Twenty Million Bats

Tony Leather | February 9, 2011 | 0 Comments

Beetles, mosquitoes, flies, moths and any other flying insects are at risk, after dark, in the area of the USA where the Mexican free tail bat lives, because when they emerge, at dusk, for a night of hunting prey, each individual will probably eat its own weight, in insects, in that single hunt. That is why a colony can dispose of 250 tons in a single night night, the nursing females of the species eating double the amount that males consume.

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This bat species is migratory, arriving in Texas during late February, having migrated from Mexico. Females, after breeding is completed, raise the young in the nursery section of the roost, while the males live separate lives in the bachelor colony. At two years old, males get to mate for the first time, the gestation period for the females averaging about 78 days, though individual females do not reproduce every year.

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Early June is the normal time-frame for the birth of young Mexican free tailed bats, parents bearing only one a year, which usually weighs in at under one ounce. Pups get nursed to six weeks of age, mother bats producing as much as 25% of her body weight in milk during 24 hour period. Mothers make many foraging trips whilst nursing young, though failure to feed the babies at least once a night increases mortality rates.

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Late during the month October or early in November are the times the bats return to Mexico, having been helpful at controlling pests, helping reap a better crop, though these bats are known to be carriers rabies, and can reach as eleven years of age in the wild. They are the most common bat in the Southwestern USA, said to number more 100 million, living in vast colonies, often in large caverns, individuals squeezed together tightly, up to 3,000 bats per square meter.

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Young bats of this species roost separately from mothers, who can recognize their offspring by voice. Strong, and fast flyers, These bats can reach speeds of 60 mph, flying as much as 50 miles from the roost, in search of food. It was possibly10,000 years ago that these bats first arrived at the Bracken Cave, near Austin, in Texas, to where they return every Spring, some 20 million of them.

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Now famous for the spectacle that happens every night during their Texas stay, this colony is priceless as a resource for the farming community in the area. At dusk, people gather for what has to be an utterly mesmerizing experience. Suddenly, a few bolder bats become first to emerge, flying up from the dark mouth of the cave. Then the single flyers become a trickle, as yet more of the braver individuals appear, then the teasing trickle becomes a ferocious flood, as untold thousands of frantic bats corkscrew upwards.

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Looking, from distance, like a single organism, the vast cloud of hungry bats, gaining speed as it climbs into the heavens, sends a distinct, whispering flutter of many millions of wings, sending an artificial breeze, wafting gently over the land. Overnight, this massive colony will have consumed vast numbers of pests, that would normally be wreaking untold damage on corn and cotton crops. The Bracken bat colony, emerging so majestically from the roost, is an experience that all should have once in their lifetime, the absolute wonder of the natural world.