia) and Elegant Terns (S. elegans) nesting at the south end of San Diego Bay, California. Randomly collected Caspian Tern eggs contained signficantly (P < 0.05) higher mean concentrations of DDE (9.30 ppm) than did Elegant Tern eggs (3.79 ppm). DDE may have had an adverse effect on Caspian Tern reproduction but the relationship between hatching success and DDE concentration was not clear. We found an unusually high incidence of chicks (4.6%) that died in hatching. Caspian Tern eggs that broke during incubation or contained chicks that died while hatching had shells that were significantly (P < 0.05) thinner than eggs collected before 1947, and DDE was associated with reductions in shell thickness index (i.e., lowered eggshell density). Fish brought to Caspian Tern chicks contained up to 3.0 ppm DDE and 1.1 ppm PCBs. Organochlorine concentration brains of terns found dead were not high enough to suggest such poisoning as a cause of death.

California↗
USGS1997

Female reproductive dynamics in a Maryland population of ringneck snakes (Diadophis punctatus)

Adult female ringneck snakes (Diadophis punctatus) collected from a Maryland population during five successive summers laid a total of 50 clutches in which all eggs hatched successfully under laboratory conditions. Mean hatchling mass was not significantly related to female mass or clutch size when each was evaluated in separate analyses, but was significantly related to these factors when they were evaluated in a joint analysis. Mean hatchling masses of 0.6-1 g appear most adaptive; when females are large enough to produce 1-g eggs, the tendency is to produce a larger number of relatively smaller eggs. The relationship of clutch mass to female mass was unaffected by clutch size. Reproductive effort, measured as relative clutch mass (RCM, clutch mass/female mass), increased with age, as indicated by snout-vent length (SVL); also, the relationship of clutch mass to female mass indicated that clutches equaled a larger percentage as female mass increased. Clutch size averaged 3.55 eggs and ranged from 2 to 6. Clutches were laid from 17 June through 21 July (35 d), median 2 July. Clutches hatched during the 20-d interval 8-27 August (median August 18). Larger clutches were laid earlier in the season on average than smaller clutches. Incubation periods for clutches averaged 47 (range 42-51) d. Clutches laid later in the season averaged shorter incubation periods than clutches laid earlier.

Journal of Herpetology↗
USGS1990

Estimation of recruitment from immigration versus in situ reproduction using Pollock's robust design

Recruitment to animal populations can occur through both immigration and in situ reproduction. These two components of recruitment are conceptually distinct and lead to different mechanistic models of population dynamics. We describe a capture—recapture design that can be used to obtain separate estimates of two recruitment components. We then illustrate the use of our method and estimators with capture—recapture data from a population of Microtus pennsylvanicus at the Patuxent Wildlife Research Center in Maryland.

Ecology↗
USGS1984

Reproduction by an altricial songbird, the red-winged blackbird, in fields treated with the organophosphate insecticide fenthion

(1) Breeding red-winged blackbirds were used as a model to study the effects of a single application of an organophosphate insecticide, fenthion, on reproduction of altricial songbirds. (2) The insecticide had no significant effect on frequency of nest abandonment, clutch size, hatching success, or fledgling success. (3) Growth rates of young nestlings were lower in nests on one of two treated areas, but overall growth rates of survivors were not significantly different from controls in nests on nearby unsprayed areas. (4) The insecticide had no measured effect on male spatial organization. (5) Measures of abundance of the principal nestling food item, noctuid larvae, showed that one application of the insecticide significantly reduced the abundance of the food supply, but the reduction of food supply did not result in a decrease in nestling growth rates or fledgling success.

Wyoming↗
USGS1989

Leopard frog and wood frog reproduction in Colorado and Wyoming

Between 1978 and 1988, we recorded reproductive information from populations of ranid frogs in Colorado and Wyoming. Egg masses from five plains and montane populations of northern leopard frogs ( Rana pipiens ) contained 645-6272 eggs (x̄ = 3045, N = 68 egg masses). In two montane populations of wood frogs ( Rana sylvatica ) numbers of eggs per egg mass varied from 711-1248 (x̄ = 876, N = 15) and probably were equal to total clutch size. Mean hatching success was 90% in egg masses from one R. sylvatica population and ranged from 70% to 99% in R. pipiens egg masses. Rana pipiens egg masses from one location were assigned to three overlapping size distributions, which we believe reflects the underlying age structure of female frogs.

Colorado;Wyoming↗
USGS1978

Endocrine function and reproductive impairment in an irradiated population of the lizard Uta stansburiana

This study describes gonadal changes in lizards ( Uta stansburiana ) exposed to chronic low levels of γ radiation (1.5-10 R/day) under field conditions and attempts to evaluate endocrine involvement in these changes. Reproductive impairment in irradiated males is demonstrated during the breeding season by reduced testes weights and by seminiferous tubules devoid of germ cells. Ultrastructural morphology of Leydig cells, plasma testosterone levels, and developed accessory sex structures indicate normal steroidogenesis in such males; cytology of the pituitary gonadotropes and pituitary gonadotropin content indicate normal gonadotropin levels. These findings suggest that low levels of radiation affect the spermatogenic process directly, rather than through damage to the pituitary. Comparable irradiation causes complete resorption of ovarian tissue in some female Uta . The oviducts are atrophic and the pituitary gonadotropes hyperactive. Resemblance of gonadotropes to those of castrated animals and reduced pituitary hormone content suggest elevated levels of gonadotropin production, probably due to the absence of ovarian steroid feedback in affected animals. The continued mitotic activity of oogonia in adult reptiles and their limited number contribute to the vulnerability of germinal tissue in irradiated female lizards. Destruction of the germ cells is accompanied by resorption of all ovarian tissue including steroidogenic elements. Thus, in females as in males, radiation appears to damage gametogenesis rather than pituitary function.

