June 2004 Notes 257 by 7.5-cm glass stacking bowls containing de- quired during a brief period of time rather chlorinated tap water and labeled with collec- than through an accumulative process. tion dates. I fed and kept small cray®sh alive Although several species of aquatic mollusks for up to 3 months in the laboratory. Tech- occurred at the study site, I made no attempt niques I used in their culture were those of to collect and screen them for larval trematode Black and Huner (1979). Mortality within infections. However, the pattern of seasonal groups was minimal, and eventually I necrop- prevalence (Fig. 1) suggests that cercariae be- sied all surviving specimens when each had gan leaving mollusks between early and mid grown to about 25 mm in length. By early De- October. By early April, the process of infect- cember, some cray®sh in the ®eld, as well as ing young cray®sh was complete. Thus, infec- tions among the P. clarkii population apparent- some reared in the laboratory, had grown larg- ly were acquired over a 5-month period. er and, if infected, harbored worms mature (oviferous) enough to be apparent at necropsy. I thank M. Paulissen for preparing the ®gure and Beginning in December, I removed the R. Garza for help with the Spanish translation. This paired antennal glands from 465 P. clarkii, dis- research was supported by a Jack V. Doland En- sected them under a stereomicroscope, and ex- dowed Professorship awarded the author. amined them for presence of worms. I pre- pared a representative voucher specimen of A. LITERATURE CITED ®liformis for deposit in the United States Na- BLACK,J.B.,AND J. V. HUNER. 1979. Breeding cray- tional Parasite Collection (USNPC 089114). In- ®sh. Carolina Tips 42:13±14. fections with A. ®liformis ®rst appeared in mid TURNER, H. M., AND K. C. CORKUM. 1977. Allocorrigia October (Fig. 1). Prevalence of infection in- ®liformis gen. et sp. n. (Trematoda: Dicrocoelii- creased steadily, and by early April, 100% of dae) from the cray®sh, Procambarus clarkii (Gi- rard, 1852). Proceedings of the Helminthological the sampled population was infected. Worms Society of Washington 44:65±67. harbored by individual hosts seemed to be at or near the same stage of development, sug- Submitted 18 February 2003. Accepted 18 September 2003. gesting that individual infections were ac- Associate Editor was Steven Goldsmith. DIETS OF NEWLY METAMORPHOSED AMPHIBIANS IN WEST TEXAS PLAYAS LOREN M. SMITH,* MATTHEW J. GRAY, AND ABIGAIL QUARLES Wildlife and Fisheries Management Institute, Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock, TX 79409-2125 (LMS) Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Knoxville, TN 37996-4563 (MJG) Department of Plant and Soil Sciences, Texas Tech University, Lubbock, TX 79409-2122 (AQ) *Correspondent: [email protected] ABSTRACT Although amphibians are the dominant vertebrate inhabiting playa wetlands during spring and summer in the Southern Great Plains, little is known about their diet and role in playa trophic structure. Because new metamorphs are more numerous than other terrestrial life stages of amphibians, we describe the diets of recently (,2 weeks) metamorphosed Great Plains toad (Bufo cognatus), barred tiger salamander (Ambystoma tigrinum), and New Mexico spadefoot (Spea multiplicata). Cultivation has greatly altered most playa watersheds (.95%); therefore, we also examined this in¯uence on diets of Great Plains toad metamorphs. Diets of all 3 species were dominated by coleopteran taxa, and diversity of prey taxa did not vary among species. Amount of speci®c prey consumed varied among species, with Great Plains toads preying more on scarab beetles and formicid ants than New Mexico spadefoots and tiger salamanders. New Mexico 258 The Southwestern Naturalist vol. 49, no. 2 spadefoot metamorphs consumed more chrysomelid and elaterid beetles than tiger salamanders or Great Plains toads. Given the high numerical abundance of metamorphs, they likely have a strong in¯uence on secondary production in playas. Great Plains toad metamorphs in playas with grassland watersheds had a much more diverse diet than those using playas with cultivated water- sheds. Conservation of amphibians in the Southern Great Plains should focus on preserving playas with native grassland watersheds or restoring those with cultivated watersheds. RESUMEN Los an®bios son los vertebrados maÂs abundantes durante la primavera y el verano en los lagos playa de las Grandes Planicies SurenÄas. Sin embargo, poca informacioÂn existe sobre su dieta y posicioÂn en la estructura tro®ca. Porque los recieÂn metamorfoseados son maÂs abundan- tes que los otros estadios terrestres de an®bios, describimos las dietas de animales recientemente metamorfoseados (,2 semanas) de