Eats fruits and nectar
Among the largest bats in the world, the male can reach a wingspan of a meter in length and reach a kilogram in weight.
The original group was brought from a wildlife shelter in Australia, with group members with injured wings who were unable to fly. Since then, individuals were born who can fly, and a few of them do. The grey-headed flying fox is considered one of the largest species of bats. Its foxlike head and size earned it the name of flying fox.
These bats are relatively large, with the largest species having a wingspan of close to two meters. Group members live only in Africa, Asia, and Australia and are nourished from fruits, although several species eat flower nectar. In the wild, throughout the world, fruit bats are considered an important player in forest preservation, as they distribute tree seeds, whose fruits they consume.
There were previous claims that they are agricultural pests, because of their fondness for fruits. As such, they were hunted and destroyed in many areas, including within Israel. Today, we understand that they mainly eat very ripe fruits, those which are generally not preferred by humans or used and sold in markets. In Israel, there is one species of fruit bat, the Egyptian fruit bat. In the past, their population was reduced because of deliberate persecution, however when that stopped, and a culture of decorative gardens developed alongside green urban areas, the bats bred and today are a nuisance for residents, who suffer from their droppings on their homes and on their drying laundry.
In the past, there have been claims that bats were insect-eaters, based on many of the species’ nutrition, or alternatively that they are related to rodents, because of the small size among most of the species. Major research on the morphological properties has concluded, however, that they are related to Colugos (a small and rather unknown group of amphibian species in Southeast Asia) and to primates. But in 2001, major science and nature publication Nature published two studies which examined their relation to mammals through genetics. The two studies concluded that bats are in fact relatives of the Ungulate species (which include mammals which chew their cud, horses, whales, and others). Through their evolution, bats have developed a property which characterizes them today, and that is the ability to fly. Essentially, bats are the only mammals which can fly. Bat wings are formed through a flying membrane, which connects the fingers, with the exclusion of the thumb, which remains free. It connects to the back feet and tail, to increase their size when extended. Bats are divided into two groups: fruit bats (Megachiroptera, which are large) and insect bats (Microchiroptera, which are small) The two groups differ in size, as indicated by their scientific group names, by their main sources of nutrition, as indicated by their Hebrew group names, and by their senses and lifestyles.
In contrast to fruit bats, insect bats are small. The smallest species weigh only 1.5 – two grams, and they are also the smallest mammals. The hundreds of species of insect bats can be found across a much more expansive habitat than that of fruit bats, with a habitat that extends across all continents, except Antarctica. Their main source of nutrition is insects, although several species have evolved to eat other foods, such as fish, frogs, nectar, fruits, small mammals, and even blood. Like fruit bats, insect bats are active at night, however in contrast, they do not rely on their sense of vision (although they are not blind!) to catch their food. Instead, they use the phenomenon of echo. Locating food through echo is a mechanism which characterizes certain species and specific groups. Animals gifted with this ability make sounds and use the subsequent echoes from various objects to gather information and envision their surroundings. Bats, with the aid of echo location, can ascertain the size of objects, their location, their speed compared to that of the bat, and even the texture of objects. So why are our ears not deafened by these sounds from bats which surround us? The fact that our nights are relatively quiet stems from the fact that the sounds made by most species of bats for echo location are heard at frequencies which far exceed human hearing capacity. Humans are capable of hearing sounds ranging between 20 hertz and 15-20 kilohertz (depending on age), and bats’ echo location noise frequency can be heard at 9 – 200 kilohertz. When the bats go out to hunt at night, they make their location sounds relatively slowly to navigate and search for prey, however when they approach their prey the pace of sounds increases to update the situation faster and to succeed in capturing elusive prey. This method has proven itself. Bats are excellent hunters. Some species can eat hundreds of mosquitoes within an hour!! The volume of mosquitoes and other insects that bats devour during their active hours is much higher than what we are capable of exterminating using pesticides. Unfortunately, a combination of the two is untenable, as bats which prey upon insects which have been poisoned may also become poisoned and die. In Israel, there are over 30 species of insect bats, only a small number of which live in all of Europe. Many species in Israel, however, are in danger of extinction. The two main reasons for their disappearance from Israel and also for the increase in mosquitoes and other insects, is the increased use of pesticides in agriculture and harm to the caves where bats live. Without caves, certain species have taken refuge in houses, but often, they are expelled out and openings to attics and roofs and other shelter options are closed. All the popular beliefs about bats are simply superstitions! Have you seen bats in your house or nearby? Don’t worry; they won’t get caught in your hair or poke your eyes, and apparently, they are not a sign of a curse put on you. They essentially eliminate mosquitoes and other insects from your environment.
Photo: Ariel Tenaami