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Eumops floridanusFlorida bonneted bat

By Allison Schain

Geographic Range

Florida bonneted bats, Eumops floridanus, have one of the most restricted ranges of any bat in the United States. They are only found in southern Florida, excluding the Florida Keys. These bats are located in three Gulf Coast counties (Charlotte, Collier, and Lee) and Miami-Dade County on the Atlantic Coast. (Gould, 2013; Solari, 2016)

Habitat

Florida bonneted bats roost in a variety of habitats. Being solely located in southern Florida, these bats are never found above 50 m above sea level. Habitats include tropical and subtropical forests as well as suburban and urban areas. They roost in tree cavities made by woodpeckers, along limestone cliffs, in caves along the cliff faces, throughout marshes, in pine trees and the shafts of royal palm (Roystonea regia) leaves. In suburbs and cities, they’re likely to be found under Spanish-style shingles, along chimneys, and in shrubs. (Best and Hunt, 2020; Gore, et al., 2015; Harvey, et al., 2011; Skipwith, 2020)

  • Range elevation
    0 (low) m
    0.00 (low) ft

Physical Description

Florida bonneted bats range in pelage color from black to a pale reddish-brown. The individual hairs are bicolored, fading from their dominant color to a whitish color at the base. Like all bonneted bats in the genus Eumops, they have large, round ears that come to a rounded point at the peak and measure from 20 to 31 mm. Not much is known about young Florida bonneted bats as pregnant females abort fetuses under stress, often caused by being caught and studied.

Sexual dimorphism exists within this species as males have longer and larger wings and a gular throat pouch. These bats belong to the family Molossidae (free-tailed bats), and their tails measure 46 to 57 mm long. Their feet measure 11 to 15 mm. Male Florida bonneted bats have a forearm range of 61 to 66 mm, while females are usually smaller at 53 to 66 mm. Total lengths are between 130 and 165 mm with an average wingspan of 500 mm and a weight between 30 to 47 grams. They have a dental formula of 1123/2123 with a total of 30 teeth. (Best and Hunt, 2020; Ober, et al., 2017a; Smith, et al., 2019; Timm and Genoways, 2004)

  • Sexual Dimorphism
  • male larger
  • sexes shaped differently
  • Range mass
    30 to 47 g
    1.06 to 1.66 oz
  • Range length
    130 to 165 mm
    5.12 to 6.50 in
  • Average wingspan
    500 mm
    19.69 in

Reproduction

Florida bonneted bats form harems with one male and multiple females where males exhibit resource-defense polygyny at roost sites. Males have gular glands similar to other bats within the genus Eumops and there is a female bias among adults in the species. It is suspected that each roost has one dominant male, but the stability among the harem and defensive roles males may take on are unknown. Harems contain between two and thirty-four individual bats whose majority will mate between May and September. (Gore, et al., 2015; Ober, et al., 2017a)

The Florida bonneted bat breeding season is year-round, but the majority of pregnancies take place between May and September. When considered conspecific to Wagner's mastiff bats (Eumops glaucinus), Beguelini et al. (2010) indicated a concentration of pregnancies in August and September in Florida. Beguelini et al. also noted that these bats are polyestrous.

Females breed once a year and give birth to a pup after an estimated gestation period of 80-90 days. The lactation period of Wagner's mastiff bats is 5-6 weeks. Florida bonneted bats likely have a similar lactation period. Based on the weight of female bats, the average birth mass of pups is estimated at 15 grams. Age of sexual maturity is unreported for both sexes. (Beguelini, et al., 2010; Gore, et al., 2015; Ober, et al., 2017a)

  • Breeding interval
    Once a year
  • Breeding season
    Year-round, concentrated in April through June
  • Average number of offspring
    1
  • Range gestation period
    80 to 90 days

Little is known about the parental investment of Florida bonneted bats. Like all bats, this species is assumed to be altricial, requiring parental care at birth. It is assumed that females are the primary care-givers for young, with little to no involvement from the males. It has been documented that unmated males visit multiple family groups throughout the year. (Gore, et al., 2015; Ober, et al., 2017a; Ober, et al., 2017b)

Lifespan/Longevity

The lifespan of Florida bonneted bats is unknown, but based on prior research, Gore et al. (2010) inferred their lifespan to be between 10 and 20 years in the wild. These bats are not kept in captivity. (Gore, et al., 2015; Gould, 2013)

  • Typical lifespan
    Status: wild
    10 to 20 years

Behavior

Florida bonneted bats are mobile hunters with a single home-base. Unlike other bats in the United States, Florida bonneted bats do not migrate or hibernate. Because of southern Florida's mild winters, they remain active from dusk to dawn year-round. are a social species.

