Ronald Brooks
University of Guelph, Integrative Biology, Faculty Member
We wished to determine whether free-ranging snapping turtles (Chelydra serpentina) would use aquatic and atmospheric basking to maintain body temperature at the mean temperature (28–30 °C) selected by snapping turtles placed in a... more
We wished to determine whether free-ranging snapping turtles (Chelydra serpentina) would use aquatic and atmospheric basking to maintain body temperature at the mean temperature (28–30 °C) selected by snapping turtles placed in a controlled aquatic thermal gradient. Body temperatures from eight adult snapping turtles in three different lakes in Algonquin Provincial Park were monitored by radiotelemetry during July and August 1987. Mean body temperature of all eight turtles over the study period was 22.7 °C, and mean temperature of every individual was well below the reported mean selected temperature for this species. The turtles did not maintain body temperatures near the available maximum environmental temperature. The mean body temperatures of the turtles were not significantly different among the three study lakes although these lakes had different physical characteristics. Similarly, there were no significant differences, among individual turtles, between air temperatures or operative environmental temperatures recorded concurrently with their body temperatures Nevertheless, mean body temperatures differed significantly among individuals; foraging tactics, metabolic rates, and home range structure may account for these differences.
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The chromosomes of 18 laboratory-born Dicrostonyx richardsoni (= D. groenlandicus richardsoni) were examined. Eight females had 2n = 44 and two large metacentric chromosomes, three females and two males had 2n = 43 and three large... more
The chromosomes of 18 laboratory-born Dicrostonyx richardsoni (= D. groenlandicus richardsoni) were examined. Eight females had 2n = 44 and two large metacentric chromosomes, three females and two males had 2n = 43 and three large metacentrics, and two females and three males had 2n = 42 and four large metacentrics. The observed chromosomal polymorphism was explained as a Robertsonian transformation in which metacentrics underwent centric fission to form two telocentrics, or two telocentrics fused to form a metacentric. No chromosomal differences were observed between males and females that had the same number of large metacentrics. The laboratory sex ratio at weaning was 0.38:1 (363 males, 596 females). Observed and expected distributions of proportions of male offspring among dams were significantly different if dams were assumed to produce males with binomial probability 0.5, or with probability 0.38. There was qualitative support for three female types, each producing males with probability 0.50, 0.25, or 0.33, as has been hypothesized for Dicrostonyx torquatus from Asia.
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Ages of 114 wild-caught beaver (Castor canadensis) had been estimated by cementum layer technique. Relationships between total lens dry weight, body weight, axillary girth, and these estimated ages are described. Total lens dry weight was... more
Ages of 114 wild-caught beaver (Castor canadensis) had been estimated by cementum layer technique. Relationships between total lens dry weight, body weight, axillary girth, and these estimated ages are described. Total lens dry weight was better than either body weight or axillary girth as a predictor of age. However, none of these criteria, whether used alone or in combination in a multiple regression model, allowed animals more than 1 year old to be placed into year classes with confidence. Linear regression of log10 body weight on log10 axillary girth yielded a slope of 2.0. The discrepancy between this value and slopes obtained for other species may reflect a functional difference in shape and growth of beaver.
Research Interests: Zoology, Animal Science, Biology, Body Size, Beaver, and 3 moreBody Weight, Linear Regression, and Dry Weight
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Using temperature-sensitive radio transmitters, we tested the hypothesis that recently fed snapping turtles (Chelydra serpentina) would inhabit warmer microhabitats than would unfed individuals. We used free-ranging adult turtles from a... more
Using temperature-sensitive radio transmitters, we tested the hypothesis that recently fed snapping turtles (Chelydra serpentina) would inhabit warmer microhabitats than would unfed individuals. We used free-ranging adult turtles from a population in Ontario, Canada near the northern limit of the species' distribution. In late July 1989, four radio-transmittered adults were fed by hand and their sub- sequent behavior and ambient temperature were recorded. Seven other radio-tagged individuals served as a control group. Following feeding, experimental turtles did not bask or experience an increase in habitat temperature, nor did they experience significantly warmer temperatures than did unfed controls. Instead, fed turtles buried themselves in the substrate and were less active and remained in shallower water than the control group. We conclude that in this population turtles do not use basking and thermophilic behavior to accelerate their rate of digestion.
