Institute of Ecology at National Autonomous University of Mexico (2014)
Mexico National Bat Monitoring
Last Updated: August 17th, 2020
Bats perform a number of ecological services essential for ecosystem integrity and human well-being including pollination, seed dispersal, and insect population control. Threats such as habitat destruction, wind farming, and white-nose syndrome kill millions of bats each year, but there is little information to evaluate short and long-term population trends of bats in tropical countries. Acoustic monitoring of bats is rapidly becoming the tool of choice to document bats at large spatiotemporal scales. However, most bat monitoring programs occur on localized scales in temperate areas and center on only a few species, over short time periods. These programs are limited in scope due to high costs and human resource requirements. In the tropics, there is currently no standardized effort to monitor bat populations, even in the short term. The Mexican Federal Government asked Dr. Rodrigo Medellín to design a long-term, nationwide bat monitoring program to add bats to the existing National Forest Inventory (NFI), one of the best large-scale longitudinal natural resource monitoring programs in the world. The NFI is an enormous effort that deploys staff over 60,000 points across Mexico which are visited every 5 years (12,000 points per year), and tracks not only forest resources, but population data for birds, large mammals, invertebrates, fish, and reptiles. Thus, there is a need in Mexico to develop an efficient, sustainable, consistent acoustic monitoring protocol for bats across the entire country.
Key Objectives and Activities
The goal is to design and implement a standardized, nationwide, long-term acoustic bat-monitoring program in Mexico, integrating the latest technology in bat detectors and automated data analysis. This project will develop and validate acoustic monitoring protocols at a small number of sites, providing a proof-of-concept for expanding the spatiotemporal scale of acoustic monitoring, and generating best-practices for monitoring in other locations. Bat occurrence data will be contributed to Mexico’s premier open-access biodiversity data repository, CONABIO, and made available to scientists, stakeholders, and land managers. These data will facilitate assessments of natural and anthropogenic impacts on bat populations, and can be used to develop mitigation, restoration, or conservation strategies.
- Establish 16 locations for permanent acoustic bat monitoring stations in two biosphere reserves in Mexico with contrasting ecosystems: Chamela-Cuixmala Biosphere Reserve (tropical dry forest) and Montes Azules Biosphere Reserve (tropical rain forest).
- Conduct two cycles of standardized acoustic bat monitoring at each reserve and produce a collection of pre-filtered bat recordings.
- Analyze all sound files containing a bat call using a combination of already published software (AVISOFT) and a custom software to identify each recording to the family or sonotype level.
- Make the complete database containing the data produced during the first year of monitoring available to the public through CONABIO.
- Offer a workshop for two staff members in charge of monitoring programs in each reserve where personnel will be trained on bat identification, acoustic bat monitoring techniques and technology, design and implementation of nation-wide, long-term monitoring programs.
- Conduct a six-day long workshop for members of the Bat Conservation Africa (BCA) network to facilitate transfer of knowledge and technology and strengthen the infrastructure of bat conservation programs in Africa.
The aim of this project and its leaders is the incorporation of bat distribution data in the National Forestry Inventory (NFI), and the use of that information by thousands of Mexicans and non-Mexicans, in support of research and conservation decision-making.
This project will generate a validated monitoring protocol that establishes a set of rules and criteria for how acoustic bat surveys, including metadata of environmental conditions, should be conducted on large spatiotemporal scales. This standardization is essential to permit comparison of data taken at different locations or times, and by different workgroups throughout Mexico. Results of nationwide monitoring will crucially enhance the understanding of bat species distribution, diversity, abundance, and activity patterns in relation to different environmental conditions and threats, contributing to effective species and habitat conservation. An additional outcome will be the use of the tools and techniques pioneered in Mexico by this project by African bat researchers, to foster enhanced bat research and monitoring in sub-Saharan Africa.
Primary Software Platforms
The bat acoustic calls will be analyzed and processed by integrating AVISOFT, an existing bioacoustics software platform, with custom-built software, to automate the classification of bat calls. Data on bat distribution, diversity, and relative abundance will be managed in CONABIO’s software for data management, BIOTA.
Results to Date
- Through an iterative, adaptive management process the team successfully developed and refined a monitoring protocol for bat acoustics.
