Project Update: June 2005

In order to register bat diversity, richness, fluctuations of abundance, and reproduction patterns, eleven visits were made between February 2004 and January 2005 expending a period of 3 fieldwork days. Bats were caught using one harp trap, and each capture session began at sunset and finished three hours before sunrise. Each bat caught was identified, and its body condition, age, weight, forearm length, reproductive status, and other biological information were recorded before it was set free. Our work team consisted of 3 to 6 persons.

The cave studied is located in the Neotropical Mexican Pacific Slope. The vegetation around the cave consists of tropical dry deciduous forest with some species of "Huizache" (Acacia sp.) and "Palo brazil" (Haematoxyllum). The cave is also located near agricultural and cattle farms with tomato, lemon tree, sorghum, and tequila agave plantations. The climate is warm-subhumid with a rainy season from June to September and a long dry season from October to May.

The study identified 10 bat species that use the cave as a main roost: one emballonurid (Balantiopteryx plicata); four mormoopids (Mormoops megalophylla, Pteronotus davyi, P. parnellii, and P. personatus); five phyllostomids (Glossophaga morenoi, G. soricina, Glyphonycteris sylvestris and Macrous waterhousii); and one natalid (Natalus stramineus). 9,660 individuals were caught along the study time, 29.7% of which belong to Pteronotus personatus, 26.9% to P. davyi, 25.87% to Mormoops megalophylla, 5.8% to Glossophaga soricina, 5.7% to P. parnellii and 4.6% to Natalus stramineus. Other species (Macrotus waterhousii, G. morenoi, Balantiopteryx plicata and Glyphonycteris sylvestris) represented less than 2% of captures. There is a disparity in species abundance between the rainy and dry seasons.

Our results indicate that the "Cave El Salitre" is of great importance as a refuge for several bat species, especially those that utilize the caves as a main roost. The cave is humid and warm in the principal room, and conditions are thermally stable in the refuge throughout the year.

Among other reasons, the "Cave El Salitre" is important for conservation because of the different reproductive evens, including use of the cave as a maternity roost by several species that occur in the cave. Furthermore, the cave is used permanently or temporarily as diurnal roost for at least eight bat species. The cave shelters a great number of bat species as well as a great quantity of individuals (>7 species and >1000 individuals) and is therefore are an important roost in terms of diversity. This importance is underscored by the fact that only 10% of Mexican caves contain six or more bat species, and to find caves with high abundance is rare.