Nevada↗
USGS1979

Methylmercury: Reproductive and behavioral effects on three generations of mallard ducks

Three generations of mallard ducks ( Anas platyrhynchos ) were fed either a control diet or a diet containing 0.5 ppm mercury in the form of methylmercury. The levels of mercury in adult tissues and eggs remained about the same over 3 generations. The methylmercury diet had no effect on adult weights or weight changes during the reproductive season. Females fed a diet containing 0.5 ppm mercury laid a greater percentage of their eggs outside their nestboxes than did controls, and also laid fewer eggs and produced fewer ducklings. Methylmercury in the diet appeared to result in a small amount of eggshell thinning. Ducklings from parents fed methylmercury were less responsive than controls to tape-recorded maternal calls, but were hyper-responsive to a frightening stimulus in avoidance tests; there were no significant differences in locomotor activity in an open-field test.

Journal of Wildlife Management↗
USGS1976

Methylmercury: Second generation reproductive and behavioral effects of mallard ducks

Mallard ducks ( Anas platyrhynchos ) whose parents were fed a diet containing 0.5 ppm mercury (equal to about 0.1 ppm mercury in a natural diet) also were fed a diet containing 0.5 ppm mercury beginning at 9 days of age and continuing through their reproductive season. Mercury in the eggs of treated hens averaged 0.86 ppm. Hens fed 0.5 ppm mercury made less efficient use of feed and laid a greater percentage of eggs outside nestboxes compared with controls. Hens fed mercury also produced fewer 1-week-old ducklings than did controls. There were no significant differences between controls and ducklings from parents fed 0.5 ppm mercury in approach responses to tape-recorded maternal calls, in avoidance of a frightening stimulus, or in open-field behavior. Ducklings from parents fed 0.5 pprn mercury did not grow as fast as did control ducklings.

Journal of Wildlife Management↗
USGS1993

Effects of harness transmitters on behavior and reproduction of wild mallards

Radio telemetry has been an important research tool in waterfowl studies for >20 years, yet little effort has been made to evaluate potential effects of transmitters on the birds that carry them. As part of a 4-year mallard (Anas platyrhynchos) study in the prairie pothole region of North Dakota and Minnesota, we compared radio-marked and unmarked female mallards in terms of percent time observed feeding, resting, and preening; nest initiation date; and clutch size and egg volume. Radio-marked females carried a 23-g back-mounted transmitter attached with a 2-loop harness (Dwyer 1972). On average, radio-marked females tended to feed less, rest and preen more, initiate nests later, and lay smaller clutches and eggs than unmarked females. Thus, behavioral and reproductive data from ducks marked with back-mounted harness-attached transmitters may be biased. We recommend that new designs of radio packages be field tested and caution that effects may be masked under extreme environmental conditions.

Journal of Wildlife Management↗
USGS1978

Variation in reproductivity with age in the brown pelican

About 10% of the Brown Pelicans breeding in South Carolina are in immature plumage. In comparison to adult breeders, immatures nested later, laid a smaller clutch, nested more frequently in low ground that was flooded, lost a larger proportion of nestlings, and produced fewer downy young per nest. Factors such as experience in breeding and fishing success probably influence reproductive success of pelicans of various ages.

The Auk↗
USGS1996

Reproductive success, growth and survival of black-crowned night-heron ( Nycticorax nycticorax ) and snowy egret ( Egretta thula ) chicks in coastal Virginia

We studied reproductive success, growth, and survival of Black-crowned Night-Heron ( Nycticorax nycticorax ) and Snowy Egret ( Egretta thula ) chicks in two mixed-species heronries on marsh islands in Chincoteague Bay, Accomack County, Virginia in 1992 and 1993. We attached radio transmitters with mortality sensors to the oldest chicks (A-chicks) in 11 to 22 nests of both species to monitor survival during the mid- to late nestling period and into the postnesting dispersal period. For both species, we found significant differences between 1992 and 1993 in growth rates and survival. Mass growth rates of chicks were higher in 1993 than in 1992 for both species. Culmen-length growth rates varied significantly due to year-colony effects for night-herons, but only for hatching order for egrets. Differences in survival rates due to hatching order were found for the egrets in both years, but were found only in 1992 for night-herons. As with mass growth rates, survival of chicks was higher in 1993 than 1992. Survival of radio-marked A-chicks did not differ between species or years for the period from hatching to fledging or from fledging through the end of the study (ca. two months postfledging). Survival ranged from 0.80 to 1.00 from the time radio transmitters were attached (ca. two weeks of age) until dispersal age (53-55 days for egrets; 55-60 days for night-herons). After birds left the colony, survival rates were lower during the next 40 to 55 days, ranging from 0.25 to 0.60. These results suggest that, at least for Snowy Egrets, A-chicks may be buffered from annual variations in food conditions, but that growth and survival of other brood members may provide a barometer of local conditions. Despite problems of variability in measurement, some of these parameters show promise as bioindicators of estuarine conditions. We recommend that a cost-efficient wading-bird monitoring program would include: (1) estimating numbers of nesting birds of selected species (e.g. Snowy Egrets) at particular estuaries, and (2) monitoring "initial brood sizes" and survival of young to at least two weeks of age in a sample of nests for each focal species. However, additional biomonitoring (e.g. marsh forage fish, contaminant loads) is necessary to evaluate how well top trophic-level organisms such as fish-eating birds respond to changes in estuarine production or quality.

The Auk↗