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
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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
Key words: caudal diJplalj, prerat 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 obsoletspecies 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
r'ig. 1. OnHbl (li~tnlclion in £lapfUl ofISofeta ~1J1loides (digitized £roOl viut.'ot'lp,;-:d obsel'vut.ions). Bhm'cd silhouettes of tail imli<:atc maximum eurvahn'c of tail during perfimmul<:c ufheh.wiol'. 1999] CAUDAL BEHAVIOR IN ELAPliE 365
TABLE L Capture stl(..'<..'t:ss as a function of the duration When performing caudal distraction, DO (!'iec; mean ± 1 sx-) of caudal distraction disphy in adult subject ever positioned its tail close «30 em) gray rat snakes (Elt.,phe obsolet.!:l spiloides). Sample sizes are given in pa.rentheses. Values in 2nd and 3rd columns to its head. Had mice been lured to the tail are different (Pearson's r = 0.71, P = 0.003). movement, they would not have been enticed to within striking distance of the snake. Thus, Omlltlon of Duration of Durati.on of caudal distraction caudal distraction the desclibed behavior appears to serve more caudal when 1st strike when 1st sbike as a distraction than it does as a lure to poten distraction succoodl.'rodent toward the mouse than when stationary, how species (Lima and Dill 1990). Subtle differences ever, indicating that any importance associated in response to snake presence by captive-bred with crypsis or stealth that might elicit a dis and wild-caught mice (Dell'omo and Alleva placement behavior was negligible. It is also 1994) suggest that caudal distraction would be worth noting that caudal distraction was of similar effect on small rodents in natural repeatedly displayed by snakes maintained in settings. captivity for durations of 1-16 months, 366 GREAT BASIN NATUHALlST [Volume 59 indicating that behavior was not suppressed special thanks for digitizing the figure of tJ,e hy conditions ofcaptivity (Warwick ]990). descrihed behavior. 1 am grateful for discus A few other cautions warrant (.'onsjderation: sions witJl G. Burghardt and comments from M. domesticus is not native to the geographic E.D. Brodie, Jr., R. Cooper, M. Ferkin, N. Ford, distribution of Elaphe; other small rodent taxa S. Fox, W Gutzke, A. Price, R. Reiserer, G. sympatric with gray rat snakes (e.g., Peromys Rodda, and 3 anonymous reviewers that im CIJS, Microtus, Sigmodon, etc.) may behave dif proved this mauuscript. Funding was provided ferently in response to caudal distraction by in pari by the Department of Biology, Univer snakes during a predator-prey encounter. Edge sity of Memphis. effects (a feature of noucircular enclosures; Krebs 1989) or space limitations of the enclo LITERATURE CITED sure may have ma.,ked a difference in ability to capture prey that wa!l' dependent upon cau AllNOLD. S.J. 1986. Laboratory and field approaches to the ~1:udy ofadaptation. Page-.s 157-179 in M.E. Feder and dal distraction frequency or duration. G.Y. Laudel; editors, Predator-prey relationships. The following observations suggest that Un.iversity ofChicago Press, Chicago, IL. much remains to be examined in the func BECK, OJ). 1996. Effects offeeding on body temperatures tional and ontogenetic development o( as well of rattJe.'makes: a field experiment. Pbysiological Zoology 69:1442-1455. as the importance of specific stimuli in elicit BUll(;~IAlmT, C.M. 1991. Cognitive ethology and critical ing, caudal hehaviors in Elaphe. (1) \Vhereas anthropomorphism: a snake with two heads and hog caudal luri,ng has heen documented in both nose snakes that play dead. Pages 53-90 in C.A.. Ris juveniles and adults of several taxa (Chiszar et I"nll, editor, C..ogniti.ve ethology: the minds of other animals. ErlbrlUm & Assoc., Hillsdale, NJ. al. 1990, and Jackson 1997, nebont 1997, Sisk CARPENTEIl, C.C. 1971. Communication and displays of and references therein), eaudal distraction has snakes. American Zoologist 12:217-223. not been observed in rat snakes <2.4 yr old CARPRNTER, C.C., AND C.w. FgI\GUSON. 1977. Variation (Mullin ]998). 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