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Caldasia

Print version ISSN 0366-5232

Caldasia vol.37 no.1 Bogotá Jan./June 2015

http://dx.doi.org/10.15446/caldasia.v37n1.50992 

doi: http://dx.doi.org/10.15446/caldasia.v37n1.50992

THE ROLE OF PLANTATIONS OF THE AFRICAN PALM (ELAEIS GUINEENSIS JACQ.) IN THE CONSERVATION OF SNAKES IN COLOMBIA

Las plantaciones de palma africana (Elaeis guineensis Jacq.) y las poblaciones de serpientes en Colombia

JOHN D. LYNCH

Instituto de Ciencias Naturales, Facultad de Ciencias, Universidad Nacional de Colombia, Apartado 7495, Bogotá D. C., Colombia. jdlynch@unal.edu.co

ABSTRACT

Monocultures of the African oil palm (Elaeis guineensis Jacq.) were studied between 2006 and 2013 so as to determine which species of snakes frequented them and to estimate the abundances of each species encountered. Thirty five species of snakes (three boas, one coral, 27 colubrids, one tropidophid, one typhlopid, and two vipers) were captured within palmeras. Palm plantations are revealed to (1) augment the densities of ten species of snakes well beyond the densities found by collectors in natural and/or relatively transformed habitats and (2) to not offer benefits to at least 75% of the snake community found in the vicinities of palm plantations. The majority of snake species (60%) found in palmeras are nocturnal species. The most common species (defined by having 15 or more captures) were Atractus univittatus, Bothrops asper, B. atrox, Epicrates maurus, Leptodeira annulata, Liophis melanotus, Ninia atrata, Oxyrhopus petolarius, Pseudoboa neuwiedii, and Tantilla melanocephala. Palm plantations permit substantial local population sizes for a fraction (< 25%) of the local snake community. Internal practices of such plantations could be modified so as to protect a larger share of the fauna by means of two practices: (1) construction and maintenance of paleras as well as (2) creating a mosaic of palm plantations enclosing "islands" of secondary forests.

Key words. African oil palm, microhabitats within plantations, snake abundances, snake communities.

RESUMEN

Los monocultivos (plantaciones) de la palma de aceite Africana (Elaeis guineensis Jacq.) fueron estudiados entre el 2006 y 2013, para determinar cuáles especies de serpientes se podrían encontrar, y también para estimar las abundancias de cada especie encontrada. Treinta cinco especies de serpientes (tres güíos, una coral, 27 colúbridos, un tropidófido, un tiflópido y dos vipéridos) fueron capturadas dentro de las palmeras. El trabajo de campo en estas plantaciones revela que: (1) aumenta la densidad de diez especies de serpientes, más que la densidad encontrada en hábitats naturales o moderantemente transformados y (2) pero no hay beneficios para los 75% de la comunidad de serpientes encontradas en los alrededores de la plantacion. La mayoría de especies de serpientes encontradas (60%) son de actividad nocturna. Las especies más comunes (definido por tener 15 o más capturas) son Bothrops asper, B. atrox, Epicrates maurus, Leptodeira annulata, Liophis melanotus, Ninia atrata, Oxyrhopus petolarius, Pseudoboa neuwiedii y Tantilla melanocephala. Las plantaciones de palma permite la subsistencia de poblaciones locales de tamaños sustanciales, lo cual corresponde a una fracción (< 25%) de la comunidad local de serpientes. Las prácticas internas de las plantaciones pueden ser modificadas para proteger una fracción mayor de la fauna; implicando dos cambios: (1) la construcción y el mantenimiento de paleras y (2) la creación de un mosaico de parcelas de palma intercalada con "islas" de bosque secundario.

Palabras clave. Abundancias de serpientes, comunidades de serpientes, la palma de aceite africana, microhábitats dentro de plantaciones.

Recibido:  10/01/2015

Aceptado: 30/05/2015

INTRODUCTION

Snakes constitute a biological group under serious threat in Colombia. The principal threats are (1) destruction of the native habitats and (2) the indiscriminate killing of snakes by persons living or working in rural areas (Lynch, 2013). In the developed and populated part of Colombia, few national parks exist but there are some regional parks maintained by municipalities or private concerns. Some eight years ago, I realized that a cultivation, that of the African oil palm, might play a major role in snake conservation.

