Citizen science sheds light on patterns and causes of road-mortality of bats in Taiwan.
Written By Joe Chun-Chia Huang, Wan-Jyun Chen and Te-En Lin
13th September 2022
WARNING: This article contains images that some readers may find upsetting
Road length and traffic volume are expanding rapidly across the globe. The rapid growth of traffic can greatly threaten biodiversity through, for example, road mortalities due to wildlife-vehicle collisions. The effect of road mortality on wildlife populations could be critical if the rate of roadkill is high and the populations of the victim species are small or declining.
In tropical Asia, the development of roadways is rapid, and wildlife road mortality is expected to be high. However, data on wildlife roadkill is generally patchy and limited, particularly for small animals, such as bats. The lack of bat roadkill information in tropical Asia is partially due to the difficulties of surveys and identification of species. As the region is home to over 400 bat species, accounting to nearly one-third of global bat diversity, it is essential to quantify the rate of roadkill, investigate the factors responsible and develop effective mitigation strategies.
Formosan tailless leaf-nosed bat, (Wei-Yi Tasi, CC-BY-NC 4.0), is a protected species in Taiwan but also threatened by the development of road in the mountain.
Citizen science
Established in 2011, the Taiwan Roadkill Observation Network (https://roadkill.tw/, TaiRON) represents the first road ecology citizen science project in Asia. The team aims to collect long-term roadkill data of terrestrial vertebrates across Taiwan and use the results to develop wildlife-friendly designs to mitigate the impact of road mortality to animal populations. Mr. Te-En Lin, who is also the primary investigator of the project and a senior herpetologist in the Endemic Species Research Institute, has been leading the project since the beginning. The team designed a web-based platform for trained volunteers to upload images of animal corpses using their mobile phones. The TaiRON team also provides an express delivery service to collect the corpses as voucher specimens. The victims in the images are tentatively identified by the volunteers and then further identified by experts. By 2018, the project had collected over 1,100 records of 20 bat species, which represents the largest known bat roadkill dataset in Asia. Some of the species found dead on roads include the Formosan tailless leaf-nosed bat, Formosan golden bat and hairy-winged tube-nosed bat, which are considered rare across their distribution ranges in Asia.
In 2018, TaiRON introduced a new survey methodology to assess road mortality of wildlife using a systematic grid across Taiwan to control for sampling biases observed in previous citizen science records.
Factors influencing bat mortality
From the data collected through TaiRON, we found bat roadkill shows strong aggregation patterns across space and species on the main island of Taiwan, where most records were reported at low elevations. Despite high bat species diversity recorded by the team, the majority of bat roadkill was composed of 7 of the 20 species on the island. Working together with Dr. Joe Chun-Chia Huang, a regional bat expert of Southeast Asian Bat Conservation Research Unit, and Wan-Jyun Chen, a landscape ecologist based at ESRI, the team explored how morphological traits and landscape features affected roadkill rates of bats. We found that the mechanisms behind bat roadkill were complicated. Elevational distribution ranges of species only explained the occurrence of roadkill of rare species at high elevations across Taiwan. We also found that bat roadkill were found more often in protected areas than non-protected area at higher elevations. However, neither elevation nor the presence of a protected area explained patterns of bat mortality at low elevation where most of the records were observed. Instead, mortality of common bat species was best explained by high levels of light pollution at low elevations, aerial hawking hunting mode by the bats, and use of non-cave roosts. These results suggest that species of bats which live in houses and vegetation in lowland areas might be exposed to higher collision risk when they are attracted to insects around streetlights.
Geographic and elevational distributions of road casually events of bats in Taiwan collected by TaiRON from 2013 to 2018
These findings can help scientists by providing valuable information on why some species of bats and some areas have higher rates of road mortality than others. The TaiRON team plans to work with local road management agencies to design bat friendly structures to mitigate the impact of road development to bats in the future. These measures could include adopting insect-friendly streetlights, increasing the height of streetlights to increase the space between bats and vehicles and avoiding setting up artificial roosts near roads in the low elevation areas of Taiwan. As bat roadkill appears to be spatially clustered in some areas, it may also be possible to implement acoustic deterrents to reduce the number of bat-vehicle collisions.
A scale card designed by the TaiRON team was used to show the size of a victim bat. The cards were given to citizen scientists who are volunteering to wildlife road collision surveys.
Author information:
Joe Chun-Chia Huang 1,*, Wan-Jyun Chen 2, 3, and Te-En Lin 2,*
1 Southeast Asian Bat Conservation Research Unit, Lubbock, TX 79409, USA
2 Endemic Species Research Institute, 1, Ming-shen East Road, Jiji, Nantou 552, Taiwan; jyun@tesri.gov.tw (W.J.C.).
3 Institute of Ecology and Evolutionary Biology, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 106, Taiwan.
* Correspondence: dnlin@tesri.gov.tw; Tel.: +886- 49-276-331, ext. 566 (T.E.L.); ecojoe.huang@gmail.com (J.C.C.H.)
Source:
Huang, J. C.-C., W.-J. Chen, and T.-E. Lin. 2021. Landscape and Species Traits Co-Drive Roadkills of Bats in a Subtropical Island. Diversity 13:117. https://doi.org/10.3390/d13030117
Editor:
Manisha Bhardwaj
Cite this summary:
Huang, J. C.-C., W.-J. Chen, and T.-E. Lin. (2022). Citizen science shed light of patterns and causes of road-mortality of bats in Taiwan. Edited by Bhardwaj, M. TransportEcology.info, Accessed at: https://transportecology.info/research/citizen-science-bat-taiwan [Date accessed].