Patterns of foraging activity and fidelity in a Southeast Asian flying fox

Background: Improved understanding of the foraging ecology of bats in the face of ongoing habitat loss and modification worldwide is essential to their conservation and maintaining the substantial ecosystem services they provide. It is also fundamental to assessing potential transmission risks of zoonotic pathogens in human-wildlife interfaces. We evaluated the influence of environmental and behavioral variables on the foraging patterns of Pteropus lylei (a reservoir of Nipah virus) in a heterogeneous landscape in Cambodia. Methods: We employed an approach based on animal-movement modeling, which comprised a path-segmentation method (hidden Markov model) to identify individual foraging-behavior sequences in GPS data generated by eight P. lylei. We characterized foraging localities, foraging activity, and probability of returning to a given foraging locality over consecutive nights. Generalized linear mixed models were also applied to assess the influence of several variables including proxies for energetic costs and quality of foraging areas. Results: Bats performed few foraging bouts (area-restricted searches) during a given night, mainly in residential areas, and the duration of these decreased during the night. The probability of a bat revisiting a given foraging area within 48 h varied according to the duration previously spent there, its distance to the roost site, and the corresponding habitat type. We interpret these fine-scale patterns in relation to global habitat quality (including food-resource quality and predictability), habitat-familiarity and experience of each individual. Conclusions: Our study provides evidence that heterogeneous human-made environments may promote complex patterns of foraging-behavior and short-term re-visitation in fruit bat species that occur in such landscapes. This highlights the need for similarly detailed studies to understand the processes that maintain biodiversity in these environments and assess the potential for pathogen transmission in human-wildlife interfaces

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

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

Location of Chhngauk hill in southern Cambodia.

<p>Location of Chhngauk hill in southern Cambodia.</p

Insectivorous bat reproduction and human cave visitation in Cambodia: A perfect conservation storm? - Fig 2

<p><b>Reproduction of a) <i>Hipposideros larvatus</i> s.l. and b) <i>Taphozous melanopogon</i> at Chhngauk hill from February 2014 to January 2016 in relation to monthly rainfall (44 year means) in southern Cambodia.</b> The first row of figures below each graph represents the total number of parous, pregnant and lactating females caught each month and the second row represents the same for juveniles. The ‘pregnant’ category is confined to non-lactating pregnant bats, while the ‘lactation’ category includes all lactating bats, whether pregnant or not. Relative proportions for juveniles were derived by dividing the respective monthly total by the study total × 100. The figures are based upon captures of a) 178 bats and b) 131 bats, and data from the same month in each study year are combined for each species.</p

Mean monthly visitation to Vihear-Tuk Bonn cave (Chhngauk hill, southern Cambodia) and mean monthly international arrivals in Cambodia from January 2007 to May 2014.

<p>Vertical whiskers represent standard deviations.</p

Annual visitation to Vihear-Tuk Bonn cave (Chhngauk hill, southern Cambodia) from January 2007 to December 2013.

<p>Annual visitation to Vihear-Tuk Bonn cave (Chhngauk hill, southern Cambodia) from January 2007 to December 2013.</p