It has been suggested that tropical defaunation may unleash communitywide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause-effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understorey plant diversity. We established plot triplets (n ¼ 25) representing three defaunation contexts: terrestrial-mammal exclosure (TE), medium/large mammal exclosure (PE) and open access controls (C). Seedlings/saplings 30-100 cm tall were marked and identified within each of these plots and re-censused three times to record survival and recruitment. In the periods 2010-2011 and 2011-2013, survival was greater in PE than in C plots and recruitment was higher in TE plots than in C plots. Overall, seedling density increased by 61% in TE plots and 23% in PE plots, whereas it decreased by 5% in C plots. Common species highly consumed by mammals (e.g. Brosimum alicastrum and Ampelocera hottlei) increased in their abundance in TE plots. Rarefaction curves showed that species diversity decreased in TE plots from 2008 to 2013, whereas it remained similar for C plots. Given the prevalence of tropical defaunation, we posit this is an anthropogenic effect threatening the maintenance of tropical forest diversity.

Abstract:Wildlife species population density estimation is important from both ecological and management perspectives. The pellet-group counting method has been used to evaluate density of the white-tailed deer (Odocoileus virginianus). This species is an important component of human diet in tropical habitats. The objectives of this study were to: 1) compare density estimates using four methods: counts in circular plots (FSC, Fecal Standing Crop and FAR, Fecal Accumulation Rate), and counts in transects (LT, Line Transect and ST, Strip Transect); 2) simulate the effect of increased sampling effort on density and precision, and; 3) evaluate the effort required to detect changes in population density using LT. From 2006 to 2007, we intensively sampled a 1 km 2 quadrant in a Mexican tropical dry forest. The results indicate that all four methods produce similar mean population density estimates. However, estimates of precision were dependent on sample size which in turn was associated with the particular counting method used. In descending order of estimate precision, the methods ranked as: LT, ST, FSC, and FAR. To detect population changes of < 20%, we suggest the establishment of 5 to 22 transects (LT) of 390 m during the dry season. To reduce bias in density estimation, it is important to obtain defecation and pellet decomposition rates in the study site.Key words: fecal counts; sampling methods; density; precision; Odocoileus virginianus. Resumen:Desde una perspectiva ecológica y de manejo es necesario estimar la densidad poblacional de la fauna. El método de conteo de grupos fecales es empleado frecuentemente para estimar la densidad de muchas especies incluido el venado cola blanca (Odocoileus virginianus). Este cérvido es importante en la cacería de subsistencia en regiones tropicales. Los objetivos del estudio fueron: 1) comparar las estimaciones de densidad empleando cuatro métodos: conteos en parcelas circulares (FSC, "Fecal Standing Crop" y FAR, "Fecal Accumulation Rate"), y conteos en transectos (LT, "Line Transect" y ST, "Strip Transect"); 2) simular el efecto de aumentar el esfuerzo de muestreo sobre la densidad y su precisión, y 3) evaluar el esfuerzo requerido para detectar cambios en la densidad empleando LT. De 2006 a 2007, monitoreamos intensivamente un cuadrante de 1 km 2 localizado en un bosque tropical seco del centro de México. Encontramos que los cuatro métodos proporcionan estimaciones poblacionales similares. Sin embargo, la precisión de las estimaciones dependió del tamaño de muestra, el cual a su vez fue determinado por el método de conteo utilizado. Así, LT produjo la estimación de densidad más precisa, seguido por ST, FSC y finalmente FAR. Para detectar cambios poblacionales < 20%, sugerimos poner 5-22 transectos (LT) de 390 m de longitud durante la época seca. Para reducir el sesgo de la estimación es importante obtener las tasas de defecación y de descomposición de los excrementos en el área de estudio.

No abstract

Resumen: Tanto desde una perspectiva ecológica como de manejo, es importante conocer la proporción de sexos y la estructura de edades de las poblaciones de venado cola blanca (Odocoileus virginianus). Sin embargo, en aquellos lugares donde no es posible ver directamente a los animales en vida libre, no es sencillo determinar su edad y sexo por lo que se han empleado métodos indirectos como el análisis morfométrico de los pellets. Con el fin de determinar si la variación entre pellets de individuos de diferentes edades y sexo permite su correcta categorización, se colectaron los grupos fecales de individuos conocidos en cautiverio en la UMA-Zoológico Flor del Bosque, Puebla. Se obtuvieron 180 muestras de las cuales 18 fueron de crías (< 1 año), 78 de juveniles (2-3 años) y 84 de adultos (> 3 años). Se comparó el promedio de todas las variables morfométricas entre grupos fecales de un mismo individuo y entre individuos de la misma clase de edad y sexo. Nuestros resultados sugieren que dada la alta variación presentada en las medidas morfométricas de los pellets de un mismo individuo en una misma época y entre épocas del año, y la baja variación mostrada entre grupos fecales de individuos de diferentes clases de edad y sexo, el análisis morfométrico de pellets es una metodología poco confiable para determinar la estructura de edad y sexo de una población de O. v. mexicanus. En consecuencia, la técnica de clasificación fuzzy no logra una categorización adecuada de la población en estudio pues sólo separa a los machos adultos de 5 y 6 años, mientras que los machos de menor edad y juveniles, así como hembras adultas y juveniles no son discriminados en clases separadas. Se sugiere realizar análisis similares a este con otras subespecies de venado que no exhiban un fuerte dimorfismo sexual como aquellas distribuidas hacia el centro y sur de México. Palabras clave: estructura de edades, método indirecto, pellets, técnica fuzzy, Odocoileus  virginianus.Abstract: Both from an ecological perspective as management, it is important to know the sex ratio and age structure of populations of white-tailed deer (Odocoileus virginianus). However, in places where you can not directly see the animals in the wild is not easy to determine their age and sex so indirect methods have been used as a morphometric analysis of the pellets. To determine whether the variation between pellets of individuals of different age and sex allows proper categorization, fecal groups were collected from known individuals in captivity in the Zoo UMA-Flor del Bosque, Puebla. We obtained 180 samples of which 18 were young (<1 year), 78 juveniles (2-3 years) and 84 adults (> 3 years). We compared the average for all morphometric variables between groups fecal same individual and between individuals of the same age class and sex. Our results suggest that given the high variation shown in the body measures of the pellets from the same individual in the same season and between seasons, and low fecal variation shown between groups of individuals of different age classes and sex, analysis morphometry of pellets is an unreliable method to determine the age and sex structure of a population of O. v. mexicanus. Consequently, the fuzzy classification technique does not achieve appropriate categorization of the study population because only separates adult males of 5 and 6 years, while younger males and juveniles and adult females and juveniles are not discriminated against in separate classes. Similar analysis suggested this to other subspecies of deer that do not exhibit strong sexual dimorphism as those distributed to the central and southern Mexico.Key words: Structure of ages, indirect method, pellets, technology fuzzy, Odocoileus  virginianus.

