Showing papers in "Canadian Journal of Zoology in 1993"
TL;DR: In late September and October 1987–1990 and early July 1988–1991, 66 radio-collared female caribou of the Central Arctic Herd were captured and weighed 117 times; parturition status, calving date, and perinatal calf survival were determined.
Abstract: In late September and October 1987–1990 and early July 1988–1991, 66 radio-collared female caribou (Rangifer tarandus granti) of the Central Arctic Herd were captured and weighed 117 times. Caribou were relocated repeatedly during early June 1988–1991; parturition status, calving date, and perinatal calf survival were determined. Mean autumn body weights of subsequently parturient (90.0 kg) and nonparturient (82.5 kg) females differed significantly (P < 0.01). Mean summer weights 4 – 5 weeks after parturition were significantly higher for females that had calved on or before 7 June (82.2 kg) than for those that had calved after 7 June (72.1 kg; P < 0.01), and for females whose calves survived at least 2 days post partum (80.2 kg) than for those whose calves died within 2 days (70.3 kg; P < 0.01). Significant logistic models were generated for relationships between parturition rate and autumn weight (P < 0.01), between the occurrence of early calving and summer weight (P < 0.05), and between calf survival ...
260 citations
TL;DR: One of the feeding techniques used by killer whales is referred to as the carousel method, whereby whales cooperatively herded herring into a tight ball close to the surface, whereby killer whales stunned their prey by slapping the edge of the school with the underside of their flukes and then ate the stunned fish one by one.
Abstract: Killer whales (Orcinus orca) feeding on herring (Clupea harengus) were observed both from the surface and underwater. We refer to one of the feeding techniques used by killer whales as the carousel...
205 citations
TL;DR: Gravid Hysterothylacium aduncum from the intestine of eelpout, Zoarces viviparus, were used as the source of eggs for study and the two first moults occurred in the egg.
Abstract: Gravid Hysterothylacium aduncum from the intestine of eelpout, Zoarces viviparus, were used as the source of eggs for study. The two first moults occurred in the egg, which does not normally hatch ...
198 citations
TL;DR: Two species of entomopathogenic nematodes, an ambush forager and a cruising forager, were assayed for their responses to volatiles associated with Galleria mellonella and Steinernema glaseri showed no significant response to any treatments tested.
Abstract: Two species of entomopathogenic nematodes, an ambush forager (Steinernema carpocapsae) and a cruising forager (S. glaseri), were assayed for their responses to volatiles associated with Galleria me...
193 citations
TL;DR: Photographic identification and standardized zigzag surveys were used to study the distribution and abundance of bottlenose dolphins in Doubtful Sound, New Zealand, and the majority of the dolphins in the catalogue were found in each survey period, indicating their residency in the fiord.
Abstract: Photographic identification and standardized zigzag surveys were used to study the distribution and abundance of bottlenose dolphins in Doubtful Sound, New Zealand. Forty individuals were identifie...
189 citations
TL;DR: The tannin-binding specificity of salivary proteins in several mammals was investigated as a possible explanation for observed food habits in Moose and beaver.
Abstract: The tannin-binding specificity of salivary proteins in several mammals was investigated as a possible explanation for observed food habits. Moose (Alces alces) and beaver (Castor canadensis) produc...
185 citations
TL;DR: An allopatric origin through two invasions of marine sticklebacks is consistent with both the geological history of the area and the details of local distributio... both lake morphometry and altitude appear to influence local distribution.
Abstract: Pairs of plankton-feeding and benthos-foraging sticklebacks (Gasterosteus aculeatus) (limnetics and benthics) coexist in six small lakes in southwestern British Columbia. In spite of a persistent low level of hybridization the pairs maintain themselves as distinct genetic and ecological entities; because of this they are viewed as biological species. They appear to be restricted to the central Strait of Georgia region, and the geological history of the area argues that they are of postglacial origin. The pairs occur on three islands (Vancouver, Texada, and Lasqueti), but even on these islands they are not found in all available lakes. Both lake morphometry (size and depth) and altitude appear to influence local distribution. Hypotheses that might explain the origin of the pairs are examined. Neither theory nor data support a sympatric origin, but an allopatric origin through two invasions of marine sticklebacks is consistent with both the geological history of the area and the details of local distributio...
182 citations
TL;DR: The factors affecting variation in age at first reproduction of bighorn ewes (Ovis canadensis) were investigated in two marked populations in Alberta, and there was wide overlap in body mass between early and late producers.
