The ontogeny of antipredator behavior: age differences in California ground squirrels (Otospermophilus beecheyi) at multiple stages of rattlesnake encounters

Newborn offspring of animals often exhibit fully functional innate antipredator behaviors, but they may also require learning or further development to acquire appropriate responses. Experience allows offspring to modify responses to specific threats and also leaves them vulnerable during the learning period. However, antipredator behaviors used at one stage of a predator encounter may compensate for deficiencies at another stage, a phenomenon that may reduce the overall risk of young that are vulnerable at one or more stages. Few studies have examined age differences in the effectiveness of antipredator behaviors across multiple stages of a predator encounter. In this study, we examined age differences in the antipredator behaviors of California ground squirrels (Otospermophilus beecheyi) during the detection, interaction, and attack stages of Pacific rattlesnake (Crotalus oreganus) encounters. Using free-ranging squirrels, we examined the ability to detect free-ranging rattlesnakes, snake-directed behaviors after discovery of a snake, and responses to simulated rattlesnake strikes. We found that age was the most important factor in snake detection, with adults being more likely to detect snakes than pups. We also found that adults performed more tail flagging (a predator-deterrent signal) toward snakes and were more likely to investigate a snake’s refuge when interacting with a hidden snake. In field experiments simulating snake strikes, adults exhibited faster reaction times than pups. Our results show that snake detection improves with age and that pups probably avoid rattlesnakes and minimize time spent in close proximity to them to compensate for their reduced reaction times to strikes

A pooled analysis of dietary sugar/carbohydrate intake and esophageal and gastric cardia adenocarcinoma incidence and survival in the USA

Background: During the past 40 years, esophageal/gastric cardia adenocarcinoma (EA/ GCA) incidence increased in Westernized countries, but survival remained low. A parallel increase in sugar intake, which may facilitate carcinogenesis by promoting hyperglycaemia, led us to examine sugar/carbohydrate intake in association with EA/GCA incidence and survival. Methods: We pooled 500 EA cases, 529 GCA cases and 2027 controls from two US population-based case-control studies with cases followed for vital status. Dietary intake, assessed by study-specific food frequency questionnaires, was harmonized and pooled to estimate 12 measures of sugar/carbohydrate intake. Multivariable-adjusted odds ratios (ORs) and hazard ratios [95% confidence intervals (CIs)] were calculated using multinomial logistic regression and Cox proportional hazards regression, respectively. Results: EA incidence was increased by 51-58% in association with sucrose (ORQ5vs.Q1=1.51, 95% CI=1.01-2.27), sweetened desserts/beverages (ORQ5vs.Q1=1.55, 95% CI=1.06-2.27) and the dietary glycaemic index (ORQ5vs.Q1=1.58, 95% CI=1.13-2.21). Bodymass index (BMI) and gastro-esophageal reflux disease (GERD) modified these associations (Pmultiplicative-interaction ≤ 0.05). For associations with sucrose and sweetened desserts/beverages, respectively, the OR was elevated for BMI < 25 (ORQ4-5vs.Q1-3=1.79, 95% CI=1.26-2.56 and ORQ4-5vs.Q1-3=1.45, 95% CI=1.03-2.06), but not BMI≥25 (ORQ4-5vs.Q1-3=1.05, 95% CI=0.76-1.44 and ORQ4-5vs.Q1-3=0.85, 95% CI=0.62-1.16). The EA-glycaemic index association was elevated for BMI≥25 (ORQ4-5vs.Q1-3=1.38, 95% CI=1.03-1.85), but not BMI < 25 (ORQ4-5vs.Q1-3=0.88, 95% CI=0.62-1.24). The sucrose-EA association OR for GERD < weekly was 1.58 (95% CI=1.16-2.14), but for GERD≥weekly was 1.01 (95% CI=0.70-1.47). Sugar/carbohydrate measures were not associated with GCA incidence or EA/GCA survival. Conclusions: If confirmed, limiting intake of sucrose (e.g. table sugar), sweetened desserts/ beverages, and foods that contribute to a high glycaemic index, may be plausible EA risk reduction strategies