Observations on the Burrowing Behavior of the Hog-Nosed Snake

Abstract

THE hog-nosed snakes, of the genus Heterdon, are noted for the shovellike development of the rostral region that distinguishes them from all other snakes in the United States. This striking morphological condition seems to have aroused small interest among herpetologists, however, and little has appeared on its relation to the habits of the animal. Hay (1892: 512-13) was one of the few whose curiosity was aroused by the highly modified snout: What the use of the sharp-edged, pointed snout? Is it used in burrowing? Or it employed in rooting up the ground in search of insects and other food? Apparently unknown to Hay these questions had been partly answered some years earlier. That delightful chronicler of nature, Charles C. Abbott, wrote of Heterodon contortrix (1884: 289) that he had them partial to loose, sandy soils, as in cultivated fields, in which they burrow with all the facility of a mole. They burrow, I am led to believe, only to a shallow depth, and think it in search of earth worms and insect larvae, and not merely for the sake of shelter. In several instances, where I have detected them coming out of the ground, I have found in their stomachs semi-digested animal matter which were believed to be the remains of earthworms and insect larvae. Surface (1906: 182) ventured the opinion that the modified rostral is doubtless used by the serpent in boring into the ground to find a suitable place for bringing forth its young, or passing a dry or cold season. These few lines appear to be about all that known of the burrowing behavior of the members of this genus. In order to observe in detail the method used by these snakes in burrowing, a number of individuals were brought into the laboratory and observed under various conditions. The observations given below were made on one of two specimens of Heterodon contortrix from Union County, Illinois, but the behavior typical of others brought in from various sources and observed from time to time. The snakes, a twenty-three inch male and a female three inches shorter, were released in a box containing six inches of fine, dry sand. The initial movements of both snakes were directed solely toward escape. They ranged freely about the box, seeking a means of escape. Shortly after being released the female flattened her head and neck, apparently without provocation. She crawled about in this attitude for about 15 seconds. Ten minutes later, at 4:25 P.M., the male began to burrow voluntarily. The beginning of the process was not witnessed. Three minutes later the partly buried snake was pulled out and the sand smoothed over. The following excerpts from notes made at the time show what probably approximately the normal burrowing behavior of this species. 4:29 P.M.: The snake was returned to the box. It slid its head along the sand with the rostral region just below the surface. The head was bent slightly downward at the articulation with the neck. The head disappeared