en el sureste mexicano Spatial and temporal analysis of the structure of the community of medium and large body sized mammals in the Biosphere Reserve El Ocote, southern Mexico

Fruits reaching the floor of tropical forests constitute an attractive resource for a variety of mammals. Study of the characteristics of the frugivory interaction can help to advance in the understanding of the mechanisms favoring animal's coexistence. However, there are few studies focused on analyzing patterns of activity of mammals feeding on fruits in the forest floor. Camera traps were used to record consumption of Licania platypus and Pouteria sapota fruits by Cuniculus paca, Dasyprocta punctata, Nasua narica, Dycotiles crassus and Tapirella bairdii. Patterns of mammal activity were characterized based on the day, time and tree in which they were recorded. Overlap in daily (delta coefficient) and spatial occurrence (same tree and day, Jaccard, Ochiai indices and V ratio) was assessed. High segregation in the activity of frugivores occurred during the day (mean delta = 0.291 and 0.191 for L. platypus and P. sapota, respectively) and among trees/days (max. Jaccard = 0.14 and 0.19 for L. platypus and P. sapota, respectively). Our results suggest that activity overlap among mammalian frugivores feeding in the forest floor is lower than expected. This likely relates to the fact we conducted our analysis at a finer detail than previous studies (for example those focusing exclusively on dietary overlap). Thus, our study increases our understanding of the possible factor that can favor coexistence of tropical frugivorous mammals. Los frutos depositados en el piso del bosque tropical son un recurso sumamente atractivo para una amplia variedad de mamíferos. El estudio de las características de esta interacción puede permitir avanzar en el entendimiento de los mecanismos que favorecen la coexistencia entre especies de mamíferos. Se usaron cámaras trampa para registrar el consumo de frutos de Licania platypus y Pouteria sapota por Cuniculus paca, Dasyprocta punctata, Nasua narica, Dycotiles crassus y Tapirella bairdii. Con base en la información del día, la hora y el árbol donde se registró la fauna, se caracterizó el nivel de traslape en actividad a lo largo del día (coeficiente de traslape, delta) y espacialmente (visitas a los mismos árboles en los mismos días, índices de asociación de Jaccard, Ochiai y cociente V). Se encontró una alta segregación en la actividad diaria (delta promedio = 0.291 y 0.191 en L. platypus y P. sapota, respectivamente) y entre árboles/días (máx. Jaccard = 0.14 y 0.19 en L. platypus y P. sapota, respectivamente). Nuestros resultados indican que el grado de traslape en la actividad de mamíferos alimentándose de frutos en el piso de la selva es en general bajo. Esto puede deberse al hecho de que nuestro estudio analiza los patrones de actividad de la fauna con un mayor nivel de detalle que estudios previos que, por ejemplo, se han concentrado exclusivamente en la dieta de la fauna. Nuestro estudio permite avanzar en el entendimiento de los mecanismos que permiten la coexistencia entre distintas especies de mamíferos frugívoros.

No abstract

The coyote (Canis latrans) is a widespread predator with a high degree of adaptation to different ecosystems. The objective of this study was to estimate the relative abundance index, habitat selection, and diet of C. latrans through scent stations, in two types of vegetation located in northwestern Chihuahua. From April 2018 to March 2019, ten fixed scent stations (SS) were placed in pine-oak forest and other ten in semi-open grassland, with a linear separation of 500 meters between each station to achieve a five km transect in each vegetation during 12 samplings (two sampling night per month) for totaling 420 SS after discarding inactive SS. The relative abundance index of coyote showed that both types of vegetation, pine-oak forest (0.30) and semi-open grassland (0.23) were used in a similar way. The habitat selection test (Chi2) showed that coyote abundance and type of vegetation were independent (χ2 = 2.96, P > 0.05), not showing statistically significant differences in annual relative abundance index of coyotes between the two vegetation types. The food items detected in thirty-four scats collected belonged to mammals (55.9 %), fruits (35.3 %) and arthropods (8.8 %). Rodents and lagomorphs were the main source of food. Throughout the sampling period, the pine-oak forest showed the greatest relative abundance index of C. latrans. This may be because the forest provides them with shelter from climatic situations and a greater variety of seeds, fruits and insects. In this study the two seasons with the highest relative abundance were spring and autumn in both ecosystems, coinciding with an increase in rainfall, resulting in an abundance of potential prey (rodents and lagomorphs), and other food items like fruits. Regarding annual diet the most consumed prey were mammals. We found differences in diet between seasons, that can be explained by the variation in food availability among seasons.