Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 78-79)

The raccoon (Procyon lotor) is a species that has likely benefited from environmental conditions that followed European settlement of North America. As such, the raccoon has experienced vast range expansion during the past century, moving northward across the continent. However, little is known about the factors that currently govern the northern distribution and the ecology of raccoons at the northern edge of its range. Thus, I studied the population dynamics and social ecology of raccoons in southern Manitoba during spring, summer, and autumn, 2002-2005.<p>To understand how intrinsic and extrinsic factors affected population dynamics, I examined how winter severity, body condition, age, and gender influenced over-winter survival of raccoons. Winter severity (measured by temperature and snow accumulation) was the most important factor influencing survival (â = 1.08, 95% CI = 0.99-1.17). Over-winter survival estimates ranged from 0.51 (95% CI: 0.41, 0.75) during the harshest winter to 0.84 (95% CI: 0.71, 0.97) during the mildest winter on record for Manitoba. There was no apparent relationship between autumn body condition and autumn food indices and no correlation between autumn and spring body condition. Adults experienced higher survival than yearlings while males had a greater chance of dying compared to females. Variation in abundance natural food items thought to be important during autumn hyperphagia are likely overwhelmed by the presence of grain as an alternative food source, as autumn body condition was constant across all years and plateaued at ca. 20% body fat. I conclude that changes in climatic conditions will likely have the greatest impact on raccoon demographics, with milder winters leading to higher survival. <p>I also examined the spatial ecology of raccoons to determine if spacing behaviour could limit population growth and to test hypotheses regarding social tolerance and the formation of male coalition groups. Female home ranges were regularly spaced throughout the study site, with minimal spatio-temporal overlap among adult females. However, there where instances where females did display tolerance among conspecifics as well as the ability to partition areas of overlap to use them dissimilarly. While females were generally non-gregarious, plasticity in social tolerance likely precludes spacing behavior from regulating densities of this population. Male social behavior was more complex than previously described for northern populations; most adults (ca. 80%) formed a coalition pair with another male. There was little overlap among male groups and high overlap within groups. The dynamic interaction tests confirmed association in movements for male dyads. Male coalition groups formed despite females being regularly spaced, which contradicts working hypotheses of mechanisms explaining grouping behavior in male carnivores. I propose that group formation occurred because of the benefits that dominant males received through increased efficiency in territory maintenance and the increased likelihood of territory inheritance by subordinate males.

The raccoon (Procyon lotor) is a species that has likely benefited from environmental conditions that followed European settlement of North America. As such, the raccoon has experienced vast range expansion during the past century, moving northward across the continent. However, little is known about the factors that currently govern the northern distribution and the ecology of raccoons at the northern edge of its range. Thus, I studied the population dynamics and social ecology of raccoons in southern Manitoba during spring, summer, and autumn, 2002-2005.<p>To understand how intrinsic and extrinsic factors affected population dynamics, I examined how winter severity, body condition, age, and gender influenced over-winter survival of raccoons. Winter severity (measured by temperature and snow accumulation) was the most important factor influencing survival (â = 1.08, 95% CI = 0.99-1.17). Over-winter survival estimates ranged from 0.51 (95% CI: 0.41, 0.75) during the harshest winter to 0.84 (95% CI: 0.71, 0.97) during the mildest winter on record for Manitoba. There was no apparent relationship between autumn body condition and autumn food indices and no correlation between autumn and spring body condition. Adults experienced higher survival than yearlings while males had a greater chance of dying compared to females. Variation in abundance natural food items thought to be important during autumn hyperphagia are likely overwhelmed by the presence of grain as an alternative food source, as autumn body condition was constant across all years and plateaued at ca. 20% body fat. I conclude that changes in climatic conditions will likely have the greatest impact on raccoon demographics, with milder winters leading to higher survival. <p>I also examined the spatial ecology of raccoons to determine if spacing behaviour could limit population growth and to test hypotheses regarding social tolerance and the formation of male coalition groups. Female home ranges were regularly spaced throughout the study site, with minimal spatio-temporal overlap among adult females. However, there where instances where females did display tolerance among conspecifics as well as the ability to partition areas of overlap to use them dissimilarly. While females were generally non-gregarious, plasticity in social tolerance likely precludes spacing behavior from regulating densities of this population. Male social behavior was more complex than previously described for northern populations; most adults (ca. 80%) formed a coalition pair with another male. There was little overlap among male groups and high overlap within groups. The dynamic interaction tests confirmed association in movements for male dyads. Male coalition groups formed despite females being regularly spaced, which contradicts working hypotheses of mechanisms explaining grouping behavior in male carnivores. I propose that group formation occurred because of the benefits that dominant males received through increased efficiency in territory maintenance and the increased likelihood of territory inheritance by subordinate males.

