Great Basin Naturalist Volume 59 Number 4 Article 8 10-15-1999 Caudal distraction by rat snakes (Colubridae, Elaphe): a novel behavior used when capturing mammalian prey Stephen J. Mullin University of Memphis, Memphis, Tennessee Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Mullin, Stephen J. (1999) "Caudal distraction by rat snakes (Colubridae, Elaphe): a novel behavior used when capturing mammalian prey," Great Basin Naturalist: Vol. 59 : No. 4 , Article 8. Available at: https://scholarsarchive.byu.edu/gbn/vol59/iss4/8 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Ba....in Naturalist 59(4), ©1999, pp. 361....167 CAUDAL DISTRACTION BY RAT SNAKES (COLUBHIDAE, ELAPHE): A NOVEL BEHAVIOR USED WHEN CAPTURING MAMMALIAN PREY Stephen]. Mullin1 AJ3S11UCT.--el.mthtl movement in snakes trulY serve ei.ther a pl'Cdatory (e.g., caudal luring) or defensive (e.g., rattling, aposem,ttism) fUllction, I descliho n new behavioral pattern of tai.l movement in snakes. Gray rat snakl.'$ (Elaphe OhSO!etd spiloid.es) fi)raging on ~ma11 mmnmnls (Mus d01ne~·ticus) Inoved. their tails in un erratic, whiplike fashion uIter detecting prey in their vidnity. The thrashing movement in the horizontal plfme was audibly and visually obviolls, resulting in dis­ placement of leaf litter around the hlil. All subjects displayed the behavior, hilt not in all foraging episodes. Shorler durations ofcaudal distraction~1.l1lecl in greater predator SIIt.'t.'eSS during the 1st attempt <It prey c<lpl'ure. Caudal dis­ traction may facilitate prey capture by gray rat snakes by directing tbe attention of prey away fmm lhe approHching head of the snake. Key words: caudal diJplalj, pre<!awry behaviol; deceit, Elaphe obsolela, flUUnrludian p'-ey, rat snake, Cnlul.1t'hlae. Visual communication by snakes (Carpenter 1993, Rahatsky and Farrell 1996) and at least 1 1977, Carpenter and Ferguson 1977) occurs in lizard specics (Morray et at. 1991). It is typi­ the absence of appendages used by many cally displayed by snakes foraging from lin other vertebrate taxa (CuUen 1972, Enquist et ambush posture (Chiszar et al. 1990). al. 1985). Limblessness necessitates the use of Both defensive tail vibration and caudal lur­ head, body, or tail for visual display. Snake de­ ing have been observed in rat snakes (Elaphe fens:ive displays frequently il1volve tail move­ obsolet<I; TIebout 1997; personal observation). ment or posturing (Greene 1988, Sazima and While observing a gray rat snake (E. o. spiloides) Abe 1991). In particnl",; members of the sub­ foraging for a small mammal (Mus dorne.1icus), family Crotalinae have evolved a specialized 1 recorded a tail display unlike that of either morphology at the taU tip, the rattle. Greene loring (Chiszar et aI. 1990) or defensive rat­ (1992) suggested that the incipient structure tling or tail vibration (Greene 1988). During serves us a warning device to snake predators. subsequent observations, several individuals a conclusion that is the subject of continued displayed similar taU movement when approach­ discussion (Sisk and Jackson 1997, Tiehout ing their prey. The purpose of this study is to 1997). Several species ofcolubrid snakes (Greene descrihe a heretofore undocurnented prellu­ 1988) and other elongate reptiles (Greene 1973) tory behavior of gray rat snakes that was dis­ also perform defensive tail displays. played only in tl,e presence of mammalian Another fonn of taU movement, termed prey. Frequency and duration of this behavior caudal/tIring, fucilitates prey capture. This be­ and its facilitation of prey capture arc also havior is described as a slow, undulatory or reported. Becaose this behavior parallels cau­ vermiform movement of the tail while it is dal luring and defensive tail vibration, I term held upright in close proximity to the snake's the novel behavior caudal distraction.. head (Heatwole ,uld Davison 1976). Caudallur­ ing is presumably mimetiC, in that the move­ MATERIALS AND METHODS ment is thought to resemble an insect huva OT worm and thus attracts potential prey to within r first noticcd caudal disb'action in a 113­ striking dLstance of the otherwise motionless em snout-vent length (SVL) female gray rat snake. Caudal luring has been documcnted in snake foraging for a mixed-sb'ain mouse (M. nearly aU fiunilies of snakes (Carpenter et at. domesticus). The snake was in an enclosure 1978, Radcliffe et al. 1980, Sazima and Puorto tllat simulated a bottomland hardwood forest 1Dellurtll1<:nt of 13inJO/,.'Y. University of Me,nphi~> Mell1phl~, TN 38152. l'r~enl (u::Idre$~' [kplll'tO\onl of 13iolOjl;1cul Scf«llOO&. EiI.I!I,,·n lllilmis UIlive-!'!'It.v. Charleston, IL 61920. 