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Four male snapping turtles (Chelydra serpentina) were located by radiotelemetry during the summers of 1985 and 1986 in 5.5-ha Broadwing Lake, Algonquin Park, Ontario. We measured sizes and overlaps of home ranges and core areas. Average... more
Four male snapping turtles (Chelydra serpentina) were located by radiotelemetry during the summers of 1985 and 1986 in 5.5-ha Broadwing Lake, Algonquin Park, Ontario. We measured sizes and overlaps of home ranges and core areas. Average size of home range did not differ greatly between years, and location of individual home ranges remained stable from one year to the next in two of three turtles studied both years. Within individual home ranges, the distribution of locations of most turtles was aggregated, but was not significantly different from Poisson distributions. Home ranges overlapped, but the proportion of areas used intensively by individuals was not different in overlapping and nonoverlapping areas, indicating that the areas of intensive use were not exclusive. However, the turtles spaced themselves farther apart than expected from the geometry of the home ranges, possibly the result of intraspecific aggression. If territory is defined as a fixed, exclusive, defended area, then male snapping turtles are not territorial during the summer, but occupy relatively stable home ranges which overlap, and whose spacing may in part be determined by aggressive interactions.
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Many oviparous reptiles nest in aggregations and with temporal synchrony. We hypothesized that these traits reflect attraction by conspecifics rather than limiting suitable habitat. We quantified whether Painted Turtles (Chrysemys picta... more
Many oviparous reptiles nest in aggregations and with temporal synchrony. We hypothesized that these traits reflect attraction by conspecifics rather than limiting suitable habitat. We quantified whether Painted Turtles (Chrysemys picta (Schneider, 1783)) in Algonquin Park, Ontario, Canada, were nesting communally, identified cues females used to select nest sites, and tested whether hatching success was higher in spatially clustered nests. We found that nests were closer to one another than expected by chance (i.e., were clustered), but that individual nest-site selection was only weakly influenced by microhabitat characteristics. Survival of clustered nests (49%) was not significantly higher than that of solitary nests (39%). When turtle models were placed on the nesting embankment, females nested most often with the highest density of models. Given that reproductive lifespan is the major axis of fitness and that there was little benefit to nest survival in clustered nests, we sug...
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The effects of conspecific densities on dispersal have been well documented. However, while positive and negative density-dependent dispersal based on conspecific densities often are shown to be the result of intraspecific competition or... more
The effects of conspecific densities on dispersal have been well documented. However, while positive and negative density-dependent dispersal based on conspecific densities often are shown to be the result of intraspecific competition or facilitation, respectively, the effects of heterospecific densities on dispersal have been examined far less frequently. This gap in knowledge warrants investigation given the potential for the analogous processes of interspecific competition and heterospecific attraction to influence dispersal patterns and behavior. Here we use a long-term live-trapping study of deer mouse (Peromyscus maniculatus), eastern chipmunk (Tamias striatus), red-backed vole (Myodes gapperi), and jumping mice (Napaeozapus insignis and Zapus hudsonius) to examine the effects of variation in conspecific and heterospecific abundances on dispersal frequency. In terms of conspecific abundance, jumping mice were more likely to disperse from areas with fewer conspecifics, while re...
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Body size may influence ectotherm behaviour by influencing heating and cooling rates, thereby constraining the time of day that some individuals can be active. The time of day at which turtles nest, for instance, is hypothesized to vary... more
Body size may influence ectotherm behaviour by influencing heating and cooling rates, thereby constraining the time of day that some individuals can be active. The time of day at which turtles nest, for instance, is hypothesized to vary with body size at both inter- and intra-specific levels because large individuals have greater thermal inertia, retaining preferred body temperatures for a longer period of time. We use decades of data on thousands of individual nests from Algonquin Park, Ontario, Canada, to explore how body size is associated with nesting behaviour in Painted Turtles (Chrysemys picta (Schneider, 1783); small bodied) and Snapping Turtles (Chelydra serpentina (Linnaeus, 1758); large bodied). We found that (i) between species, Painted Turtles nest earlier in the evening and at higher mean temperatures than Snapping Turtles, and (ii) within species, relatively large individuals of both species nest at cooler temperatures and that relatively larger Painted Turtles nest l...
