Víctor H. Serrano-Cardozo

Diet of the Andean Frog Ranitomeya virolinensis (Athesphatanura: Dendrobatidae)

Abstract The effects of sex, ontogeny, and season on the diet of Ranitomeya virolinensis were studied over one year. The diet of this Andean species is composed mainly of small prey; the most important prey categories according to index of relative importance (IRI) were Acari, Formicidae, Holometabolous larvae, and Collembola. There were no differences in total prey gut content over time assessed in number and volume; however, the diet composition of this Santander Poison Frog changed between dry and wet seasons, with Formicidae, holometabolous larvae and Collembola as the prey categories that contributed most to the difference. Males had fewer prey in their guts than females, but there were no compositional differences between sexes. There was a shift in the importance of prey caused by ontogeny. Mean prey volume increased with body size, whereas the occurrence of Acari and Formicidae varied inversely with SVL. Formicidae was the second most important prey category according to IRI. Therefore it is an important category as has been described previously for other Dendrobatid species. However, its importance fluctuated with the season. Acari was the most significant prey type in R. virolinensis as is the case for other small related species of the genus, although its importance changed with the ontogeny. The diet of this frog had a substantial phylogenetic component because closely related species have similar diets; nevertheless, its diet is clearly affected by other intrinsic and extrinsic factors.

Diet, microhabitat use, and thermal preferences of Ptychoglossus bicolor (Squamata: Gymnophthalmidae) in an organic coffee shade plantation in Colombia

Ptychoglossus bicolor es un pequeno lagarto de la familia Gymnophthalmidae, que habita el valle del Rio Magdalena de Colombia. Se estudiaron las caracteristicas ecologicas de la dieta, uso de microhabitat y preferencias termales de una poblacion que habita una plantacion de cafe organico bajo sombra en la Cordillera Oriental colombiana. La dieta en esta poblacion esta dominada por isopodos. El Indice Valor de Importancia Relativa fue del 98.8% y no hubo diferencias mensuales significativas en el contenido estomacal y el volumen de isopodos consumidos durante el ano, ni tampoco entre las estaciones de lluvia y seca. Un gran numero de lagartos fueron encontrados activos entre la hojarasca, enterrados junto a las raices de los arboles y bajo o dentro de troncos en descomposicion. La temperatura corporal estuvo positivamente correlacionada con las temperaturas del suelo y del aire y no hubo diferencias significativas en temperatura corporal entre los sexos. En esta localidad no encontramos lagartos fuera de los campos de cultivo de cafe. Nuestros resultados sugieren que estos lagartos sobrellevan exitosamente las condiciones ofrecidas por los cafetales organicos como resultado del sistema de cultivo. Asi, esta poblacion podria ser vulnerable a cualquier modificacion del habitat que cambie la disponibilidad de microhabitats y la abundancia de isopodos.

ANNUAL REPRODUCTIVE ACTIVITY OF GONATODES ALBOGULARIS (SQUAMATA: GEKKONIDAE) LIVING IN AN ANTHROPICAREA IN SANTANDER, COLOMBIA

Abstract We studied the reproductive characteristics of a population of Gonatodes albogularis in an Andean tropical dry forest with a bimodal rainfall regime. Females were smaller than males in snout-vent length (SVL). Males and females reached sexual maturity at similar body sizes (close to 31 mm SVL) and had continuous reproductive activity during the sampling year. All adult females were reproductive (vitellogenic and gravid females); they were found throughout the year and we did not observe differences among months in reproductive stages, nor in the follicular and ovarian sizes. Gravid females produced only one egg and had simultaneously one large vitellogenic follicle, suggesting a continuous reproductive activity. Adult males had spermatozoa in testes and ducts during all months and there were no significant changes among months in the volume and mass of testes adjusted to body size. These data, plus the observation of neonates and communal nests in every month of the year, confirm a pattern of continuous reproductive activity with multiple clutches. Despite the low mean annual rainfall, and the marked seasonality of rainfall in the area, the population exhibited an aseasonal reproductive pattern that suggests a continuous availability of resources for reproduction.