- The team established 16 locations for permanent acoustic bat monitoring stations in both Chamela-Cuixmala Biosphere Reserve and Montes Azules Biosphere Reserve.
- Each monitoring station was active 4 hours over 30 consecutive nights, resulting in 120 hours of footage per monitoring station. This collection was repeated over two time periods, resulting in a total of 4,320 hours of audio recordings.
- Within the Chamela-Cuixmala bat activity was recorded during 15-20% of the hours, while in the Montes Azules bat activity was recorded only 5-16% of the hours.
- The team analyzed over 179,700 audio files of bat recordings. They used a combination of machine learning and pattern recognition to develop automated identification techniques. Using these methods the team was able to 1) identify all calls to family level, 2) identify most calls to genus level, and 3) identify some particular calls to species level with a classification accuracy of 70-95%
- The team produced and published a field manual for deployment of monitoring stations.
- All data and metadata collected during this project was deposited in the System of Integration of Acoustic Information (SIAI) of the CONABIO.
- A 6 day workshop to introduce researchers of Bat Conservation Africa (BCA) to automated bat monitoring techniques took place in April 2017 at the headquarters of the Kenya Wildlife Service Training Institute (KWSTI) in Naivasha, Kenya. The workshop involved 13 bat biologists from 5 different African countries.
- An exciting outcome of the workshop was the creation of the Eastern Africa Bat Conservation Network (EABCN). This organization hopes to serve as a regional platform linking the organization and needs of local, regional, and international partners. The group is already preparing a manuscript on Eastern Africa Bat Monitoring via Acoustic Surveys.
Dr. Medellín and his group have demonstrated flexibility that enabled them to make the most of unanticipated delays and challenges. Bioacoustic monitoring technology is advancing rapidly, such that cutting-edge gear is quickly superseded by smaller, more sensitive, more reliable equipment. Waiting as long as possible to obtain the very latest technology is preferable, but risks delaying implementation if delivery takes longer than anticipated. The team capitalized off the time afforded by such delays to conduct additional training.
Ecological field studies are beholden to whims of nature; unpredicted events can be both challenges and opportunities. Hurricane Patricia caused the postponement of the workshop to train staff at Chamela-Cuixmala Biosphere Reserve. However, the natural disaster also offered a natural experiment on which to test the efficacy of the protocol. The team will return to Chamela-Cuixmala for a third sampling cycle, training reserve staff and gathering post-disturbance data to determine whether the monitoring protocol can be used to assess the response of the bat community to changes brought by the hurricane.
- López-Hoffman, L, R Wiederholt, C Sansone, KJ Bagstad, P Cryan, JE Diffendorfer, J Goldstein, K LaSharr, J Loomis, G McCracken, RA Medellín, A Russell & D Semmens. 2014. Market forces and technological substitutes cause fluctuations in the value of bat pest-control services for cotton. PLoS One, 9(2): 7 pages. DOI:10.1371/journal.pone.0087912 (link)
Project Director Biography
Dr. Rodrigo Medellín researches conservation of mammals with emphasis on applied and policy-driven science, as a Senior Professor at the Institute of Ecology UNAM. He is an established leader in the field of mammal conservation, and is President of the Society for Conservation Biology (2013-2015), and Scientific Councilor of the Convention on Migratory Species. The majority of Medellín’s work is dedicated to bats: he founded RELCOM, a network for conservation of bats in Latin America in 2007, and currently co-chairs the IUCN Bat Specialist Group. He has authored more than 170 publications trained more than 40 graduate students, and has projects or students in 16 countries on five continents. He is a Rolex Award Laureate, and 2012 Whitley Gold Award winner.
Notes from JRS
In 2014, JRS called for proposals that feature innovations in biodiversity informatics and Dr. Medellín’s proposed large scale bat monitoring is innovative and holds the potential to lower costs, increase scale, and automate biodiversity monitoring activities. With encouragement from JRS, the project team included training and technology transfer to Africa, which we hope might plant the seeds of future collaborations and projects. This award is JRS’ third for bats, making bats the mammal with most JRS grants. Today, this project from UNAM and the investment in the work of Dr. Bruce Miller and Dr. Bruce Patterson remain un-linked. We hope that our efforts to make bat call data accessible and better documented will help support global collaboration and knowledge transfer regarding the biodiversity monitoring of this important species.