Cueva Del Diablo: a Bat Cave in Tepoztlan 1Gabriela López Segurajáuregui, 2Karla Toledo Gutiérrez, and 3Rodrigo A
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264 AMCS Bulletin 19 / SMES Boletín 7 — 2006 Cueva del Diablo: a Bat cave in Tepoztlan 1Gabriela López Segurajáuregui, 2Karla Toledo Gutiérrez, and 3Rodrigo A. Medellín 1 [email protected] 2 [email protected] 3 Laboratorio de Ecología y Conservación de Vertebrados, Instituto de Ecología, UNAM, Circuito Exterior s/n anexo al Jardín Botánico Exterior, C. P. 70 – 275 Ciudad Universitaria, UNAM, 04510 México, D. F.; [email protected] Abstract not only by quantity but also because economically important plants (Kunz their evolutionary radiation has led and Pierson, 1994). They pollinate plants In Mexico, almost half of the 140 spe- the group to an unparalleled ecologi- associated with tropical and subtropi- cies of bats use caves as alternative or cal and morphological diversification. cal dry areas, such as agaves, cactus primary roosts. One volcanic cave that Bats occupy several trophic guilds, and a variety of tropical trees (Arita houses important colonies of these ani- from primary consumers to predators; and Wilson, 1987). They disperse seeds mals is Cueva del Diablo in Tepoztlan, they roost in many types of natural and occurring in the plant families to which Morelos, central Mexico. At least three human-made structures in numbers from figs and relatives belong, like Moraceae bat species have been reported in this a few animals to millions, creating the and Piperaceae, among others (Flem- cave. One of them, the Mexican long- greatest concentrations of warm-blooded ing, 1987). Worldwide, there are more nosed bat (Leptonycteris nivalis), is of vertebrates (Medellín, 2003). than 750 plant species that have been particular importance in economical and There are 9 families of bats in Mexico listed as visited by bats (von Helversen ecological terms. This species migrates that comprises 64 genera and 140 spe- and Winter, 2003). Flower – visiting from central to northern Mexico and cies, 15 of which are endemic (Teje- bats in Mexico are represented by 12 southern United States in mid spring and dor, 2005; Ceballos et. al., 2002). The species, most of which have restricted come back in mid autumn. In Mexico, Mexican bat fauna is rich because of distribution; two of them are endemic L. nivalis is classified as a threatened the country’s complex topography, the to the country, two others to Middle species, and in the U.S. as an endan- fact that Mexico contains virtually every America and ten use caves as a main gered one. known vegetation type (Rzedowski, or alternative roost (Arita and Santos Owing to the fact that Cueva del Dia- 1978), and because it has three distinct del Prado, 1999). blo is the only known roost in which this biogeographical elements: neotropical, Despite the importance of bats for species mates, the cave was proposed neartic (the limits of which are entirely ecological processes and for humans, by us as a sanctuary to the CONANP contained within Mexico’s borders), and this group of animals is facing great (National Commission of Natural Pro- endemic (Medellín, 2003). population declines and extinction pres- tected Areas) in 2004. In addition to Chiropterans play several major sures worldwide (Hutson et. al., 2001). this proposal, the PCMM (Program for ecological roles in many ecosystems. About 24% of bats (248 species) are Conservation of Mexican Bats) has con- Insectivorous bat species are the pri- considered at risk by the IUCN (2006): ducted environmental education efforts mary consumers of nocturnal insects, 32 critical endangered, 44 endangered in the region as an attempt to modify the and given the relatively large volumes and 172 vulnerable. Mexico has a similar negative ideas about bats and to share the consumed (up to 100% of body weight percentage of species at risk but at a information concerning their importance per night) and the long distances trav- national level: 12 under special protec- and that of caves for them. eled (several km per night), these bats tion, 15 threatened and 4 endangered, Other PCMM studies conducted in are thought to play a major role in regu- including 5 endemic species (SEMAR- this cave focus on the diet of the species lating nocturnal insect population and NAT, 2002). and understanding its mating system, intransporting nutrients across the land- Over the past 400 years, at least 9 among the first studies on those subjects scape (Kunz and Pierson, 1994). Bats species of bats have become extinct for this species. This document repre- are major predators of nocturnal flying (IUCN, 2006). Bat populations in many sents a compilation of those works in insects, and an important biological countries are thought to have declined Cueva del Diablo with emphasis in their control agents of insect pests (Russell, over the past 50 – 100 years, and al- importance for the general conservation et. al. 2005; Medellín, 2003), includ- though the evidence for such reduc- of bats and caves. ing cucumber beetles, June bugs, corn tions is often