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Thyroptera tricolorSpix's disk-winged bat

By Waitta Jarso

Geographic Range

Spix's disk-winged bats (Thyroptera tricolor) are native to the Neotropical region. Their range extends from southern Mexico, through most of Central America, and into South America as far as northern Bolivia. In South America, their range extends as far west as Ecuador and Peru, east of the Andes mountains. Their range continues east through forested regions of Bolivia and Brazil, and along most of coastal Brazil. Their range also includes other countries in northern South America, such as Colombia, Guyana, Suriname, French Guiana, Trinidad and Tobago, and parts of Venezuela. (Boada, et al., 2010; Tavares and Mantilla, 2015; Velazco, et al., 2014)

Habitat

Spix's disk-winged bat inhabit tropical regions. They are typically found at elevations from 0 to 600 m above sea level (asl), but have been reported in areas up to 1800 m asl. They are found in forests, rainforests, and montane regions.

Spix's disk-winged bat roost in rolled-up leaves of native trees, such as lobster-claws (genus Heliconia). Young leaves of such trees naturally curl into cone shapes, with a small opening (40 to 100mm in diameter) at the end of each leaf. Because lobster-claw leaves quickly unroll as they grow, Spix’s disk-winged bats change roost sites frequently. (Boada, et al., 2010; Findley and Wilson, 1974; Velazco, et al., 2014; Wilson and Findley, 1977)

  • Range elevation
    0 to 1800 m
    0.00 to 5905.51 ft
  • Average elevation
    600 m
    1968.50 ft

Physical Description

Adult Spix's disk-winged bats are 67 to 79 mm long, from head to tail, and have body masses from 3.4 to 5.1 g. They have dark brown dorsal pelage, and lighter, cream-colored ventral pelage. Spix's disk-winged bats have conspicuous circular pads on their thumbs and hind feet. These pads function similarly to suction cups, allowing Spix's disk-winged bats to adhere to flat surfaces, such as the leaves of lobster-claws (genus Heliconia), where they tend to roost.

Spix's disk-winged bats exhibit some sexual dimorphism. Adult females weigh more (average body mass = 4.0 g) and have longer forearms (average forearm length = 37.1 mm) compared to adult males (average body mass = 3.7 g; average forearm length = 36.7 mm). Adult males have longer tails (average tail length = 28.6 mm) and hind feet (average hind foot length = 5.9 mm) than females (average tail length = 27.3 mm; average hind foot length = 5.7mm). Both sexes have similar average ear lengths of around 12.3 mm. Spix's disc-winged bats have 38 teeth, with a dental formula of 2133/3133.

Spix's disk-winged bats are born hairless, and reach average adult mass at around seven months. Birth mass of young is dependent on the mass of pregnant females. In general, the mass of a newborn is 26 to 31% of the mass of its mother prior to pregnancy. (Chaverri and Vonhof, 2011; Riskin and Fenton, 2001; Velazco, et al., 2014; Wilson and Findley, 1977)

  • Sexual Dimorphism
  • female larger
  • Range mass
    3.4 to 5.1 g
    0.12 to 0.18 oz
  • Range length
    67 to 79 mm
    2.64 to 3.11 in

Reproduction

The re is limited information regarding the mating systems of Spix's disk-winged bats. Although it is suspected that they are polygynous, males do not exhibit mate-guarding behaviors typical of other tropical, polygynous bat species. Because Spix's disk-winged bat change roosting sites often, they do not defend specific locations or social groups.

Spix’s disk-winged bats and tend to stay within the same home range and social groups throughout their lives, but manage to avoid inbreeding. Although they typically have low dispersal rates, males may travel up to 500 m away to breed with females in separate social groups. Genetic studies have also reported low levels of relatedness between males and females within social groups.

