Showing papers in "Canadian Journal of Zoology in 1987"
TL;DR: New data on guppies (Poecilia reticulata) are presented and the recent literature is reviewed to support the notion that animals in such situations behave so as to maximize fitness.
Abstract: It is virtually impossible to predict the next 25 years of research in aquatic ecology and behaviour with any accuracy. However, by identifying those areas that are the current frontiers of the dis...
368 citations
TL;DR: If reduction in relative surface area is indeed an adaptation to conserve heat, then mammals should increase in size from south to north at rates two orders of magnitude greater than they do, and Bergmann's rule has no basis in fact or theory.
Abstract: Bergmann's rule, claiming that in homeotherms body size increases inversely with temperature so that, intraspecifically, body size increases latitudinally, is not valid, nor is the explanation of t...
356 citations
TL;DR: The literature on the substrates, enzymes, pathway, regulation, and physiological function of gluconeogenesis in teleost fishes is reviewed and it is suggested that the third task can be achieved only through the integration of an isolated enzyme to whole organism.
Abstract: The literature on the substrates, enzymes, pathway, regulation, and physiological function of gluconeogenesis in teleost fishes is reviewed. The information presently available reveals considerable...
249 citations
TL;DR: Handling time for prey of different sizes and morphological types was studied in the largemouth bass (Micropterus salmoides) and results indicated that handling time was influenced by prey size and shape.
Abstract: Handling time for prey of different sizes and morphological types was studied in the largemouth bass (Micropterus salmoides). Prey ranged in size from about 1/10 to 2/3 the length of the bass. Hand...
196 citations
TL;DR: The authors monitored echolocation calls to measure the activity of insectivorous bats at study sites in southwestern Ontario during the summer of 1985, relying on feeding buzzes to identify foraging activity.
Abstract: We monitored echolocation calls to measure the activity of insectivorous bats at study sites in southwestern Ontario during the summer of 1985, relying on feeding buzzes to identify foraging activi...
195 citations
TL;DR: Consistent evidence from several biological disciplines shows that protowings evolved from thoracic side lobes, which probably originated from serial, articulated outer appendages of the arthropodan leg.
Abstract: A new Upper Carboniferous japygid, Testajapyx thomasi n.gen. et n.sp., shows that only Diplura of Entognatha shared an ancestral ground plan with Insecta–Ectognatha. Pleuron, palps, thoracic and ab...
174 citations
TL;DR: Before calving and after birth, caribou cows sought to space themselves out on snow-free areas in small aggregations at high elevations above treeline to increase the distance between themselves and wolves and bears travelling in the valley bottoms, as well as the main alternate prey, moose, which calved only in forest cover at lower elevations.
Abstract: Survival of caribou (Rangifer tarandus) calves until 4 months of age was monitored for 8 years in four herds in northern British Columbia, Canada. The chief cause of mortality was predation by wolv...
171 citations
TL;DR: Observations of calves feeding suggest that weaning may begin when calves are 5–6 months of age, and that females with calves associate with other whales less frequently than females without calves.
Abstract: Humpback whale mother–calf pairs from a currently unexploited population were observed in Massachusetts Bay between 1979 and 1985. During this period, 44 individually identified mature females were observed, with a total of 72 calves. Of the 20 mothers observed with more than one calf during the study period, 12 had two calves and 8 had three calves. The observed calving intervals were 1 year (n = 1), 2 years (n = 16), 3 years (n = 10), and 4 years (n = 1). The crude birth rate varied from a low of 0.045 in 1981 to a high of 0.103 in 1983 (mean = 0.075). An alternative calculation of reproductive rate yielded a range of 0.30–0.43 calves per mature female per year. Mature females were observed significantly more frequently in years when they had a calf than in years when they did not. Females with calves associate with other whales less frequently than females without calves. Observations of calves feeding suggest that weaning may begin when calves are 5–6 months of age. Forty-five of the 49 calves born be...
163 citations
TL;DR: The narrow distribution of δ13C values for Western Gulls from the Southeast Farallon Island colony suggests that gull colonies may be calibrated so that changes in dependence on terrestrial protein can be monitored.
