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At least 109 records · Page 6Linked to original sources
USGS1985

Glugea pimephales Fantham, Porter, and Richardson, 1941, n comb (Microporidia: Glugeidae) in the fathead minnow, Pimephales promelas

A microsporidan parasite, fitting the description of Nosema pimephales Fantham, Porter and Richardson, 1941, was found in fry of the fathead minnow, Pimephales promelas Rafinesque, from the Wray Fish Hatchery near Fort Morgan, Colorado. More detailed studies proved it to be a typical species of Glugea Thélohan, 1891, to which genus it was transferred. Presence of a delicate sporophorous vesicle, like that recently demonstrated in the type species, was observed. A sequence of three distinct kinds of divisions within that membrane, beginning with the plasmodium and ending with sporoblasts, was recognized. These were plasmotomy, multiple fission, and binary fission. The first two kinds, under the one name or the other, have been treated as one process in previous studies on species of Glugea . Results of this, a well as of recent studies, compel us to reconsider our concepts of "sporont" and "sporogony."

Canadian Journal of Zoology↗
USGS1985

Nutritional ecology of a fossorial herbivore: protein N and energy value of winter caches made by the northern pocket gopher, Thomomys talpoides

Northern pocket gophers ( Thomomys talpoides ) are fossorial herbivores that excavate belowground plant parts for food. In subalpine areas during autumn and winter, pocket gophers hoard plant parts in caches placed in or under snow. We examined the size and composition of 17 nival caches and tested the hypotheses that (i) cached food can provide complete energy and protein N sustenance during typical periods when burrowing is precluded by soil conditions, and (ii) cached food is a random sample of items encountered by burrowing gophers during tunnel excavation. Our data indicate that caches provide substantially more energy than protein in terms of a pocket gopher's daily maintenance requirements. Nevertheless, quantities stored are sufficient to allow individuals to endure commonly encountered adverse environmental conditions without entering negative energy or protein balance. Analysis of stomach contents and a comparison of cache composition to availability of plant species suggests that gophers consume high-protein items as they are encountered, and store low-protein items in caches.

Canadian Journal of Zoology↗
USGS1985

Maneuverability of the Humboldt penguin (Spheniscus humboldti) during swimming

Analyses of high-speed film of captive Humboldt penguins ( Spheniscus humboldti ) show that there is no correlation between the radii of submerged turns and swimming speed. The sharpest turns had a mean turn radius ( n = 5) of 0.14 m (0.24 body lengths), were powered by beating wings, and used multiple steering structures (beak, tail, feet, wings) and a flexing body. This turn radius is similar to that of fast-swimming fish with rigid bodies and lunate tails but is greater than that of slower fish with flexible bodies. The maximum turning rate was 10.05 radians s −1 . Maneuverability is augmented by neck-extending strike behavior and porpoising leaps.

Canadian Journal of Zoology↗
USGS1986

Effect of Orthene on an unconfined population of the meadow vole (Microtus pennsylvanicus)

The possible impact on Microtus pennsylvanicus of ground applications of Orthene ® insecticide was investigated in old-field habitats in northern Maryland during 1982 and 1983. The treatment grids in 1982 and 1983 were sprayed at 0.62 and 0.82 kg active ingredient/ha, respectively. A capture–recapture design robust to unequal capture probabilities was utilized to estimate population size, survival, and recruitment. Data on reproductive activity and relative weight change were also collected to investigate the effect of the insecticide treatment. There were no significant differences in population size or recruitment between control and treatment grids which could be directly related to the treatment. Survival rate was significantly lower on the treatment grid than on the control grid after spraying in 1983; however, survival rate was higher on the treatment grid after spraying in 1982. Significantly fewer pregnant adults were found on the treatment grid after spraying in 1982, whereas the proportions of voles lactating or with perforate vaginas or open pubic symphyses were slightly higher or remained unchanged during this period. Relative weight change was not affected by the treatment. Results do not indicate any pattern of inhibitory effects from the insecticide treatment. Field application of Orthene ® did not have an adverse effect on this Microtus population.