Thesis (Ph.D.)--Pennsylvania State University, 2007. / Mode of access: World Wide Web.

Thesis (Ph.D.)--Pennsylvania State University, 2007. / Mode of access: World Wide Web.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 67-76). Also available via the Internet.

In response to an epidemic of rabies in the mid-Atlantic region, the Virginia Department of Health and the Consolidated Laboratory Services in 1982, redesigned their submission forms for animals being tested for rabies in an effort to elicit detailed information about the epidemiology of rabies in Virginia. The information collected from those submission forms was used in a mathematical model analysis of the epidemiology of raccoon rabies in Virginia for the years 1984 through 1987. Eleven explanatory variables and one response variable (positivity for rabies) were examined. The objective of this study was to develop a model, through logistic regression, that would explain the epidemiology of rabies in raccoons in Virginia, and determine the risk factors for prediction for positivity for rabies in raccoons in Virginia. This information would aid further surveillance efforts, preventive education programs, and in formulating future oral vaccination programs in raccoons. Multiway contingency tables were constructed (involving 2,3,4,5,and 6 way interactions), and log-linear models were fitted using an iterative fitting process to generate maximum likelihood estimates. The goodness of fit of each model was judged using the likelihood-ratio-chi-square p value (0.01). The backward stepwise model selection process was performed on logit models to find the best fitting model (0.01). The final model consisted of a combination of 17 four variable term models. Eight of the eleven explanatory variables remained important risk factors in the prediction of positivity for rabies in raccoons. To validate the model, it was applied to data collected in the years 1988 through July 1989. The model fit at the 0.01 level. Parameter estimates were calculated for each term in the model. All eight variables had main order effects (direct) on the response variable (positivity for rabies). Three second order effects were evident: age and season, behavior and season, and year and season. Future studies will involve applications of this model to other species to further explore the epidemiology of rabies, and to refine the model for practical applications. / Ph. D.

Ph.d.-afhandling. University of Helsinki, 2006. / Også elektronisk adgang via Internettet.

This study investigated selective pressures associated with encephalization in mammals and discussed broader implications. Relative brain size as measured by EQ (Encephalization Quotient) was compared between ecological categories. Omnivores had higher average EQ than ecological specialists. Since specialists are disproportionately affected by extinction events, selection for ecological generalism is proposed as encephalization mechanism. This mechanism may reinforce the more widely known Cognitive Buffer Hypothesis (CBH)—the idea that possessing relatively large brains has buffered lineages against environmental change. CBH is tested here by comparing EQs in Procyon lotor (raccoon) in urban and rural environments. CBH predicts that raccoons in the most radically altered environment, the city, experience the strongest selection for encephalization. Urban raccoons studied here exhibit a higher EQ. Although results are preliminary, data suggest that encephalization is accelerated during abrupt periods of environmental change. Finally, implications for the evolution of biological complexity more generally are discussed.

