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Lead concentrations and reproduction in highway-nesting barn swallows
Swallows (Hirundo rustica) collected within the right-of-way of a major Maryland highway were greater than those found in Barn Swallows nesting within a rural area. Lead concentrations in the feathers of adults from the highway colony were also greater than Lead concentrations in the carcasses and stomach contents of adult and nestling Barn those of rural adults, but concentrations in the feathers of nestlings from the two locations were similar. Activity of u-aminolevulinic acid dehydratase in red blood cells was lower in highway-nesting adults and their young than in their rural counterparts, although hemoglobin concentrations and hematocrits did not differ. The number of eggs, nestlings, and body weights of the latter at 16-18 days of age were similar in the two colonies, as were body weights of adults from the two areas. These results suggest that contamination of roadside habitats by lead from automotive emissions does not pose a serious hazard to birds that are aerial feeders.
Acadian flycatcher nest placement: Does placement influence reproductive success?
We located 511 Acadian Flycatcher (Empidonax virescens) nests in bottomland hardwood forest of eastern Arkansas. Microhabitat characteristics were measured and their relationship with nest success evaluated. Fifty-two percent of all nesting attempts resulted in predation. Attributes of nest placement were similar between successful and unsuccessful nests, although successful nests were placed higher. Similarly, nonparasitized nests were typically higher than parasitized nests. Nests initiated late in the breeding season were placed in larger trees with higher canopy bases resulting in increased vegetation around the nest. Fifteen different tree species were used for nesting. Acadian Flycatchers chose nest trees in a nonrandom fashion, selecting Nuttall oak (Quercus nuttallii) and possumhaw (Ilex decidua) in greater proportions than their availability. However, there was no relationship between tree species used for nesting and nest success. Nest height was positively correlated with concealment at the nest site, supporting the predator-avoidance theory. No other attribute of nest placement differentiated successful nest sites, suggesting that nest predation is likely a function of random events in space and time.
Age, sex, reproduction, and spatial organization of lynxes colonizing northeastern Minnesota
From 1972 through 1978, lynxes ( Felis lynx ) emigrating from Canada were studied in northeastern Minnesota. Fourteen individuals were radio-tracked, 8 were ear-tagged, and 49 carcasses were examined. Sex ratios of the samples were equal during the first years of the study, but females predominated later. At least half of the radio-tagged lynxes were killed by humans; no natural mortality was detected. Home range sizes ranged from 51 to 122 km 2 for females and 145 to 243 km 2 for males, up to 10 times the sizes of those reported by other workers. Ranges of females tended to overlap. Males and females appeared to be segregated in the population.
Reproduction and survival of the desert tortoise (Scaptochelys agassizii) in Ivanpah Valley, California
No abstract available.
Contaminants in wood stork eggs and their effects on reproduction, Florida, 1982
One egg was removed from five Wood Stork (Mycteria americana) nests at each of eight colonies in central and northern Florida in 1982. DDE and mercury were present in all eggs with concentrations ranging up to 9.4 and 0.73 ppm wet weight, respectively. PCBs were detected in 25 eggs (63%) with a high value of 3.5 ppm. Other organochlorine compounds occurred in less than 30% of the eggs. Contaminant concentrations were remarkably similar among colonies. Overall, DDE and PCB concentrations were significantly less (P < 0.05) in Wood Stork eggs collected in Florida in 1982 vs. those collected in 1973. DDE was negatively correlated with eggshell thickness (r = -0.48 P <.0.01). Eggshell thickness was greater in 1982 than it was during the period 1967-73 (P.< 0.09) but was still 4.3% less than in eggs collected before 1947 (P < 0.05). Eggs from nests with less than 100% hatching success were linked with higher DDE concentrations (2.92 ppm vs 1.01; P = 0.09), but contaminants showed no significant link to fledging success. Although it is possible that a few individuals may have been affected by DDE, we found no evidence that organochlorine pesticides, PCBs, or mercury were significantly depressing Wood Stork populations.
