Geoffroy’s bats choose summer roosts that include caves in mountainous areas and human habitation. These human-made structures include attics, houses, and barns. They forage over farmlands, shrub lands, and forested areas, sometimes near areas of water. During the day, males roost alone while the females form maternity colonies that average around 200 individuals. Both sexes hibernate in caves at temperatures of 6 degrees Celsius or greater. While no maximum elevation has been recorded for this species, their habitat elevation ranges from sea-level (0 m) and 1800m. (Flaquer, et al., 2008; Zahn, et al., 2010)
Wingspans of adult Geoffroy’s bats average to about 261.10mm (range 230-270mm). Their mass averages at 8.65g (range 6-15g). The forearm length observed averages at 41.57mm (range 40.42-42.72mm) and their hindfoot ranges from 9-11.5mm. They have body length excluding their tail measurements of an average of 47.5 (range 41-54mm) and a tail length of 42 (range 38-46mm); total body length averages 70.3 mm (range 41-100mm). There are no differences between the male and female measurements of the species.
Their underbellies consist of a yellowish-cream color. Geoffroy’s bats have small black eyes. They have large, leathery, black pointed ears ranging from 15-17mm, short snouts, and black to dark grey leathery wings. On their wings they have small thumbs that are hook-like, that help them move and climb on the ceilings of caves. The dental formula for Geoffroy's bats is 2/2 1/1 3/3 1/1.
Eghbali and Sharifi (2018) described the developments of Geoffroy’s bat pups into adults. In Geoffroy’s bats, pups start out with little fur, growing more of the wool-like fur as they age. The pelage starts out light grey before turning into darker reddish brown in the span of a couple of months. When they grow closer to adulthood their darker reddish brown fur lightens. The pups measured and weighed at one day old had a mean body mass of 2.57g (range 1.72 to 3.14g) and forearm lengths averaging at 17.37mm (range 14.41 to 19.96mm). (Eghbali and Sharifi, 2018; Eghbali and Sharifi, 2020; Spitzenberger and Weiss, 2017)
Copulation between male and female Geoffroy’s bats occurs at the end of the summer to fall, from late June to early August. Multiple males attract a single female using their scent glands. When the male bats have attracted a female, they compete with other males and act aggressive. These bats are polygynandrous, meaning both males and females have many mates in their lifetimes. (Spitzenberger and Weiss, 2020)
Female Geoffroy’s bats form maternity colonies in late spring to early summer months, typically May and June, giving birth to one pup each around that time. Their breeding season is between the months of July and August. The nursing colonies can include 20 to 500 females. Spitzenberger at el. (2020) showed that these bats tend to give birth earlier in the summer months if it means having a longer hibernation period at the expense of reproductive success rates. Because female bats can hold sperm from fall to spring with delayed fertilization, it’s hard to pinpoint their exact gestation periods. Gestation times are suspected to last between 1 to 3 months if the conditions are good. At birth, pups have a mass of 2.24-2.90g and take 5 to 10 days for weaning. Young pups take about 6 weeks after they are born to become independent. Both sexes reach the age of sexual maturity around 16 to 19 months. (Spitzenberger and Weiss, 2020)
Geoffroy’s bat females, while in the maternity colonies, take care of their young mainly by providing milk for the pups after they are done foraging for themselves. When the pups no longer need milk, the mother start to feed them insects that they bring back from foraging. Females provide nourishment and protection for their pup in the colony. Depending on the supply of food and change in the weather, some females might leave the maternity colonies early before their pups are independent. The pups are independent when they take their first flight, which is about 6 weeks of age. Beyond the act of mating, males provide no parental care for the pups. (Spitzenberger and Weiss, 2020)
The maximum longevity of Geoffroy's bats in the wild is up to 22.7 years. Geoffroy’s bats are not kept in captivity. Threats of predation and other natural causes may shorten the lifespan of these bats. (Wilkinson and South, 2002)
Geoffroy’s bats are social animals, living in colonies. They are not a species that migrate and they travel very little. Geoffroy's bats are mobile animals, foraging nightly using gleaning methods. The gleaning method is uncommon with other bat species and is to prey on spiders in their webs. Geoffroy's bats have a short form of hibernation called torpor, which is common in other bat species, mainly staying in underground caves during winter. Females form maternity colonies in the spring, while males roost in small groups, spending their time foraging. Methods of bat communication can vary; the bats’ calls are used for finding mates, signaling that they are going out to forage, returning with food for their young, as well as warning other bats when acting angered or aggressive towards them. Especially during mating when the bats are finding mates, male bats have to compete for other female bats and would act aggressive towards other males during that time. Although males have no role in raising pups, females provide nourishment and protection for the first 6 weeks of life. (Dietz, et al., 2014; Kervyn, et al., 2012)
Geoffroy's bats are mobile and can move from different cave systems across Europe. Individual bats have home ranges of 287-1,492 ha and forage at a linear distance of up to 6km away from the colony at night. Flaquer et al. (2008) studied habitat selection of Geoffroy’s bats in a breeding colony within the Mediterranean landscape; foraging juvenile pups, on average, fly 1.6km less than adults. Olive gardens and forests are important foraging habitats for the bats. When their colonies are attacked, they do not protect their home range and instead flee. (Dietz, et al., 2014; Flaquer, et al., 2008; Spitzenberger and Weiss, 2017)
Geoffroy’s bats are nocturnal animals. These bats, much like other species of bats, rely on echolocation when foraging as they have poor visibility during the nighttime. Their echolocation calls begin at high frequencies ranging around 140 kHz and decreases to a frequency of 38 kHz.
