Herpetologists' League The Diets of Hispaniolan Colubrid Snakes II. Prey Species, Prey Size, and Phylogeny Author(s): Robert W. Henderson, Teresa A. Noeske-Hallin, Brian I. Crother, Albert Schwartz Source: Herpetologica, Vol. 44, No. 1 (Mar., 1988), pp. 55-70 Published by: Herpetologists' League Stable URL: http://www.jstor.org/stable/3892198 Accessed: 16/09/2008 16:57 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=herpetologists. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit organization founded in 1995 to build trusted digital archives for scholarship. We work with the scholarly community to preserve their work and the materials they rely upon, and to build a common research platform that promotes the discovery and use of these resources. For more information about JSTOR, please contact [email protected]. Herpetologists' League is collaborating with JSTOR to digitize, preserve and extend access to Herpetologica. http://www.jstor.org March 1988] HERPETOLOGICA 55 STICKEL, L. F., W. H. STICKEL, AND F. C. SCHMID. WRIGHT, A. H., AND A. A. WRIGHT. 1957. Hand- 1980. Ecology of a Maryland population of black book of Snakes of the United States and Canada. rat snakes (Elapheo. obsoleta). Am. Midl. Nat. 103: Cornell University Press, Ithaca, New York. 1-14. ZAPPALORTI, R. T., AND J. BURGER. 1986. The im- USDA. 1980. A Soil Survey of Ocean County, New portance of man-made habitats to pine snakes. En- Jersey. U.S. Department of Agriculture, Somerville, viron. Cons. 12:358-361. New Jersey. Accepted: 13 April 1987 WEATHERHEAD, P. J., AND M. B. CHARLAND. 1985. Habitat selection in an Ontario population of the Associate Editor: Raymond Semlitsch snake, Elaphe obsoleta. J. Herpetol. 19:12-19. Herpetologica, 44(1), 1988, 55-70 ? 1988 by The Herpetologists'League, Inc. THE DIETS OF HISPANIOLAN COLUBRID SNAKES II. PREY SPECIES, PREY SIZE, AND PHYLOGENY ROBERT W. HENDERSON', TERESA A. NOESKE-HALLIN', BRIAN I. CROTHER2, AND ALBERT SCHWARTZ3 'Section of VertebrateZoology, Milwaukee Public Museum, Milwaukee, WI 53233, USA 2Departmentof Biology, University of Miami, P.O. Box 249118, Coral Gables, FL 33124, USA 3BiologyDepartment, Miami-Dade Community College-North Campus, Miami, FL 33167, USA ABSTRACT: Eight species of xenodontine colubrid snakes (n = 1874 specimens) from Hispaniola were examined for prey remains and yielded 557 prey items of which 63.1% were lizards of the iguanid genus Anolis. With the exception of Darlingtonia haetiana, an Eleutherodactylus frog specialist, all of the species in our sample preyed heavily upon anoles. In general, Hispaniolan colubrids were opportunistic predators, but the widespread exploitation of a single prey genus (Anolis) may be unique to the West Indies. Frequently exploited prey species were geographically widespread and generally found at high densities (Osteopilus dominicensis, Anolis coelestinus, A. cybotes, Ameiva chrysolaema). Active foraging snakes (Alsophis, Antillophis) were more eury- phagic, while sit-and-wait strategists (Hypsirhynchus, Uromacer oxyrhynchus) were trophically specialized. All of the species in our sample tended to eat relatively small prey items, even though larger individuals of a given prey species were available. The historical (phylogenetic) component of trophic ecology of these snakes is discussed. Key words: Anolis; Eleutherodactylus; Phylogeny; Hispaniola; Snake diets DESPITE its richness and geographical addition, anoles are uniformly exploited as uniqueness, the Antillean snake fauna has, food by colubrid snakeson all majorislands until recently, been ignored ecologically. and island groups in the Antilles (50-60% Investigation of the diets of West Indian of all prey items; Henderson and Crother, boid, tropidophiid, colubrid, and viperid 1988). Hispaniola has the richest snake snakes has revealed a spectacular (al- fauna and one of the largest anole faunas though not altogether surprising) trophic (second only to Cuba) of any West Indian relationship between the snakes and the island, and it has been singled out for de- iguanid lizard genus Anolis. Nearly 57% tailed studies of its boid (Henderson et al., of all prey items (n = 707) and 75.8% of 1987b) and colubrid (e.g., Henderson, all lizards recovered from the digestive 1984a; Henderson et al., 1987a,c) snakes. tracts of West Indian colubrid snakes were Besides a rich anole fauna, Hispaniola har- anoles (Henderson and Crother, 1988). In bors the richest frog and lizard faunas in 56 HERPETOLOGICA [Vol. 44, No. I the West Indies: i.e., a vertebrate fauna items for col- C)c very rich in potential prey 0 ubrid snakes. 