Showing papers in "Canadian Journal of Zoology in 1990"
TL;DR: This work has shown that predation is a major selective force in the evolution of several morphological and behavioral characteristics of animals and the importance of predation during evolutionary time has been underestimated.
Abstract: Predation has long been implicated as a major selective force in the evolution of several morphological and behavioral characteristics of animals. The importance of predation during evolutionary ti...
7,461 citations
TL;DR: The typical population response to food supplementation was two- to three-fold increase in density, but no change in the pattern of population dynamics, which points to the need for researchers to conduct food supplementation experiments in tropical environments.
Abstract: I reviewed 138 cases in which terrestrial vertebrates received supplemental food under field conditions. These cases are strongly biased toward small-bodied herbivores in north temperate environmen...
832 citations
TL;DR: In this review, information about bat foraging is considered in the context of structural and functional features, the former relating to bats' access to habitats of different complexity and the latter to their behavioural responses.
Abstract: The results of recent studies of the foraging behaviour of animal-eating bats are considered in this review. The advent of small (< 1 g) radio transmitters has made it possible to collect data on i...
375 citations
TL;DR: The relationships between diet composition and digestive efficiency can be used to begin evaluating the nutritional quality of diets consumed by free-ranging bears.
Abstract: Digestive and metabolic efficiencies of black bears (Ursus americanus) and grizzly bears (Ursus arctos) were determined in 7-day total collection trials using seven single foods and four mixed diet...
238 citations
TL;DR: It is postulated that herbivory, defined as predation on living plants, may have been rare in early Paleozoic terrestrial ecosystems, and that most primary productivity of terrestrial arthropods was diverted into higher trophic levels.
Abstract: The available fossil evidence for the ecology of terrestrial arthropods in the Paleozoic is reviewed and reinterpreted. Some original data are provided, derived mainly from the detailed morphology of mouthparts, genitalia, cuticular vestiture, and body form. Paleozoic chelicerates were more diverse than their modern descendants and were probably dominant ground-level and arboreal predators. Web-building spiders and highly diversified mites appear to have been absent. Paleozoic myriapods include possibly the earliest land animals, and as abundant detritivores, provided a major conduit for primary productivity into higher trophic levels. Paleozoic insects present many difficulties of interpretation, but appear to have been extraordinarily diverse and may have played quite different ecological roles from today's insects, viewed as a whole. It is postulated that herbivory, defined as predation on living plants, may have been rare in early Paleozoic terrestrial ecosystems, and that most primary productivity wa...
208 citations
TL;DR: Growth appeared to be suppressed by high levels of aggressive interactions, and an increase in swimming speed caused a marked increase in schooling behaviour, with a concomitant reduction in agonistic activity.
Abstract: The effects of long-term moderate exercise on the behaviour and the food intake – growth relationship of individually marked Arctic charr, Salvelinus alpinus L., were examined. Direct monitoring of food intake of individual fish was carried out using an X-radiographic method. Growth (weight gain) was significantly improved with increasing swimming speed, and a maximum specific growth rate was obtained at a swimming speed of approximately 1.75 body lengths/s. Growth appeared to be suppressed by high levels of aggressive interactions, and an increase in swimming speed caused a marked increase in schooling behaviour, with a concomitant reduction in agonistic activity. The exercising fish did not consume more food than controls, and moderately exercised Arctic charr showed improved growth – food intake ratios at all levels of food intake compared with fish held in standing water. Furthermore, the proportions of nonfeeding fish were significantly reduced at increasing water velocities. Thus, the relationship b...
198 citations
TL;DR: Right whales in Cape Cod Bay, Massachusetts, were studied to determine the relationship between their surface feeding behaviour and the density and composition of their planktonic prey.
Abstract: Right whales in Cape Cod Bay, Massachusetts, were studied to determine the relationship between their surface feeding behaviour and the density and composition of their planktonic prey. The swimmin...
176 citations
TL;DR: The distribution and movements of polar bears during the ice-free period in western Hudson Bay were studied using mark and recapture and radiotelemetry locating of animals of know species.
Abstract: The distribution and movements of polar bears (Ursus maritimus) during the ice-free period in western Hudson Bay were studied using mark and recapture and radiotelemetry locating of animals of know...