Abstract: Stable-carbon isotope analyses of bone collagen of gulls (Larus spp.) were used to estimate the relative proportion of marine and terrestrial protein in the diets of gulls that are known to use both types of food sources. Mean δ13C values for Glaucous-winged Gulls (n = 23) collected at a Vancouver dump and for Western Gulls (n = 18) from Southeast Farallon Island were −15.0 ± 1.3 and −15.1 ± 0.5‰, respectively. No significant difference in δ13C values was found between adult male and female Western Gulls. Archaeological gull bones (n = 3) show a mean δ13C value of −13.6 ± 1.0‰ and support the assumed marine end point of −13.0‰. The range of terrestrial protein in the diets of coastal gulls was 0–61%. The narrow distribution of δ13C values for Western Gulls from the Southeast Farallon Island colony suggests that gull colonies may be calibrated so that changes in dependence on terrestrial protein can be monitored.
142 citations
TL;DR: Energy expenditure during locomotion on a level treadmill, up and down slopes, and in snow was measured for barren-ground caribou and compared with that of other species.
Abstract: Energy expenditure during locomotion on a level treadmill, up and down slopes, and in snow was measured for barren-ground caribou (Rangifer tarandus granti) and compared with that of other species ...
140 citations
TL;DR: Testing the hypotheses that small-bodied ruminant browsers have higher weight-specific dry matter intake rates, shorter retention times, and lower digestive efficiency than larger-bodied grazers found that retention time is inversely related to dietary browse concentration found that this hypothesis was correct.
Abstract: We tested the hypotheses that small-bodied ruminant browsers have higher weight-specific dry matter intake rates, shorter retention times, and lower digestive efficiency than larger-bodied grazers,...
TL;DR: Mature females depleted reserves of dissectiblefat and muscle considerably during both winters of the study, particularly the second, when nearly all dissectible fat and 32% of estimated fall muscle mass were lost.
Abstract: Twelve collections of mature female caribou and calves (Rangifer tarandus groenlandicus) were conducted between June 1982 and June 1984 on Coats Island, Northwest Territories, Canada, to study seasonal changes in body composition in this winter mortality limited population. Mature females depleted reserves of dissectible fat and muscle considerably during both winters of the study, particularly the second, when nearly all dissectible fat and 32% of estimated fall muscle mass were lost. Recovery of fat and muscle was rapid during the two summers, because of good quality forage and little environmental disturbance. Lactation appeared to slow fattening in early summer 1983, but by October females achieved fatness similar to that in 1982, when a majority of females in summer and fall were nonlactating. Low rumen fill and consistently high fat and muscle levels in fall 1982 and 1983 suggested that mature females then approached "set points" in body fat and muscle content. Calves grew rapidly in summer; most of...
TL;DR: Fecal pellet counts provide a quick and accurate method for snowshoe hare censuses on an extensive scale and are related to the variance of these counts by Taylor's power law with exponent 1.30, indicating a clumped pattern in turd deposition.
Abstract: We counted the number of snowshoe hare (Lepus americanus) fecal pellets on 50 quadrats of 0.155 m2 on each of six areas near Kluane Lake, Yukon Territory, once a year from 1977 to 1983. On four of these areas we livetrapped hares once a month and estimated population density from the Jolly–Seber model. Average hare density for the year was linearly related to fecal pellet counts (r = 0.94) over the range 0–10 hares/ha. Mean turd counts also are related to the variance of these counts by Taylor's power law with exponent 1.30, indicating a clumped pattern in turd deposition. Fecal pellet counts provide a quick and accurate method for snowshoe hare censuses on an extensive scale.
TL;DR: It is argued that elevated plasma levels of epinephrine in the first 12 h of hypercapnia may serve to stabilize red blood cell pH during the severe reduction of whole blood pH, thereby preventing excessive depressions of arterial oxygen content.
