Tadarida aegyptiaca
Egyptian free-tailed bat

Tadarida aegyptiaca, the Egyptian free-tailed bat, has an Old World distribution, stretching from Morocco across central and east Africa to southwest Asia, India, and Sri Lanka, excluding the Sahara desert. The range of T. aegyptiaca includes much of the African continent to South Africa. (Bernard and Tsita, 1995; Denys, Bogdanowicz, and Aulagnier, 1995; Nowak, 1994)

This species has a patchy distribution throughout its range. It is poorly known through northwestern Africa, but in other parts of its range it is quite abundant and widespread, including India and South Africa. (Advani, 1982; Bernard and Tsita, 1995; Denys, Bogdanowicz, and Aulagnier, 1995)

Tadarida aegyptiaca is usually found in warm, semi-arid and arid regions. It is generally not found in forested or mountainous habitats. (Advani, 1982)

Egyptian free-tailed bats prefer rock crevices and cliff faces for diurnal roosts. They nest in human structures as well, including the roofs of houses and churches. They are also known to roost in caves, crevices, and dead trees. (Advani, 1982; Bernard and Tsita, 1995; Denys, Bogdanowicz, and Aulagnier, 1995)

Tadarida aegyptiaca is sexually dimorphic, with males slightly smaller than females. Males range in size from 11.0 to 20.0 g, with an average of 15.8 g, while females range from 13.8 to 20.5 g, averaging 16.3 g. The snout is long and slightly upturned at the lip. Ears are very large (18 to 23 mm long) and forward-pointing. The tragus is square with an accessory appendage. These bats have a grayish-brown dorsal coat, with particularly dark areas on the back of the head and the back. Tadarida aegyptiaca shares only with Tadarida brasiliensis among Tadarida the distinct separation of the ears along the top of the head. (Hoath, 2003; Nowak, 1994; Silva and Downing, 1995)

The wingspan of T. aegyptiaca averages 35.4 cm, while the wing area is 0.0130 m^2. The aspect ratio for the wings is 9.7, with a wing loading of 12.0 Nm^-2. Body length is 104 to 120 mm, tail length is 41 to 46 mm, and forearm lenth is 47 to 56 mm. The dental formula is 1/2, 1/1, 2/2, 3/3. (Denys, Bogdanowicz, and Aulagnier, 1995; Hoath, 2003; Norberg and Rayner, 1987)

Data for Tadarida aegyptiaca is lacking, but the lifespan for molossids in general averages about ten years, plus or minus about three years. (Barclay and Harder, 2003)

Like other molossids, Tadarida aegyptiaca has high-aspect-ratio wings and high wing loadings. These characteristics allow them to fly high and fast. Among Molossidae, however, T. aegyptiaca has one of the lowest wing loadings, so it likely flies slower than other species in this family. Coupled with its long, narrow-band echolocation calls, T. aegyptiaca is well suited to sustained, high-altitude flight. Physiologically, this species is able to sustain such prolonged, active flight because it has a relatively higher than expected oxygen carrying capacity in its blood for a mammal of its size. (Fenton and Griffin, 1997; Norberg and Rayner, 1987; van Aardt, Bronner, and de Necker, 2002)

Egyptian free-tailed bats ARE apparently active later in the night than many other sympatric species of bats. One study has shown that this species emerges fairly late in the evening (after 1840 h) and stays active well past midnight in the summer. (Fenton and Thomas, 1980)

Home Range

No data exist documenting the home range of Tadarida aegyptiaca. The New World taxon Tadarida brasiliensis is known to have a home range of up to 400 km^2, with foraging flights extending to a distance of up to 25 km from their roosts. According to Nowak (1994), T. brasiliensis may in fact fly up to 65 km to foraging areas. (Nowak, 1994; Williams, Ireland, and Williams, 1973)

Like all microchiropterans, Tadarida aegyptiaca depends on echolocation to some degree. Apart from navigation, T. aegyptiaca uses its echolocating abilities in active pursuit of insectivorous prey. (Fenton and Griffin, 1997)