Spix's disk-winged bats use contact calls to find potential mates. Males fly around emitting mating calls, and receptive females respond to these calls from their roosting sites, typically in the rolled leaves of lobster-claws (genus Heliconia). (Buchalski, 2013; Chaverri and Vonhof, 2011; Gillam and Fenton, 2016; Vonhof, et al., 2001)

Spix’s disk-winged bats are iteroparous, with a mating season between August and September. Females gestate their young for 3.5 to 4 months, and nurse their pups for another 4 months. Females produce one offspring per breeding season and the birth mass of pups typically is 26 to 31% the mass of their mothers. Juveniles reach independence after approximately 4 months, but are volant after 2 months. Males reach sexual maturity within one year, whereas females reach sexual maturity within two years. (Chaverri and Vonhof, 2011; Findley and Wilson, 1974; Hernández-Pinson, et al., 2021)

  • Breeding interval
    Spix's disk-winged bats breed once yearly.
  • Breeding season
    August to September
  • Average number of offspring
    1
  • Range gestation period
    3.5 to 4 months
  • Range weaning age
    3.5 to 4 months
  • Average time to independence
    4 months
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    1 years

Female Spix's disk-winged bats protect and nurse their young for about 4 months following parturition. Due to the ephemeral nature of the roosts that Spix's disk-winged bats use, mothers transport pre-volant pups between different heliconia (genus Heliconia) leaves frequently. Males provide no parental investment beyond the act of mating. There is a low dispersal rate within bats of the same natal group, suggesting that Spix's disk-winged bats show some level of maternal association following independence. (Buchalski, 2013; Hernández-Pinson, et al., 2021; Vonhof, 2003)

  • Parental Investment
  • altricial
  • female parental care
  • pre-weaning/fledging
    • provisioning
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • female
  • post-independence association with parents

Lifespan/Longevity

There is currently no reported lifespan for Spix's disk-winged bats, or any other bats in the genus Thyroptera. However, a study from 2013 estimated mean lifespan using survivorship rates across three age groups: juveniles (< 1 years old), prime-age adults (2 - 3 years old), and senescent adults (> 4 years old). In this study, senescent adults had the lowest annual survival rate (0.45), followed by juveniles (0.55) and then prime-age adults (0.77). Based on these survivorship, the mean lifespan Spix's disk-winged bats of in the wild was estimated at 2.81 years. There are no reports of Spix's disk-winged bats being kept in captivity and therefore no reports of captive lifespans. (Buchalski, 2013)

  • Average lifespan
    Status: wild
    2.81 years

Behavior

Spix's disk-winged bats form and maintain social groups over long periods. Within social groups, individuals form pairs which maintain contact for as long as 400 consecutive days. Spix's disk-winged bats maintain group cohesion by emitting contact calls, which allow group members to recognize one another. Spix’s disk-winged bats roost in groups of up to six bats. Social groups are composed of males and females, but groups are slightly male-biased on average. Though there is no clear hierarchy, both male and female bats tend to associate more strongly with other males. Male and female bats of the same social group never mate, but maintain non-sexual associations.

The ephemeral nature of their roosting sites influences the movements of Spix's disk-winged bats. Though they have strong ties within social groups, it is rare for all members to roost in the same leaf every night. Although Spix's disk-winged bats exhibit fission-fusion dynamics within their social group, they typically avoid interaction with other social groups outside of breeding season.

Spix’s disk-winged bats are nocturnal insectivores. They forage for food and move between roost sites at night. When choosing new roost sites, Spix's disk-winged bats typically choose longer leaves (average leaf length = 122.0 cm) with smaller leaf-mouth diameters (average diameter = 13.2 cm). Longer leaves provide space for more roosting bats, while smaller leaf-mouth diameters help conceal bats from predators and insulate them from fluctuating temperatures. Tighter rolled leaves also better amplify the contact calls that roosting bats emit to communicate with flying bats. (Findley and Wilson, 1974; Gillam and Chaverri, 2012; Montero, 2015; Solano-Quesada and Sandoval, 2010; Vonhof, 2003; Vonhof, et al., 2004)

Home Range

Spix’s disk-winged bats have an average home range of 1780 m^2 (range = 70 - 6200 m^2). The inherent fission-fusion dynamics of social groups means that Spix's disk-winged bats typically have overlapping home ranges. There is no consistent difference between home range sizes of Spix's disk-winged bats based on sex. They do not defend specific territories, as they usually change roosting sites every night. (Vonhof, et al., 2004)

Communication and Perception

Spix’s disk-winged bats rely heavily on acoustic stimuli to communicate and perceive their environment. They communicate with conspecifics using echolocation and contact calls. Their echolocation calls are low intensity, with frequencies averaging 45 kHz, and short range, suggesting that Spix’s disk-winged bats hunt by gleaning insects off of surfaces.

