Natural history of Bats

Posted May 16, 2015 10:54 am by



BATS are perhaps one of the most successful mammals on earth just like us. It has mastered the art of flying. They are the experts who have adapted themselves very well in nature. THEIR ADAPTATION HAS HELPED THEM IN SUCH A WAY THERE IS HARDLY ANY COMPETITOR FOR FOOD, WHEN BATS FEED.  BATS FORAGE AND FEED IN THE NIGHT(NOCTURNAL) WHILE MOST BIRDS FORAGE AND FEED IN THE DAY (DIURNAL). Bats belong to the order known to biologists as CHIROPTERA 

Our bat is a great hero who patrols the night, seeking out the villains that torment and harass us. He uses his highly developed bat senses to zero in on the perpetrator, then with uncanny accuracy, he swoops down to nab the villain the mosquitoes and other harmful insects. He eats the same food as birds, but prefers to hunt at night.

In fact, the Bat’s  goals in life is to cruise the night skies seeking insects that plague us humans, quite often moths and mosquitoes, for his dinner. A single bat can eat hundreds of insects in a single night.

THE BAT HOLDS THE DISTINCTION OF BEING THE ONLY MAMMAL THAT CAN SUSTAIN FLIGHT. Most bats are better flyers than birds, being able to fly more slowly and with far better maneuverability.

Birds and bats are both the only winged bipeds (two legged), naturally adapted to be active by day (birds are diurnal animals) or active by night (bats are nocturnal animals).


Birds and Bats have a great similarity between them. Perhaps this has made our scientists to say that both have the same common ancestor (fore fathers), the amphibious (animals that can live both on land and in water- like frogs) reptile.


We saw that there are mainly three important modifications in Mammals. These modifications between mammals may be, 

a. BEHAVIOURAL such as hunting by groups instead of

     Hunting individually;

Most bats roost (take rest or sleep) during the day as groups. This helps them to defend themselves as a group.

b. PHYSIOLOGICAL such as the ability to conserve


The membranous wings help in radiating heat and helps in cooling the body system of bats during flight. ; when the bats land on tree or their nesting site, after flight, the elastic membranes in its wings collapse like an umbrella folded, so that heat loss could be reduced.

c. STRUCTURAL such as to allow them to live in water

     or fly.

The fore limbs of bats have become elongated during evolution, especially the four fingers, the index finger to the little finger, which supports Bats’ membranous wings. The thumb is free and the bats use it for hanging upside down, or climb about in trees or crawl on their nesting site.


Thus we see an example for all the three modifications of mammals in BATS. Therefore, I wanted to write about this remarkable mammal.


Birds and bats are both the only winged bipeds (two legged), naturally adapted to be active by day (birds are diurnal animals) or active by night (bats are nocturnal animals).

Why do bats fly after Sunsets?

When we run or jump or when we do exercises or even when we cycle, our body becomes warm and we feel hot. At that time our body sends out water in drops to cool our body system. We call this process as perspiration or sweating. We as mammals have sweat glands. Sweat glands are like tear glands that make us cry when we are sad. Sweat glands send water out when our body becomes warm. During this time some times our heart beat increases and we find it difficult to even breathe. This we call as panting for breath. 

Similarly birds and bats fly a lot. During their flight they flap their wings; there by they do a lot of exercise. As they need lot of energy to fly they eat lot of food. Their rate of metabolism is faster than the mammals. During digestion these food are also burnt to give heat.

The extra heat generated by animals under normal conditions would result in over heating, fever and death.

Birds have lungs, but they do not have sweat glands. So they cannot sweat like us. But birds have air sacs. Using lungs and air sacs birds remove their body heat as fast as the heat is produced. One of the major functions of air sacs, a feature peculiar to birds, is to promote internal perspiration.  ‘Water vapour diffuses from the blood into these cavities and passes out via lungs with which they are indirectly connected’. Thus birds are able to cool themselves. THEREFORE BIRDS CAN FLY DURING THE DAY, WHEN ITS IS HOT. OUR SUN NOT ONLY GIVES US LIGHT, BUT IT ALSO WARMS OUR PLANET.

Bats do not have air sacs like that of birds. Hence they do have some difficulty in removing the excess heat from its body.

We already saw that the fore limbs of bats have become elongated during evolution, especially the four fingers, the index finger, middle finger, the ring finger and the little finger. These four fingers support the membranous wings of bats. But each of the fingers can move independently, so that the bat could make stable alteration to the wing surface. This helps bat in its flight manoeuvres. The membranes stretch from the fingers backwards, supported by the sides of the body, the back, the legs and the tail if present. We can perhaps say that the bats have developed a parachute like expansion of the skin of the sides of the body and limbs.

The thumb is free and the bats use it for hanging upside down, or climb about in trees or crawl on their nesting site.

Two reasons may be cited for their activity by night:

First bats cool themselves by radiating heat through their naked wings. This method of cooling will be disadvantageous in sunlight, when heat would be absorbed rather than lost in radiation. Black or Grey colours take heat in while White colours reflect heat back. Since all the bats are coloured grey to deep brown, their body will take in (absorb) heat from the sun. This will increase the body temperature of bats. Hence they fly during the cooler times such as evenings and night. (Note: Black colour or shades take in heat while white colour or light shades reflect heat; hence we use black umbrellas during cooler rainy days and white umbrellas during hot summer)

differnces-    simlarity-bet-bats&birdsy

How do Bats avoid obstacles during its night flight and how does find its food?

Secondly bats posses a well-developed sensory system for flight navigation at night.

The insect eating bats have poorly developed eyes but an excellent echolocation system. These bats can navigate easily even in pitch dark to find their food. They will not mind moving even if they are blind folded. They emit a constant train of sound pulses during flight or even when active on the ground.  The actual sound frequencies range, from about 15KHZ (Just audible) to 150KHZ, with wavelengths ranging from 2.2 – 0.22cms.  Of these ranges leaving the rare extremes the normal range, has been observed to be 20-100 KHZ.  The sound pulses also vary from 0.25 milliseconds to 60 milliseconds. It has been observed that the insectivorous bats are capable of avoiding even wires, which are barely 0.1mm thick! These bats are capable of locating and catching their preys even in mid air.        

On the other hand the fruit eating bats or FLYING FOXES are less specialised for echolocation and would be totally helpless if blind folded.

“What? Can FOXES fly? Are you mad Abid?” asked Aleena .

No Alena. “The fruit eating bats are larger than insect eating bats and have large eyes and large round ears. Their muscles are also large like dogs. Due to this large eye they can locate obstacle and food even in the night. Their face looks like that of a fox. Hence they are called flying foxes. They are in no way related to the real foxes”.

Now let us see some of the general nature of the two types of bats namely, insect eating bats and the fruit eating bats.


The insect eating bats or the insectivorous bats, as they should be called right, are usually smaller than their counterparts, the fruit eating bats. Biologists call it as MICRO CHIROPTERANS.

These bats have poorly formed eyes. But they have an excellent eco-location (locating objects using echo) system.

They can easily move about even in pitch darkness to locate their food. Even if you blind fold them, they will easily fly and locate their food.

Article by Mr. R Venkata Ramanan. Chennai based educational consultant. See linkedIn profile.

R Venkata Ramanan
Educational Consultant
Padmini V Ramanan Educational Resource Centre
4/27-B, IIT colony 1st Street,
Narayanapuram, Pallikaranai,
Chennai- 600100
9444127974 ; 91-044-22463148

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