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The consequences of individual variation in life‐history traits have been well studied due to their importance in evolutionary ecology. However, a trait that has received little empirical attention is the rate of indeterminate growth. In... more
The consequences of individual variation in life‐history traits have been well studied due to their importance in evolutionary ecology. However, a trait that has received little empirical attention is the rate of indeterminate growth. In long‐lived ectotherms, subtle variation in growth after maturity could have major effects over the animals’ lifetimes. These effects are difficult to measure due to the challenges involved in reliably estimating individual variation in the face of environmental stochasticity, and the need to account for trade‐offs among growth, reproduction and survival. However, modelling advances have made such analysis possible if long‐term high‐quality datasets are available. We used an integrated state‐space modelling framework to reveal relationships between indeterminate growth, reproduction and survival in a population of North American snapping turtles (Chelydra serpentina) using a 41‐year dataset for 298 adult females. A hierarchical version of the von Ber...
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Ictalurid catfishes have sharp spines on their dorsal and pectoral fins that can be hazardous to predators. The pectoral spines may lock in an abducted position, effectively increasing body size and preventing ingestion by gape-limited... more
Ictalurid catfishes have sharp spines on their dorsal and pectoral fins that can be hazardous to predators. The pectoral spines may lock in an abducted position, effectively increasing body size and preventing ingestion by gape-limited predators. Further, sharp spines may injure predators or increase prey handling time, affording catfish opportunities for escape. As part of a long-term mark–recapture study of turtle ecology in Algonquin Provincial Park, Ontario, Canada, we documented the presence of Brown Bullheads, Ameiurus nebulosus, in the diet of Snapping Turtles, Chelydra serpentina. Here, we report on injuries inflicted by the pectoral spines of bullheads on Snapping Turtles during predator–prey interactions and provide a brief literature review of the functional significance and potential dangers of catfish pectoral spines to predators.
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We compare diet and feeding behaviour of Snapping Turtles (Chelydra serpentina) and Midland Painted Turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada. We observed young Chelydra and Chrysemys turtles... more
We compare diet and feeding behaviour of Snapping Turtles (Chelydra serpentina) and Midland Painted Turtles (Chrysemys picta marginata) in Algonquin Provincial Park, Ontario, Canada. We observed young Chelydra and Chrysemys turtles feeding on insect and amphibian larvae in ephemeral ponds, adult Chrysemys terrestrially foraging on odonate larvae, and adult Chelydra consuming aquatic vegetation and seeds. These and other observations highlight the importance of seasonally available habitat and food for juvenile turtles. We also discuss the evidence for, and importance of, turtles as seed-dispersal agents for aquatic vegetation. Illustrative video recordings accompany our dietary observations.
Research Interests: Herpetology, Wetlands, Wildlife Biology, Biology, Seed Dispersal, and 14 moreDiet, Natural History, Ecology, Wetland Ecology, Foraging, Reptiles, Ecology of Amphibians and Reptiles, Turtles, Ecology and Conservation of Amphibians and Reptiles, Chelydra serpentina, Freshwater turtles, Freshwater Turtle Biology and Conservation, Juvenile, and VERNAL POOLS
Research Interests: Evolutionary Biology, Genetics, Zoology, Biology, Medicine, and 14 moreHeredity, Phylogeny, Canadian, Mitochondrial DNA, Animals, Karyotyping, Sympatric Speciation, Reproductive Isolation, Allopatric Speciation, Genetic Polymorphism, Phylogenetic Tree, Subspecies, Chromosomes, and DNA Restriction Enzymes
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Forage analyses revealed that mowed orchards provide a relatively high quality forage to meadow voles (Microtus pennsylvanicus), especially in the fallo Mowed forage was characterized by significantly higher protein and moisture content... more
Forage analyses revealed that mowed orchards provide a relatively high quality forage to meadow voles (Microtus pennsylvanicus), especially in the fallo Mowed forage was characterized by significantly higher protein and moisture content and significantly lower acid and neutral detergent fibre and lignin than forage from an abandoned orchard. Energy and fat were not significantly affected by mowing.. However, vole numbers declined markedly in mowed regions in comparison to undisturbed areas. Voles preferred to inhabit areas with dense cover even though vegetative dieback had occurred. Voles did not exhibit any distinct preference for either cracked corn (rodenticide carrier agent) or available forage at any time during the study. Voles did not change rates of forage consumption over the 6-month study. We conclude that mowing will not reduce acceptability of cracked corn and that removal of dense ground cover from the orchard would be one of the most effective and economical ways to r...