0 + Hen- 0~~~~~~~~~~~~0 In this paper, a continuation of derson (1984a), we describe the prey exploited by the xenodontine col- "0 0 -~~~~> species C) o i~~~~~~~~~t ) c ubrid snakes of Hispaniola, the West In- dian island with the richest colubrid fauna. Specifically, we address not only questions CD~~~~~~C "0 CL. ~- originally posed by Henderson (1984a) but CO ~ "C~ C)"~ 0 -.~~~~~~~0.~~~~~0c also ask: (1) What prey species make the greatest contributions (frequency and vol- colubrids? C) 0 ~~~ -C C)CO ume) to the diets of Hispaniolan (2) What characteristics(if any) are shared * 0~~~~W0 by frequently eaten prey species? (3) Do Hispaniolan colubrids, despite having po- tential access to rich frog and lizard (other than Anolis) prey faunas, still predomi- 4- * "~~~~~~~~~~~~~~~ C)~~~~~~- nantly exploit anoles as their primary food source? (4) Is there an historical (phylo- C) ~~~~~~~~~~~~~~~f genetic) component to trophic ecology of Co ~ ~ ~ L) ~~~C) ~6i(= C these snakes? 0 MATERIALS AND METHODS '44 +I" ~~~~~~~~ A sample of 1874 colubrid snakes (rep- C). :) C resenting six genera and eight species) was examined for prey items. All were from -~~ J~~ 0 t~~o AC 00 Hispaniola except for Alsophis cantheri- a0C N gerus, which is native to Cuba and the "0 ~~~~~~005u7Z +I -, Cayman Islands. Hispaniola harbors two CO bJD c C)~v O+ C"~ endemic species of Alsophis, but because of their rarity in museum collections, we chose the closely related A. cantherigerus 0 C's0 1 to represent the genus. It is common in C4 1 0- collections and is intermediate in -Z CZ museum E~~~~~0., size between the two HispaniolanAlsophis (A. anomalus and A. melanichnus). Ta- C) CO C) 0 >O~ ~ C) 0 bles 1 and 2 provide brief summaries of OCO co 0 the natural history of Hispaniolan colu- brids and A. cantherigerus. of dissection, determination 0 0 ' Techniques of prey volumes, and recording morpho- C) Q logical measurements were explained in "0 " detail in Henderson (1984a). Many prey C) >>CZ 0 ( items were not identifiable to species, and we generally did not determine volumes for such items. There is probablysome bias in our prey identifications.Some common, frequently exploited species (e.g., Anolis cybotes) were easily identified, even from largely digested remains. Other less com- mon and infrequently consumed species -t TABLE 2.-Comparison of different aspects of the biology of three species of Uromacer. All are arboreal and diurnal. Variable U. catesbyi U. frenatus U. oxyrhynchus Source Head and body blunt snout; heavy body; wide attenuated snout; slender attenuated snout; slender Henderson et al., 1981 morphology head body; narrow head body; narrow head Henderson et al., 1987c Skull morphology least specialized highly specialized highly specialized Maglio, 1970 Internal topogra- anterior organ position intermediate organ position, posterior organ position Martinez et al., 1985 phy (= primitive) but closer to oxyrhynchus Foraging mode active and sit-and-wait sit-and-wait sit-and-wait Henderson 1982 Henderson et al., 1987c Binocular field of presumably the narrowest of presumably wide very wide Walls, 1942 | vision genus Striking distance strikes from closer distance; strikes from greatest distance intermediate between catesbyi Ulrich and Ford, 1985 0 and accuracy misses more frequently; and rarely misses and frenatus 0 chases prey C Diet tree frogs; trunk and ground terrestrial Ameiva; grass, primarily trunk and ground Henderson et al., 1987c Anolis trunk, and ground Anolis Anolis, some grass Anolis Mean prey size 4.0 ? 1.0 2.8 ? 0.3 2.2 ? 0.3 Henderson et al., 1987c (cm3) Movement ecology moves long distances on probably intermediate be- rarely travels on ground; uses Henderson et al., 1981, 1982 ground; uses heavy tween catesbyi and oxyrhyn- slender branches branches chus Distribution islandwide "south" island "north" island with invasion Horn, 1979; Schwartz, 1980 of "south" C,' -. 58 HERPETOLOGICA [Vol. 44, No. 1 were difficult to identify from body frag- History (USNM). The snakes were col- ments. lected at many localities throughout His- Index of relative importance (IRI) was paniola over a span of about 80 yr. Some used to evaluate the relative importance comparisons were made with diets of His- of food items in snake diets (Pinkas et al., paniolan boids (Epicrates) of which 214 1971). IRI was calculated by summing the were examined (Henderson et al., 1987b). numerical and volumetric percentage val- Species of snakes were categorized by ues of a food item (= prey species) and foraging mode on the basis of quantitative multiplying by percentage of occurrence (Henderson et al., 1982) and qualitative (N + V)F = IRI observations in the field by the authors (Henderson and Schwartz) and by col- where N = numerical percentage, V = leagues.