Radiata2010(4)e

Dieter Gramentz Notes on

Dieter Gramentz Notes on the Defensive Behaviour of the Florida Softshelled Turtle, Apalone ferox Introduction Defensive strategies have so far been described in detail only from a few species of chelonians, with Mertens (1946) and Greene (1988) summarizing and discussing a large portion of these. It has never been attempted, though, to catalogue the entire inventory of defensive strategies of a species of soft-shelled turtle. Many descriptions of defensive behaviour are instead limited to individual or only a few behavioural observations in this respect, and a large portion of them merely refer to biting attacks on humans that were noted when these turtles were handled. Werner (1912), for one, reported of Apalone ferox that were caught with fish hooks that they would repeatedly snap into the air and could cause serious bite wounds if one came too close to them. He also referred to Bell, who had reported the case of a turtle collector who had lost a finger in an encounter. It is likely, however, that this incident in fact involved an alligator snapping-turtle (Macrochelys temminckii), which is native to northern Florida, or a Florida common snapping-turtle (Chelydra serpentina osceola). Wright & Funkhouser (1915) then were the first to describe a forward leap of a Florida soft-shelled turtle. Brought on land, this specimen was able to perform a leap that about equalled its body length. That these turtles would also raise themselves in defence had already been reported a century earlier by Oken (1816). Apalone ferox is known to venture on land often. Extended overland migrations were observed, for example, by Goff & Goff (1935), and these stays on land often result in the animals falling victim to traffic on the roads (Pritchard & Bloodwell 1986, Aresco 2005). The turtles furthermore like to bask outside of the water (Duellman & Schwartz 1958, Brattstrom 1965, Ernst et al. 1994), and the females are obviously required to go on land for oviposition. All this increases the likelihood of encounters between turtle and predator. Material and Methods The defensive behaviour of Apalone ferox on land was studied in three specimens. The study period extended from 1995 through 1997. An about 40 cm-tall teddy bear attached to a broomstick of 1 m in length served as Fig. 2A-G: Stills from a film of an Apalone ferox male leaping and landing in a normal body position 26 RADIATA 19 (4), 2010

Florida Soft-shelled Turtle, Apalone ferox Fig. 1A-H: Defensive behaviour in Apalone ferox on land (explained in the text). a dummy for a predator; other experiments involved a human moving on all fours, and attacks by a bird were simulated by means of a 15 cm-long wooden beak dummy whose tip was rounded to prevent injuries. The head and neck of the bird were in this case replaced with the hand and forearm of the conductor of the experiment. The human on all fours would occasionally touch the anterior margin of the carapace with a finger. The responses of the turtles were both photographed and filmed. The line drawings presented here were then made from paper prints of the photographs by tracing the outlines on transparent paper. The filmed sequence of a leaping male Apalone ferox (male 1, comp. Tab. 1) was made in March of 1997, at which point of time the animal’s carapace length was 23.8 cm (straight line) and its weight 1,205 g. As the tape material was subsequently left unprocessed for some time, several recopying runs were eventually required, which had a detrimental impact on its quality. The turtle had originally been filmed with a Hi8 video camera (Sony). This tape material was then played back on a TV and refilmed with a Super-8 camera. This Super-8 film was eventually digitalized. A total of 38 leaps were filmed. Results The intensity of the individual behavioural responses varied, which was probably a function of individual temperaments. The responses observed were nevertheless principally the same. If the turtle is approached with a predator dummy from the front, it will threaten the dummy with the mouth open while retracting the limbs far into the shell (Fig. 3). (explained in the text). RADIATA 19 (4), 2010 27