Determinants of male reproductive success in American black bears

Costello, Cecily M.; Creel, Scott; Kalinowski, Steven T.; Vu, Ninh V.; Quigley, Howard

doi:10.1007/s00265-009-0828-0

Cited by 77 publications

(48 citation statements)

References 35 publications

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“…The result suggests that the body size of male bears is adapted to regional nutrient availability over several generations but not within a generation, and the geographical variation in diets causes the geographical variation in the body size of brown bear subpopulations. Generally, a larger size is advantageous when in competition for mates, so male body size should be related to reproductive success (McLellan 1994;Schwartz et al 2003;Zedrosser et al 2007;Costello et al 2009). Therefore, size should be an adaptive characteristic of male bears; they should exhibit larger overall sizes when the available nutrients are plentiful.…”

Section: Discussionmentioning

confidence: 99%

Testing for a predicted decrease in body size in brown bears (Ursus arctos) based on a historical shift in diet

et al. 2016

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A recent study found a historical decline in the proportion of meat in the diet of brown bears (Ursus arctos L., 1758) in the Hokkaido Islands, Japan. Because feeding habits are strongly correlated with the body size of animals, the shift in diet should have led to a decrease in the size of these bears. To predict the effects of this dietary shift on the skeletal size in bears, we correlated the femur length in Hokkaido brown bears with the carbon and nitrogen stable isotope values from bone samples and predicted the historical change in their body size. The variation in the femur lengths of the male and female subpopulations was positively correlated with their ␦ 15 N values, but not with their ␦ 13 C values, and the explanatory power of the constructed model was higher in males than in females. Based on the model and the ␦ 15 N values for historic and modern bears, the skeletal size of bear subpopulations in eastern Hokkaido was estimated to have decreased by 10%-18% for males and 8%-9% for females. Our results suggest that a historical dietary shift caused the decrease in the size of the Hokkaido brown bears.Key words: dietary shift, body size, brown bear, stable isotope, downsize, Ursus arctos. Résumé :Une étude récente établit une baisse historique de la proportion de viande dans le régime alimentaire des ours bruns (Ursus arctos L., 1758) dans les îles d'Hokkaido (Japon). Comme les habitudes d'alimentation sont fortement corrélées à la taille du corps des animaux, ce changement de régime devrait avoir mené à une diminution de la taille de ces ours. Afin de prédire les effets de ce changement de régime sur la taille des squelettes d'ours, nous avons corrélé la longueur du fémur d'ours bruns d'Hokkaido aux valeurs d'isotopes stables du carbone et de l'azote d'échantillons d'os et prédit le changement historique de la taille de leur corps. Les variations de la longueur des fémurs des sous-populations de mâles et de femelles présentaient une corrélation positive avec les valeurs de ␦ 15 N, mais pas avec les valeurs de ␦ 13 C, et la puissance explicative du modèle construit était plus grande pour les mâles que pour les femelles. À la lumière du modèle et des valeurs de ␦ 15 N pour les ours passés et actuels, il est estimé que les tailles des squelettes de sous-populations d'ours dans l'est d'Hokkaido ont diminué de 10 % à 18 % pour les mâles et de 8 % à 9 % pour les femelles. Nos résultats donnent à penser qu'un changement historique du régime alimentaire a causé une diminution de la taille des ours bruns d'Hokkaido. [Traduit par la Rédaction] Mots-clés : changement du régime alimentaire, taille du corps, ours brun, isotope stable, réduction de la taille, Ursus arctos.

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Section: Discussionmentioning

confidence: 99%

Testing for a predicted decrease in body size in brown bears (Ursus arctos) based on a historical shift in diet

et al. 2016

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“…The predictor variables for model building included sex (S ¼ 0 female and 1 male), age (A ¼ yr), age ). I initially created sex-specific models because growth curves show large differences between the sexes in rate of body size gain and mature weight (Mahoney et al 2001;Costello et al 2009;Bartareau 2011;Bartareau et al 2012). I tested for sex differences in model intercept and coefficient of predictor variables and combined models if they did not differ.…”

Section: Data Analysis and Model Buildingmentioning

confidence: 99%

“…I tested for sex differences in model intercept and coefficient of predictor variables and combined models if they did not differ. I assessed the effect of age as a quadratic function, assuming a nonlinear increase in growth to an asymptote (Mahoney et al 2001;Bartareau 2011) and decrease in weight associated with senescence (Noyce and Garshelis 1994;Costello et al 2009). I assessed the effect of body length because it is an indicator of skeletal size and maturity (Mahoney et al 2001;Bartareau 2011).…”