las especies del sapo de las Grandes Planicies (Bufo cognatus), la salamandra tigre (Ambystoma tigrinum), y el sapo montõÂcula de espuela (Spea multiplicata). El cultivo de la tierra ha alterado de gran manera el haÂbitat de la mayorõÂa de los lagos playa (.95%), por lo que tambieÂn examinamos el efecto de este factor sobre las dietas de metamorfoseados de B. cognatus. La presa principal de las tres especies fue coleoÂptera y no hubo diferencias entre especies en la diversidad de presas. La cantidad de presas especõ®cas consumidas sõ varioÂ. Bufo cognatus consumioÂmaÂs escarabajos escaÂrabos y hormigas formõÂcidas que S. multiplicata y A. tigrin- um. Los recieÂn metamorfoseados de S. multiplicata consumieron maÂs escarabajos crisomeÂlidos y elateÂridos que A. tigrinum o B. cognatus. Debido a la gran cantidad de metamorfoseados, hay una alta posibilidad que ellos tengan una in¯uencia fuerte sobre la produccioÂn secundaria en los lagos playa. Metamorfoseados de B. cognatus que residen en lagos playa con cuenca pastizal tuvieron una dieta maÂs diversa que los en lagos playa con cuenca de cultivos. Esfuerzos para la conservacioÂn de an®bios en las Grandes Planicies SurenÄas deben enfocarse en la preservacioÂn de lagos playa con cuencas de pastizales nativas o en la restauracioÂn de los que han sido alterados. Playa wetlands are the primary wetland hab- (Bufo cognatus), New Mexico spadefoot (Spea itat for amphibians in the Southern Great multiplicata), and barred tiger salamander (Am- Plains (Anderson et al., 1999a). Playas are shal- bystoma tigrinum) are typically dominant (An- low (generally ,2 m), depressional wetlands derson et al., 1999a; Gray, 2002). Information that only receive water from precipitation or on the diets of these species is necessary to bet- runoff and lose water only through evapora- ter understand amphibian life history, the im- tion, transpiration, and recharge (Smith, portance of amphibians in playa wetland tro- 2003). There are approximately 25,000 to phic structure, and the potential in¯uence of 30,000 playas in the region (Osterkamp and landscape modi®cation on amphibian popula- Wood, 1987), although they only occupy about tion and community structure (e.g., Toft, 1981; 2% of the extensively cultivated landscape Beebee, 1996; Anderson et al., 1999b). (Haukos and Smith, 1994). Given the semi-arid The objectives of this study were to describe climate of the region, water availability in pla- and compare the diets of recently emerged yas for successful reproduction of amphibians sympatric barred tiger salamander, Great is highly variable on a seasonal and annual ba- Plains toad, and New Mexico spadefoot meta- sis (Bolen et al., 1989). Cultivation of the wa- morphs in playa wetlands from West Texas, tershed surrounding playas has further in¯u- and to examine potential in¯uence of anthro- enced the availability of water in playas by in- pogenic landuse on diets of metamorphs of creasing sedimentation and altering hydroper- the Great Plains toad. Moreover, we selected iods (Luo et al., 1997). These in¯uences on new metamorphs because they emerge in large hydroperiod can affect population and com- numbers (e.g., .10,000/night/6-ha playa; munity attributes of the entire amphibian as- Gray, 2002) and are more numerous than semblage (Skelly, 1997; Gray, 2002). adults, potentially intensifying competitive re- Although amphibians are the most numerous lationships among species at this life stage vertebrate group inhabiting wet playas of the (Werner and Gilliam, 1984; Flowers and Southern Great Plains during spring and sum- Graves, 1995). Because the historical landscape mer (Smith, 2003), their importance in playa of the Southern Great Plains was primarily trophic structure is unknown. Great Plains toad shortgrass prairie (Haukos and Smith, 1997) June 2004 Notes 259 TABLE 1ÐAggregate proportional mass and familial diversity and richness of invertebrates in stomachs of metamorph Great Plains toad (GPT; n 5 17 stomachs), New Mexico spadefoot (NSF; n 5 13), and barred tiger salamander (BTS; n 5 21) at 4 cropland playas on the Southern High Plains, Texas, 1999. GPT NSF BTS Order and indices Family Meana SE Meana SE Meana SE Arachnidae unknown 0.047 A 0.041 0.160 A 0.091 0.143 A 0.072 Coleoptera Carabidae 0.006 A 0.006 0.051 A 0.041 0.184 A 0.075 Chrysomelidae 0 A 0 0.013 B 0.007 0 A 0 Cleridae 0 A 0 0.004 A 0.004 0 A 0 Curculionidae 0.014 A 0.014 0 A 0 0.014 A 0.014 Dytiscidae 0 A 0 0.019 A 0.019 0 A 0 Elateridae 0 A 0 0.157 B 0.099 0 A 0 Histeridae 0 A 0 0.009 A 0.009 0 A 0 Scarabaeidae 0.383 A 0.102 0.034 B 0.034 0 B 0 Staphylinidae 0.057 A 0.036 0.023 A 0.018 0 A 0 unknown 0 A 0 0.077 A 0.077 0 A 0 Collembola unknown 0 A 0 0.043 A 0.037 0 A 0 Diptera Tephritidae 0.018