Yucatán’s ‘Bat Sweep’ Called Illegal and Dangerous

'They have no idea of the damage to the environment and human well-being they are going to cause'

Conservation organizations are demanding the immediate halt of a program by Yucatán’s state government that distributes nets to cattle ranchers for the mass capture and killing of bats, calling the initiative both illegal and scientifically unfounded.

The Yucatán Rural Development Secretary (Seder) launched what it terms a “bat sweep” as a preventative measure against screwworm, a parasitic infection affecting livestock. However, prominent environmental groups argue the program violates federal environmental laws and threatens both biodiversity and public health.

“They have no idea of the damage to the environment and human well-being they are going to cause,” said Rodrigo Antonio Medellín Legorreta, a renowned Mexican conservation biologist and ecologist, in a statement shared on social media. “Stop the unjustified killing of bats. Stop violating environmental laws.”

Government Program Lacks Required Permits

The controversy centers on the state government’s distribution of mist nets to livestock groups for the indiscriminate capture of flying mammals. Environmental defenders say the program operates without required permits from SEMARNAT, Mexico’s Ministry of Environment and Natural Resources, making it illegal under federal law.

A joint statement from three leading conservation organizations—the Mexican Bat Conservation Program (PCMM), the Mexican Association of Mammalogy (AMMAC), and the Latin American and Caribbean Network for Bat Conservation (RELCOM)—emphasizes that bat capture “can only be carried out with official authorization and by previously trained personnel.”

The organizations warn that these actions “threaten beneficial species, since they do not distinguish between blood-sucking bats and those that perform vital functions such as plant pollination, fruit dispersal, and insect pest control.” Some of these species are listed as threatened under Mexico’s official endangered species norm, NOM-059-SEMARNAT-2010.

Scientific Evidence Contradicts Government Claims

Contrary to the state government’s rationale, conservation experts assert there is no scientific evidence linking vampire bat bites to screwworm infection. The parasitic condition, they explain, typically results from other causes including surgical procedures like castrations and dehorning, newborn navel injuries, insect bites, accidental cuts, scratches, birth wounds, and endemic diseases.

This scientific position aligns with broader research on bat conservation efforts in Mexico, which shows these mammals play crucial ecological roles. Bats consume thousands of insects nightly, including mosquitoes and crop-damaging pests, while also serving as pollinators for over 300 plant species worldwide.

The Yucatán Peninsula hosts approximately 60 bat species with diverse feeding strategies that collectively provide essential ecosystem services. Unlike many small mammals, bats have slow reproductive rates because they typically give birth to only one pup per year, making any population loss challenging to replace and making bats particularly vulnerable to extinction without protection.

Public Health Risks Identified

Beyond environmental concerns, the conservation groups highlight serious public health risks associated with the untrained capture of bats. They warn that personnel lacking proper training face increased risk of accidental bites, potentially leading to rabies transmission to humans.

This concern reflects broader issues with wildlife management in Mexico, where federal authorities have struggled to enforce environmental protections, particularly in cases involving economic interests. The lack of trained personnel for such operations violates established protocols for wildlife handling.

Government Cites Rising Screwworm Cases

The Yucatán government justifies its bat capture program by pointing to mounting screwworm cases across the state. In its most recent weekly report, authorities documented 50 new cases across 27 municipalities, bringing the year’s total to 431 confirmed infections.

The municipalities with the highest case numbers include Tizimín with eight cases affecting cattle and dogs, Izamal with seven cases in cattle and sheep, Tunkás with four cases in cattle, and Tzucacab with two cases affecting one bovine and one deer. Additional cases have been detected in Cacalchén, Espita, Kopomá, and other communities throughout the state.

Affected animals range in age from four days to seven years and include cattle, sheep, pigs, and dogs. The most common injuries leading to infection were bat bites and lacerations from barbed wire fencing, according to government data.

Conservation Groups Propose Alternative Solutions

Rather than mass bat killing, environmental organizations advocate for comprehensive livestock management programs that address the root causes of screwworm infection. Their recommendations include targeted control strategies for vampire bats conducted by expert personnel trained in species identification and capture techniques.

The groups also call for parallel actions to control flies and screwworms, which they identify as critical factors in disease transmission. They emphasize the need for training and direct support to help livestock farmers implement timely vaccination programs and proper wound care to prevent injuries from becoming entry points for parasites.

“Instead of promoting ineffective and dangerous measures, comprehensive livestock management programs should be implemented,” the conservation groups stated.

Broader Environmental Context

This controversy reflects wider tensions between agricultural interests and environmental protection in the Yucatán Peninsula, a region facing mounting pressure from development and tourism expansion. The area has experienced several high-profile environmental conflicts in recent years, including deforestation in protected areas and coastal development threatening mangrove ecosystems.

The conservation organizations have offered to provide training in vampire bat control methods that would target specific species while protecting beneficial bat populations. The joint statement was signed by Celia Selem Salas, coordinator of PCMM; Santiago Burneo, coordinator of RELCOM; and Gerardo Sánchez Rojas, president of AMMAC.

Environmental groups are now demanding that competent authorities immediately suspend the bat killing practices and establish “sustainable and scientific alternatives to address livestock health without compromising biodiversity and public health.” The outcome of this dispute could set important precedents for wildlife management throughout Mexico’s southeastern states.