Reproduction of Ptychoglossus bicolor (Squamata: Gymnophthalmidae) in an Andean Coffee Shade Plantation in Colombia

ABSTRACT. The pattern of annual reproductive activity and other reproductive characteristics were studied in a population of the gymnophthalmid lizard Ptychoglossus bicolor that inhabits the leaf-litter of an organic coffee shade plantation located on the Cordillera Oriental of the Colombian Andes. Males and females reached sexual maturity at a similar body size (approximately 45 mm snout vent length); however, adult males were significantly larger than females in body size, body mass, and head size. All adult males showed convoluted epididymides, enlarged testes with continuous spermatogenesis and spermiogenesis throughout the year. However, testis mass varied significantly among months and between seasons and was positively correlated with the amount of rainfall. Females were reproductively active (vitellogenic, ovigerous, and vitellogenic and ovigerous simultaneously) during all months of the year, and clutch size was always two. Abdominal fat bodies did not vary over time, neither in males nor in females, Together with the observation of juveniles in most months, this indicates a pattern of continuous reproductive activity and confirms the production of multiple clutches in this population. This aseasonal reproductive pattern suggests a continuous availability of resources that can be supplied in favourable conditions offered by the organic farming.

Oviposition, Site Preference, and Evaluation of Male Clutch Attendance in Espadarana andina (Anura: Centrolenidae)

Abstract We evaluated patterns of site preference for oviposition in Espadarana andina based on the identification and characterization of microhabitats during rainy and dry seasons. We also evaluated the presence of males and females at oviposition sites and the proximity of the adults to the clutches. An electivity index was used to determine which microhabitats were selected for oviposition and calling by males. Additionally, abiotic factors that might influence the oviposition site preference in this species were evaluated. Espadarana andina selected green leaves of Hedychium coronarium along the stream edge, at a height of 70–140 cm for both oviposition and calling sites. All the recorded clutches were found exclusively on leaves of H. coronarium, an invasive plant, suggesting that this plant offers advantages for the reproductive activity of E. andina over other plant species present along the stream border. There was no difference in site selection for calling, mating, and oviposition between dry and rainy seasons and among months. Males stood near clutches during the night, calling from the same plant. Although they were significantly closer to the clutches than females, they did not show any action to increase the survival of the embryos in the clutches. Therefore, we did not observe true egg attendance in E. andina; this observation fits with the absence of parental care behaviors described for the Centroleninae. Resumen Evaluamos los patrones de preferencia de sitio para la oviposición en Espadarana andina basados en la identificación y caracterización de los microhábitats durante las estaciones de lluvia y sequía; también evaluamos la presencia de machos y hembras en los sitios de oviposición y la cercanía de los adultos a las posturas. Un índice de electividad fue usado para determinar cuáles microhábitats fueron seleccionados para la oviposición y llamado de los machos. Adicionalmente, fueron evaluados los factores abióticos que podrían influir en la preferencia por el sitio de oviposición en esta especie. Espadarana andina seleccionó hojas verdes de Hedychium coronarium a lo largo del borde de la quebrada, a un rango de altura de 70–140 cm tanto para la oviposición como para los sitos de canto. Todas las posturas registradas fueron exclusivamente encontradas sobre las hojas de H. coronarium, una planta invasiva, por lo tanto, esta planta parece ofrecer mejores ventajas para la actividad reproductiva de E. andina que otras especies de plantas presentes a lo largo del borde de la quebrada. No hubo diferencias en la selección de sitios para canto, apareamiento y oviposición entre las estaciones de lluvia y seca, ni entre meses. Los machos permanecieron cerca de las posturas durante la noche, cantando desde la misma planta. Aunque los machos estuvieron significativamente más cerca de las posturas que las hembras, ellos no mostraron ninguna actividad para incrementar la supervivencia de los embriones en las posturas. Así, una verdadera atención a los huevos en E. andina no fue establecida; esta observación coincide con la ausencia de comportamientos de cuidado parental descrita para los Centroleninae.