Canadian Journal of Zoology↗
USGS1987

Common Murre ( Uria aalge ) attendance patterns at Cape St. Mary's, Newfoundland

Attendance patterns of common murres ( Uria aalge ) at Cape St. Mary's, Newfoundland, were observed during hatching to post-fledging periods of 1980 to 1984. Six study plots on breeding ledges (ca. 450 birds total) and a "club" on the water were monitored for seasonal fluctuations in numbers attending. Attendance on ledges was similar between years, being relatively stable from hatching through to median fledging, and declining steadily thereafter. Attendance at the club usually peaked between median hatching and fledging, then declined rapidly during the fledging period. Numbers of murres attending neighboring study plots were often significantly correlated, but correlations were much weaker between distant plots. There were few significant correlations between attendance and wind speed or tidal oscillations in any year of study. Numbers of murres attending individual study plots varied significantly between years; four declined, one increased, and one showed no significant change. Overall, there was a small decline in total numbers of murres attending all study plots between 1980 and 1984.

Newfoundland↗
USGS1987

Dehydration of seabird prey during transport to the colony: Effects on wet weight energy densities

We present evidence to indicate that dehydration of prey transported by seabirds from capture sites at sea to chicks at colonies inflates estimates of wet weight energy densities. These findings and a comparison of wet and dry weight energy densities reported in the literature emphasize the importance of ( i ) accurate measurement of the fresh weight and water content of prey, ( ii ) use of dry weight energy densities in comparisons among species, seasons, and regions, and ( iii ) cautious interpretation and extrapolation of existing data sets.

Canadian Journal of Zoology↗
USGS1987

Growth and physiological condition of black ducks reared on acidified wetlands

Acid deposition has been identified as one of several possible factors contributing to the decline of some waterfowl populations in North America. In an effort to examine the effects of acidification on black duck (Anas rubripes) recruitment, growth and physiological condition were monitored in ducklings foraging for a 10-day trial (days 10-20 of life) on acidified (pH 5.0) and : circumneutral (pH 6.8) fish-free emergent wetlands. Acidification of these wetlands suppressed phytoplankton and algal growth, and reduced invertebrate biomass. Ducklings maintained on acidified wetlands grew poorly compared with ducklings reared on circumneutral wetlands, as evidenced by lower final body weight and culmen and tarsus length. Plasma growth hormone concentration was elevated and triiodothyronine levels were lower in stunted ducklings, in part substantiating impairment of growth-regulating processes. Ducklings exhibiting poor growth tended to have lower hematocrit, lower plasma protein, glucose, and cholesterol concentrations, and higher uric acid levels, presumably reflecting alterations in metabolism and development due to inanition. These findings suggest that acid deposition may lower food production in wetlands and ultimately impair duckling growth, condition, and survival.

Canadian Journal of Zoology↗
USGS1988

Distribution patterns during winter and fidelity to wintering areas of American black ducks

The distribution patterns during winter of American black ducks ( Anas rubripes ) were compared among age – sex classes using band recovery data. In addition, fidelity to wintering areas was compared between sexes and between coastal and inland wintering sites. We did not find evidence of age- or sex-specific differences in distribution patterns ( P > 0.10). Black ducks exhibited a stronger fidelity to coastal wintering areas ( P < 0.01), but there were no sex-specific differences ( P > 0.30). We believe that the early formation of breeding pairs and possibly predictable food resources may reduce age – sex segregation in distribution patterns during winter. The predictability of food resources in coastal, as opposed to inland, wintering areas is likely responsible for the greater fidelity of black ducks to coastal wintering sites.

Delaware, Illinois, Labrador, Maine, Maryland, Mas↗
USGS1989

Importance of individual species of predators on nesting success of ducks in the Canadian prairie pothole region

We followed 3094 upland nests of several species of ducks. Clutches in most nests were lost to predation. We related daily nest predation rates to indices of activity of eight egg-eating predators, precipitation during the nesting season, and measures of wetland conditions. Activity indices of red fox (Vulpes vulpes), striped skunk (Mephitis mephitis), and raccoon (Procyon lotor) activity were positively correlated, as were activity indices of coyote (Canis latrans), Franklin's ground squirrel (Spermophilus franklinii), and black-billed magpie (Pica pica). Indices of fox and coyote activity were strongly negatively correlated (r = -0.51), as were those of badger (Taxidea taxus) and skunk (r = -0.46). Nest predation rates in the early part of the breeding season were positively related to indices of fox, American crow (Corvus brachyrhynchos), and badger activity. Predation rates in the latter part of the season were positively related to indices of fox and skunk activity. Predation rates on early-season nests were lower in areas and years in which larger fractions of seasonal wetlands contained water. For late-season nests, a similar relationship held involving semipermanent wetlands. We suspect that the wetland measures, which reflect precipitation during some previous period, also indicate vegetation growth and the abundance of buffer prey, factors that may influence nest predation rates.