Florida bonneted bats have a unique social system, forming harems with one breeding male and multiple females. Their hierarchy is headed by the breeding male with breeding females coming next, non-breeding mature males and females below, and finally adolescents and young. When they emerge from their roosts at sunset, they do so in order within their hierarchy. Breeding males, their contenders, and non-breeding males emerge earlier than females and mid-tier contending males. Non-reproductive females emerge last. Living in harems provides socialization with up to 30 conspecific bats. However, Ober reported average groups sizes to be 10 individuals, with adults being more likely to return to the same roost than sub-adults.

A unique feature of Florida bonneted bats is their ability to take flight from the ground. However, Gore et al. (2018) reported that 7 of 8 captured individuals climbed a tree before taking flight; it's unknown how often these bats will take off from the ground. They may also spend time on the ground, as a salvaged bat was reportedly found during a bulldozing excavation. It had been found under rocks. When in flight, they typically do so at heights of at least 10 m, making them difficult to catch in mistnets. When they forage, they emit echolocation pulses at a low frequency that can be heard by humans, and do so in open-canopied habitats. (Alvarez, et al., 2018; Best and Hunt, 2020; Gore, et al., 2015; Gore, et al., 2018; Harvey, et al., 2011; Ober, et al., 2017b; Timm and Genoways, 2004)

Home Range

Florida bonneted bats will make multiple hunting trips in one night for varied times. With a home roost in the center, the average travel time is three hours per foray. Home ranges are unknown, as these bats fly at altitudes higher than most mist nets can reach. The dominant male, however, is assumed to be territorial over their home roost as there are often pregnant or lactating females remaining in the roost at night. This roost area has not been quantified. (Alvarez, et al., 2018; Bailey, et al., 2017; Timm and Genoways, 2004)

Communication and Perception

Florida bonneted bats use echolocation and eyesight to detect and hunt prey. Florida bonneted bats use long, low-frequency calls to communicate with each other socially (8-10 kHz). These frequencies are a large part of calls recorded and indicate that these bats are highly social. When foraging, they emit a call frequency of 10 to 18 kHz and an overall range of 16 to 22 kHz. This is one of the lowest frequencies found in North American bats.

Males have gular glands which secrete pheromones they use to mark their roost site and for harem defense. Females will use scent to identify their young and form a tactile relationship with them until they reach sub-adulthood. (Bohn and Gillam, 2018; Gould, 2013)

Food Habits

Florida bonneted bats are classified as insectivores and maintain a diet that is dependent on beetles (order Coleoptera), flies and mosquitoes (order Diptera), moths (order Lepidoptera), and true bugs (order Hemiptera). In-depth diet studies have not yet been completed. They are open-space hunters that use narrowband search signals. Once they locate and capture their flying insect, they eat it aerially. (Best and Hunt, 2020; Gould, 2013; Harvey, et al., 2011; Kunz and Racey, 1998)

  • Animal Foods
  • insects

Predation

Barred owls (Strix varia) attempt to take Florida bonneted bats from their roosts and are attracted to the calls that the bats make. Predation rates have not been quantified. These bats have been found in unidentified regurgitated pellets from owls or other birds of prey. (Best and Hunt, 2020; Gore, et al., 2015; Gore, et al., 2018; Gould, 2013)

Ecosystem Roles

Florida bonneted bats are secondary consumers. Their main predators are suspected to be owls and other birds of prey. These bats are general insectivores and could have a local impact on the flying insect community. However, given the rarity and endemism of these bats, it is unlikely that the impact is substantial. No parasites have been documented in this species. (Best and Hunt, 2020)

Economic Importance for Humans: Positive

There are no known positive economic effects of Florida bonneted bats on humans. Although these bats could control insect pest populations, their rarity on the landscape presumes that the impact is negligible. (Skipwith, 2020)

Economic Importance for Humans: Negative

There are no known negative economic effects of Florida bonneted bats on humans.

Conservation Status

Florida bonneted bats are listed as federally endangered by the USFWS and state-endangered in Florida. The IUCN Red List classifies them as "Vulnerable." The species is not listed by the State of Michigan or CITES.

With small population sizes, low survival rates, and low reproductive rates, it is estimated that there may be less than 250 adults of this species remaining. They also face threats from their limited range, vanishing habitats, as well as chemicals used in agricultural practices.

Core areas for Florida bonneted bats have been identified, and the state of Florida has proposed that connection to suitable habitats must be preserved along with core areas of activity. To provide a proper buffer between the bats and the threats they face, both protection and management of critical areas must be maintained by wildlife services. Many basic aspects of natural history still remain unknown for this species, and continued research is emphasized. (Best and Hunt, 2020; Gould, 2013; Skipwith, 2020; Solari, 2016)

Contributors

Allison Schain (author), Radford University, Logan Platt (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

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.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

colonial

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.

crepuscular

active at dawn and dusk

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

echolocation

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.

endothermic

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.

female parental care

parental care is carried out by females

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

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).

marsh

marshes are wetland areas often dominated by grasses and reeds.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

polygynous

having more than one female as a mate at one time

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

Alvarez, V., J. Gore, C. Pylant, J. Austin. 2018. A conservation genetic analysis of the endangered Florida bonneted bat. Journal of Undergraduate Research, 19/3: 1-6.