Abstract: The factors affecting variation in age at first reproduction of bighorn ewes (Ovis canadensis) were investigated in two marked populations in Alberta. One population was studied for 20 years, the o...
178 citations
TL;DR: The range used for calving and for the first month of lactation by the Riviere George Caribou Herd showed signs of overgrazing, in contrast to that used by the adjacent Riviere aux Feuilles Herd, illustrating that priority goes to reproduction rather than to growth under suboptimal foraging conditions.
Abstract: The range used for calving and for the first month of lactation by the Riviere George Caribou Herd (RGH), which peaked at over 600 000 individuals in the mid-eighties, showed signs of overgrazing, in contrast to that used by the adjacent Riviere aux Feuilles Herd. Density of females in the tundra habitat below 600 m asl averaged 11.2 animals/km2 on the overgrazed range in 1988, in comparison with ≈0.5/km2 on the other range. Inadequate foraging conditions during the first month of lactation caused complete exhaustion of fat reserves in females on the poor range; milk production was seemingly insufficient, as calves were lighter and grew at a slower rate than calves born on the better summer range or born in captivity from dams fed ad libitum. Moreover, females on the poor range were shorter and lighter than their counterparts on the good range, illustrating that priority goes to reproduction rather than to growth under suboptimal foraging conditions. Accretion of body fat and protein in RGH females was ra...
156 citations
TL;DR: This study was undertaken to establish whether fatty acids are generally oxidized at the same rate or if a pattern of oxidation rates exists to protect certain fatty acids from degradation for ATP formation.
Abstract: This study was undertaken to establish whether fatty acids are generally oxidized at the same rate or if a pattern of oxidation rates exists to protect certain fatty acids from degradation for ATP ...
150 citations
TL;DR: Since, similar to natural conditions, chirps summated with the beat caused by interference of the fish's own electric organ discharge and the imitating discharge, the size and shape of the chirp's amplitude envelope varied greatly according to its phase relative to the beat cycle; however, the frequency of theChirp amplitude modulation was always 50–100 Hz.
Abstract: Apteronotus leptorhynchus, a gymnotiform fish, produces highly regular electric organ discharges of 600–1000 Hz. Short-term modulations of the electric organ discharge ("chirps") were elicited by imitating the discharges of neighboring fish. Chirps displayed an increase in frequency of approximately 100 Hz, a duration of about 15 ms, and an absolute amplitude of 0.5–2 mV. Since, similar to natural conditions, chirps summated with the beat caused by interference of the fish's own electric organ discharge and the imitating discharge, the size and shape of the chirp's amplitude envelope varied greatly according to its phase relative to the beat cycle; however, the frequency of the chirp amplitude modulation was always 50–100 Hz. All 21 males examined chirped, but their rate of chirping varied considerably (range 2–59 chirps/30 s; mean 22 chirps/30 s). In contrast, only one out of nine females chirped (mean 0.25 chirps/30 s). The latency between stimulus onset and first chirp was variable and often long (rang...
TL;DR: A study of 518 individually identified humpback whales in the southern Gulf of Maine between 1979 and 1988 showed high rates of both within-season occurrence and annual reticulation.
Abstract: A study of 518 individually identified humpback whales (Megaptera novaeangliae) in the southern Gulf of Maine between 1979 and 1988 showed high rates of both within-season occurrence and annual ret...
TL;DR: A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.
Abstract: The food requirements of dependent sons and daughters have important implications for evolution of the sex ratio, according to current sex allocation theory. We studied food requirements of nestling American kestrels (Falco sparverius), a moderately size-dimorphic falcon, by hand-feeding 61 birds from hatching to fledging. Daughters, the larger gender, consumed 6.99% more food than did sons. Sons did not have higher energy expenditure from higher effort during sibling competition than daughters did, so parents must supply more food to satisfy daughters' needs than to satisfy sons'. A review of all related studies shows a strong positive association between the degree of sexual size dimorphism and gender difference in food requirements.
TL;DR: The observed pattern may be the result of latitudinal variation in selection on egg size and (or) clutch size, as well as on the optimal trade-off between these two ...
Abstract: Reproductive and body size data from 169 populations of 146 species (56% of those recognized), 65 genera (75%), and 11 families (92%) of turtles were tabulated to test for latitudinal variation in egg and clutch size. Body-size-adjusted correlation analysis of all populations (as well as within most families) revealed (i) a significant negative relationship (r2 = 0.26) between latitude and egg size, (ii) a significant positive relationship (r2 = 0.21) between latitude and clutch size, and (iii) no relationship between latitude and clutch mass. Phylogenetic contrast analyses corroborated these patterns. Clutch size was also negatively correlated with egg size across all populations as well as within most families. We evaluate the applicability to turtles of hypotheses postulated to explain such latitudinal patterns for other vertebrate groups. The observed pattern may be the result of latitudinal variation in selection on egg size and (or) clutch size, as well as on the optimal trade-off between these two ...