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A c t i v i t y and s o c i a l behavior o f f ree-ranging meadow voles (M ic ro tus pennsylvanicus) were examined i n summer, f a l l and w i n t e r using capture-recapture and radiotelemetry. The composition o f our study populat ion... more
A c t i v i t y and s o c i a l behavior o f f ree-ranging meadow voles (M ic ro tus pennsylvanicus) were examined i n summer, f a l l and w i n t e r using capture-recapture and radiotelemetry. The composition o f our study populat ion changed from predominantly reproduc t i ve ly -ac t i ve (RA) voles i n summer and f a l l t o e n t i r e l y nonreproductively-active (NR) voles i n w in te r . RA males had l a r g e r a c t i v i t y areas than RA females. A c t i v i t y areas o f RA females d i d n o t over lap w i t h those o f o ther RA females, b u t a c t i v i t y areas o f RA males overlapped extens ive ly w i t h those o f both RA males and RA females. However, any contact among RA voles was rare, unless females were estrous. NR voles showed greater over lap o f a c t i v i t y areas and lower l e v e l s o f a c t i v i t y than d i d RA voles. Space use and a c t i v i t y were s i m i l a r f o r NR males and females and t h e i r a c t i v i t y underwent l i t t l e...
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A province-wide eva lua t ion o f the amount, d i s t r i b u t i o n , source and c o n t r o l o f damage t o Ontar io apple t rees was i n i t i a t e d . Data wereobtained from 280 responses t o a quest ionnai re d i s t r i b u t e d... more
A province-wide eva lua t ion o f the amount, d i s t r i b u t i o n , source and c o n t r o l o f damage t o Ontar io apple t rees was i n i t i a t e d . Data wereobtained from 280 responses t o a quest ionnai re d i s t r i b u t e d t o growers across Ontario, and from t r a p censuses i n three widely separa ted areas. Meadow voles (Microtus pennsyl vani cus) damaged o r dest royed 8,423 t rees i n o u r quest ionnai re sample and o ther mamnals damaged another 10,307 t rees . No re1 a t ionsh ip was found between a p p l i c a t i o n o f roden t i c ide and l e v e l s o f damage, b u t roden t i c ide t rea ted b a i t s sharp ly reduced numbers o f voles on our t r a p p l o t s . Orchards wi t h h igh l e v e l s o f damage were on average only oneth i rd as l a r g e as the average orchard i n our t o t a l sample. A l l damage by voles appeared t o be caused by meadow voles and no p ine voles (M. pinetorum) were found. Numbers o f voles va r ied g r e a t l y among our...
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INTRODUCTION Corn depredation by red·winged blackbirds (Agelaius phoeniceus) has been an agricultural problem in southwestern Ontario for many years. Large marsh areas along the shoreline of Lakes Erie and St. Clair provide ideal habitat... more
INTRODUCTION Corn depredation by red·winged blackbirds (Agelaius phoeniceus) has been an agricultural problem in southwestern Ontario for many years. Large marsh areas along the shoreline of Lakes Erie and St. Clair provide ideal habitat for breeding and roosting. Concurrently, the vast monocultural field corn acreages in Kent and Essex Counties have over the years been the centers for blackbird depredation in the province. The expansion of corn production into other areas of Ontario has, however, resulted in a province·wide distribution of damage, and substantial crop losses for specific individual farmers (Tyler and Kannenberg, 1980). The Ontario Ministry of the Environment (OME) provided funding for a four·year research program on the importance, ecology and control of blackbirds in 1976 following mounting concern by Ontario corn producers. Dyer (1968) completed a major study on red-winged blackbirds in Dover Township, Kent County during the period 1964-68; however, the evaluatio...
