Insectivorous bat reproduction and human cave visitation in Cambodia: A perfect conservation storm?

Abstract

Cave roosting bats represent an important component of Southeast Asian bat diversity and are vulnerable to human disturbance during critical reproductive periods (pregnancy, lactation and weaning). Because dramatic growth of cave tourism in recent decades has raised concerns about impacts on cave bats in the region, we assessed the reproductive phenology of two insectivorous species (Hipposideros larvatus sensu lato and Taphozous melanopogon) at three caves in Cambodia for 23 months in 2014–2016 and evaluated human visitation to these sites between 2007 and 2014. Despite the differing foraging strategies employed by the two taxa, the temporal consistency observed in proportions of pregnant, lactating and juvenile bats indicates that their major birth peaks coincide with the time of greatest cave visitation annually, particularly for domestic visitors and namely during the Cambodian new year in April. They also reflect rainfall patterns and correspond with the reproductive phenology of insectivorous cave bats in Vietnam. These findings were predictable because 1) insect biomass and thus food availability for insectivorous bats are optimal for ensuring survival of young following this period, and 2) the Khmer new year is the most significant month for religious ceremonies and thus domestic cave visitation nationally, due to the abundance of Buddhist shrines and temples in Cambodian caves. While the impact of visitor disturbance on bat population recruitment cannot be empirically assessed due to lack of historical data, it is nonetheless likely to have been considerable and raises a conservation concern. Further, because growing evidence suggests that insectivorous cave bats exhibit reproductive synchrony across continental Southeast Asia where countless cave shrines are heavily frequented during April in Theravada Buddhist countries (e.g., Myanmar, Thailand, Cambodia and Laos), our results may have wider applicability in the region. We consequently advocate for increased emphasis on sustainable cave management practices in Cambodia and further investigations to determine whether our findings present a broader concern for cave bat conservation in Southeast Asia.

Reproductive Ecology of Wrinkle-Lipped Free-Tailed Bats Chaerephon plicatus (Buchannan, 1800) in Relation to Guano Production in Cambodia

“…This is supported by the fact that they also match the reproductive phenology of the species in south-central Thailand [16,18], and central and coastal Myanmar [17]. However, while growing evidence suggests that seasonally monoestrous insectivorous cave bats exhibit reproductive synchrony across Southeast Asia, even in areas with limited seasonality in rainfall [34], it remains unclear whether the same might be true for a species with two annual breeding cycles such as C. plicatus. This is due to an apparent lack of information on the reproduction of the species in range countries such as China, Vietnam, Malaysia, Indonesia and the Philippines.…”

Longitudinal monitoring in Cambodia suggests higher circulation of alpha and betacoronaviruses in juvenile and immature bats of three species

“…The samples tested in this study originated from two sites in Cambodia where bats were previously captured and sampled to assess their diet and reproduction phenology (Fig. 1 ) 24 – 26 . The first site consisted of three caves (Bat Khteas, Phras Mea Kong Kea and Trai Lak) at Chhngauk hill in Kampot Province, which harbours populations of several cave-roosting bat species.…”

“…The first site consisted of three caves (Bat Khteas, Phras Mea Kong Kea and Trai Lak) at Chhngauk hill in Kampot Province, which harbours populations of several cave-roosting bat species. Details regarding this site are provided by Thavry et al 25 and Lim et al 26 . The second site was a roost of a single flying-fox species ( Pteropus lylei ) located in Kandal Province, for which further details are provided by Cappelle et al 24 .…”

“…In each of the 13 sampling sessions, bats were captured using mist-nets over 3 consecutive nights (1 night per cave). Details on capture methods are provided by Thavry et al and Lim et al 25 , 26 . Bats were captured and handled in the field in accordance with guidelines approved by the American Society of Mammalogists 27 , in addition to the requirements of the statutory study permission provided by the national authority responsible for wildlife research, the Forestry Administration of the Cambodian Ministry of Agriculture, Forest and Fisheries.…”

Bats in a cave tourism and pilgrimage site in eastern India: conservation challenges

“…At Gupteswar caves visitation was highest during the reproductive period of several of the bat species present. Similarly, in Cambodia the time of year with greatest visitation to caves coincided with the breeding of several cave dwelling insectivorous bats (Lim et al, 2018).…”