Reproductive ecology of the ploughshare tortoise (Geochelone yniphora)
No abstract available.
Vine maple clone growth and reproduction in managed and unmanaged coastal Oregon Douglas-fir forests
Vine maple (Acer circinatum Pursh.) clone development, expansion, and regeneration by seedling establishment were studied in 5-240 yr old managed and unmanaged Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stands in coastal Oregon. Stem length, number of stems, and crown area were all significantly (P ≤ 0.01) related to stand age, and clone development was most rapid during the first 50 yr of stand development. Following clear-cutting, clones were clumps of 1-3 m long upright stems. Fifty years after disturbance, clones consisted of 5-15 drooping aerial stems >10 m long and basal sprouts 1-2 m long; some stems had been pinned to the forest floor by fallen trees or branches and had layered. In stands >120 yr in age, clones were often quite complex, composed of several decumbent stems each of which connected the ramets of 1-10 new aerial stems. Vine maple clone expansion occurs by the layering of long aerial stems. Over 95% of the layered stems we observed had been pinned to the forest floor by fallen debris. Unsevered stems that we artificially pinned to the forest floor initiated roots within 1 yr. Thinning may favor clonal expansion because fallen slash from thinning often causes entire clones to layer, not just individual stems. Clonal vine maple seed production and seedling establishment occurred in all stages of stand development except dense, young stands following crown closure. There were more seedlings in thinned stands than in unthinned stands and in unburned clearcuts than in burned clearcuts.
Distribution of the spotted bat (Euderma maculatum) in Nevada, including notes on reproduction
No abstract available.
Supplements to yellow corn for winter-maintenance and subsequent reproduction of quail
No abstract available.
The role of calcium in reproduction of the ring-necked pheasant
No abstract available.
Reproduction, growth, and tissue residues of deer fed dieldrin
Feeding tests were conducted from January, 1966, to January, 1969, to ascertain the effects of daily ingestions of sublethal amounts of dieldrin on white-tailed deer ( Odocoileus virginianus ). Groups of deer on 0 ppm dieldrin (controls), 5 ppm, and 25 ppm dieldrin were maintained at these respective levels, as were their progeny. Treated food was readily accepted. Dieldrin intoxication was not observed, and 9 of 10 animals of each group survived 3 years of treatment. No differences in conception or in utero mortality were found between groups. Fawns from dieldrin-fed does were smaller at birth and greater post-partum mortality occurred. Fertility of male progeny was not affected. Growth was slower and remained reduced in dieldrin-treated females which were immature when the study began. Hematologic values and serum protein concentrations were not significantly ( P > 0.05) related to treatment. Liver/body weight ratios were significantly ( P < 0.05) larger for the 25-ppm-dieldrin group. Pituitary glands were smaller and thyroids were larger in dieldrin-fed deer. Weight gains of fawns were significantly ( P < 0.05) reduced 2 of 3 years in dieldrin-treated groups. Placental transfer of dieldrin occurred. Whole milk from does fed 25 ppm dieldrin contained residues of 17 ppm. Residue levels in brain, liver, and thigh muscle tissues showed no evidence of increasing with length of treatment, but showed definite relationships to levels of dieldrin in daily diets. Nursing fawns had higher residues in brain tissues than did older deer on 5 ppm a d 25 ppm dieldrin. Highest brain residues (12.60 and 12.10 ppm, wet weight) occurred in fawns only a few days of age at death. Equilibrium between ingestion and storage or excretion of dieldrin occurred prior to 200 days and continued until nearly 1,100 days. There was no evidence of a sharp decline in residues after a long period of continued dosage. Daily ingestion of 100 and 200 ppm of dieldrin proved fatal to yearling male deer at 27 and 22 days, respectively.