TL;DR: I examined the components generating selectivity in wolves preying on five ungulate species in Banff National Park, Alberta, and found overall selectivity for elk and deer species, and apparent avoidance of bighorn sheep and mountain goats, were due primarily to lower habitat overlap of wolves with the latter two species.
Abstract: I examined the components generating selectivity in wolves preying on five ungulate species in Banff National Park, Alberta. Overall selectivity for elk and deer species, and apparent avoidance of bighorn sheep and mountain goats, were due primarily to lower habitat overlap of wolves with the latter two species, and therefore lower encounter rates. For social ungulates, I argue that the herd should be considered the unit of encounter, with encounter rates proportional to the number of herds rather than the number of individuals. However, large herds predictably associated with certain areas may be visited intentionally by wolves, increasing effective encounter rates. Foraging theory suggests that all ungulate prey should be equally profitable to wolves upon encounter and therefore the factors affecting encounter rates are critical in determining prey selectivity. A simple model incorporating different habitat overlap, herd sizes, and predictable herds predicts qualitatively different functional responses ...
TL;DR: The hypothesis that lake trout displace or exclude bull trout from lakes is tested by determining the outcome of introductions of lake trout into two lakes that supported indigenous bull trout.
Abstract: Indigenous lacustrine populations of bull trout (Salvelinus confluentus) and lake trout (S. namaycush) are spatially separated within the southern part of the zone of distributional overlap (northe...
TL;DR: It is suggested that under natural conditions, black grouse inhabited the early-successional stages of forest following burns, hazel grouse inhabitability in the less intensively managed area.
Abstract: Sympatric forest grouse in intensively managed conifer-dominated forests of the southern boreal zone in Sweden occupied different forest successional stages. Black grouse (Tetrao tetrix) selected f...
TL;DR: It is shown that juvenile yellow perch can detect and recognize prey using only near-ultraviolet visual cues, and this finding is discussed in terms of the visual ecology of juvenile and adultyellow perch.
Abstract: The intensity of light required for juvenile yellow perch, Perca flavescens, to strike at planktonic prey was determined at 14 wavelengths, particular attention being paid to the near-ultraviolet region of the spectrum. Juvenile yellow perch are known to possess near-ultraviolet-sensitive photoreceptors, which are absent in adults. The action spectrum obtained shows three peaks: one between 640 and 700 nm, one between 490 and 525 nm, and one in the near-ultraviolet range, between 360 and 400 nm. The relative amplitude of the near-ultraviolet peak is greater than the amplitudes of the other two peaks. These results reveal that juvenile yellow perch can detect and recognize prey using only near-ultraviolet visual cues. This finding is discussed in terms of the visual ecology of juvenile and adult yellow perch.
TL;DR: Total pectoralis muscle glycogen levels and the activity of pyruvate kinase increase, suggesting a higher capacity for glycogenolysis, which may be important during intense levels of energy demand.
Abstract: In late summer, semipalmated sandpipers (Calidris pusilla) migrate nonstop from eastern Canada to wintering sites on the northwest coast of South America. Before their transoceanic flight, the birds feed intensively for about 15 days during which time lipids are stored. The fat-free dry mass of the pectoralis muscle increases during the fattening period, probably increasing the maximal power output of the muscle. Plasma free fatty acids and triglycerides, pectoralis muscle lipid content, and the activity of carnitine oleoyl coenzyme A transferase are higher in heavy (fat) than in light (lean) birds. These alterations imply an enhanced capacity to utilize fatty acids as a metabolic fuel during migration. Total pectoralis muscle glycogen levels and the activity of pyruvate kinase increase, suggesting a higher capacity for glycogenolysis, which may be important during intense levels of energy demand. Heart size and protein content per gram of tissue increase in association with an increase in body mass. Howe...
TL;DR: Milk samples were collected on 135 occasions from fasting polar bears (Ursus maritimus) on land and from 26 feeding polar bears on the sea ice to analyze for fat, protein, carboh...