Le raton laveur (Procyon lotor) est porteur de nombreux parasites dont certains sont des agents de zoonose. Il nous est apparu opportun d’étudier la faune parasitaire intestinale du raton laveur québécois, particulièrement l’espèce Baylisascaris procyonis. L’étude a donc porté sur l’examen de matières fécales (n = 301) et de contenus intestinaux (n = 203) de 351 ratons laveurs provenant de deux programmes gouvernementaux sur la rage du raton laveur et d’excréments (n = 409) provenant de latrines dans des parcs nationaux du Québec. Des oeufs de B. procyonis étaient excrétés par 23,3 % des ratons laveurs, alors que 29,1 % étaient porteurs de vers. La charge parasitaire moyenne des vers B. procyonis de tout stade variait de 8,5 chez les adultes à 27,1 chez les juvéniles. Chez ces derniers, la charge parasitaire était 11,4 fois supérieure à celle des ratons adultes (p < 0,0001) dont 23,7 fois plus de vers immatures (p < 0,0001) et 9,1 fois plus de vers matures (p = 0,01). Le nombre d’oeufs était 24,7 fois plus élevé chez les ratons juvéniles (p = 0,02) et 50,0 fois moins élevé chez la femelle allaitante. La probabilité du raton d’excréter des oeufs l’automne était de 11,1 (IC95 %: 1,21-101,60) par rapport au printemps et de 21,1 (IC95 %: 2,91-153,18) par rapport à l’été (p < 0,01). La sensibilité (Se) et la spécificité (Sp) de la coproscopie comparée à la nécropsie (norme étalon) ont été calculées en se basant sur l’observation des vers matures (Se : 81,8 %; Sp : 97,7 %) et des vers de tout stade (Se : 53,9 %; Sp : 97,0 %). De plus, la recherche des parasites intestinaux nous a permis de découvrir des ookystes de Giardia (6/159), espèce parasitaire nouvellement rapportée chez le raton. En 2007, nous avons trouvé, par échantillonnage unique, des oeufs de B. procyonis dans 15,8 % des latrines (n = 165) identifiées dans des parcs nationaux du sud du Québec et en 2008, par échantillonnage multiple, dans 89,7 % des latrines (n = 26) actives situées dans des secteurs accessibles à l’homme dans trois parcs nationaux de la Montérégie. Le potentiel zoonotique de B. procyonis est un problème de santé publique qui pourrait devenir sérieux étant donné le pourcentage élevé de ratons laveurs qui excrètent le parasite et qui contaminent des secteurs accessibles par les humains. / Raccoons are carriers of many parasites, some of which are zoonotic. We wanted to expand our knowledge of the Quebec raccoon intestinal parasitic fauna, specifically the Baylisascaris procyonis species. The study consisted of fecal matter (n = 301) and intestinal content examinations (n = 203) collected from 351 raccoons originating from two government programs on raccoon’s rabies and excrements collected (n = 409) from latrines in Quebec national parks. Eggs from B. procyonis were excreted by 23.3 % of raccoons while 29.1 % were worm carriers. The average parasitic burden of all stages of B. procyonis worms varied from 8.5 in adults to 27.1 in juveniles. In juveniles, the parasitic burden was 11.4 times superior to adult raccoons (p < 0.0001) with 23.7 times more immature worms (p < 0.0001) and 9.1 times more mature worms (p = 0.01). The number of eggs was 24.7 times superior in juvenile raccoons (p = 0.02) and 50.0 times lower in breast-feeding females. The probability of raccoons excreting eggs in autumn was 11.1 (IC95 %: 1.21-101.60) in comparison to spring and 21.1 (IC95 %: 2.91-153.18) in comparison to summer (p < 0.01). The sensitivity (Se) and specificity (Sp) of coproscopy compared to necropsy (gold standard) were calculated based on observations of mature worms (Se: 81.8 %; Sp: 97.7 %) and worms of all stages (Se: 53.9 %; Sp: 97.0 %). In addition, our intestinal parasitic research permitted the finding of Giardia oocysts (6/159), which is a newly found parasite species in raccoons. In 2007, B. procyonis eggs were found in 15.8 % of latrines (n = 165) identified in Southern Quebec national parks and in 89.7% of active latrines (n = 26) in three Eastern Townships national parks sites accessible to man in 2008. The zoonotic potential of B. procyonis is a public health issue that could become serious considering the high percentage of raccoons excreting the parasite thus contaminating sectors accessible to man.