Mircea G. Hidalgo-Mihart

Coyote (Canis latrans) Food Habits in a Tropical Deciduous Forest of Western Mexico

Abstract We studied the food habits of the coyote (Canis latrans) in a tropical deciduous forest along the Mexican Pacific coast during 1996 and 1997. Small mammals, chiefly the Jaliscan cotton rat (Sigmodon mascotensis), were the main prey items during the dry season. Cultivated fruits, like mango and papaya, were the most important food for coyotes during the wet season. Given the importance in our study area of human related food items like the Jaliscan cotton rat, mango and papaya, we expect the expansion of coyote populations due to deforestation of the tropical deciduous forest.

Effect of a landfill on the home range and group size of coyotes (Canis latrans) in a tropical deciduous forest

The effect of an open landfill and the seasonality of a tropical deciduous forest in Jalisco, Mexico, was tested on the home range and group size of coyotes Canis latrans under the Resource Dispersion Hypothesis (RDH), which proposes that in social carnivores dispersion of patches of limited resources determines home-range size, whereas independently, abundance of resources affects group size. The predictions in this study were that coyotes using the landfill, where food is available all year due to the continuous arrival of food wastes that are concentrated in a single patch, would have smaller, seasonally constant home ranges than coyotes living outside, where food is distributed in several patches. In this area, coyotes would increase their home ranges during the dry season due to seasonal changes in resource availability. Also, a larger coyote group size should exist in the landfill, where food abundance is greater. Home-range size and group size of coyotes living in and outside the landfill were estimated by radio-tracking. Home ranges of coyotes in the landfill varied from 0.9 to 9.5 km 2 , whereas home-range sizes of coyotes outside the landfill varied from 10.9 to 43.7 km 2 . Seasonality had no effect on the home-range sizes. We identified a group of four adult coyotes in the landfill and no group formation in coyotes outside. These results support the predictions about home-range and group size of coyotes in relation to landfill presence, and indicate that under the circumstances of our study, coyotes follow the postulates proposed by the RDH.

Leishmania (L.) mexicana Infected Bats in Mexico: Novel Potential Reservoirs

Leishmania (Leishmania) mexicana causes cutaneous leishmaniasis, an endemic zoonosis affecting a growing number of patients in the southeastern states of Mexico. Some foci are found in shade-grown cocoa and coffee plantations, or near perennial forests that provide rich breeding grounds for the sand fly vectors, but also harbor a variety of bat species that live off the abundant fruits provided by these shade-giving trees. The close proximity between sand flies and bats makes their interaction feasible, yet bats infected with Leishmania (L.) mexicana have not been reported. Here we analyzed 420 bats from six states of Mexico that had reported patients with leishmaniasis. Tissues of bats, including skin, heart, liver and/or spleen were screened by PCR for Leishmania (L.) mexicana DNA. We found that 41 bats (9.77%), belonging to 13 species, showed positive PCR results in various tissues. The infected tissues showed no evidence of macroscopic lesions. Of the infected bats, 12 species were frugivorous, insectivorous or nectarivorous, and only one species was sanguivorous (Desmodus rotundus), and most of them belonged to the family Phyllostomidae. The eco-region where most of the infected bats were caught is the Gulf Coastal Plain of Chiapas and Tabasco. Through experimental infections of two Tadarida brasiliensis bats in captivity, we show that this species can harbor viable, infective Leishmania (L.) mexicana parasites that are capable of infecting BALB/c mice. We conclude that various species of bats belonging to the family Phyllostomidae are possible reservoir hosts for Leishmania (L.) mexicana, if it can be shown that such bats are infective for the sand fly vector. Further studies are needed to determine how these bats become infected, how long the parasite remains viable inside these potential hosts and whether they are infective to sand flies to fully evaluate their impact on disease epidemiology.

Diet and food resource use by the pygmy skunk (Spilogale pygmaea) in the tropical dry forest of Chamela, Mexico

The diet and pattern of food resource use by the pygmy skunk Spilogale pygmaea , an endemic and threatened species of western Mexico, was evaluated in the tropical dry forest of Chamela, Jalisco. Analysis of scats ( n = 104) and stomach contents ( n = 5) obtained during 1997, 1998 and 2000 showed that pygmy skunks fed mainly on invertebrates. Insect larvae constituted the most represented food item in samples. During 2000, food resource use was quantified by comparing occurrence of available prey with occurrence of items found in scats. Even though pygmy skunks seem to be opportunistic foragers, some invertebrates were positively selected, such as insect larvae and Myriapoda, thus suggesting that pygmy skunks may target prey of high nutritional value. The diet varied considerably between consecutive dry and rainy seasons of the studied years, with little overlap in food items. Pygmy skunks may adjust food resource use in response to temporal variations in prey abundance, by incorporating other food items in their diet during the dry season, when food is scarce. Dietary switching between seasons indicates that pygmy skunks may exhibit strategies similar to those of other tropical carnivores to deal with a highly seasonal environment.