The African Palm was introduced into Colombia some 40-45 years ago and has become a growth industry. New plantations are created on lands that have had recent use as banana or rice cultivations, pasturelands, or natural vegetation (usually represented by secondary forests). The reactions of biologists, conservationists, and ecologists to the expanding palm plantations have been negative, reflecting either distaste for mono-cultures or the invasion of this agricultural frontier into natural habitats (or both). In my personal experience (Santander, 2007), I have seen parcels of rastrojo alto burned and shortly thereafter planted with this invasive species. African palm has been introduced even into areas never forested (savannahs in eastern Meta and in Vichada). However, plantations of mature African palm occur in areas that once supported humid tropical forest or dry tropical forest.

I first visited a plantation in 2004 but, aside from catching some caecilians and a few snakes there, remained indifferent (or antagonistic) towards the industry until 2006 (see below). Perhaps as a result of the biases of biologists against the industry, biological investigations of palmeras do not exist eventhough, in Colombia, the geographic extension grew by 41,000 Ha in 2010, summing 402,000 Ha (Fedepalma, 2011) and continues to expand (to 452,400 Ha en 2013, El Tiempo, 2 dic. 2013, p. 20).

Snake studies in African palm plantations are rare; I am aware of one study in Nigeria that focused upon the snake community of climbing snakes (Akani et al., 2007).

Part of the problem with having Neotropical snakes as an object of study has been the view that they are uncommonly encountered even when one is actively searching for them. My experiences collecting in the tropics of Colombia and Ecuador (1967-2005) were such that finding three snake individuals in one day made that day memorable (until 2006). However, memories are not scientific data; fortunately, I can consult my fieldnotes so as to measure the rate of success. In 1983, I collected specimens along the Rio Calima, below Lago Calima, in Valle del Cauca, and later participated in the II ExpediciónBotánica in the Tayrona National Park (Magdalena). These were two of my most successful trips (based on memories). From my fieldnotes, I collected for 13 days at each place. In May-June, I collected in natural forests along the middle part of the Rio Calima (Valle del Cauca) and captured 48 snakes (20 preserved, fourteen delivered live to the Instituto Nacional de Salud, and 14 liberated) of fourteen species at a rate of 3.6 snakes/ day. In June-July, I collected within the Parque Nacional Natural Tayrona (Magdalena) and secured 32 specimens (22 preserved and ten delivered live to the Instituto Nacional de Salud) of thirteen species at a rate of 2.5 snakes/ day. Excepting our field trip to Antioquia and that to Casanare, fieldtrips to palmeras resulted in better successes of 3.3-13.1 snakes/ day (Table 1)

In my explorations of African Palm plantations (2006-2013), I have acquired an impression (incidentally) of the natural history of this introduced species where it exists as plantations. Initially, small plants are planted in a matrix lacking ground cover beyond grasses. The palms begin to be productive at four to six years after planting but the ground between palms remains exposed to full sunlight (ecologically equivalent to a pasture—dry, with a fluctuating temperature regieme). By the time the plants are eight to ten years old (after planting), the canopy closes resulting in higher humidity near ground level and a more homogeneous temperature regieme. Although the plants can live a very long time, practices in Colombian palmeras restrict their accumulated ages to 30 to 35 years after planting (facilitating the extraction of fruits). After this time, the plantation is cleared and the cycle re-initiated. Larger plants produce not only more fruits, they also produce more leaves (fronds) that must be cut so as to gain easy access to the fruit clumps. Cut fronds fall to the ground where they are gathered into piles within the plantation so that they do not interfere with the collection, fertilization, and fumigation activities of workers. Frond piles (paleras) guard even higher levels of humdity and the discarded plant parts initiate decomposition creating a density gradient (of humidity and humus) from the outside of the pile to its base. The trunk of the palm during the first third of its productive life is studded with the petiole bases of cut fronds and accumulates a cloak of epiphytes. Trees fifteen to twenty years of age have advanced the decomposition of the petiole studs to the point that the weight of the cloak begins to sag toward the base of the palm, leaving a relatively smooth trunk. The work of my students and I in palmeras reveals that the best place to find snakes within a palmera is in the frond piles, followed by the cloak or the accumulated debris at the base of the trunks. We had our least success searching in other facies of the palm plantation (canopy, open spaces under the shade of the canopy, and trunks).