circumstantial, there are Introduction borers, Jerusalen crickets, leafhoppers cases where declines have been well and noctuid moths which are important documented (Mohr, 1972; Stebbings, With 1116 extant species recognized agricultural pests on such crops as corn, 1988; Rabinowitz and Tuttle, 1980; R. worldwide, bats are second only to ro- spinach, pumpkins, cotton, potatoes or A. Medellín, pers. obs.). dents in terms of total number of species tomatoes (Whitaker, 1993). Factors behind the decline of bat (Simmons, 2005; Wilson and Reeder, Bats are pollinators and seed dispers- populations are often related to hu- 2005). Diversity of bats is noteworthy ers for a number of ecologically and man destruction of habitat and roosts AMCS Bulletin 19 / SMES Boletín 7 — 2006 265 (Medellin and Gaona, 2000). An increas- adaptations and demographic response. and the tropical deciduous formations ing human population brings with it extra These animals spend over half their lives (Hoffman et. al., 1986). The cave is demands for land, resources and food, subjected to the selective pressures of located in the latter type of vegetation, which often results in the degradation, their roost environment. For many bats characterized by a semi-warm wet cli- destruction or fragmentation of certain the availability and physical capacity mate with summer rain (A) C (w2) (w) i g habitat types with a concomitant effect of roosts can set limits on the number (García, 1986) and in an altitude of 1850 on bat populations (Hutson et. al., 2001). and dispersion of roosting bats, and masl. In summer, it presents an average Impacts of agriculture and its deriva- this in turn can influence the type of external temperature of 28°C during tives (e. g. reduction of fallow periods, social organization and foraging strat- day, which decreases while entering overgrazing, loss of important plant egy employed (Kunz, 1982). Roosts are the cave down to 16°C in the majority species for bat foraging, replacement important sites for mating, hibernation, of internal chambers. of natural vegetation with cash crops and rearing young. They often facilitate A full description of the cave was and monoculture as a result of that, use complex social interactions, offer protec- made by Hoffman et.al. (1986). This of pesticides that affects insect fauna tion from inclement weather, promote refuge has a volcanic origin, from a and are potentially sub-lethal for bat’s energy conservation, and minimize risks subterranean lava flow that stopped, and breeding performance, among others), of predation (Villa-R, 1967; Kunz and eventually forms a various chamber’s as well as industrial activities, fire, de- Lumsden, 2003). system with a 1 937m length (including forestation, introduced predator species Underground sites, both natural (e. all the ramifications) and a maximum or pollution, can affect negatively bat g. caves) and artificially created (e. g. depth of 110m respect the entrance populations (Hutson et. al., 2001). mines), are crucial to the survival of (Hoffman et. al., 1986). Linking bats to witchcraft and magic many bat species worldwide (Hutson Tepoztlan represents a transition point has given rise to many of the fears people et. al., 2001). In relation to other roosts, between neartic and neotropical faunas, have about them (McCracken, 1992). caves stand out because of their extend- and a confluence center of migratory Within the same topic, the feeding habits ed use among these organisms (Avila, species. In Cueva del Diablo there are of the vampire have been so exaggerated 2000). A great proportion of world’s bats three main bat species according their and confused with Old World legends can be considered cave – dwellers and, presence in the cave: Leptonycteris niva- that the animal is of particular interest. probably, caves host more individuals lis, Pteronotus parnellii mexicanus and It has been considered a threat both to than other roosts, even combined (Hill Desmodus rotundus (Hoffman, 1986) people and to their domestic animals in and Smith, 1984). Besides that, great and isolated captures of Anoura geof- Latin America (Nowak, 1994), where, dimensions and complex topography in froyi (Edmundo Huerta, pers. comm.), as an ironic fact, populations of vampire one cave only can offer several perch Artibeus jamaicensis (Rodrigo Me- bats have increased sharply in areas to sites for different individuals or colonies dellín, pers. comm; Gabriela López, which European livestock have been in- (Medellín and López – Forment, 1985; pers. comm.) and Myotis velifer (Rodrigo troduced (Hutson et. al., 2001). Common Hill and Smith, 1984; Kunz, 1982) as Medellín, pers. comm; Gabriela López, vampire bat is extensively persecuted well as different microclimates (Me- pers. comm.) as a vector of rabies, that is transmitted dellín and López – Forment, 1985). The naked – backed bat, moustached to cattle and other ungulates on which In Mexico, there are over 10 000 bat or leaf – lipped bat (Nowak, 1994) it feeds, although its incidence is low caves (Lazcano, 2001), mostly karstic Pteronotus parnelli (Gray, 1843) is ba- (<1%).