175 citations
TL;DR: Lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) population characteristics and use of habitats were studied during 1985–1987 in north central Washington.
Abstract: Lynx (Lynx canadensis) and snowshoe hare (Lepus americanus) population characteristics and use of habitats were studied during 1985–1987 in north central Washington. Lynx used areas above 1463 m el...
150 citations
TL;DR: Exercise-induced increases in the levels of citrate synthase, β-hydroxyacyl CoA dehydrogenase, and hexokinase induced cardiac growth that was isometric with body growth, since ventricle mass relative to body mass was constant.
Abstract: Rainbow trout, Oncorhynchus mykiss, were exercise trained for 28–52 days. Trained fish were 13% larger and swam 12% faster in an aerobic swimming test. Training induced cardiac growth that was isom...
143 citations
TL;DR: The energetic component of reproductive effort of male northern elephant seals, Mirounga angustirostris, was estimated from mass loss over the breeding season and correlated with dominance rank and age and was positively correlated with body size (mass or length) for both age-classes.
Abstract: The energetic component of reproductive effort of male northern elephant seals, Mirounga angustirostris, was estimated from mass loss over the breeding season and correlated with dominance rank and...
TL;DR: Incursion into relatively warm brackish water was associated with decreased thickness of the stratum externum and sloughing of a superficial layer of degenerative epidermal cells, changes that resulted in the loss of a distinctive yellow hue apparent over the dorsal body surface of whales examined during spring migration.
Abstract: Epidermal morphology and proliferation were examined in beluga whales during three phases of their annual cycle: spring migration from oceanic wintering grounds, summer occupation of estuaries in Hudson Bay, and return migration in fall. Incursion into relatively warm brackish water was associated with decreased thickness of the stratum externum and sloughing of a superficial layer of degenerative epidermal cells, changes that resulted in the loss of a distinctive yellow hue apparent over the dorsal body surface of whales examined during spring migration. Proliferation rate, determined by incorporation of tritiated thymidine in germinal cells, averaged 13.8–16.6% in all three seasons, but exceeded 20% in 7 of 16 whales examined in the estuaries; similarly high values were not observed during spring migration, and in only one of nine animals sampled in the fall. Average proliferation rate in 13 captive belugas was 14.2–16.6%, two to three times higher than any reported value for other cetaceans or terrestr...
TL;DR: Two nest site characteristics, nest site dispersion and cavity height, were similar for birds in both nesting environments, and greater cavity entrance area at natural cavities resulted in increased interspecific competition in natural populations.
Abstract: Several studies concerned with mate choice, reproductive performance, and life history strategies have been conducted with secondary cavity nesting birds breeding in nest boxes Although the need for comparative studies has been recognized, populations breeding in nest boxes often have not been compared with those breeding in natural cavities We compared the ecology of Tree Swallows breeding in nest boxes and natural cavities to determine if nest box populations of Tree Swallows are accurate models of natural populations Two nest site characteristics, nest site dispersion and cavity height, were similar for birds in both nesting environments Greater cavity entrance area at natural cavities resulted in increased interspecific competition in natural populations, involving larger competitors, more species, and a greater abundance of each species Clutch size was smaller in natural cavities compared with nest boxes, likely because floor area was smaller in natural cavities Fledging success did not differ
TL;DR: It is suggested that the seasonal body mass changes are mostly due to changes in body fat content, and found no evidence of significant changes in core mass in adult seals.
Abstract: Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) from the Svalbard Islands are described. The blubber content of adult females decreased from a high of about 50% at the beginning of the pupping season in March–April to a low of 31% during moulting in June. In adult males, the blubber content decreased from 41% in March to 29% in June. By estimating an individual seal's body mass by 1 April from its standard body length, we calculated an average daily loss of body mass of 160 g/day in adult females and 100 g/day in adult males from the start of lactation to the middle of moulting. The blubber content of sexually immature seals was less in June and July than in April, but the seasonal changes were smaller than in adult seals. We found no evidence of significant changes in core mass in adult seals, and suggest that the seasonal body mass changes are mostly due to changes in body fat content.