The frequencies vary slightly depending on perceived or actual habitat clutter. Schumm et al. (1991) reported that when foraging and gleaning off of dense vegetation, their pulses are quick and high-frequency: starting at 124 kHz and falling to 52 kHz. In a building, the same feeding situation would produce calls of 105 kHz dropping to 25 kHz. Their feeding buzz (right before and when they capture insect prey) is quick, with many short pulses of lower frequency: 45 kHz, falling to a range of 20-35 kHz. This buzz is a common pattern across bat species.
Geoffroy’s bats communicate with each other by using vocalization of squeaks, whistle calls, and noisy screech calls. These calls are used for finding mates, signaling that they are going out to forage, returning with food for their young, as well as to warn other bats when acting as if angered. Schumm et al. (1991) showed that frequencies of these calls used while communicating and cruising-flying are different from those when foraging, starting around 100kHz before dropping to 40kHz within 1ms.
Peterson et al. (2019) recorded the different types of calls that bats used when within captive colonies. They noted that calls that rose in frequency were similar to that of echolocation calls. Other recorded calls such as the whistle calls had low frequency and noisy screech calls had low peak and maximum frequencies.
Given their ability to echolocate and communicate at lower frequencies, Geoffroy's bats are described as having adequate hearing for bats.
Touch is also a way for the bats to communicate with one another whether it is a male and female mating, or a mother and her pup during feeding or sharing warmth. Bats rely on touch and smell when they are within the darkness of the caves. Using their senses of touch and smell to crawl towards other bats, huddle with them, shifting their positions, and solo flying.
Along with touch and smell, chemical communication is used in bats when they are searching for another bat with which to mate. Although females are reported to utilize pheromones more than males, both sexes attract each other with pheromones. (Brinkmann and Steck, 2006; Peterson, et al., 2019; Piraccini, 2016; Schumm, et al., 1991)
Geoffroy’s bats are insectivorous, specializing on arachnids (mostly spiders), moths (order Lepidoptera), lacewings (Hemerobiddea), and flies (order Diptera). Vallejo et al. (2019) found that these bats opportunistically focused on one species of stable flies (Stomoxys calcitrans) in the Iberian Peninsula. They employ echolocation to capture insects in mid-air and arachnids via gleaning - plucking them off of shrubs or webs. The flies on which they feed are found near farming areas in cattle barns, while spiders are gleaned off of shrubs or trees. Goiti (2011) pointed out that while the bats using a gleaning strategy for spiders, Geoffroy’s bats’ primarily caught flies and moths in mid-air.
Kervyn et al. (2012) supported these findings when they examined the bats’ feces. They discovered a surprising number of spiders within pellets.
Goiti et al. (2011) studied bat foraging in the Mediterranean region, and showed that Geoffroy’s bats forage in dense habitats such as farmland, scrubland, and, most commonly Aleppo pine (Pinus halepensis) plantations near bodies of water which has a higher population of insects. Spiders comprised 79% of volume and were detected in 95% of bats’ feces. Flies were comprised of 65% of the volume examined in feces, and moths comprised 7% of volume(kg) in feces. Nightly foraging distances average ca. 6km per bat, taking breaks within trees or cattle sheds around the areas in between those distances for feeding. (Goiti, et al., 2011; Kervyn, et al., 2012; Vallejo, et al., 2019)
Geoffroy’s bats don’t have many predators that are known to actually hunt them, other than recorded accounts of owls such as tawny owls (Strix aluco). Spitzenberger et al. (2014) reported that owls will opportunistically prey on bats returning to their colonies. This is especially the case with maternity colonies. To avoid owls, these bats may fly very fast and erratically while others performed circles and loops before slipping into the opening. Other bats moved away from the colony when they presumably detected the owl via echolocation. Pups have markings and stripes when they are born, and maintain fairly darker fur colors as they age which can help them blend into surfaces of the caves. Few nocturnal predators actually hunt the bats as they are agile while flying and hard to see. (Spitzenberger and Weiss, 2017; Spitzenberger, et al., 2014)
Geoffroy’s bats are insectivores and may specialize on spiders, as well. Typical predators may include owls. Frank et al. (2015) reported several ectoparasites that feed off of Geoffroy’s bats, including castor bean ticks (Ixodes ricinus) and multiple species of mites. These mites include those in the genus Ichoronyssus, Steatonyssus periblepharus,and Spinturnix myotis. Bat bugs (Cimex dissimilis) also parasitize these bats. (Frank, et al., 2015)
Besides opportunistically feeding on insects, Geoffroy’s bats have no positive economic impact on humans. (Piraccini, 2016)
Geoffroy’s bats are carriers for diseases that affect animals and humans, and there is the possibility of causing foodborne diseases with their feces. From blood and saliva samples collected, Picard-Meyer et al. (2011) did not find the rabies virus in Geoffroy's bats. Wolkers-Rooijackers et al. (2018) showed bats that consumed flies and other insects can carry the bacterias known as Escherichia coli, Carnobacterium maltaromaticum, and Streptococcus sanguinis, and can transmit it through their feces. (Picard-Meyer, et al., 2011; Piraccini, 2016; Wolkers-Rooijackers, et al., 2018)
The IUCN Red List ranks Geoffroy’s bats as being of “Least Concern.” The US Federal List, CITES, and State of Michigan List have no special status reported for the species.
The primary threats to Geoffroy’s bats are habitat loss (deforestation) by humans, disturbance via human recreational activities, conventional farming that uses chemical pesticides instead of organic farming, and general disturbance via construction work. The natural threats include fires and modifications to their ecosystems that lead to declines in insect populations.
Conservation efforts focus on educating people about bats in general and managing bat communities through surveys and natural history observations. The deployment of bat boxes for roosting is one active measure for conserving these and other bats. (Piraccini, 2016)
Victoria Raulerson (author), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
uses smells or other chemicals to communicate
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.
The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
Living on the ground.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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