African Palm plantations are not distributed uniformly within the country (Fedepalma, 2011) and for many regions where cultivation has begun, production is so low that no extraction plants have been constructed (meaning that cultivations are too young or not yet of a sufficient density). Planning fieldtrips in 2011-13 took into consideration whatever might indicate older palms (extraction plants) so as to improve our chances of finding snakes.

At present, the productive African palm industry of Colombia is distributed mostly within the populated and productive triangle of Colombia (below 500 m elevation above sea level, Appendix 1). This region is also the most severely transformed (ecologically). The Andean zone (slopes of the Andes) is likewise severely transformed ecologically but the impact on snake communities is reduced because snake diversity declines sharply with increased altitude (Lynch, 2013). Within the transformed lowlands few areas are protected (the National Parks of Macuira and Tayrona and the Salamanca Santuary) but available biological data on snake communities for these protected areas are scarce (because most biological collections of the country are younger than 30-50 years). Valuable snake collections were obtained by the Museo de La Salle in the first half of the 20th century and summarized by NicéforoMaría (1942) but transformation of these areas had occurred centuries previously, eliminating the dry tropical forest and severely reducing the extent of the wet tropical forest; the latter remnants were cut early in the early part of the second half of the 20th century.

For much of the transformed part of Colombia, the habitats offered are drier and experience brusk changes in temperatures during 24 hours (owing to the reduction in vegetative cover). Snake species are known from these regions (NicéforoMaría, 1942), but there, snakes are subjected to intense human persecution and vehicular traffic; such specimens rarely are deposited in scientific collections. My impression is that African palm plantations mimic the moderating climates of the dry and wet tropical forests that once covered these transformed lowlands (IGAC, 1962; Espinal, 1977). Additionally, these plantations offer refuges from human persecution and vehicular traffic, at least for species of crepuscular and/or nocturnal activities (the majority of tropical snake species).

It was into this strange world that I was drawn in May of 2006. My students and I were looking for lizards under these piles of fronds that we found in the shady recesses of a palm plantation (Palmeras del Meta, vereda Casteñada, municipio de San Martín, Meta) then aged at 20 years since planting. During three half-days (three to four hours of searching per day), we captured 46 snakes (six species: Atractus univittatus, Bothrops atrox, Epicrates maurus, Leptodeira annulata, Ninia atrata, and Oxyrhopus vanidicus) as well as a variety of frogs and lizards. Our capture-rate was so unexpected (by me) and so novel (as many as six snakes per hour) that I decided to continue investigating palm plantations as a means of access to sufficient snake specimens as to permit populational studies in the tropics. In October of the same year, we had the opportunity to spend more time in the same palmera (five days) and collected an additional 87 snakes of eight species (Atractus elaps, A. univittatus, Bothrops atrox, Epicrates maurus, Leptodeira annulata, Ninia atrata, Oxyrhopus petolarius, and Tantilla melanocephala), confirming my intellectual speculation. In 2012, we briefly collected again in the same palmera securing 33 snakes of five species (Atractus univittatus, Bothrops atrox, Ninia atrata, Oxyrhopus petolarius, and Tantilla melanocephala), the five most abundant species taken in 2006 of the total of nine species found in this palmera.

MATERIALS AND METHODS

This study was undertaken so as to learn the generality of my 2006 discoveries of notable snake abundances in the Neotropics and the lack of seasonal effects on those abundances. Subsequently, an effort was made to determine the importance of such plantation in the conservation of snakes within Colombia. The study is not an ecological study although I use some terms used frequently by ecologists. It is a study of how common are encounters of individual snakes in the experience of a collector of natural history specimens in different habitats, including that of a cultivated species (Elaeis guineensis) in Colombia, and inferences concerning their conservation.