TL;DR: Results indicate that C. fluminea can make physiological adjustments to its filtration rate to achieve some "optimal" rate of particle removal, and within each habitat, particle concentration had a significant effect on filTration rates for the Tombigbee River and Tangipahoa River populations.
Abstract: Filtration rates of Corbicula fluminea were measured using 2-μm microspheres from three riverine habitats which differed in ambient suspended particle concentration; rates were measured at particle concentrations spanning the range for the three habitats. Filtration rates were significantly different across the three habitats, and were inversely correlated with the mean ambient suspended particle concentrations: 66.4 mL/h for 11 mg/L, 100.2 mL/h for 7 mg/L, and 144.9 mL/h for 4 mg/L for the Tombigbee, Ouachita and Tangipahoa rivers, respectively. However, the weight of particles filtered by clams from the three rivers was not significantly different. These results indicate that C. fluminea can make physiological adjustments to its filtration rate to achieve some "optimal" rate of particle removal. Within each habitat, particle concentration had a significant effect on filtration rates for the Tombigbee River and Tangipahoa River populations; maximal filtration rates were observed in the range of ambient p...
TL;DR: Gammarus lacustris infected with cystacanths of Polymorphus paradoxus display an abnormal behavior and respond to disturbance by swimming to the surface and clinging to a solid object.
Abstract: Gammarus lacustris infected with cystacanths of Polymorphus paradoxus display an abnormal behavior. They respond to disturbance by swimming to the surface and clinging to a solid object (W. M. Beth...
TL;DR: The causal nature of this relationship is examined by manipulating status within a laboratory population of sibling fish to determine whether fish of high social status are more likely to become 1+ smolts.
Abstract: Under good growing conditions, juvenile Atlantic salmon metamorphose into the migratory smolt stage at 1+ or 2+ years of age. The life-history decision on whether or not to migrate at 1+ years is made in July–August of the previous year. After this time, populations develop a bimodal size distribution, the larger fish (upper modal group) being the 1+ smolts and the lower modal group being fish that will smolt at 2+. Fish of high social status are more likely to become 1+ smolts. We examined the causal nature of this relationship by manipulating status within a laboratory population of sibling fish. The absolute status of individual fish was estimated within 2 weeks of first feeding. Relative status was then manipulated by dividing the population into two, half containing the fish with the highest absolute status (high ranking) and the remaining half of fish of lowest absolute status (low ranking). The status of individually marked fish was then determined within each of the two groups. Individual growth r...
TL;DR: Velocities during surface swimming and diving were measured with microprocessor recorders in four otariid species: northern fur seals (Callorhinus ursinus), Galapagos sea lions (Zalophus california...
Abstract: Velocities during surface swimming and diving were measured with microprocessor recorders in four otariid species: northern fur seals (Callorhinus ursinus), Galapagos sea lions (Zalophus californianus wollebaeki), Galapagos fur seals (Arctocephalus galapagoensis), and Hooker's sea lions (Phocarctos hookeri). Mean surface swimming velocities ranged from 0.6 to 1.9 m/s. Transit distances to feeding sites (1.2–90 km) were calculated using these velocities. Dive velocities, recorded every 15 s, ranged from 0.9 to 1.9 m/s. These velocities were consistent with calculated minimal cost of transport velocities in the smaller species. Using time partitioning, the metabolic cost of a northern fur seal foraging trip is estimated on the basis of recorded velocities and their calculated energy costs. This value is within 6% of that previously made with doubly labeled water techniques.
TL;DR: The results suggest that snail populations separated by paved roads with high traffic densities may be isolated from each other.
Abstract: The effect of road width on dispersal in the land snail Arianta arbustorum was examined by recording displacements of marked individuals during one activity season (3 months) in central Sweden. For...
TL;DR: Plasma osmolality levels following 24-h, 29‰ salinity challenge tests indicated a photoperiod-independent development of hypoosmoregulatory mechanisms preceding completion of smoltification that was significantly correlated with fish body size.
Abstract: Potential yearling (1+) smolts were maintained under 8.25 h light: 15.75 h dark and constant temperature (10.0 °C) from late December. Groups were subjected to an abrupt increase to 16 h light: 8 h...