Coyote Habitat Use in a Tropical Deciduous Forest of Western Mexico

Abstract

Alopecia in Bats from Tabasco, México

We report alopecic syndrome (hair loss in areas of the body, including chest, abdomen, and back) in four frugivorous bat species (Artibeus jamaicensis, Artibeus lituratus, Sturnira lilium, and Sturnira ludovici) within urban and periurban areas of Villahermosa, Tabasco, México, during 2007 and 2008. The overall prevalence of alopecic syndrome was 5.25% (135/2,567 bats). The highest prevalence was found in A. lituratus (5.6%; 62/1,105), followed by A. jamaicensis (5%; 3/ 1,462). We found a higher prevalence in the dry season, when more than 90% of the alopecic individuals (n=122) were captured. Higher prevalence of alopecia was recorded in urban areas (80% of captured alopecic bats, n=108) than in periurban areas (20%, n=27). Histopathologic studies revealed no evidence of infectious agents. The syndrome may be related to nutritional or endocrinal deficiencies. Spatial and seasonal aggregation in urban areas suggests that anthropogenic activities may interfere with nutritional processes. Further studies are needed to confirm the etiology of the syndrome as well as its impact on population dynamics. This is the first report of alopecic syndrome in sylvatic bats.

Relationship between the abundance of the Endangered volcano rabbit Romerolagus diazi and vegetation structure in the Sierra Chichinautzin mountain range, Mexico

The volcano rabbit Romerolagus diazi is endemic to the mountains of central Mexico, where its habitat has been gradually destroyed to make way for agriculture, ranching and logging, and by forest fires. The volcano rabbit is categorized as Endangered on the IUCN Red List. We evaluated the relationship between the abundance of the volcano rabbit and vegetation structure at a small scale (0.25 ha). Using a general linear model we generated a set of 21 predictive models and proposed the best model as a habitat quality index. Our results suggest that greater height and cover of bunchgrasses and the presence of a shrub layer offer the volcano rabbit the best refuge from predators. The habitat quality index and the limited available habitat documented in our survey indicate that the populations of volcano rabbits in the study area are more threatened than previously thought. As R. diazi is a habitat specialist it does not have the option of moving to another habitat type.

Can You Judge a Disease Host by the Company It Keeps? Predicting Disease Hosts and Their Relative Importance: A Case Study for Leishmaniasis

Zoonoses are an important class of infectious diseases. An important element determining the impact of a zoonosis on domestic animal and human health is host range. Although for particular zoonoses some host species have been identified, until recently there have been no methods to predict those species most likely to be hosts or their relative importance. Complex inference networks infer potential biotic interactions between species using their degree of geographic co-occurrence, and have been posited as a potential tool for predicting disease hosts. Here we present the results of an interdisciplinary, empirical study to validate a model based on such networks for predicting hosts of Leishmania (L.) mexicana in Mexico. Using systematic sampling to validate the model predictions we identified 22 new species of host (34% of all species collected) with the probability to be a host strongly dependent on the probability of co-occurrence of vector and host. The results confirm that Leishmania (L.) mexicana is a generalist parasite but with a much wider host range than was previously thought. These results substantially change the geographic risk profile for Leishmaniasis and provide insights for the design of more efficient surveillance measures and a better understanding of potential dispersal scenarios.

Registro de pecarí de labios blancos (Tayassu pecari) en la región de la laguna de Términos, Campeche, México

We report at least one group of white lipped peccaries (Tayassu pecari) in Selva La Montaña located in the southwestern portion of the Términos Lagoon Flora and Fauna Protection Area, Campeche, Mexico. The record was obtained using camera traps. The presence of this species in the area shows the importance of the region for biodiversity conservation, particularly for protected species.

Effect of nesting environment on incubation temperature and hatching success of Morelet's crocodile (Crocodylus moreletii) in an urban lake of Southeastern Mexico.

Incubation temperature is an important aspect in terms of biological performance among crocodiles, and several controlled experiments have demonstrated a significant relationship between incubation temperature, success in hatching and survival of hatchlings. However, a few studies have tested these relationships in the wild. The objective of this study was to determine the relationship of nest characteristics and environment (hatch year, nest basal area and height, clutch size, distance to shore line, and vegetation cover), to incubation temperature and hatching success among Morelets crocodile (Crocodylus moreletii). The study was carried out during the nesting seasons of Morelets crocodile, from 2007 to 2009 in the Laguna de Las Ilusiones, an urban lake located in Villahermosa, Tabasco, Mexico. We physically characterized 18 nests and inserted a temperature data logger in each nest chamber. At the end of the nesting season and prior to hatching, we recovered the crocodile eggs and data loggers and calculated hatching success, under laboratory conditions. We related the environmental variables of the nest with the mean and fluctuation (standard deviation) of nest temperature, using linear models. We also related the environmental variables affecting the nest, to mean nest temperature and fluctuation in incubation temperature and to hatching success, using linear models. Although we found differences in incubation temperature between nests, mean incubation temperature did not differ between years, but there were differences in nest thermal fluctuation between years. The mean incubation temperature for 11 nests (61.1%) was lower than the suggested Female-Male pivotal temperature (producing 50% of each sex) for this species, and all hatchlings obtained were males. There were no differences in clutch size between years, but hatching success varied. Our study indicates that hatching success depends on certain environmental variables and nest conditions to which the eggs are subjected, including season, nest size and clutch size. We also discuss the importance of the fluctuation of incubation temperature on hatching success and sex determination.