361 362 GREAT BASiN NATURALIST [Volume 59 habitat (see below). Behavior was documented Adult male lllic-e were placed in the enclo­ on videotape to permit detailed description. sure for a minimum of 10 min for acclimatiza­ Several other adult snakes displayed this tion. Only adult maJe mice having dark brown behavior with IitUe departure from the oligi­ pelage were used as prey duling the observa­ nal pattern. To examine possible differences in tions to minimize visual and vomeronasal dif­ capture success and latency to prey capture ferences among prey available to snakes (J ~oop that might be dependent on the use of this 1970) and provide prey visually similar to behavior, I recorded adult gray rat snakes (n those which sn.\kes encounter in the field. All =15) involved in {(>raging episodes under sim­ mice had similar mass (30.7 + 0.5 g, n = 30), ilar conditions. although the ratio of prey mass to snake mass Subjects (10 males and 5 females. >100 cm was not fixed during the study. A gray rat snake SVL) were obtained fi·OOl forested and semi· was placed in thc corner of the enclosure far­ rural areas within Shelby County, Tennessee, thest removed from the prey. Because observer and maintained 'in captivity at temperature presence may influence snake behavior (Drum­ and photopeliod regimes of 26-29°C and mond 198.3), behaviors were recorded by a 14:10 h light:dark, respectively. Suhjects had video carner.! on a tripod elevated over the spent between 1 and 16 months in captivity enclosure floor. The camera was always Oli­ prior to examination. Snakes were housed jn­ ented toward the snake, meauing that possible uividually in cages measuring a minimum of differences in prey behavior were not recorded. 30 x 60 x 30 ern, provided with water ad libi­ Occasionallv,, caudal distraction was initiated tum, and fed either KorUlem Bobwhite Quail with the b,il outside the field of view; bow­ (Colinus vir{"rinianlls) eggs or mixed-strain mice ever, tail movement was audibly discernible as weekly. Excepting; o<..:ca.~iona1 cage cleaning and leaf litte.- in the immediate vicinity was dis­ monthly SVL (±O.5 Col) measurements, sub­ turbed and could thus be recorded from its jects were handled as little as possihle to mini.· initial occurrence. mize any hehavioral modifications resulting The latency to suc(.--essfiIl mouse capture may from prolonged captivity (Warwick 1990, Ford lwve depended, in part, on initial distances 1995). Because recently fed snakes may exhibit separating the snake and its prey. Howevel; shilts in behavioral pattern (Beck 1996) or the colJlined, relatively sm,Jl euclosure proba­ alteTation of locomotor pClformance (Martin bly limited the influence of initial separation 1996), individuals were placed on a restricted distance. Missed attempts at capturing the diet (water alone) for 3 wk prior to experimen­ mouse and frequency and duration of caudal llJ trials. Between 23 April 1995 and 25 March distraction were recorded from videotaped 1996, snakes were allowed to forage indiVidu­ observations. A repeated-measures analysis of ally for mice on at least 2. different occasions, variance (ANOVAR; each mbject was recorded each separated by a 3-wk resmeted diet. on 2 occasions) was used to determine An enclosure (2.25 m2 and 2 m in height), whether those snakes exhibiting caudill dis­ c'Onstructed to simulate bottomland hardwood traction required fewer attempts to Sllccess­ forest ofthe wildlile m'magement area ofnearby /llily capture mke. l'aramemc statistics (Scheffe Mecman-Shelby Forest State Park (MSFSP), 1959, Cohen 1965) were also used to detect Tennessee, ,;vas maintained at the photoperiod any relationships between frequency and/or and temperature regimes described above. duration of caudal distraction and snake gen­ ArtHicial vegetation simulated mean recorded der (ANOVAR) or sile (Pearson's regression). level of vegetation density al MSFSP (mea­ Statistical tests were conducted using Super­ sured in June 19<J4; ,. + 1 Sf = 64 + 2.3 plants ANOVA~ software (Abacus Conccpts) at an 01-2, n = 144). Leaves, obtained at field siles accepted sil,'Dificanee level ofa = 0.05. where snakes were collected, pro,idee! a nat­ ural substrate on the ellclosure floor. Light RESULTS intensity on the enclosure Hoor approximated Description levcls measured at MSFSP during UlC vegeta­ tion sampling period (for IllJiher details on Caudal distraction is the use of tail move­ hahitat sampling and enclosure construction, ments by an elongate predator which serve to see Mullin 1998, Mullin et al. 1998). hold the attention of a prey animal while the 1999J CAUDAL BEHAVIOR IN El..1I'H£ 363 predator's bead is moved to within slrildng distraction dJsplay; instances ofstationary t:au­ range ofthe prey. dal distraction were frequently accompanied In E. o. spiloides c-audal disb1lction displaL-ed by some time displaying the hehavior while leaves near the blil. was visually conspicnous advancing toward the mouse. There was no when unobscurcd by emergent vegetation, and difference in the amount of time a snake dis­ was audible from a distance ofseveral meters.