All specimens collected are deposited in the collections of the Instituto de Ciencias Naturales of the Universidad Nacional de Colombia or form part of the live snake collection of the Serpentario del Instituto Nacional de Salud. Collecting methods have changed during the course of the investigations during these seven years. Initially, we merely removed the decomposing fronds in our frenzy to collect and, later, also excavated the moist soil beneath the mound to a depth of 10-15 centimeters. We subsequently began to restore the pile after searching for specimens. Restoration of piles is ecological sound because it restores a habitat that has fostered snake collecting and it is wise to continue that fostering. It is also a courtesy to those who gave permission to search for snakes in their property. Subsequently, we also searched the accumulated rubble at the base of palm trunks. Much later (2011), during a fieldtrip to Cesar, we began to strip the vegetative cloak on palm trunks. To facilitate our searches, we pay close attention to the abundance of potential prey items under piles of fronds (worms, soft-bodied insects and spiders, frogs, and rodents) because we expect (and have had) little success in a snake search when we fail to detect appreciable quantities of prey items.

Fieldwork has been carried out in palm plantations in the departments of Antioquia (one), Bolívar (two), Casanare (four), Cesar (four), Cundinamarca (one), Magdalena (three), Meta (eight), Nariño (two), and Santander (four), covering the geographic extent of productive plantations in Colombia.

The taxonomy followed here is conservative or traditional and does not admit molecular genera unless these are corroborated by at least one other class of data/evidence. Hence, I do not follow Adalsteinsson et al. (2009), Hedges et al. (2014), or Zaher et al. (2009) for their molecular genera, in part for reasoning advanced by Curcio et al (2009) and Myers (2011). Likewise, I do not adopt the recognition of molecular species within widespread taxa when corroborating morphological evidence has not been presented.

RESULTS

In the course of the fieldtrips during 2006-2013, I and my students have visited 30 palm plantations varying in size from five hectáreas to more than 20,000 Ha. These include privately held palmeras as well as those of organized companies. Success-rates varied widely (generally less success during the dry season than during the wet season and greater success when the palmeras had some internal policies that indirectly, and unintentionally, favored snake collecting and snake density). Fieldwork in the departments of Bolívar, Casanare, Cundinamarca, and Magdalena was carried out during very dry seasons resulting in little (Casanare), or no (Cundinamarca) success as well as very successful visits (Bolívar and Magdalena). Our success-rate was not diminished when we collected in the aseasonal climates of the Chocó biogeográfico (Nariño). Unsurprisingly, species lists do vary geographically.

In all of the collections made in palmeras, a total of 35 species of snakes was taken (Table 1). There are several species of lowland snakes that are known (or expected) to occur in all parts of the country (Boa constrictor, Clelia clelia, Corallus hortulanus, Imantodes cenchoa, Leptophis ahaetulla, Ninia atrata, Oxyrhopus petolarius, Tantilla melanocephala, and the species pairs of Bothrops asper or B. atrox, Epicrates cenchria or E. maurus, and Leptodeira annulata or L. septentrionalis). Although two species of Leptodeira are currently recognized for the country (Duellman, 1958), I here treat these as a single species; documentation of this proposal will be defended elsewhere. Seven other species (Chironius carinatus, Erythrolamprus bizona, Lampropeltis triangulum, Mastigodryas boddaertii, M. pleei, Sibon nebulatus, and Typhlops reticulatus) occur across the regions sampled but do not occupy all lowlands of Colombia. All of these except Imantodes cenchoa, Lampropeltis triangulum, and Sibon nebulatus were captured in at least one palmera. In most local regions visited (in palmeras), the snake group also collected in other situations (bananeras, fincas, native vegetation, pastures, rastrojos, towns, and along degraded streams with some sort of gallery forest beside them). No species of snake known from Colombia is distributed exclusively in palm plantations (hardly surprising, given that the African Palm is a recently introduced species in the American tropics).