Abstract: Branchial solute fluxes as well as blood respiratory, ionic, and acid–base variables were monitored before, during, and after 72 h of exposure to external hypercapnia (1% CO2; ). Hypercapnia induced an immediate extracellular respiratory acidosis that was gradually regulated over the 72-h period by an elevation of the plasma bicarbonate level. Red blood cell pH changed in a manner similar to whole blood pH but the reduction of red blood cell pH during hypercapnia was significantly less than that predicted from in vitro experiments. We argue that elevated plasma levels of epinephrine in the first 12 h of hypercapnia may serve to stabilize red blood cell pH during the severe reduction of whole blood pH, thereby preventing excessive depressions of arterial oxygen content. Elevated external CO2 tension caused changes in the branchial net flux (JnetCl−) such that the arithmetic difference between sodium net flux (JnetNa+) and JnetCl− (JnetNa+ – JnetCl−) increased during hypercapnia and then decreased post-hype...
TL;DR: It is shown that seasonal changes in odor preference and behavioral interactions coincide with varying patterns of social organization and female exclusiveness during the breeding season is supported.
Abstract: Olfactory cues play a major role in inter- and intra-sexual agonistic behavior for Microtus pennsylvanicus. We show that seasonal changes in odor preference and behavioral interactions coincide wit...
TL;DR: The authors studied the components of mass transfer from mother to pup during the lactation period and weight loss by fasting pups postweaning in the hooded seal, Cystophora cristata.
Abstract: We studied the components of mass transfer from mother to pup during the lactation period and weight loss by fasting pups postweaning in the hooded seal, Cystophora cristata. Measurements were take...
TL;DR: It is concluded that behavioral and physiological reactions to chemical stimuli from predators do not change and that rinses from human skin or L-serine were behaviorally avoided, but neither stimulus induced physiological stress responses.
Abstract: Behavioral and physiological reactions were examined in juvenile coho salmon (Oncorhynchus kisutch) before and after the chemodetection of alarm substance and chemical stimuli released from predators and nonpredators. Chemical stimulus from northern squawfish (Ptychocheilus oregonensis) was avoided in a two-choice Y trough, whereas stimulus from the largescale sucker (Catostomus macrocheilus) was not. Paradoxically, both stimuli induced a stress response as indicated by elevations in plasma Cortisol and glucose. Plasma thyroxine was not a sensitive indicator of stress. Extracts from the broken skin of squawfish or suckers induced a physiological stress response, thereby raising the possibility of a nonostariophysan fish recognizing an ostariophysan alarm substance. Rinses from human skin or L-serine were behaviorally avoided, but neither stimulus induced physiological stress responses. A conclusion from these results is that behavioral and physiological reactions to chemical stimuli from predators do not ...
TL;DR: Five types of species can be identified in large mammals, and the evolution of three types, Ice Age giants, island dwarfs, and hybrids, can be explained, but not that of tropical food specialists and hybrids.
Abstract: Five types of species can be identified in large mammals. The evolution of three types, Ice Age giants, island dwarfs, and hybrids, can be explained, but not that of tropical food specialists and continental paedomorphs. Ice Age giants, which arose while colonizing latitudes (altitudes) with increasingly seasonal climates and productivity pulses, are characterized by ornate social organs, large bodies, and ecological plasticity. Colonizing landscapes with decreasing seasonality appears to conserve (or re-evolve) primitiveness, producing paedomorphs. Island dwarfs appear to be shaped by efficiency selection in the absence of predators. The explanation of mammalian Ice Age evolution hinges on the sensitivity of mammals to environmental factors, in particular nutrition. Extremes in food abundance generate extremes in phenotypes and selection regimes. Abundance is linked to colonization and selection for new social and ecological adaptations; scarcity is typical of settled areas and maintenance regimes. These...
TL;DR: Juvenile cod were more abundant in inshore areas with abundant fleshy macroalgae (Desmarestia spp.) than they were in green sea urchin dominated areas with only crustose coralline al...
Abstract: Juvenile cod (Gadus morhua) were more abundant in inshore areas with abundant fleshy macroalgae (Desmarestia spp.) than they were in green sea urchin dominated areas with only crustose coralline al...
TL;DR: Freeze tolerance and ice formation were examined in a population of Rana sylvatica from southern Ohio following their emergence in February and the directly determined time course of ice formation roughly paralleled the duration of the exotherm in this species.