Canadian 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↗
USGS1989

Hybridization of ciscoes ( Coregonus spp.) in Lake Huron

Gill raker number and length were compared for lake herring, Coregonus artedii LeSueur, and bloater, Coregonus hoyi (Gill), collected in 1917, 1956, and 1984-1985 at four locations in western Lake Huron to examine the effects of suspected introgressive hybridization on these distinctive species characters. Gill raker length showed no change from 1917 to 1984-1985, but gill raker number became similar in the two species over that period. Between 1917 and 1984-1985, mean gill raker counts decreased from 48.0 to 45.8 in lake herring, but increased from 41.8 to 43.1 in bloaters. The modal count for both species was 43 in 1984-1985. Intermediate gill raker counts were consistent with the hypothesis of hybridization. Bloater abundance increased greatly in the 1980's, but lake herring remained scarce. Under these circumstances, the rare lake herring would be increasingly likely to encounter abundant ripe bloaters during the overlapping spawning seasons of these species, increasing the probability for hybridization. Basic biological differences between the species, such as lower vulnerability of bloaters to commercial harvest, better survival of bloater fry, or greater fecundity of bloaters, may have contributed to the substantially better success of bloaters. Cisco populations are fragile; only the bloater has ever made a strong and sustained recovery after a severe decline. Hybridization with bloaters may impede the recovery of lake herring in Lake Huron.

Canadian Journal of Zoology↗
USGS1990

Home range and movements of postfledging American black ducks in eastern Maine

We monitored the movements of 97 female and 15 male juvenile American black ducks (Anas rubripes) in the vicinity of Moosehorn National Wildlife Refuge in eastern Maine and southwestern New Brunswick from September through mid- December, 1985-1987.. Movements were described by estimating home ranges and radial movements from the primary roost marsh. Overall home range sizes averaged 4987 ha (range 54 - 28 070 ha), and maximum distances moved from the roost averaged 9.9 km (range 0.9-42.8 km). Home ranges were linear (linearity index 2.8), and home range area and distance of movements from the roost both increased monthly. Ducks that used >15 % riverine habitat had larger home ranges and moved greater distances from the roost than ducks using <15% riverine wetlands. Movements did not differ between ducks usually alone and those usually in flocks. Juvenile black ducks moved in small flocks and were often alone (34% of 355 observations). Most ducks showed fidelity to one roost-marsh complex from September until migration in late November. Daily and seasonal movement patterns were similar to those predicted for refuging systems.

Canadian Journal of Zoology↗
USGS1990

Host-parasite relationships and geographic distribution of Salmincola corpulentus (Copepoda: Lernaeopodidae) on bloater ( Coregonus hoyi ) stocks in Lake Huron

Examination of the branchial cavities of 8347 adult bloaters ( Coregonus hoyi ) collected from seven locations in Lake Huron for parasitic copepods yielded only the lernaeopodid Salmincola corpulentus ; its distribution was limited to bloaters collected in the southern two-thirds of the lake. The infections were highest off Au Sable Point and on Six Fathom Bank, where 12 and 22%, of the bloaters examined were infected, respectively. All copepods seen were sexually mature females. The dorsal anterior portion of the branchial rim was the preferred site of attachment. The prevalence of S . corpulentus increased with length of the bloaters, reaching a maximum of 40% in fish longer than 330&ensp;mm; none were seen in bloaters shorter than 182&ensp;mm. The mean intensity of S . corpulentus was unusually low (1.0&ndash;1.9) for a lernaeopodid copepod and the maximum number of copepods found on a single bloater was five. Prevalences of copepods differed significantly ( P &ensp;<&ensp;0.05) between bloaters collected at different geographic locations, suggesting that S . corpulentus may be of value in bloater stock determination.

