Siers Shane R, Mungaray Juan-Carlos, Kastner Martin, Jayne Bruce C
United States Department of Agriculture, Wildlife Services National Wildlife Research Center Barrigada Guam.
Research Corporation of the University of Guam University of Guam Mangilao Guam.
Ecol Evol. 2025 Apr 21;15(4):e71338. doi: 10.1002/ece3.71338. eCollection 2025 Apr.
Snakes are a useful model for gaining insights into the relationships between predator and prey sizes and resource utilization because their anatomy limits the size of prey that can be swallowed whole. However, data are sparse regarding how commonly gape-limited predators eat or attempt to eat prey with sizes up to or exceeding their maximal gape. Thus, for an invasive predator, the brown treesnake (), we fed captive snakes dead birds with an extremely large range (17%-447%) of relative prey area (RPA = prey cross-sectional area/snake gape area) to test the predictive value of RPA for snakes attempting to ingest or successfully ingesting prey. As expected, RPA significantly predicted (logistic regression < 0.0001) the probability of birds being eaten, with an upper size limit similar to the maximal gape of the snakes. Although RPA also significantly predicted ( = 0.003) the probability of attempting to eat a bird, it was less accurate in predicting attempts than successes, and many snakes attempted to eat birds too large to swallow. Twenty-five snakes attempted to eat birds with RPA ranging from 130% to 447%. The longest durations of unsuccessful feeding attempts were often for values of RPA near 100% rather than the extremely large values. For six large birds with mean measured RPA = 93%, the prey diameter soon after ingestion averaged 14% less than that measured prior to ingestion, which can allow snakes to consume 30% more mass than would otherwise be possible. Our findings complement a recent field study that concluded brown treesnakes regularly attempt to eat live birds too large to swallow. Our results also greatly expanded the known range of avian prey sizes that these snakes attempt to eat. Consequently, brown treesnakes pose a risk to birds with sizes well beyond the limit on prey size imposed by gape.
蛇是一种有用的模型，有助于深入了解捕食者与猎物大小之间的关系以及资源利用情况，因为它们的解剖结构限制了能够整个吞下的猎物大小。然而，关于口裂受限的捕食者食用或试图食用大小达到或超过其最大口裂的猎物的频率，数据却很稀少。因此，对于一种入侵性捕食者——棕树蛇（），我们给圈养的蛇投喂相对猎物面积（RPA = 猎物横截面积/蛇口裂面积）范围极大（17% - 447%）的死鸟，以测试RPA对蛇试图摄取或成功摄取猎物的预测价值。不出所料，RPA显著预测了（逻辑回归 ＜ 0.0001）鸟类被吃掉的概率，其大小上限与蛇的最大口裂相似。尽管RPA也显著预测了（ = 0.003）试图吃鸟的概率，但在预测尝试方面不如预测成功那么准确，而且许多蛇试图吃太大而无法吞下的鸟。25条蛇试图吃RPA在130%至447%之间的鸟。不成功喂食尝试的最长持续时间往往是RPA接近100%的值，而不是极大的值。对于6只平均测量RPA = 93%的大型鸟类，摄入后猎物直径平均比摄入前测量的直径小14%，这使得蛇能够比其他情况下多消耗30%的质量。我们的研究结果补充了最近的一项野外研究，该研究得出结论，棕树蛇经常试图吃太大而无法吞下的活鸟。我们的结果还极大地扩展了已知的这些蛇试图食用的鸟类猎物大小范围。因此，棕树蛇对大小远超口裂所限制的猎物大小范围的鸟类构成了风险。