Abstract: Freeze tolerance and ice formation were examined in a population of Rana sylvatica from southern Ohio following their emergence in February. Frogs were tolerant of freezing at −2.5 °C but did not s...
TL;DR: At some times of the year, certain zooplankton populations (especially noncolonial rotifers, small copepods, and small cladocerans) were strongly influenced by Chaoborus predation.
Abstract: Chaoborus populations were studied in two lakes in which fish predation was experimentally reduced, and in a reference lake. In Tuesday Lake, major reduction of fish predation led to substantial increases in density of Chaoborus punctipennis. Analysis of crop contents and estimates of consumption rates suggested that C. punctipennis caused declines of rotifer and copepod populations following the manipulations. In Peter Lake, lesser changes in fish predation caused no major change in density of Chaoborus flavicans, perhaps because food limitation compensated for effects of reduced predation. In both Peter Lake and the reference lake, Paul Lake, C. flavicans preyed heavily and selectively on Daphnia less than about 1.4 mm in total length. Bioenergetic calculations indicated that up to 46% of the daphnids were consumed daily. At some times of the year, certain zooplankton populations (especially noncolonial rotifers, small copepods, and small cladocerans) were strongly influenced by Chaoborus predation.
TL;DR: Weight of the intestinal tract with contents provides an indicator of daily food intake, but the gross dimensions of the alimentary tract cannot be used to differentiate between energy requirements and diet quality.
Abstract: Deer mice were maintained on diets diluted with 25, 30, and 45% fibre at 20 °C and on diets of standard laboratory chow at 20, 15, 10, and 5 °C to determine the effects of decreased diet quality and increased energy requirements on the dimensions of the alimentary tract. Weight of the small intestine with contents and of the caecum with contents showed the greatest responses to decreasing diet quality. These increased 59 and 61%, respectively, when diet contained 45% cellulose. Weight of the small intestine with contents showed the greatest response to increasing energy requirements by increasing 96% when temperatures were reduced to 5 °C. However, all weight and length measurements increased with both increased energy demands and decreased diet quality. Weight of the intestinal tract with contents provides an indicator of daily food intake, but the gross dimensions of the alimentary tract cannot be used to differentiate between energy requirements and diet quality.
TL;DR: A simple null model for scatterhoarding is presented, which demonstrates that prediction 1 is not exclusive to the Optimal Density Model and that "optimal densities" were not the primary goal of the caching animal, but rather the result of a positive relationship between food value and investment in caching.
Abstract: We observed a high degree of scatterhoarding in a population of red squirrels and tested two predictions of the Optimal Density Model (ODM): (1) large food items will be cached at a greater distanc...
TL;DR: The infracommunities of intestinal helminths in 96 birds belonging to four species of grebes taken from lakes in Alberta were examined for patterns of species co-occurrence and relative abundance.
Abstract: The infracommunities of intestinal helminths in 96 birds belonging to four species of grebes taken from lakes in Alberta were examined for patterns of species co-occurrence and relative abundance. Infracommunities were large (averages of 360–3640 worms) and complex (averages of 6.4–10.7 species). Three species of grebes (Aechmophorus occidentalis, Podiceps grisegena, P. nigricollis) had distinctive infracommunities, each characterized by a set (5–10) of frequent and numerous core helminth species, which regularly co-occurred with a consistent rank order of numbers. Infracommunities in Podiceps auritus overlapped those of the other two species of Podiceps and had few (2) core species. Most (11 of 14) core species are specialists in grebes, but only one was limited to a single host species. Most were shared among hosts, with the bulk of the population of each occurring in one host species. Sharing was particularly significant between the large, fish-eating grebes (A. occidentalis and P. grisegena) and betwe...
TL;DR: In the authors' sample, the pulse patterns of particular calls given by individual walruses in a series of vocalization cycles were nearly identical but were consistently different from the same call given by other animals.