TL;DR: When the water column became isothermal over the depth range of juvenile cod, they remained in shallow feeding areas throughout the diel period, which coincided with the disappearance of the shallow summer thermocline.
Abstract: We studied the movements and activity patterns of individual 3-year-old (28–33 cm total length) Atlantic cod, Gadus morhua, in Conception Bay, Newfoundland, using sonic telemetry. Cod tracked between June and early September (summer) were wide ranging (> 3 km/day), nocturnally active, and migrated daily between deep (30 m) cold water where they were inactive and shallow (< 15 m) warm water where they fed. Cod tracked between mid-September and December (autumn) stayed in shallow (< 20 m) water where they were active in relatively small (545.3–2581.6 m2) home ranges during daylight hours and inactive at consistent resting sites at night. Home ranges were over sand whereas resting sites were generally in rocky areas. The seasonal change in migratory behaviour coincided with the disappearance of the shallow (< 30 m) summer thermocline. When the water column became isothermal over the depth range of juvenile cod, they remained in shallow feeding areas throughout the diel period. We suggest that the summer diel...
TL;DR: Results indicate that increasing body size is an effective mechanism for reducing predation and that injury from a...
Abstract: The effect of tadpole body size, sibship, and tail injury on the survival of treefrog tadpoles (Hyla chrysoscelis) in the presence of dragonfly larvae (Tramea lacerata) was examined in a three-way factorial experiment. Tadpole body size had a dramatic effect on survival; large tadpoles had higher survival than medium-sized or small tadpoles. The presence of tail injury simulating an unsuccessful predation attempt significantly reduced survival. Survival of control tadpoles without tail injury in the presence of a predator was almost twice as high as that of tadpoles with 75% tail loss. Tadpole sibship had no effect on survival and indicated that genetic differences in antipredator behavior or production of alarm substances and allelochemicals, independent of body size, were not apparent. There were no significant interactions between tail injury and body size or tail injury and sibship. These results indicate that increasing body size is an effective mechanism for reducing predation and that injury from a...
TL;DR: A series of experiments in seminatural conditions with bank voles Clethrionomys glareolus (Schreber, 1780) and weasels Mustela nivalis Linnaeus, 1766 was designed to show if a short visit by a weasel into an area, and its scent alone left there, would influence the use of space by bank vols, and whether the age, sex, and reproductive activity of bank vole would differentiate their responses to the risk
Abstract: A series of experiments in seminatural conditions with bank voles Clethrionomys glareolus (Schreber, 1780) and weasels Mustela nivalis Linnaeus, 1766 was designed to show if (i) a short visit by a weasel into an area, and (ii) its scent alone left there, would influence the use of space by bank voles, and whether the age, sex, and reproductive activity of bank voles would differentiate their responses to the risk of predation. Forty-five bank voles were released into an outdoor enclosure (150 m2) divided into three pens of equal size. The risk of predation was manipulated by introducing a weasel into either one or two pens for 24 or 2 h. Changes in the use of space by voles were determined by livetrapping in pens for 11 days after each manipulation. The pens that had been penetrated by weasels were avoided by voles for several days following each introduction of a weasel. The pens where prey had contacted a predator, or where only the odour of a weasel remained, were equally avoided by voles. Sex- and age...
TL;DR: Adult female caribou lost body weight during the first 2–3 weeks of lactation, but then increased 15% above postpartum weights during the summer period, and adult female muskoxen maintained weight, with no significant changes throughout the summer.
Abstract: Growth rates, milk intake, activity patterns, and daily energy expenditures of neonatal caribou (Rangifer tarandus granti) and muskoxen (Ovibos moschatus) were compared over a 100-day period to examine the strategies of two arctic follower species with different life history patterns Relative growth rates, which reflected milk protein and energy intake, were higher for caribou during the 1st week of age and after 75 days of age than for muskox calves Daily energy expenditures, estimated with the doubly labeled water technique, were significantly greater for caribou neonates than for muskoxen Adult female caribou lost body weight during the first 2–3 weeks of lactation, but then increased 15% above postpartum weights during the summer period Adult female muskoxen maintained weight, with no significant changes throughout the summer Caribou milk was higher in protein, dry matter, and energy content than that of muskoxen
TL;DR: The crustacean amphipod genus Jassa is revised to encompass the type species J. falcata, the previously recognizedspecies J. ingens, J. herdmani, and J. marmorata Holmes, 1903, and the new Species J. thurstoni, which can be distinguished from its closest relatives by the following key characters.
