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MEDITERRANEAN BATS >
Biology and ecology
BIOLOGY AND ECOLOGY
For at least 55 million years, bats have had biological capabilities unusual among mammals: fluttering flight, locating their position in the dark by echolocation, and hibernation.
Their scientific name is Chiroptera, from the Greek Kheir or Chiro meaning "hand" and Pteros meaning "wing".
Bats are the only flying mammals. Their membranous wings are made of a very thin skin (membrane) which connects the body to the fingers and the fingers to each other, with the exception of the thumb, which remains free and is attached to the body. The majority of bats have a wingspan of 20-25 cm, with a body length of 4 to 5 cm.
Most bats position themselves using echolocation. This consists of the use of very short cries, emitted through the mouth or nose by vibrating their vocal cords, in the form of ultrasound.
The echo of the ultrasound emitted is detected by bats, which enables them to locate objects (obstacles or prey) to determine the size, movement, etc..
Bats’ vision is adapted for night time and used to control their flight altitude, to identify landscape structures and perhaps even to use the stars for long migrations. They can fly in the dark without hitting obstacles using echolocation, but they can be dazzled or disturbed by artificial lighting.
Bats can remain attached to the walls and ceilings without the slightest effort. Thanks to the articulation of the phalanges, the claws on their toes being directed backwards, and tendons designed for suspension leave them in a locked position.
Their circulation is also special because even upside down blood does not rise to their heads!
HUNTING AND DIET
The habitat of bats is selected around hunting and diet. Bats hunt at night. There are several techniques, some hunters such as Pipistrelle and other like the Rhinopolus hunt on the prowl, hanging from a tree branch.
Bats use echolocation to find their prey. In Europe, they are exclusively insectivores (insects, spiders, centipedes...), which partly explains their decline.
BATS LIVE ACCORDING TO A BIOLOGICAL CYCLE RELATED TO THE SEASONS
In winter, from October-November to March-April, boosted by the first of the cold weather and scarcity of insects, bats start their hibernation which lasts several months.
These hibernacula are underground caverns dark caves, mines, tunnels, caves, cracks, or old quarries .... These sites offer the hibernators fresh constant temperature, without breezes and with stable humidity.
The activity of the bat is greatly reduced. The entry into hibernation begins with a slow heart rate, thus leading to slower breathing and a drop in body temperature approaching room temperature.
Some species prefer to have space and others prefer gathering in groups to conserve heat.
Hibernation lasts until spring. During this period, it is essential that their peace is respected, both sound and light. Waking a hibernating bat can kill it. Natural awakening interrupts hibernation occasionally, most commonly related to a need for rehydration and this occurs on average every three weeks. Bats usually just lick the water droplets formed by condensation on their fur, then they go back to sleep.
In the spring, with the arrival of warmer days, the bats emerge from their winter rest and leave their hibernation roosts to go to transitional areas. They replenish their reserves by feeding on mainly insects and spiders. In the month of May, the males live alone and females begin their gestation which lasts 45 to 90 days depending on the species and the weather conditions. They gather together in a « birthing » colony. The selection criteria of their roosts are: high temperature, no flow of air, abundant food, and tranquillity. Females have one single offspring per year.
In the summer, from June to September, the bats are dedicated to bringing up and teaching their young. Females have two breasts to feed from. At a few days old the youngster can crawl but not fly because their wings are not developed enough. While the mothers hunt at night, the young stay with other females (nurseries).
The young become self-sufficient and capable of flying at the end of the summer, during the month of August, when they are six to eight weeks old.
Roosts can be attics, barns, stables, buildings where the heat accumulates, cracks, small holes .... Isolated males, excluded from the nurseries can live in cracks in walls, under roofs, bridges, caves or holes in trees ...
Sexual maturity is reached between the bats first and third year depending on the species.
In autumn, from September to November, the bats go hunting intensively to build up their fat reserves for hibernation. Males and females come together for mating, but fertilization is delayed to early spring to save the mother's reserves during hibernation.