Neoichnology and Tracemaking Behavior of Desmodus rotundus

Trace fossils are useful tools for interpreting the behavior of extinct and ancient organisms as well as providing clues to the potential distribution and occurrence of organisms in areas where body fossils are absent. Tracks and trackways of flying organisms are present in the fossil record, including insects, birds, and pterosaurs; bat trace fossils, however, are not known. The absence of bat trace fossils may be due to their small size, unfavorable preservation conditions of the environment, or misidentification. The lack of traces is likely not due to an aversion to terrestrial locomotion, as modern bats display a range of terrestrial abilities from strictly aerial insectivores to the unique terrestrial behaviors of the common vampire bat (Desmodus rotundus) and the New Zealand short-tailed bat (Mystacina tuberculata). We present the first study of the trackway-making ability of the common vampire bat, and compare it to the terrestrially inept genus Carollia. Four Desmodus rotundus were captured at Reserva Ecológica Bijagual de Sarapiquí in the Caribbean lowlands of Costa Rica during early summer 2014. A custom-built Plexiglas® and PVC enclosure allowed the bats to walk across sediment but prevented them from flying. The resulting trackmaking behaviors were video recorded and trackways were cast with plaster and analyzed. All Desmodus exhibited a more typical quadrupedal gait than did Carollia. Desmodus, in contrast, did not display the breaststrokelike crawl performed by the less terrestrially-adept species. Trackways produced by Desmodus are characterized by deep manus impressions and scattered, more infrequent pedal tracks.