Moms Do Not Get Sick Days: Lack of Sickness Behavior in Free-Ranging Lactating Fish-Eating Bats

By mimicking a bacterial infection in free-ranging bats to induce sickness behavior, the study showed that lactating bats do not interrupt their foraging activities. Maternal care prevails. When animals become sick, some behavioral changes occur that have an adaptive value to fight the infection. Non-reproductive captive and free-ranging mammals exhibit anorexia, weight loss, fever, and lethargy when bacterial infection is imitated with a lipopolysaccharide (LPS) challenge. Anorexia leads to a reduction of caloric and nutrient intake, which might represent a serious conflict when the animals is involved in reproductive activities. Lactation is the most expensive period for reproductive mammals due to the costs of mammary tissue development, milk production and parental care. We tested to what extent free-ranging lactating females of the fish-eating myotis Myotis vivesi modulated sickness behavior in their foraging activity when exposed to LPS. We placed GPS tags on lactating females in Partida Norte island, Gulf of California, Mexico in June 2019. We administered a dose of LPS and a dose of saline on separate nights to each individual, and we monitored their foraging activity on each trial. We found no significant differences between the 2 treatments in total flight time length, foraging flight time length, commuting flight time length, total flight distance, and flight speed. Our study demonstrated that behavioral changes associated with the infectious process in free-living mammals may be compromised when they must sustain activities that are key for population survival.