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Forage analyses revealed that mowed orchards provide a relatively high quality forage to meadow voles (Microtus pennsylvanicus), especially in the fallo Mowed forage was characterized by significantly higher protein and moisture content... more
Forage analyses revealed that mowed orchards provide a relatively high quality forage to meadow voles (Microtus pennsylvanicus), especially in the fallo Mowed forage was characterized by significantly higher protein and moisture content and significantly lower acid and neutral detergent fibre and lignin than forage from an abandoned orchard. Energy and fat were not significantly affected by mowing.. However, vole numbers declined markedly in mowed regions in comparison to undisturbed areas. Voles preferred to inhabit areas with dense cover even though vegetative dieback had occurred. Voles did not exhibit any distinct preference for either cracked corn (rodenticide carrier agent) or available forage at any time during the study. Voles did not change rates of forage consumption over the 6-month study. We conclude that mowing will not reduce acceptability of cracked corn and that removal of dense ground cover from the orchard would be one of the most effective and economical ways to r...
The effects of conspecific densities on dispersal have been well documented. However, while positive and negative density-dependent dispersal based on conspecific densities are often shown to be the result of intraspecific competition or... more
The effects of conspecific densities on dispersal have been well documented. However, while positive and negative density-dependent dispersal based on conspecific densities are often shown to be the result of intraspecific competition or facilitation respectively, the effects of heterospecific densities on dispersal are examined far less frequently. This despite the potential for the analogous processes of interspecific competition and heterospecific attraction to influence dispersal. Here we use 51 years of live-trapping data on deer mouse (Peromsycus maniculatus), eastern chipmunk (Tamias striatus), red-backed vole (Myodes gapperi), and jumping mice (Napaeozapus insignis and Zapus hudsonius) to examine the effects of both conspecific and heterospecific densities on dispersal frequency. In terms of conspecific densities, jumping mice were more likely to disperse from areas of low conspecific densities, while red-backed voles and chipmunks did not respond to conspecific densities in...
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Dispersal is a fundamental ecological process, and population density has been observed as a driver of dispersal in various taxa. Conflicting examples of positive and negative density-dependent dispersal, however, leave little consensus... more
Dispersal is a fundamental ecological process, and population density has been observed as a driver of dispersal in various taxa. Conflicting examples of positive and negative density-dependent dispersal, however, leave little consensus regarding any general effects of density on dispersal. Deer mice (Peromyscus maniculatus) have exhibited both negative and positive density-dependent dispersal. Using 51-years of data on P. maniculatus live-trapping abundances, we examined the spatial scale of density-dependent dispersal as well as its temporal stability within this long time-series. We examined these patterns over both the entire time-series and also in ten-year shifting windows to determine whether the nature and strength of the relationship changed through time. Overall, the probability of dispersal decreased with increased local and regional population density, and the negative effect of local density on dispersal was more pronounced in years with low regional densities. Females ...
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After weaning, collared lemmings (Dicrostonyx groenlandicus) were exposed to 3 months of summer (S) photoperiod (18.5L:5.5D) or winter (W) photoperiod (6.5L: 17.5D) or to one of four 6-month photoperiod treatments (SS, SW, WW, or WS).... more
After weaning, collared lemmings (Dicrostonyx groenlandicus) were exposed to 3 months of summer (S) photoperiod (18.5L:5.5D) or winter (W) photoperiod (6.5L: 17.5D) or to one of four 6-month photoperiod treatments (SS, SW, WW, or WS). Lemmings were weighed every 3 weeks, and at the end of treatment, eye lenses were weighed and 10 body and 22 skull measurements were taken. At the end of treatment, W, SW, and WW lemmings did not differ in weight, but were significantly heavier than S, SS, and WS lemmings. Animals in WS were significantly heavier than those in SS and both were significantly heavier than S lemmings. The marked contrast of the photoperiodically induced growth pattern of Dicrostonyx groenlandicus with that of other microtines may be due to a relatively larger investment in winter reproduction by collared lemmings. Lemmings that died during the experiment were significantly larger both in body weight and skull size than those that survived. Eye lens weights of S and W lemm...
