Data usePhD Thesis
RationaleLarge areas of forest in Southeast Asia have suffered degradation through selective logging, but the conservation value of remaining patches for bat conservation is unclear. Although a high proportion of bat species persist in degraded forest (Struebig et al. 2013), their ecological responses to disturbance events such as salvage logging remain poorly understood. It is probable that forest degradation reduces insect prey diversity and alters the stability of the bat community to environmental fluctuations, but it is not known if these responses occur rapidly or are delayed ‘extinction debt’ type events.
This research is occurring in Borneo, a biodiversity hotspot containing over 100 described bat species. Despite this Borneo has lost over half of its forest area since 1940 (McMorrow & Talip 2001), with 42% of intact forest categorised of as production forest: to be logged in the future (Gaveau et al. 2014).
My research takes place predominantly at the SAFE (Stability of Altered Forest Ecosystems) project in Sabah, a novel site being subjected to the largest ever controlled deforestation experiment, studied by a multinational group of researchers in numerous disciplines (Ewers et al. 2011; Turner et al. 2012). Faecal samples collected over multiple years at the SAFE project and nearby primary rainforest sites will be used to generate food webs, allowing me to assess the impacts of habitat degradation on bat feeding ecology and potential time-lags in the impacts of disturbance events on bat-insect food webs.
This information will provide an invaluable insight into the ecology of bats in degraded forest and the importance of this habitat for their protection.
MethodsFieldwork has already taken place in 2015 at the SAFE (Stability of Altered Forest Ecosystems) Project and 2016 at the SAFE Project, Danum Valley and Maliau Basin. The SAFE Project is an area of disturbed forest undergoing experimental habitat modification, with logging having occurred between the 2015 and 2016 field seasons. Danum Valley and Maliau Basin are nearby undisturbed primary rainforest areas which function as this experiment’s control sites.
In 2017 fieldwork will take place again at the SAFE Project, Danum Valley and Maliau Basin, with harp traps and malaise traps being used to capture bats and insects in the same locations as in 2016. Adult insectivorous bats captured in harp traps that are neither pregnant or lactating will be kept in individual cloth holding bags for a period of less than 12 hours, for collection of bat faeces. Echolocation of multiple individuals per species will be recorded, to allow creation of a bat call reference library. Malaise trap samples will be collected regularly for DNA identification of flying insects to complement studies of bat diet, by giving a representative sample of the insect diversity available to them at each individual study site.
Upon returning to the UK faecal samples will have their DNA extracted and be subjected to PCR using the Zeale (2011) primers and sequencing on an Illumina MiSeq. Sequences returned will be clustered to Molecular Operational Taxonomic Units (MOTUs) and used to create bipartite food webs of bats and their arthropod prey. Network properties such as connectance, robustness and prey diversity will be compared between sites and years to show the impacts of rainforest degradation on bat-insect networks, as well as potential extinction debts from the disturbance event at SAFE in late 2015.