Babbling Bats

Below is a picture of Saccopteryx bilineata also known as the sac-winged bat:
According to and article on New Scientist the pups have a pretty unique ability.

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Bats Transmit Cultural Information Through Sound

Recently, I wrote a post on how bats used sound to recognize individual prey items based on breathing patterns. Today, Science Daily has a story on bats using sound to transmit cultural information.

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Vampire Bats and Prey Recognition

Vampire bats recognize individual prey by the unique sounds of the preys breathing according to a study in BMC Biology. Researchers examind the ability of vampire bats to detect breathing cues from prey items.

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Fossil Bats

The above is a picture of Icaronycteris, a fossil bat from the Eocene. Why am I talking about fossil bats?

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Big Brains Means Small Testes

According to a new study reported by New Scientist there is a correlation between brain size ans testes size in…bats. Researchers examined 334 species of bats for the studies. They found an inverse correlation between brain size and testes size. They relate the results to breeding systems. In bat species with highly promiscuous females, male bats had smaller brains but larger testes – related to sperm competition (something also seen in chimps). They attribute the effect to:

Both brain tissue and sperm cells require a lot of metabolic energy to produce and maintain. The different species appear to have evolved a preference for developing one organ more than the other, presumably determined by which will help them produce more offspring.


“An extraordinary range of testes mass was documented across bat species – from 0.12% to 8.4% of body mass. That exceeds the range of any other mammalian order,” says Scott Pitnick, from Syracuse University in New York, US, one of the research team. Primate testes vary between species from 0.02% and 0.75% of body mass.

Apparently, then, you can have a large brain (such as in humans) or large testes (such as in some bats and chimps) but not both.

If I remember corectly, one of the areas where researchers recently found differences between chimps and humans was in the genes for sperm production. So a change in mating patterns and social structure between chimps and humans may be one, of several, forces driving the evolution of large brains in humans.

Okay, Bats are Weirder than I Thought

Bats are weirder than I thought. Specifically, Greater Horseshoe bats.

According to National Geographic News several generations of female greater horseshoe bats mate with the same male:

During their life span, most female greater horseshoe bats (Rhinolophus ferrumequinum) revisit and breed with a specific male, according to a new study.
That means offspring born in different breeding seasons are full siblings. In addition, the researchers believe that daughters follow their mothers to mating sites to breed with the same male.
” … sharing sexual partners strengthens social ties and promotes greater levels of cooperation within the [bat] colony,” said Stephen Rossiter, a zoologist at the School of Biological Sciences, Queen Mary, University of London.
“The females are choosing their mates. We still don’t know how they do it, how they pass along the information to their daughters, or how they mostly avoid inbreeding,” added Rossiter. The zoologist is the lead author of the new study, which is described in tomorrow’s issue of the science journal Nature.
Mate sharing among bats can make for some confusing relationships. In several cases genetic tests showed that a female bat and her maternal half-aunt also were half sisters on their father’s side.

Between 1991 and 2002, Rossiter and his colleagues caught bats in nets and collected samples of skin from their wings. The scientists were able to analyze 19 different genes in a group of 452 bats, which included mothers, offspring, and potential fathers.
The researchers positively identified the mothers of 371 individual bats and the fathers of 232. The researchers also determined breeding pairs.
Further study showed that specific males and females paired together on multiple occasions more times than would have occurred at random. This finding suggests that mothers and their female offspring are selecting one male and returning to him for subsequent mating.

The Evolution of Bats

A while back I provided links on the evolution of the eye. Here are two links for a fascinating discovery concerning the evolution of bats.