The cracks of a cold drainage pipeline, abandoned in the northern part of the Water Forestare the perfect refuge for hundreds of bats that have begun to hibernate.
The unfair stigma that weighs on them falls completely when we find them among the recesses of the artificial cave, immersed in a deep sleep, either curled up, chest to the ground, or belly up, like someone sleeping soundly. Others prefer to hang from the ceilingalone, in pairs or in groups, all of them are as cold as the wet rock where they hide.
The hibernation of bats In Mexico it is a phenomenon about which little is still known, so since 2018, a team of biologists from the UNAM Institute of Ecology has taken on the task of tracking them, under the direction of Dr. Rodrigo Medellinknown as the “Batman of Mexico”.
They have been found in caves in forests in northern and central Mexico. This research has allowed double the number of hibernating bat species than were known, and quintupled the number of caves used as hibernation refuges: 16 species in more than 100 caves at 30 sites in 12 states.
“Hibernating bats are insectivorous bats that, during these cold periods, do not have food and choose to look for cold caves to hibernate.
“They have an accumulation of fat and they enter these cold caves to be able to remain in a state of hibernation, like airplane mode, to be able to survive the entire winter, until the next season where they can find food, when it is warmer,” said the biologist. Daniel Ramos Huapaya, coordinator of the Mexico Hibernating Bat Project.
Of the more than 1,400 species of bats known worldwide, In Mexico, there are around 140 species.
After carrying out studies during seven continuous winters –since the 2017-2018 winter season–, the team attached to the Laboratory of Ecology and Conservation of Terrestrial Vertebrates, of the Institute of Ecology of the UNAM, has identified that 16 species of bats hibernate in forest caves of oaks and conifers, to elevations between 1,049 and 3,633 meters above sea levelin 12 states of the country, which represent the southernmost places in North America.
“Unrelated to our project, there were publications of seven species of bats known for Mexico that could hibernate and to date we have a record of 16 species, and in the case of caves, we have been able to access 15 reports between theses and scientific articles that cited 24 caves, “We have added 98 new caves,” said Daniel Ramos, also a science teacher.
Chiropterans that hibernate have been found from the end of September to March in caves in Sonora, Chihuahua, Coahuila, Tamaulipas, Zacatecas, San Luis Potosí, Veracruz, Querétaro, Tlaxcala, Puebla, State of Mexico and Mexico City.
The most common species is the cave bat (Myotis velifer), as confirmed MILLENNIUMin an exploration carried out in the municipality of Isidro Fabela, in which researchers and defenders of the so-called Water Forest collaborate.
“What we are trying to do is investigate several things: their behavior, at what temperature their bodies decrease, because the temperature of their bodies is equal to the temperature of the environment, and well, several of the things that the team has seen is that this is as cold as the refrigerator in our homes, at 4° or less, even zero,” said biologist Tanya González, professor at the UNAM Faculty of Sciences.
Researchers in search of new species
The researchers stealthily enter the cave, in a low voice, the thesis student Aarón Romero explains that they must look carefully between the cracks “in search of bats, since they have the ability to get into the cracks and there they stay, in torpor”, that is, in a physiological state in which their metabolic levels and body temperature decrease.
“Here there is a bat, which is very, very cold and very still and what I am doing is taking its temperature, to know what temperature the animal’s fur and the rock are at,” he explains, and then dictates “-1.5 degrees “, to his partner.
“We report the temperatures, the temperature of the bat – of its fur –, the temperature of the rock adjacent to where it is perched and the temperature of the place, that is what I am pointing out right now, everything is taken in degrees Celsius and yes they are too cold ”said biology student, Mariana González.
Most of the bats are hiding in the cracks, just some perch on the roof.
“These bats look for places with very particular characteristics of humidity and temperature, and sometimes they find it in exposed areas like this, or sometimes they find it in crevices.
“The one we can see here is a Myotis velifer, sometimes there are only individuals or sometimes they are in groups of 2, 3 and we have found up to 100 individuals together, which form a large group,” explained Daniel Ramos.
He added that hibernating bats generally reduce their body temperature to between 0 and 5 °C, because “in order to save your energy”.
“They go into airplane mode, so they need to spend as little energy as possible and, therefore, they reduce their heat and thus no longer spend money on staying warm.”
In the context of climate change and biodiversity loss, this study is key to the protection of these chiropteransand is linked to the work carried out by the Bosque de Agua research group, on the risk of emerging diseases in mountain stream axolotls, due to the variability of the climate in this region of the center of the country.
“What we have investigated are systemic issues, both ecological and social factors, and diseases related to changes in climate, that is, climate change in axolotls. With our activities, we modify the non-human ecological system, and it is very important to know how, to be able to take measures to prevent it from being destroyed or altered,” explained Tanya González, also a science teacher.
For his part, Daniel Ramos warned that very little is known about the hibernation of these bats in the country.
“And considering that Mexico is the southernmost part where this hibernation occurs, it is necessary to understand what they are doing.
“If we do not preserve these hibernation sites, we would eventually be losing those bats that later in the summer fulfill their ecological role, controlling insect-pests.”
EHR