There is some evidence to suggest that Egyptian free-tailed bats have a well-developed olfactory sense. The number of perforations in the cribriform plate for this species is much higher than other members of Vespertilionoidea. The cribriform plate facilitates the targeting of olfactory receptor (OR) axons with their specific glomeruli, leading to the first synapse of OR neurons with the olfactory bulb. Therefore, a higher number of cribriform plate perforations should be correlated with greater olfactory acuity. Rather than foraging, social behavior may be the reason for such olfactory prowess. However, in their study of scent-dispersing hairs (osmetrichia) in pteropodid and molossid bats, Hickey and Fenton (1987) found distinct hair types present in scent dispersing regions of several Tadarida, but not for the Egyptian free-tailed bat. (Bhatnagar and Kallen, 1974; Hickey and Fenton, 1987; Rowe et al., 2005)

Egyptian free-tailed bats are echolocating aerial insectivores. Equipped with high-aspect-ratio wings, the actively hunts airborne prey, possibly up to 500 m above ground. They hunt using a long (10-20 ms), narrow bandwidth (5-10 kHz) search-phase echolocation call centered around 14-18 kHz. Echolocation frequencies can range up to 26 kHz, while the highest energy frequency is about 18 kHz. Tadarida aegyptiaca is considered a fast, long-range aerial-hawking insectivore. (Fenton and Griffin, 1997; Norberg and Rayner, 1987)

This species is known to consume insects of the orders Lepidoptera and Coleoptera. In a study of T. aegyptiaca in the Rajasthan desert of India (25-30ºN), Advani (1982) found a distinct seasonal variation in diet. During the winter (December through February at this latitude), the bats preferred Coleoptera, Orthoptera, Diptera, and Hymenoptera. Foods consumed in less quantities during the winter included Lepidoptera, Araneae, Neuroptera, and Dictyoptera. In the spring and summer, Coleoptera contributed to an even greater percentage of diet, nearly 40%. Orthoptera were also a major component of the diet, as was Lepidoptera. Isoptera and Hymenoptera made up a modest percent of the diet, while Dictyoptera, Diptera, and Odonata made only meager contributions. The monsoon season brought about drastic changes in dietary composition. Isoptera became the dominant food source, with Coleoptera, Hymenoptera, Lepidoptera, and Orthoptera contributing to most of the rest of the diet. Diptera and Neuroptera made minor contributions, and some plant material was found as well. In the post-monsoon period prior to winter (October and November), dietary preferences closely resembled those for the winter. Coleoptera and Hymenoptera predominated, while Orthoptera, Lepidoptera, Diptera, and Odonata all made significant contributions. Some Isoptera, Dictyoptera, Neuroptera, Araneae, and plant parts were also found. (Advani, 1982; Fenton and Thomas, 1980)

Tadarida aegyptiaca makes up a small part of the diet of owls. Young in roosts may fall prey to snakes. (Denys, Bogdanowicz, and Aulagnier, 1995)

Tadarida aegyptiaca is a common insectivore throughout much of its range. This species may also be a host to various viruses and other pathogens, including rabies. (Hill, and Smith, 1984)

Because this species is known to roost in buildings, guano deposits may cause some risk of contamination by bacteria, arthropods, and other pests. However, guano deposits are usually small and dry, so this risk is slight. There is also some risk of rabies from coming into contact with this species, like all bats. Additionally, the coarse-scale distributions of disease outbreaks of all four strains of African filovirus (including Marburg and Ebola) overlap with the range of T. aegyptiaca. A total of 38 genera and well over 100 species of small mammal share this overlap, and no work yet has been performed on Egyptian free-tailed bats to show that they serve as a host for Filoviridae viruses. (Hill, and Smith, 1984; Peterson et al., 2004)

Egyptian free-tailed bats are geographically widespread consumer of potentially damaging pest animals such as Lepidoptera and Hymenoptera. They may thus serve to control populations of harmful insects in areas where they are abundant. (Advani, 1982; Hill, and Smith, 1984)

Tadarida aegyptiaca is not listed on any threatened or endangered species lists.

One subspecies, T. a. thomasi, occurs in abundance in the Great Indian Thar Desert. When referred to in the literature, this subspecies is also associated with the common name “wrinkle-lipped bat." In Egypt, the subspecies present is T. a. aegyptiaca. (Advani, 1982; Hoath, 2003)