Abstract: Milk samples were collected on 135 occasions from fasting polar bears (Ursus maritimus) on land and from 26 feeding polar bears on the sea ice. Milk specimens were analyzed for fat, protein, carbohydrates, total solids, and gross energy. Fat content of milk from mothers with cubs captured on land declined from 35.8% when they were emerging from dens in spring to 27.5% the following autumn, and to 20.6% one year later when they had yearlings. No changes in milk fat were found for bears captured on the sea ice as offspring age increased. Milk protein levels increased while carbohydrate levels decreased through lactation for both feeding and fasting bears. Total solids ranged between 21.6 and 51.0%. For bears on land, gross energy declined from 16.9 kJ/g for females with 3-month-old cubs to 9.7 kJ/g when offspring were 34 months old. The proportion of females with cubs and yearlings that were lactating declined through the autumn. We suggest that when female polar bears do not have access to food, those with...
TL;DR: A series of supplementary feeding experiments on lesser black-backed gulls is used in conjunction with a new technique to measure pectoral muscle protein levels in live birds to investigate the relationships between food supply, body condition, and clutch size.
Abstract: Though many authors have demonstrated an adaptive relationship between food supply or territory quality and clutch size, the proximate mechanism by which clutch size is determined remains largely u...
TL;DR: Activity and diving performance of nursing ringed seal pups were quantified using time–depth recorders and the large proportion of time spent in the water, the development of...
Abstract: In this study, activity and diving performance of nursing ringed seal (Phoca hispida) pups were quantified using time–depth recorders. A total of 1040 h of activity, including 7506 diving cycles, was collected from three female pups. The pups spent 50.3% of their time in the water and 49.7% hauled out on the ice. When the pups were in the water, 20.5% of the time was spent actively diving, while 79.5% of the recorded wet time was spent at the surface. Most of the dives were shallow and of short duration. Mean dive duration was 59.1 ± 63.5 s (SD). Maximum dive durations for the three pups were 5.8, 7.5, and 12 min. Maximum recorded depths were 12, 35, and 89 m. These depths represented the bottom in the area where each pup was situated. The average duration of haul-out sessions where nursing could take place was 6.3 ± 1.6 h, and the time between these sessions was 8.2 ± 3.2 h. The mean number of breathing holes found per pup was 8.7 ± 3.5. The large proportion of time spent in the water, the development of...
TL;DR: Parturition, time to weaning, and female attendance patterns were studied over four breeding seasons in Australian sea lions, Neophoca cinerea, on Kangaroo Island, South Australia.
Abstract: Parturition, time to weaning, and female attendance patterns were studied over four breeding seasons in Australian sea lions, Neophoca cinerea, on Kangaroo Island, South Australia. Females generall...
TL;DR: Morphological analysis of sticklebacks from Misty Lake and its inlet stream reveals two forms of Gasterosteus, which are likely to be new forms of the same species.
Abstract: Morphological analysis of sticklebacks from Misty Lake and its inlet stream (Keogh River system, northern Vancouver Island) reveals two forms of Gasterosteus. Sticklebacks from the lake are large and slender bodied with a black back and sides, while sticklebacks from the inlet stream are smaller with a stockier body and mottled brown back and sides. Lake fish also have shorter jaws, longer spines, and more gill rakers than the stream fish. These differences in body shape, trophic structures, and colour are inherited, and the two forms breed true in the laboratory. This implies that they are independent gene pools rather than a single gene pool containing some complex polymorphism. The pair from Misty lake and stream is compared with ecologically similar pairs from Graham Island in the Queen Charlotte Archipelago. The lake–stream pairs on the two islands are strikingly similar. Two hypotheses are examined that might explain the origins and remarkable resemblance of these widely disjunct lake–stream pairs. ...
TL;DR: The main morphometric change recorded was that the isolated population had developed a more compact body, which is probably an adaptation to a less active, more benthic way of living.
Abstract: A marine population of Gasterosteus aculeatus recently isolated in fresh water was found in Bergen, western Norway. This discovery offered the opportunity to study early changes in a population isolated in an environment quite different from what it previously experienced. The population was sampled in 1982, 1987, and 1991. Variation of plate morph frequencies was studied, and a prediction model for the change in frequencies is proposed. An increasing frequency of specimens with four dorsal spines is observed. This may be related to high summer temperature. Changes in morphology were recorded and compared with those in the marine population from which the isolated population originated. Discriminant analysis was used to reveal differentiation in morphometric characters. The main morphometric change recorded was that the isolated population had developed a more compact body, which is probably an adaptation to a less active, more benthic way of living.
TL;DR: Captive mule deer and black-tailed deer were used in cafeteria-type, two choice feeding trials to test the hypothesis that digestible dry matter can be digested in deer.