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Ages of 114 wild-caught beaver (Castor canadensis) had been estimated by cementum layer technique. Relationships between total lens dry weight, body weight, axillary girth, and these estimated ages are described. Total lens dry weight was... more
Ages of 114 wild-caught beaver (Castor canadensis) had been estimated by cementum layer technique. Relationships between total lens dry weight, body weight, axillary girth, and these estimated ages are described. Total lens dry weight was better than either body weight or axillary girth as a predictor of age. However, none of these criteria, whether used alone or in combination in a multiple regression model, allowed animals more than 1 year old to be placed into year classes with confidence. Linear regression of log10 body weight on log10 axillary girth yielded a slope of 2.0. The discrepancy between this value and slopes obtained for other species may reflect a functional difference in shape and growth of beaver.
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The chromosomes of 18 laboratory-born Dicrostonyx richardsoni (= D. groenlandicus richardsoni) were examined. Eight females had 2n = 44 and two large metacentric chromosomes, three females and two males had 2n = 43 and three large... more
The chromosomes of 18 laboratory-born Dicrostonyx richardsoni (= D. groenlandicus richardsoni) were examined. Eight females had 2n = 44 and two large metacentric chromosomes, three females and two males had 2n = 43 and three large metacentrics, and two females and three males had 2n = 42 and four large metacentrics. The observed chromosomal polymorphism was explained as a Robertsonian transformation in which metacentrics underwent centric fission to form two telocentrics, or two telocentrics fused to form a metacentric. No chromosomal differences were observed between males and females that had the same number of large metacentrics. The laboratory sex ratio at weaning was 0.38:1 (363 males, 596 females). Observed and expected distributions of proportions of male offspring among dams were significantly different if dams were assumed to produce males with binomial probability 0.5, or with probability 0.38. There was qualitative support for three female types, each producing males with...
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Temperature has a strong effect on ectotherm development rate. It is therefore possible to construct predictive models of development that rely solely on temperature, which have applications in a range of biological fields. Here, we... more
Temperature has a strong effect on ectotherm development rate. It is therefore possible to construct predictive models of development that rely solely on temperature, which have applications in a range of biological fields. Here, we leverage a reference series of development stages for embryos of the turtle Chelydra serpentina, which was described at a constant temperature of 20 °C. The reference series acts to map each distinct developmental stage onto embryonic age (in days) at 20 °C. By extension, an embryo taken from any given incubation environment, once staged, can be assigned an equivalent age at 20 °C. We call this concept "Equivalent Development", as it maps the development stage of an embryo incubated at a given temperature to its equivalent age at a reference temperature. In the laboratory, we used the concept of Equivalent Development to estimate development rate of embryos of C. serpentina across a series of constant temperatures. Using these estimates of deve...