Methylmercury: Second-year feeding effects on mallard reproduction and duckling behavior
For 2 consecutive years mallard ( Anas platyrhynchos ) hens were fed a control diet or a diet that contained 0.5 or 3 ppm mercury as methylmercury (about 0.1 and 0.6 ppm mercury on the basis of a natural succulent diet). During the fifth egg-collection period, levels of mercury in eggs of hens fed 0.5 and 3 ppm mercury averaged 0.79 and 5.46 ppm, respectively; on a dry-weight basis, the concentration of mercury in eggs was 4.88 times as great as that in the feed of ducks fed 0.5 ppm mercury and 5.64 times as great for ducks fed 3 ppm mercury. There were no significant differences in egg production or hatching success among controls and groups fed mercury. Ducklings from hens fed 3 ppm mercury were less likely to survive to 1 week of age than were controls or ducklings from parents fed 0.5 ppm mercury. There were no significant differences in approach behavior among the offspring of controls and groups fed mercury. In avoidance behavior, ducklings whose parents were fed 3 ppm mercury were hyper-responsive compared with controls and ducklings from parents fed 0.5 ppm mercury.
Organochlorine residues and reproduction in the big brown bat
Twenty-six pregnant big brown bats ( Eptesicus fuscus ) were collected at Montpelier Barn, Laurel, Maryland, and kept in individual cages until parturition. Seven young in 5 litters were born dead; 21 litters contained only living young. Polychlorinated bipbenyl (PCB, Aroclor 1260) crossed the placenta two to three times more readily than did DDE. Concentrations of PCB were significantly greater in litters with dead young than in litters where both young were born alive. The concentration of PCB in adult females plus their litters declined with increasing age of the female.
Effects of harness-attached transmitters on premigration and reproduction of Brant
Radio transmitters are an important tool in waterfowl ecology studies, but little is known about their effects on free-ranging geese. We attached transmitters to female brant ( Branta bernicla nigricans ) to investigate migration schedules at a fall staging area, return rates to nesting grounds, and nesting rates of returning females in subsequent breeding seasons. Radio-tagged females (n = 62) carried either 35-g back-mounted transmitters attached with ribbon harnesses, or 26- or 32-g back-mounted transmitters affixed with plastic-coated wire harnesses (Dwyer 1972). Arrival and departure schedules at Izembek Lagoon, Alaska, did not differ (P > 0.05) between radio-tagged females and the entire population in 1987-89. Color-banded females with transmitters returned to the breeding colony in subsequent nesting seasons (1988-92) at a lower (P ≤ 0.003) rate (≤4%) than color-banded females without transmitters (57-83%). The 1 returning color-banded female with a transmitter did not breed, while an average 90% of the returning color-banded females without transmitters nested in subsequent breeding seasons (P = 0.005). Back-mounted, harness-attached transmitters may bias data in studies of waterfowl behavior, productivity, and survival.
Dioxins and furans linked to reproductive impairment in wood ducks
A wetland in central Arkansas was contaminated with polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans and because the area was a major waterfowl habitat, we studied the effects of the contamination on nesting wood ducks ( Aix sponsa ) during 1988-90. Residues in wood duck eggs, based on toxicity equivalency factors (TEFs) for combined compounds, ranged from 0.2 to 611 parts per trillion (ppt) wet mass (70% were the toxic isomer 2,3,7,8-tetrachlorodibenzo-p-dioxin (tetraCDD)) and were 50 times higher in eggs from near the point source than from an uncontaminated reference site 111 km away. Nest success, hatching success, and duckling production were suppressed ( P < 0.05) at nesting sites 9 and 17 km downstream, as was hatching success 58 km downstream. Egg TEFs were inversely correlated ( P < 0.001) with productivity in corresponding nests. In addition, teratogenic effects occurred in ducklings at the more contaminated nesting site nearest the point source. The threshold range of toxicity (based on TEFs) where reduced productivity was evident in wood ducks was gt 20-50 ppt. Wood ducks were sensitive to dioxin and furan contamination, and we recommend it as an indicator species for monitoring biological impacts from these contaminants.