Bailey, A., R. McCleery, H. Ober, W. Pine. 2017. First demographic estimates for endangered Florida bonneted bats suggest year-round recruitment and low apparent survival. Journal of Mammalogy, 98/2: 551-559.

Beguelini, M., B. Sergio, F. Leme, S. Taboga, E. Morielle-Versute. 2010. Morphological and morphometric characteristics of the epididymis in the Neotropical bats Eumops glaucinus and Molossus molossus (Chiroptera: Molossidae). Chiroptera Neotropical, 16/2: 769-779.

Best, T., J. Hunt. 2020. Mammals of the Southeastern United States. Tuscaloosa, Alabama: University of Alabama Press.

Best, T., W. Kiser, J. Rainey. 1997. Eumops glaucinus. Mammalian Species, 551: 1-6.

Bohn, K., E. Gillam. 2018. In-flight social calls: A primer for biologists and managers studying echolocation. Canadian Journal of Zoology, 96/8: 787-800.

Bowles, J., P. Heideman, K. Erickson. 1990. Observations on six species of free-tailed bats (Molossidae) from Yucatan, Mexico. The Southwestern Naturalist, 35/2: 151-157.

Gore, J., L. Miller, E. Braun de Torrez, M. Wallrichs. 2018. Owl predation on Florida bonneted bats (Eumops floridanus). Florida Field Naturalist, 46/4: 93-132.

Gore, J., M. Robson, R. Zambrano, N. Douglass. 2015. Roosting sites of a Florida bonneted bat (Eumops floridanus). Florida Field Naturalist, 43/4: 179-184.

Gould, R. 2013. Endangered and threatened wildlife and plants; Endangered species status for the Florida bonneted bat. Federal Register, 78/191: 61004-61043.

Harvey, M., J. Altenbach, T. Best. 2011. Bats of the United States and Canada. Baltimore, Maryland: The Johns Hopkins University Press.

Kunz, T., P. Racey. 1998. Bat Biology and Conservation. Washington, D.C.: Smithsonian Institution.

McDonough, M., L. Ammerman, R. Timm, H. Genoways, P. Larsen, R. Baker. 2008. Speciation within bonneted bats (Genus Eumops): The complexity of morphological, mitochondrial, and nuclear data sets in systematics. Journal of Mammalogy, 89/5: 1306-1315.

Ober, H., E. Braun de Torrez, J. Gore, A. Bailey, J. Myers, K. Smith, R. McCleery. 2017. Social organization of an endangered subtropical species, Eumops floridanus, the Florida bonneted bat. Mammalia, 81/4: 375-383.

Ober, H., E. Braun de Torrez, R. McCleery, A. Bailey, J. Gore. 2017. Sexual dimorphism in the endangered Florida bonneted bat, Eumops floridanus (Chiroptera: Molossidae). Florida Scientist, 80/1: 38-48.

Ober, H., L. Braun de Torrez, E. Webb, J. Gore, R. Zambrano. 2021. Urban roost selection of Florida bonneted bats. Annual Meeting of the Southeastern Bat Diversity Network, None: None.

Oetker, M. 2018. Endangered and threatened wildlife and plants; 5-year status reviews for 42 southeastern species. Federal Register, 83/151: 38320-38323.

Skipwith, A. 2020. Endangered and threatened wildlife and plants; Designation of critical habitat for Florida bonneted bat. Federal Register, 85/112: 35510-35544.

Smith, L., J. Gore, E. Braun de Torrez, E. Webb, F. Ridgley, B. Tornwall. 2019. High incidence of hypopigmented marks in the endangered Florida bonneted bat. Journal of Fish and Wildlife Management, 10/2: 410-418.

Solari, S. 2016. "Eumops floridanus" (On-line). The IUCN Red List of Threatened Species 2016: e.T136433A21984011. Accessed February 02, 2021 at https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T136433A21984011.en.

Timm, R., H. Genoways. 2004. The Florida bonneted bat, Eumops floridanus (Chiroptera: Molossidae): Distribution, morphometrics, systematics, and ecology. Journal of Mammalogy, 85/5: 852-865.

Torrez, E., H. Ober, R. McCleery. 2016. Use of a multi-tactic approach to locate an endangered Florida bonneted bat roost. Southeastern Naturalist, 15/2: 235-242.

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