During our visits to Bolìvar, Casanare, Magdalena, and Nariño, little or no effort was invested in natural or transformed habitats. During our visit to Antioquia (November 2011) where we collected 15 snakes in palmeras, we also collected in natural and transformed habitats, finding 24 snakes of 10 species, eight of which (Bothrops asper, Epicrates maurus, Imantodes cenchoa, Liophis melanotus, Mastigodryas pleei, Micrurus dumerilii, Porthidium lansbergi, and Pseudoboa neuwiedii) were not found in the palmera. In our visit to Cesar (September 2011) where we collected 33 snakes of nine species, we also collected in natural and transformed habitats, finding 25 snakes of 12 species, eight of which (Corallus hortulanus, Enilius flavotorques, Helicops danieli, Imantodes cenchoa, Leptotyphlops goudotti, Liotyphlops albirostris, Porthidium lansbergi, and Thamnodynastes gambotensis) were not found in local palmeras. During seven of the visits to Meta when we had time to search natural and transformed habitats we collected 340 snakes of 16 species in palmeras; in the natural and transformed habitats, we also collected 165 snakes of 15 species, of which seven (Atractus major, Dyrmoluber dichrous, Imantodes cenchoa, Leptophis ahaetulla, Micrurus hemprichii, Siphlophis compressus, and Thamnodynastes pallidus) were not found in local palmeras. In three visits to the western lowlands of Santander (March 2007, March 2008, and August 2011) where we collected 42 snakes in palmeras, we also collected in natural/ transformed habitats finding 32 snakes of 14 species, two of which (Imantodes cenchoa and Thamnodynastes gambotensis) were not found in local palmeras.

Of the 35 species of snakes captured in palmeras, only fourteen show some diurnal activity. Chironius carinatus, Leptophis ahaetulla, the two Liophis, Lygophis lineatus, and the three Mastigodryas are exclusively diurnal snake species. The two Enilius, Erythrolamprus bizona, and Urotheca euryzona are best described as crepuscular/diurnal (Savage, 2002). Clelia clelia is normally active at night but is also frequently encountered active by day. Eunectes murinus is also crepuscular and aquatic; its activity cycle cannot be described as diurnal or nocturnal. Typhlops reticulatus is a burrower but can be found above ground as well even during daylight hours. The remaining 21 species are exclusively nocturnal organisms.

Our visits to palm plantations were normally in the course of a single fieldtrip (fewer than 14 days). Palm plantations in Meta were visited on five distinct occasions: twice in 2006 (6 ½ days), once in 2011 (2 ½ days), once in 2012 (13 days), and once in 2013 (4 ½ days). Visits to palm plantations in Santander occurred twice (for three days in 2007 and for 7 days in 2011). The only plantation visited more than once was Palmeras del Meta (three visits, data separated in Fig. 3). Collecting success varies greatly among the eight departaments visited in terms of number of species captured (Fig. 1) and number of individuals captured (Fig. 2), each calibrated in terms of days invested in searches. There is a positive correlation to time invested in the active search for snakes and capture success. The number of species found in a given palmera is positively correlated with the total number of individuals captured (Fig. 3). During each field trip, five or six persons participated in discovery and capture of specimens for between four and six hours/ day.

In several palmeras visited during this investigation, we experienced very poor results in terms of snake captures (in Bolívar, municipality of María La Baja, two private palmeras; in Casanare, municipality of Villanueva: Palmeras del Oriente, Palmera Santa Ana, and Palmeras del Casanare and a private palmera, finca Rio Grande; in Cesar, municipality of San Martín, Palmeras de Cesar; in Cundinamarca, municipality of Paratebueno, private palmera, Hacienda La Europa; in Meta, municipality of Barranca de Upia, Palmera Guaicaramo; in municipality of Cumaral, Hacienda La Cabaña; municipality of Villavicencio, Palmera Borrego). These sites of poor results (Table 2) appear to me to derive from two or three causes (not mutually exclusive): (1) Hacienda La Cabaña and Palmera Borrego may well have produced little result because each is an island of palms within a matrix of pastures, not connected to forest remnants, which might serve as sources for species requiring forested habitat; (2) additionally, at Hacienda La Cabaña and Palmeras de Cesar, we found intense application of insecticides; (3) at the remaining poor sites, paleras were not formed or were so shallow as to allow the discarded fronds to dry out completely and few prey items were seen. Because we found few prey items, we abandoned our searches as soon as practical when possible. Nonetheless, we were "trapped" in Hacienda La Cabaña and Palmera Borrego (for lack of transport) and spent nearly two days in Palmeras del Oriente.

