Cave-dwelling Bats of south-central Mindanao — a rich but threatened biodiversity

This study is the first to provide a taxonomic report on cave bat biodiversity in south central Mindanao region. The exploration of five accessible caves in Pisan, Kabacan, North Cotabato, in south central Mindanao identified a total of 14 bat species with three endemic H. pygmaeus, P. jagori and M. wetmorei – which is considered as threatened with decreasing population (Rosell-Ambal et al 2008; Heaney et al. 2010).

Among 14 species, five species were fruit bats, comprising 36% of all bat species recorded from Pisan caves during the current survey. These frugivorous bats were observed to roost in caves near fruiting trees and in caves with large mouth openings. Species such as C. brachyotis was netted in caves near areas where fruit trees grow, while other fruit bats such as E. spelaea and R. amplexicaudatus are noted to roost in caves with large openings and near water sources such as in Usok and Cathedral cave.

On the other hand, the remaining 64% of the bat community in Pisan is comprised by insectivorous bats. The insectivorous bat H. diadema was the most abundant and common bat in all cave sites in Pisan contributing 18.69% of the total individual captures. Hipposideros diadema was also recorded in other locations in Mindanao where it was also one of the most abundant insectivorous bat species occurring in the cave. It was recorded in selected caves in Iligan, Bukidnon, and Valencia in Northern Mindanao region, Davao Oriental in Northeastern region (Nuneza et al. 2010; Galorio and Nuneza 2014) and Samal Island (Quibod et al. 2013).

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Furthermore, noteworthy on this survey is the presence of the endemic species H. pygmaeus, Megaerops wetmorei and Ptenochirus jagori in three caves in Pisan (Lope, Avenue, and Usok). Hipposideros pygmaeus is a poorly known species known from caves and secondary forests and thought to be widespread.  However, this species is negatively impacted by degradation of cave habitats (Heaney et al. 1998). In contrast, M. wetmorei is not a total endemic species to the Philippines but this species is only known to occur in Mindanao faunal region, and occurs only from primary and lightly disturbed lowland forest from 800 to 1200 m asl and probably absent in montane forest beyond 1500 m asl (Heaney et al. 2006). Ptenochirus jagori is widespread in various habitat in the Philippines with large and stable population, and tolerant to heavily disturbed habitats (Heaney et al. 1998). The presence of endemic and threatened species could pave the way in implementing conservation and protection measures at cave sites that are also tourism hotspot in Pisan, as it shows that Pisan caves are suitable habitat for many bat species.

Key Points:

The study has provided the first taxonomic information on the cave-dwelling bats in selected caves sites in south central Mindanao. A total of 14 bat species with three endemics and two vulnerable and decreasing population were identified. Threats and disturbance continue to occur and impede despite the relatively high species richness in the site. Furthermore, data and information from field surveys revealed the following: (1) accessible caves from Pisan contains bat population belonging to several different species, (2) caves were mainly exploited for tourism and recreational purposes, (3) hunting for meat and trade, and unregulated entry to caves sites were the most persistent threats to bats, (4) large species Rousettus amplexicaudatus, Eonycteris spelaea, and Hipposideros diadema are preferred game species because of their size and abundance in caves.

With the high species richness in a survey and the presence of unexplored cave sites in south central Mindanao suggests sampling and comprehensive cave exploration is necessary to fully understand the biodiversity of cave-dwelling bats in the region and wholly establish effectively and fair-party conservation advantage.

Read the full paper at Tanalgo and Tabora 2015

 

Selected references:

 

Achondo MJM, Casim LF, Tanalgo KC, Agduma AR et al.  2014 – Occurrence and abundance of fruit bats in some conservation areas of North Cotabato. Asian Journal of Conservation Biology 3, 3-20.

Tanalgo KC, Tabora, JAG. 2015 – Cave-dwelling bats (Mammalia: Chiroptera) and conservation concerns in south central Mindanao, Philippines. Journal of Threatened Taxa 7, 8185-8194

Tanalgo KC, Teves R, Salvana FP, Baleva R. 2016 – Bat-human interaction in caves of south central Mindanao, Philippines. Wildlife Biology in Practice 12, 1-14.

 

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