Big pythons, big gape, and big prey

Abstract

Knowing the size of prey that predators can consume facilitates understanding and predicting their ecological impact. Burmese Pythons (Python bivittatus) are apex predators that are larger than all but a few snake species, and their prey, which are swallowed whole, cannot exceed the size of their maximal gape. However, prey sizes smaller than maximal gape may occur because of what snakes select or if capturing and swallowing certain prey is prohibitively difficult. Our study quantified the maximal gape of three large Burmese Pythons (SVLs 410-520 cm), including the longest specimen captured in Florida (where they are invasive) and one specimen that was captured while eating a deer. All three specimens had maximal gape diameters of 26 cm that exceeded the previously reported maximal value of 22 cm, and the soft tissues between the lower jaws accounted for 56-59% of the maximal gape area. Combining our new data with previous data significantly affected the scaling equations predicting maximal gape. The smallest specimen in our study ate a 35 kg deer, which was 93% of its maximal gape area. Hence, in addition to eating prey with large absolute size, Burmese Pythons in nature also eat prey with a size near the limit imposed by gape, but how frequently this occurs remains unclear.