Herr Mark W, Graham Sean P, Langkilde Tracy
Department of Biology, The Pennsylvania State University, USA.
Department of Biology, Geology, and Physical Sciences, Sul Ross State University, USA.
Gen Comp Endocrinol. 2017 Mar 1;243:89-95. doi: 10.1016/j.ygcen.2016.11.003. Epub 2016 Nov 5.
Stress is believed to be an important factor mediating animal behavior. Here we explore the relationship between concentrations of a stress hormone and defensive behavior of a snake. The cottonmouth (Agkistrodon piscivorus) is an abundant, large-bodied pitviper that is well known for its intense defensive behaviors. The defensive behaviors and hormonal ecology of cottonmouths have been studied extensively, but the interaction between these is not well understood. We conducted field trials, recording the snake's behavior and obtaining blood samples to quantify plasma CORT concentrations, both upon first encountering a snake and after a 30min standardized confinement stressor. We found that snakes with elevated levels of baseline CORT at first encounter were more likely to strike than exhibit a threat display when approached in the field. However, this behavior was not related to the magnitude of the snake's CORT increase following confinement, suggesting that more stress-prone snakes are not more defensive. Post-stressor antipredator behavior was also not related to any of our CORT measures. This study suggests that baseline CORT levels can be important correlates of defensive behavior. If this is a causative relationship, environmental challenges that increase baseline stress levels of populations may elevate cottonmouth defensive behavior. This would increase costs associated with defensive behavior (energetic, lost opportunity, etc.) and have important consequences for animal-human interactions.
压力被认为是介导动物行为的一个重要因素。在此，我们探究一种应激激素的浓度与蛇的防御行为之间的关系。水腹蛇（食鱼蝮）是一种数量众多、体型较大的蝰蛇，以其强烈的防御行为而闻名。水腹蛇的防御行为和激素生态学已得到广泛研究，但二者之间的相互作用尚不清楚。我们进行了野外试验，记录蛇的行为，并采集血样以量化首次遇到蛇时以及在30分钟标准化禁闭应激源作用后血浆皮质醇（CORT）的浓度。我们发现，首次遇到时基线CORT水平较高的蛇在野外被接近时更有可能发动攻击而非展示威胁姿态。然而，这种行为与禁闭后蛇的CORT增加幅度无关，这表明更容易产生应激反应的蛇并非更具防御性。应激源作用后的反捕食行为也与我们的任何CORT测量指标无关。这项研究表明，基线CORT水平可能是防御行为的重要相关因素。如果这是一种因果关系，那么增加种群基线应激水平的环境挑战可能会提高水腹蛇的防御行为。这将增加与防御行为相关的成本（能量、失去的机会等），并对动物与人类的相互作用产生重要影响。
