Bat species richness in the region of the Central Valleys of Oaxaca, Mexico

Study Extent

The region of the Central Valleys is located in the State of Oaxaca, Mexico (95°54’ to 97°14’W and 16°28’ to 17°38’ N). This region has an area of 7,974 km2 and incudes the political districts of Etla, Centro, Zaachila, Ocotlán, Zimatlán, Tlacolula and Ejutla. The region of the Central Valleys of Oaxaca includes the physiographic subprovince of the Central Valleys and parts of physiographic subprovinces of the Sierra Madre of Oaxaca, Fosa of Tehuacan, Central Mountains and Valleys, Western Mountains and Southern Mountains and Valleys

Sampling

In order to estimate bat species richness, two methods were used at each location: mist netting and echolocation recordings. Mist nets were located in places with high bat activity such as flight paths, edges, within vegetation fragments, near streams and refuges; mist nets were open from 18:00 to 02:00. The total sampling effort was 3,072 m2n/h (8 sites, two nights per site). Bats captured were identified to the species level based on Álvarez et al. (1994) and Medellín et al. (1997). Voucher specimens were deposited in the mammalian collection of the Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional Unidad Oaxaca of the Instituto Politécnico Nacional (OAX.MA.026.0497; CIIDIR-Oaxaca, IPN). Bat echolocation calls were recorded with an Anabat SD1 detector (Titley Scientific, Australia). Echolocation calls recordings were performed using minor modifications from the O´Farrell et al. (1999a, 1999b) method, which consists on setting the Anabat SD1 detector at an angle of 45° at ground level, and rotate it every 10 minutes clock-wise. The Anabat SD1 was programmed with a sensitivity level of five (intermediate) and a frequency division of eight. A total of 55 hours of vocalizations were recorded in eight localities, one night per site. Echolocation calls recordings were analyzed with AnalookW version 3.8s (Corben, 2003) and species were determined based on the characteristics of search-phase, following O´Farrell and Miller (1997, 1999a, 1999b), O´Farrell et al. (2000), William et al. (2001), Gannon et al. (2004), Jung et al. (2007), Orozco-Lugo et al. (2013) and the Corben (2014) reference library.

Quality Control

Species accumulation curves were created with Species Accumulation Functions software (CIMAT, 2003). Previously, the samples were randomized 1,000 times with EstimateS software (Colwell, 2009) in order to prevent order effect and to smooth the curve (Moreno and Halffter, 2000).

Method steps

1. Finally, we consulted the mammal collection database of the CIIDIR-Oaxaca, which contains records of four national museums and 23 international museums (Briones-Salas et al., 2015) to obtain records of bat species for the region of the Central Valleys of Oaxaca. Guilds of bats were obtained from Ceballos and Oliva (2005), and scientific names for bat species were searched on the list of threatened species of the Norma Oficial Mexicana 059 (NOM-059-ECOL-2010; SEMARNAT, 2010) and the red list of the International Union for Conservancy of Nature (IUCN, 2016). Taxonomic arrangement is based on Ramírez-Pulido et al. (2014).

Chiroptera in Central Valleys of Oaxaca, Mexico

1. Emballonuridae
   rank: family
2. Molosidae
   rank: family
3. Mormoopidae
   rank: family
4. Phyllostomiidae
   rank: family
5. Vespertilionidae
   rank: family

The region of the Central Valleys is located in the State of Oaxaca, Mexico (95°54’ to 97°14’W and 16°28’ to 17°38’ N). This region has an area of 7,974 km2 and incudes the political districts of Etla, Centro, Zaachila, Ocotlán, Zimatlán, Tlacolula and Ejutla. The region of the Central Valleys of Oaxaca includes the physiographic subprovince of the Central Valleys and parts of physiographic subprovinces of the Sierra Madre of Oaxaca, Fosa of Tehuacan, Central Mountains and Valleys, Western Mountains and Southern Mountains and Valleys. The climate of the region is semi-warm, sub-humid temperate and warm semi-arid. The area has been transformed to agriculture and pastureland, but hilly areas still have dry forest and pine-oak forest.