Feeding and Reproductive Ecology of Bachia bicolor (Squamata: Gymnophthalmidae) in Urban Ecosystems from Colombia

Abstract Bachia bicolor is a small serpentiform lizard distributed from central to northern Colombia and western Venezuela; until now ecological and reproductive data are unknown for this species. We studied some ecological and reproductive aspects of a population of B. bicolor that inhabits urban areas from a Colombian city. Lizards are found in house gardens and public parks, living underground in organic-rich soils and feeding on small arthropods such as termites, insect larvae, coleopterans, and terrestrial isopods, among others. Males and females of B. bicolor reach sexual maturity with a similar body size and a similar body form; however, males have larger heads than do females. Males and females were found to be reproductively active throughout the year without differences in gonadal morphometric variables between months or seasons. Neither the amount of ingested food nor the abdominal fat body masses varied among months or seasons. These observations, together with the presence of juveniles in most months, suggest continuous reproductive activity and continuous feeding in this population. Our results show that B. bicolor lives and feeds underground as do other fossorial gymnophthalmids, and its diet clearly differs from those of semi-fossorial and surface-dweller gymnophthalmid lizards. Given its lifestyle and the favorable conditions offered by these urban systems, the ecological and reproductive characteristics of this population may be the result of either phylogenetic constraints (related to fossoriality) or a high resource availability, or a combination of both. Resumen Bachia bicolor es un pequeño lagarto serpentiforme que se encuentra distribuido desde el centro hasta el norte de Colombia, y en el oeste de Venezuela; hasta el momento los datos ecológicos y reproductivos de esta especie son desconocidos. En este trabajo estudiamos algunos aspectos ecológicos y reproductivos de una población de B. bicolor que habita en el área urbana de una ciudad Colombiana. Estos lagartos se encuentran en los jardines de las casas y parques públicos viviendo bajo tierra en suelos ricos en material orgánico y alimentándose de pequeños artrópodos como termitas, larvas de insectos, coleópteros, e isópodos terrestres entre otros. Los machos y las hembras alcanzan la madurez sexual con un tamaño corporal similar y la forma del cuerpo es también igual para ambos sexos; sin embargo, los machos tienen cabezas significativamente más grandes que las hembras. Tanto machos como hembras son reproductivamente activos a lo largo del año, sin diferencias en las variables morfométricas gonadales entre meses o estaciones. La cantidad de alimento consumido y la masa de los cuerpos grasos abdominales tampoco variaron entre los meses o estaciones. Estas observaciones, junto con la presencia de juveniles en la mayoría de los meses, sugieren una actividad reproductiva y una alimentación continua en esta población. Nuestros resultados muestran que B. bicolor vive y se alimenta bajo tierra al igual que otros gymnophthalmidos fosoriales, y su dieta claramente difiere de gymnophthalmidos semi-fosoriales y de superficie. Debido a su estilo de vida y las condiciones ofrecidas por estos sistemas urbanos, las características ecológicas y reproductivas de esta población pueden ser el resultado de limitaciones filogenéticas (relacionadas con la fosorialidad), una alta disponibilidad de recursos, o una combinación de las dos.