DISCUSSION

To date, there are no confiable data on population sizes of any snake species in Colombia. In point of fact, the impression of collectors is that densities are very low, impressions that are contradicted by our work in palmeras. Collecting in natural habitats (Vichada, 2013) has produced success rates equivalent or superior to our work in palmeras.

Fieldwork in palmeras is sometimes as poorly productive as fieldwork in natural or transformed habitats but, in four of the eight departments sampled, can be impressively successful in terms of number of individuals captured/ day (Table 1). In general, looking across these past seven years, my impression is that population sizes of snakes in palmeras are elevated in comparison to natural or transformed habitats. Furthermore, in the only palmera visited repeatedly (Palmeras del Meta), the most abundant species in each of the two visits in 2006, remained the most abundant species in 2012 (in the same order of relative abundance: Ninia atrata > Atractus univittatus > Oxyrhopus petolarius > Tantilla melanocephala > Bothrops atrox), suggesting that relative abundances of species have not changed between 2006 and 2012 (Table 3).

That said palmeras do not represent a panacea for conservation because some species apparently do not use palmeras. A case in point is Imantodes cenchoa, a relatively common snake species in both natural and transformed habitats but absent from palmeras. Two other snake species, Dipsas catesbyi and Sibon nebulatus, each common in its habitat, were not found in our explorations of palmeras. These apparent absences, like that of Imantodes cenchoa, may reflect the absence of critical prey species.

Lynch (2013) estimated the sizes of snake communities for most ecogeographic regions of Colombia. Fieldwork in Antioquia, Cesar, and Santander corresponds to the Middle Magdalena, a once humid tropical forest and that in Bolívar and Magdalena to areas of dry tropical forest. Lynch (2013) estimated each snake fauna at 45 species. Given that, fieldwork within palmeras during the Antioquia fieldtrip recovered only 13% of the estimated regional snake community, the Bolívar and Magdalena trips 27%, the Cesar trip 20%, and the Santander fieldtrips 38%. Against those percentages, one might conclude that African palm plantations do not seem important. However, I emphasize, that in Colombia, no one has ever estimated population sizes for any snake species and that, based on available data (number of preserved records) and our own experiences, many species are rarely collected, either because collectors have not yet learned to capture them or because their population sizes are very small.

For the other three departments, it is more difficult to estimate community size. Nariño is very imperfectly known for lack of collecting effort; the problem for Casanare and Meta is that each department is near the base of a peninsula (the piedmont of the eastern grasslands) and the faunal reduction (the peninsular effect of Brown & Lomolino, 1998; Simpson, 1965) requires calibration for tropical snakes. Additionally, Casanare was nearly our worst fieldtrip (poorest results). For Meta, after eight visits to palmeras, our results seemed stable (although, in our last visit, we added Erythrolamprus bizona to the list of species taken in palmeras). Meta lies near the base of the ecological peninsula and has a snake fauna of 60 species (substantially fewer than Amazonia, Lynch, 2013). Our efforts there (in palmeras) secured only 25% of the anticipated snake fauna.

Beyond the common species (Dipsas, Imantodes, and Sibon) not using palmeras, there are a number of other species collected in natural or transformed habitats within a few kilometers of palmeras that have not been found in palmeras. Their absences do not appear to be caused by lack of appropriate prey species and I suggest that their absences from palmeras is a result of the very limited number of microhabitats to be found within a monoculture of African Palm. Even transformed habitats are richer in the number of microhabitats available although including probably fewer microhabitats that natural habitats. Our fieldwork in Chocó and in Vichada was restricted to natural and/ or transformed habitats and resulted in 20 or more snake species during each visit, contrasting sharply with the observation that we never found more than 14 species (representing 143 individuals captured) in a single palmera. While intensity of effort (days invested) seems to explain diversity, combining the data for the three visits to Palmeras del Meta (San Martín, Meta) yields only nine species representing 166 individuals), suggesting that local diversity (within a palmera) may be controlled by local conditions.