Abstract: The crustacean amphipod genus Jassa is revised to encompass the type species J. falcata (Montagu, 1808), the previously recognized species J. ingens (Pfeffer, 1888), J. herdmani (Walker, 1893), J. ...
TL;DR: Large differences in the daily activity of moose were found between the study areas, and in the poor food availability area, moose browsed twigs of poor quality and were inactive a greater proportion of the time.
Abstract: The relationship between foraging behaviour and the time-energy budget of adult moose (Alces alces) cows was studied during the winter in two Norwegian populations. In the study area with lowest food availability, the moose foraged almost exclusively on birch (Betula pubescens) of poor quality (expressed as digestibility). In the other study area with higher food availability, a much more diversified species composition of the diet was found, including several Salix spp., rowan (Sorbus aucuparia), aspen (Populus tremula), and bird cherry (Prunus padus). Large differences in the daily activity of moose were found between the study areas. In the poor food availability area, moose browsed twigs of poor quality and were inactive a greater proportion of the time. They used a smaller area for foraging, but removed a much larger fraction of the available biomass from each browsing site than in the higher food quality study area. No significant difference was found between the study areas in the gross daily dry m...
TL;DR: A nested mating design was used in which 10 males were mated with 20 female chum salmon, and individuals from each of the 20 families were maintained at 6, 10, and 14 °C from egg fertilization until juveniles reached a fork length of about 61 mm.
Abstract: A nested mating design was used in which 10 males were mated with 20 female chum salmon (Oncorhynchus keta), and individuals from each of the 20 families were maintained at 6, 10, and 14 °C from egg fertilization until juveniles reached a fork length of about 61 mm. Variation in 11 morphometric and 3 meristic characters was evaluated. Rearing temperature had a marked effect on juvenile morphometric variation, enough to assign correctly 91% of the juveniles reared at 14 °C, 90% of the juveniles reared at 10 °C, and 95% of the juveniles reared at 6 °C. The addition of meristic character variation increased the classification accuracy to 97, 92, and 96%, respectively. As rearing temperatures increased, the observed levels of fluctuating asymmetry for the three meristic characters increased. Morphometric characters tended to have lower heritabilities than did meristic characters. Genotype–temperature interactions generally accounted for between 10 and 30% of observed phenotypic variation for most characters.
TL;DR: A population of individually marked adult Rana temporaria was studied during the breeding season in 1979–1988 in east-central Sweden, indicating an increased survival rate with age and overall population sex ratio was close to unity.
Abstract: A population of individually marked adult Rana temporaria was studied during the breeding season in 1979–1988 in east-central Sweden. Annual return rate averaged 31% (range 16–51%) in males and 16% (range 5–33%) in females. Return rate was not size dependent but increased with every successful previous hibernation, indicating an increased survival rate with age. Return rate was not correlated with winter harshness. Once adult, males had on average 1.5 (maximum 6) seasons with the possibility of reproducing. Corresponding values for females were 1.4 and 4. Mean length of the breeding season was 20 (SD = 2) days. Calling generally started at water temperatures below 3 °C. The lowest spawning temperature was 1 °C. Average temperatures at spawning onset and peak spawning were 5 and 6 °C, respectively. Large males tended to arrive earlier at the pond than small males. Males arrived earlier and stayed longer than did females. The overall population sex ratio was close to unity. The operational sex ratio (OSR) v...
TL;DR: Analysis of the size and spacing of vortices in the jet trail indicates that the theoretical augmentation of thrust from a pulsed jet may indeed affect the locomotory efficiency of salps.
Abstract: Several morphological and functional characteristics that affect the jet propulsion of salps are described, based on observations of living animals in situ and in the laboratory. A velocity profile...
TL;DR: All three species were sensitive to , and mild hypoxia elicited significant cardiorespiratory adjustments, including increased m...
Abstract: Cardiorespiratory responses to acute reductions of ambient oxygen were measured in skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), and bigeye tuna (Thunnus obesus). Prevente...