Section: Data Analysis and Model Buildingmentioning

confidence: 99%

“…Body weight is a particularly important measure of health for American black bears Ursus americanus, and serves as an indicator of the spatial and temporal variation in food habits (Mahoney et al 2001;McLellan 2011), nutritional condition (Cattet 1990;Noyce and Garshelis 1994;Cattet et al 2002), and growth (Mahoney et al 2001;Bartareau et al 2012), and influences reproductive and survival success (Elowe and Dodge 1989;Stringham 1990;Kovach and Powell 2003;Costello et al 2009). Smaller females cease embryo development and, as body weight increases, litter size increases while interbirth interval and age of primiparity decrease (reviewed in Stringham 1990;Noyce and Garshelis 1994;Samson and Huot 1995).…”

Section: Introductionmentioning

confidence: 99%

“…Smaller females cease embryo development and, as body weight increases, litter size increases while interbirth interval and age of primiparity decrease (reviewed in Stringham 1990;Noyce and Garshelis 1994;Samson and Huot 1995). Male reproductive success is dependent on the ability to thwart competitors, and larger males gain access to more females in estrus (Kovach and Powell 2003;Costello et al 2009). Collecting body weight measurement is therefore recommended during handling because demographic and reproductive variables are functionally dependent on weight rather than age.…”

Section: Introductionmentioning

confidence: 99%

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Estimating the Live Body Weight of American Black Bears in Florida

Bartareau

2016

Journal of Fish and Wildlife Management

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Measuring the live body weight of large-bodied animals can be impractical when equipment needed to weigh individuals is inadequate or unavailable. My objective here was to develop a model to accurately estimate the live body weight of black bears Ursus americanus floridanus in Florida based on the relationship between scale weight and sex, morphometric measurements, and age predictor variables obtainable in the field. I used an information-theoretic approach to evaluate simple and multiple linear regression models with 70% of the data, and evaluated the best model in the set using the remaining 30%. A sex-specific model was sustained because the intercept and coefficient of age variable in female and male modeled relationships differed significantly. Chest girth 2 was the best single predictor of body weight in each sex. A model including age, age 2 , and body length variables was better supported than chest girth 2 alone. I also created a reduced model to estimate body weight when personnel may not have an opportunity to determine a bear's age. Even though there was decreasing support for the reduced model, differences between the observed and estimated body weight of all models applied to the validation data set were not significant. The 95% confidence interval on the bias of the best model ranged from À1.9 to 1.6 kg in females and À1.4 to 2.1 kg in males. The 95% confidence interval of the reduced model ranged from À1.8 to 2.3 kg in females and À2.5 to 0.5 kg in males. The body weight estimation models can be used to provide more live body weight data from handled black bears in Florida that are not weighed with a scale.

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Integrating video and genetic data to estimate annual age‐structured apparent survival of American black bears

Reynolds‐Hogland¹,

Ramsey²,

Muench³

et al. 2022

Population Ecology

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Camera or genetic data are increasingly used to estimate wildlife abundance and density. We integrated video camera data with genetic data over 7 years to estimate annual age‐structured apparent survival of American black bears (Ursus americanus). We identified 70 individuals through meticulous scrutiny of 7531 video captures, cross‐referenced with 721 genetic captures from hair samples concurrently collected from stations in view of cameras. We used the Cormack–Jolly–Seber model in Program Mark to estimate annual age‐structured apparent survival for yearling males, yearling females, 2+ year‐old males, and 2+ year‐old females. We manually calculated cub survival. We compared parameter estimates based on combined video and genetic data with those based on only genetic data. Combining video and genetic data provided a means to test video‐based identification accuracy, which was highest for females (97%–100%). Annual apparent survival was highest for yearling females (φ = 0.92, SE = 0.07), followed by 2+ year‐old females (φ = 0.88, SE = 0.05), 2+ year‐old males (φ = 0.84, SE = 0.06), and yearling males (φ = 0.80, SE = 0.14). Annual cub survival (φ = 0.86, SE = 0.07) was likely biased because we could not account for mortality that occurred in‐den through early spring. Annual apparent survival and recapture probabilities derived from only genetic data were lower than those derived from combined video and genetic data. Our finding that noninvasive data can be used to estimate annual age‐structured apparent survival of a species with relatively indistinct traits is broadly relevant to wildlife research and conservation.

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Determinants of male reproductive success in American black bears

Cited by 77 publications

References 35 publications

Testing for a predicted decrease in body size in brown bears (Ursus arctos) based on a historical shift in diet

Testing for a predicted decrease in body size in brown bears (Ursus arctos) based on a historical shift in diet

Estimating the Live Body Weight of American Black Bears in Florida

Integrating video and genetic data to estimate annual age‐structured apparent survival of American black bears

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