Canadian Journal of Zoology↗
USGS1990

Food habits of wintering canvasbacks in Louisiana

We studied the food habits of canvasbacks ( Aythya valisineria ) at Catahoula Lake (inland) and the Mississippi River Delta (coastal), Louisiana, from November 1987 to February 1988. Plant foods comprised >97 aggregate percent dry mass of the canvasback diet. The proportion of plant material eaten did not vary with sex, age, or month, or differ between study sites or nocturnal and diurnal collections. Tubers of chufa flatsedge ( Cyperus esculentus ) and common arrowhead ( Sagittaria latifolia ) made up 94% of the canvasback diet at Catahoula Lake. Common and grassy arrowhead ( Sagittaria graminea ) tubers and American bulrush ( Scirpus americanus ) rhizomes and seeds formed 94% of the canvasback diet at the Mississippi River Delta. Consumption of specific food taxa did not vary with sex, age, or month at either study site. Canvasbacks at the Mississippi River Delta preferred seeds of American bulrush over all other foods, but American bulrush rhizomes were underrepresented in the diet. Densities of subterranean plant foods at Catahoula Lake and the Mississippi River Delta are apparently higher than at other major canvasback concentration areas and enable canvasbacks wintering in Louisiana to improve their physical condition before spring migration.

Louisiana↗
USGS1990

Early-winter diet of woodland caribou in relation to snow accumulation, Selkirk Mountains, British Columbia, Canada

Woodland caribou (Rangifer tarandus caribou) in the southern Selkirk Mountains of British Columbia shift from a diet of primarily vascular taxa during snow-free months to an arboreal lichen – conifer diet during late winter. We present evidence that caribou diets, during the early-winter transition period, are influenced by snow accumulation rates. Caribou shift to an arboreal lichen – conifer diet earlier during winters of rapid snow accumulation and forage extensively on myrtle boxwood (Pachistima myrsinites), an evergreen shrub, and other vascular plants during years of slower snow accumulation. The role of coniferous forage in early-winter food habits is examined. Forest management strategies can be developed to provide habitat that will enable caribou to forage in response to varying snow accumulation rates.

Selkirk Mountains↗
USGS1991

Patterns of seabird and marine mammal carcass deposition along the central California coast, 1980-1986

At monthly intervals from February 1980 through December 1986, a 14.5-km section of central California coastline was systematically surveyed for beach-cast carcasses of marine birds and mammals. Five hundred and fifty-four bird carcasses and 194 marine mammal carcasses were found. Common murres, western grebes, and Brandt's cormorants composed 45% of the bird total. California sea lions, sea otters, and harbor seals composed 90% of the mammal total. Several factors appeared to affect patterns of carcass deposition. The El Niño – Southern Oscillation (ENSO) of 1982–1983 was the dominant influence in terms of interannual variation in carcass deposition. During this ENSO, 56% of the seabirds and 48% of the marine mammals washed ashore. Patterns of intra-annual variation were species specific and were related to animal migration patterns, reproduction, and seasonal changes in weather. Nearshore currents and winds influenced the general area of carcass deposition, while beach substrate type and local patterns of sand deposition influenced the location of carcass deposition on a smaller spatial scale. Weekly surveys along a 1.1-km section of coastline indicated that 62% of bird carcasses and 41% of mammal carcasses remained on the beach less than 9 days. Cause of death was determined for only 8% of the carcasses. Oiling was the most common indication of cause of death in birds (6%). Neonates composed 8% of all mammal carcasses.

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↗
USGS1991

Cannibalism of nestling American kestrels by their parents and siblings

We examined the frequency of cannibalism of nestling American kestrels ( Falco sparverius ) in north-central Saskatchewan. We investigated human disturbance and food shortages as possible causes of it. Cannibalism of nestlings by their parents and siblings was confirmed by observation and by the presence of partially eaten carcasses, or inferred from the sudden disappearance of a nestling between frequent nest checks. Cannibalism occurred at 8% of 48 nests in 1988, and 18% of 92 nests in 1989. Not all nestlings that died were cannibalized. Where nestling mortality occurred, carcasses were eaten in at least 20% of nests in 1988, and 63% of nests in 1989. The chicks that were cannibalized died at a significantly younger age than those that died but were not cannibalized. The mass and age of the parent and the laying date were not associated with the occurrence of cannibalism. We found no strong evidence of a causal link between human disturbance and nestling mortality or cannibalism; however, the abundance of small mammal prey was inversely related to the frequency of cannibalism between years, and there were fewer prey and lower prey delivery rates in territories where cannibalism occurred than in territories where nestling mortality did not occur. The fact that some nestlings died but were not eaten suggests that such mortality was unrelated to food shortages. The food advantage of cannibalism may not outweigh potential disadvantages such as disease transmission.

Canadian Journal of Zoology↗