Diet, Microhabitat use and Daily Activity Patterns of an Andean Population of Mabuya (Squamata: Scincidae)

ABSTRACT. We studied diet composition, microhabitat use and daily activity patterns of an Andean population of Mabuya in a disturbed tropical habitat to evaluate if these features differed sexually, ontogenetically, seasonally, and among reproductive stages. Lizards ate mainly crickets plus grasshoppers, spiders and cockroaches; these prey were the most important in terms of volume and number. There were no significant differences in the number, type and abundance of prey, as well as in the length and volume of the consumed prey between males and females. There were significant differences between the diet of adults and juveniles. Lizards ate prey with similar volumes and lengths throughout the year independent of the rainfall regime. Also, there were no significant differences in prey volume and length with regard to the reproductive stages of females and males. The lack of variation in diet in this population suggests a constant availability of prey in the study area. When we compared diet composition of this population with that of other species of Mabuya, we found that diet tends to be similar among the different species and populations of Mabuya in South America. Adult lizards showed two activity peaks during the day, before and after midday; this pattern of daily activity was constant throughout the year. Preferred microhabitats used by this population are related to anthropogenic disturbance. The population of the present study seems to have quite wide ecological requirements (generalist diet, use of a wide spectrum of microhabitats and extended daily activity), which allows it to exploit disturbed habitats.

Reproductive Activity of the Andean Frog Ranitomeya virolinensis (Anura: Dendrobatidae)

Abstract We studied the pattern of annual reproductive activity in the Andean dendrobatid frog Ranitomeya virolinensis by comparing age–sex structure of the population, morphology, and morphometry of gonad among months and between seasons. The focal population is found in a mountain habitat with a bimodal pattern of rains, which suggests a seasonal pattern of reproduction, as has been observed in other Neotropical frogs. Mature and reproductive females and males were collected during the entire year and their reproduction is continuous. Sexual maturity was reached in both sexes near 16.0 mm snout–vent length (SVL); females are significantly larger than males. The diameter of the ovary and of the largest follicles did not show significant differences among months or between seasons. Clutch size in all mature females was only one egg per oviposition event; however, the simultaneous presence of advanced vitellogenic follicles with the oviductal egg suggests that females produce several clutches with short inter-clutch intervals. Testes of all mature males had seminiferous tubules with cysts of all spermatogenic stages and free spermatozoa in the lumen in each month we sampled. The size of testes did not differ among months or between seasons. Therefore, the ability to produce ova and spermatozoa is continuous throughout the year in this species. Because juveniles in the smallest size classes were observed in all months, we assume that reproduction is continuous. The continuous reproductive activity of R. virolinensis is likely favored by its semi-terrestrial mode of reproduction, in an environment where direct resources for reproduction, such as moist ground for oviposition and phytotelmata for rearing tadpoles, are available despite a seasonal rainfall pattern.

Diet and Microhabitat Use of Bolitoglossa cf. pandi (Caudata: Plethodontidae) from the Cordillera Oriental of Colombia

Abstract Bolitoglossa cf. pandi is a terrestrial salamander that inhabits a fragment of secondary forest located in the Cordillera Oriental of the Colombian Andes. Few aspects of its biology are known. Here we studied its diet, microhabitat use, population structure, and arthropod richness at the study site during rainy and dry seasons. We also recorded perch height, substrate type, and time of capture. Encounter rate for Bolitoglossa cf. pandi was very high during rainy months and low during dry season. Juveniles were more abundant than adults. To obtain consumed items we used the stomach-flushing technique; the contents of 87 stomachs were analyzed and 1324 prey items were identified and grouped in 20 prey categories. Diet was represented by a great variety of arthropods and the most important prey categories, according to the index of relative importance (IRI), were Acari, Coleoptera, and Formicidae. No differences were found in diet between sexes; however, ontogenetic variation was found: there was a shift in consumption of ants and mites related to ontogeny. Volume of coleopterans and ants in stomachs increased with body size, whereas occurrence of mites varied inversely with body size. Only Acari consumption changed between dry and wet seasons. Bolitoglossa cf. pandi forages on the ground, as well as on herbaceous vegetation; larger individuals were found in the highest perches, usually on leaves. Diet and microhabitat use of this salamander is similar to other species of Bolitoglossa and are affected by local environmental factors, such as prey availability and climate regime, and endogenous factors, such as body size.