Abstract: Adult male Atlantic walruses (Odobenus rosmarus rosmarus) vocalize extensively underwater during the breeding season. The individual calls are composed of one or more short repetitious pulses which may vary individually in the number, pattern, and rate at which they are given. Individual male walruses give repeated stereotyped vocalization cycles totalling several hundred pulses each for up to several hours at a time, both while the whole body is submerged and between breaths with the head submerged while at the surface. We analyzed the vocalization cycles of a sample of different walruses, and sound spectrograms of particular calls from within those cycles, to test the hypothesis that the stereotyped vocalizations of individuals are unique and recognizable. In our sample, the pulse patterns of particular calls given by individual walruses in a series of vocalization cycles were nearly identical but were consistently different from the same call given by other animals. One call, the diving vocalization of...
TL;DR: The results suggest that coexistence between these two species of larval salamanders results from a trade-off between exploitative and aggressive superiorities.
Abstract: We investigated the mechanisms of competition between two species of larval salamanders, Ambystoma talpoideum and Ambystoma maculatum. A laboratory experiment revealed that A. maculatum suffered higher mortality during early periods of larval growth when raised with its congener, A. talpoideum, than it did when combined with conspecifics. Ambystoma maculatum had no effect on the survivorship of A. talpoideum. However, A. maculatum inhibited the growth of A. talpoideum as well as that of conspecifics. This inhibition of growth may be evidence of exploitative competition for food. In a second experiment, A. talpoideum was more aggressive (a form of interference competition) than A. maculatum to both conspecific and heterospecific larvae. These results suggest that coexistence between these two species of larval salamanders results from a trade-off between exploitative and aggressive superiorities.
TL;DR: Behavioural observations indicated that the frequency of agonistic behaviours between individuals was important in still water, but decreased significantly in the presence of a water current, and growth, food conversion efficiency, and the deposition of lipids on the digestive tract were maximized at 0.85 bl/s.
Abstract: Yearling hatchery-reared brook charr, Salvelinus fontinalis Mitchill, were trained during a 20-day period at different water velocities: 0.00, 0.85, 1.72, and 2.50 body lengths/s (bl/s). Our result...
TL;DR: Female northern fur seals from St. Paul Island, Alaska, were equipped with head-mounted radio transmitters and located at sea to determine their movements and feeding locations during July and August, and the mean duration for feeding trips was significantly shorter than those observed in the 1960s and 1970s.
Abstract: Female northern fur seals (Callorhinus ursinus) from St. Paul Island, Alaska, were equipped with head-mounted radio transmitters and located at sea to determine their movements and feeding locations during July and August. In 1984, we followed 4 fur seals and located 7 others by ship; in 1985 we located 20 by airplane. Fur seals returned to the rookery during all hours of the day and showed no tendency to arrive during any specific hour; departure was principally from late afternoon to early morning but occurred anytime. Feeding trips averaged 5.9 days and increased in duration from 3.5 days for the first trip to over 7 days for later trips; the mean duration for feeding trips was significantly shorter than those observed in the 1960s and 1970s. During both years radio-tagged fur seals were found northwest and south-southwest of St. Paul Island and some had feeding trips resulting in round-trip distances of about 400 km; one had a round trip of about 740 km. During transit the seals swam in generally dire...
TL;DR: The present laboratory work reports on the agonistic and urinary behaviour of paired, hierarchically naive, male bank voles (Clethrionomys glareolus) before, during, and after free interaction in large enclosures provided with individual burrows.
Abstract: Available ecological data suggest that mature males of Clethrionomys species form stable hierarchical groups during the breeding season. The present laboratory work reports on the agonistic and uri...
TL;DR: Calculations of forces contributing to the expansion of the buccal cavity show that the engulfing process in feeding can be powered solely by the speed of swimming.
Abstract: The grooved throat wall of fin whales, Balaenoptera physalus, extends tremendously during feeding causing the whale to expand its profile from a cigar shape to the shape of an elongated, bloated tadpole. Ventral groove blubber associated with the engulfing feeding mechanism can be extended reversibly to as much as 4 times its resting length in the circumferential direction, and to 1.5 times its resting length along the long axis of the body. The muscle in the throat wall can be reversibly extended up to 3 times its resting length. Both these tissues have large amounts of the protein elastin in their microstructures that may function in retracting the expanded buccal cavity. Calculations of forces contributing to the expansion of the buccal cavity show that the engulfing process in feeding can be powered solely by the speed of swimming.