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Life-histories evolve in response to constraints on the time available for growth and development. Nesting date and its plasticity in response to spring temperature may therefore be important components of fitness in oviparous ectotherms... more
Life-histories evolve in response to constraints on the time available for growth and development. Nesting date and its plasticity in response to spring temperature may therefore be important components of fitness in oviparous ectotherms near their northern range limit, as reproducing early provides more time for embryos to complete development before winter. We used data collected over several decades to compare air temperature - nest date plasticity in populations of painted turtles and snapping turtles from a relatively warm environment (southeastern Michigan) near the southern extent of the last glacial maximum, to a relatively cool environment (central Ontario) near the northern extent of post-glacial recolonization. For painted turtles, population-level differences in reaction norm elevation for two phenological traits were consistent with adaptation to time constraints, but no differences in reaction norm slopes were observed. For snapping turtle populations, the difference in reaction norm elevation for a single phenological trait was in the opposite direction of what was expected under adaptation to time constraints, and no difference in reaction norm slope was observed. Finally, among-individual variation in individual plasticity for nesting date was detected only in the northern population of snapping turtles, suggesting that reaction norms are less canalized in this northern population. Overall, we observed evidence of phenological adaptation, and possibly maladaptation, to time constraints in long-lived reptiles. Where present, (mal)adaptation occurred by virtue of differences in reaction norm elevation, not reaction norm slope. Glacial history, generation time, and genetic constraint may all play an important role in the evolution of phenological timing and its plasticity in long-lived reptiles. This article is protected by copyright. All rights reserved.
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Malignant neoplasms were present in 39/66 Dicrostonyx groenlandicus of varying ages, examined from a laboratory colony. The presence of multiple neoplasms in some resulted in an overall average of 1.15 tumors/affected animal. Gastric... more
Malignant neoplasms were present in 39/66 Dicrostonyx groenlandicus of varying ages, examined from a laboratory colony. The presence of multiple neoplasms in some resulted in an overall average of 1.15 tumors/affected animal. Gastric squamous papillomas were present in nine, and locally invasive or metastatic gastric squamous cell carcinomas in a further 36 animals. Three mammary adenocarcinomas, one pancreatic islet cell tumor, one probable pancreatic adenocarcinoma and one adrenal cortical adenoma were also seen in lemmings with gastric tumors. Two others had mammary adenocarcinoma alone, and one animal had bilateral Harderian gland adenocarcinoma. Lesions resembling glomerulonephrosis of rats were seen in 23/51 animals whose kidneys were examined. These findings were not considered artefacts of captivity since concurrent gastric squamous cell carcinoma, mammary adenocarcinoma and glomerulonephrosis were present in the single animal examined directly from the wild at Eskimo Point,...
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A preliminary examination was conducted of range size and distribution of female woodland caribou (Rangifer tarandus caribou) in northeastern Ontario. Annual and seasonal ranges were calculated using satellite telemetry data collected for... more
A preliminary examination was conducted of range size and distribution of female woodland caribou (Rangifer tarandus caribou) in northeastern Ontario. Annual and seasonal ranges were calculated using satellite telemetry data collected for 30 female caribou between 1998 and 2001. The mean annual home range size of collared females was 4026 km2. Seasonal ranges varied in size depending on time of year (P<0.05). Calving and summer ranges were significantly smaller than autumn and late winter ranges. Early winter ranges were significantly larger than calving ranges and smaller than late winter ranges. Overall, range sizes of female woodland caribou in northeastern Ontario were larger than those reported for caribou in other Boreal Forest regions across Canada.
Page 1. J. Parasitol., 76(2), 1990, p. 190-195 ? American Society of Parasitologists 1990 OCCURRENCE OF PLACOBDELLA PARASITICA (HIRUDINEA) ON SNAPPING TURTLES, CHELYDRA SERPENTINA, IN SOUTHEASTERN ONTARIO ...
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... Testing the Precision and Accuracy of Age Estimation Using Lines in Scutes of Chelydra serpentina and Chrysemys picta RONALD J. BROOKS, MARGARET A. KRAWCHUK, CAMERON STEVENS, AND NICOLA KOPER Department ...
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-- , AND J. VILLA R. 1986. Introduction to the herpetology of Costa Rica. Contr. to Herp., Soc. Stud. Amph. Rept. 3:1-207. SCOTT, N. J. 1969. A zoogeographic analysis of the snakes of Costa Rica. Unpubl. Ph.D. dissert., Uni- versity of... more
-- , AND J. VILLA R. 1986. Introduction to the herpetology of Costa Rica. Contr. to Herp., Soc. Stud. Amph. Rept. 3:1-207. SCOTT, N. J. 1969. A zoogeographic analysis of the snakes of Costa Rica. Unpubl. Ph.D. dissert., Uni- versity of Southern California.