Abstract: Captive mule deer (Odocoileus hemionus hemionus) and black-tailed deer (O. h. sitkensis) were used in cafeteria-type, two choice feeding trials to test the hypothesis that digestible dry matter (energy) and nontannin phenolics of tree, shrub, and forb leaves are major determinants of diet preference. Deer selected plants in relation to a trade-off between the benefit derived from digestible dry matter and the cost of nontannin phenolics presumably associated with toxicity when absorbed. When one of the forages contained both the highest digestible dry matter and lowest nontannin phenolics, the deer always preferred that plant. When one forage had the highest digestible dry matter but the other plant had the lowest nontannin phenolics, the deer selected the high-energy plant when the difference in nontannin phenolics was relatively small, but they preferred the low-energy plant when the other forage had much higher levels of nontannin phenolics. Tannins influenced diet choice only as one of the factors red...
TL;DR: Sperm whales were tracked continuously for periods of days totalling months off the Galapagos Islands, Ecuador, and vocalizations were tape recorded systematically to gain insight into the function of sperm whale vocalizations known as codas.
Abstract: To gain insight into the function of sperm whale vocalizations known as codas (short, patterned series of clicks), sperm whales (Physeter macrocephalus) were tracked continuously for periods of day...
TL;DR: Habituation selection in the common eider, Somateria mollissima L., wintering in the Gulf of St. Lawrence, eastern Canada, predicted that they should select feeding habitats characterized by high prey density and shallow water to minimize the time and energy spent while diving.
Abstract: We studied habitat selection in relation to prey density and water depth in the common eider, Somateria mollissima L., wintering in the Gulf of St. Lawrence, eastern Canada. In this region, eiders are confronted with low temperatures, ice cover, and reduced day length. We predicted that they should select feeding habitats characterized by high prey density and shallow water to minimize the time and energy spent while diving. About 1000 flocks were localized by triangulation on our study site (20.5 km2). We inferred the diving depth and the habitat being used from the position of eiders on bathymetric and community maps. The highest density of prey occurred in shallow water reefs where there were patches of blue mussels, Mytilus edulis L., and green sea urchins, Strongylocentrotus droebachienensis (Muller). Despite the fact that eiders can dive to depths as great as 42 m to feed, they strongly aggregate in shallow water, and their distribution closely coincides with the highest density of prey. The degree ...
TL;DR: To help distinguish the species, internal and external features, ultrastructure, and composition of D. polymorpha, M. leucophaeata, and the quagga mussel shells were determined using stereoscopic, scanning electron microscopic, and X-ray diffraction techniques.
Abstract: Dreissena polymorpha, recently introduced to freshwater habitats of North America, has been confused with Mytilopsis leucophaeata, a related species that is native to brackish and fresh waters of North America. The 1991 discovery of a second exotic dreissenid mussel, the "quagga" mussel, suggests there may be more than one species of Dreissena in the Great Lakes, resulting in even more confusion in identification within the family Dreissenidae. To help distinguish the species, internal and external features, ultrastructure, and composition of D. polymorpha, M. leucophaeata, and quagga mussel shells were determined using stereoscopic, scanning electron microscopic, and X-ray diffraction techniques. The most reliable diagnostic feature is the presence of an apophysis in M. leucophaeata and its absence in D. polymorpha and the quagga mussel. Mytilopsis leucophaeata and quagga mussels also lack the acute shoulder or ridge located ventrolaterally. Dreissena polymorpha, M. leucophaeata, and the quagga mussel al...
TL;DR: There were no significant differences between years or sexes in the age and mass at weaning or in the rate of mass loss during the postweaning period of harbour seal pups on Sable Island, Canada.
Abstract: We studied changes in body mass and body composition of harbour seal pups from weaning to 5 – 6 weeks postweaning in June – August 1988 and 1989 on Sable Island, Canada. Known-age pups (n = 52) were captured at 3-day intervals from late lactation through about 40 days postweaning. Pups were weaned, on average, at 24.1 ± 0.44 days (mean ± SE) postpartum at a body mass of 24.9 ± 0.45 kg. There were no significant differences between years or sexes in the age and mass at weaning or in the rate of mass loss during the postweaning period. The duration of the postweaning fast averaged from 15 – 17 days as assessed by stomach lavage. The rate of mass loss was independent of weaning mass. At weaning, pups contained an average of 47.7% water and 32.8% fat, based on deuterium oxide dilution. During the first 14 days postweaning, the estimated body composition of pups did not change, despite the loss of body mass. Over the next 26 days, the estimated percent body water increased to about 63% and body fat declined to...