For the six departments for which it is possible to estimate snake community sizes, the mean value of species found in palmeras is only 25% of the estimated snake community. This means that although palmeras do enable larger than expected population sizes for certain species, they do not protect snake species diversity even so well as secondary forests (probably for the improverishment of microhabitat diversity). If my argument is sound, that suggests a strategy for improving palm plantations as protectors of snake diversity. That strategy is against extensive monoculture and in favor of a mosaic, with patches of secondary forest interspersed among parcels of monoculture.

The Colombian African palm industry could be a major factor in conservation biology of snakes in Colombia where mortality caused by rural workers exceeds 100 million snakes/ year and no fewer than 50,000 snakes die/ year due to vehicular traffic (Lynch, 2013). However, to be a partner in conservation will require two changes in the industry: (1) that all waste fronds be piled into mounds (paleras) within the plantation and allowed to decompose slowly. This provides refuges for snakes (as well as easy access to prey) and reduces encounters by humans (reducing snake bites and reducing movements which can result in mortality on roads), and (2) that palmeras cease to convert rastrojos (parcels of secondary forest) in more monoculture of palms. Doing so provides a source fauna (the parcels of rastrojo) as well as increasing the number of microhabitats (and the prey base). Each of these activities contributes to preserving the snake fauna (either by elevating population sizes or, most likely, by increasing local species diversity).

Palm plantations do represent the best of the monocultures available in Colombia because some snake species do quite well within palm plantations (in contrast to other monocultures: Acacia, Eucalyptus, pine, and teka plantations as well as bananas, pasturelands, and rice fields). This affirmation is based not upon systematic field work but on my successes catching snakes in Colombia during the past 35 years.

ACKNOWLEDGMENTS

I was greatly helped by a number of my current and past students as well as by students from other universities who participated in the collecting efforts (Carolina Amorocho, Marvin Anganoy, Teddy Angarita, Gustavo Ballén, Lucas Barrientos, Edgar Bernal, Rances Caicedo, Iván Delgado, David Echavarría, Lina Escobar, Diego Gómez, ÁngelaHurtado, Juan Pablo Hurtado, Vanesa Mosquera, Jonh Jairo Mueses, Jhon Jairo Ospina, Pablo Palacios, RaúlPedroza, Camila Andrea Rodríguez, Herón Romero, and David Sánchez), by colleagues from the Instituto Nacional de Salud (Carlos Castro, Jairo Maldonado, Francisco Ruiz, and Ricardo Vanegas), by local guides (Jonathan Bernal, William Bland, Beiker Casteñeda, Misael Santiago, and certain of our drivers (Fabricio Lara, E. Pinto). Three anonymous reviewers provided me with many useful suggestions to improve the manuscript.

Access to palm plantations was granted by the managers or owners of finca Tipaná (Antioquia, Chigorodò), Palmera Aguas Blanca and two private palmeras (Bolívar, María La Baja), finca Rio Grande, Palmeras del Casanare, del Oriente, Palmera Santana (Casanare, Villanueva), Palmeras de Cesar, Palmera La Cacica, and Promipalma (Cesar, San Martín), INDUPALMA (Cesar, San Alberto), Hacienda La Europa (Cundinamarca, Paratebueno), barrio Macondo (Magdalena, Aracataca), private palmar de Botero, finca El Vogel, Hacienda La María (Magdalena, El Retiro), private palmera (Meta, Acacias), Palmera Gaicaramo (Meta, Barrancas del Upia), Hacienda La Cabaña (Meta, Cumaral), Cultivo de Palma Sapuga, Palmera Sillalava (Meta, Puerto Gaitán), Palmeras del Meta, Palmasol (Meta, San Martín), Palmera El Borrego (Meta, Villavicencio), two private palmeras (Nariño, Tumaco), four private palmeras (Santander, Sabana de Torres), finca El Vaivén, Palmeras Las Brisas (Santander, Puerto Wilches).

Lastly, financial support for this investigation was provided by two agreements (Convenios) between the Ministerio de Medio Ambiente & Desarrollo Territorial-Instituto Nacional de Salud-Universidad Nacional de Colombia (031 of 2011 and 083 of 2012) as well as incidentally during the fieldtrips of Introduccion a la Taxonomia Animal/ Introduccion a la Sistematica Animal (2004-2011).

LITERATURE CITED

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