Spix’s disk-winged bats use contact calls to identify conspecifics at roosting sites. Bats in flight make contact calls, which nearby roosting bats detect and respond to with their own contact calls. Contact calls are suspected to be specific to individuals, allowing Spix’s disk-winged bats to identify others within their social group, as well as potential mates outside of their social group. The specificity of contact calls also allows parents to identify their pups. The frequency of contact calls between males and ovulating females is relatively high, suggesting that reproductive cycles influence how receptive roosting female bats are to flying male bats.

Spix’s disk-winged bats also use visual and tactile stimuli to communicate and perceive their environment. They use touch to capture prey and to communicate with pups or potential mates. They also have well-developed vision in low light, which they use to capture prey, find mates, and communicate within roosts. Spix's disk-winged bats also detect chemical stimuli, such as pheromones released by conspecifics. (Fenton, et al., 1999; Gillam and Chaverri, 2012; Gillam and Fenton, 2016; Montero, 2015)

Food Habits

Spix’s disk-winged bats are primarily insectivores. While they sometimes consume prey by aerial hawking, they mostly glean insects off of surfaces, such as leaves or the trunks of trees. Spix’s disk-winged bats are considered opportunistic feeders.

A study from 2006 found that the diets of Spix’s disk-winged bats consisted primarily of non-volant arthropods across two classes and nine orders. The frequency of occurrence for different insect groups in fecal pellets varied widely. However, 93% of pellets contained jumping spiders (family Salticidae), 81% contained leafhoppers (family Cicadellidae), 63% contained adult moths and butterflies (order Lepidoptera), and 59% contained true flies (order Diptera). Insect larvae from the orders Hymenoptera and Lepidoptera were present in 43% of fecal pellets, and fecal pellets also included adult beetles (29%; order Coleoptera), earwigs (28%; order Dermaptera), hymenopterans (25%; order Hymenoptera), and lacewings (23%; order Neuroptera). (Dechmann, et al., 2006; Gillam and Chaverri, 2012; Wilson and Findley, 1977)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Spix's disk-winged bats are most vulnerable to predation while changing roosts. To minimize exposure to predators during this time, flying bats emit contact calls, which roosting bats respond to with their own contact calls. Individuals vary in their responsiveness to contact calls, but the amount of energy expended by flying bats is inversely related to the amount of vocalizations emitted by roosting bats. Because vocalization requires energy, physical wellness and reproductive status both influence the amount that roosting bats vocalize. For example, lactating bats are the least likely to respond to calls from flying bats, as any response puts them at higher risk of predation.

Spix’s disk-winged bats have cryptic coloration that helps them avoid predation. Furthermore, their preferred roosting sites in rolled-up Heliconia leaves provides them natural cover from predators. Known predators of Spix’s disk-winged bats include hawks (genus Buteo), falcons (genus Falco), white-faced capuchin monkeys (Cebus imitator), raccoons (Procyon lotor), and South American coatis (Nasua nasua). (Chaverri and Gillam, 2010; Sagot, et al., 2018; Solano-Quesada and Sandoval, 2010)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Spix's disk-winged bats are primarily insectivores and likely play a role in controlling populations of prey species. They also serve as a source of prey for falcons, monkeys, and other diurnal predators.

Spix's disk-winged bats are hosts for ectoparasitic flesh flies (Sarcofahrtiopsis thyropteronthos), which live on their wings and are also found in their roost sites. (Pape, et al., 2010)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

There are no known positive economic impacts of Spix's disk-winged bats on humans.

Economic Importance for Humans: Negative

There are no known negative economic impacts of Spix's disk-winged bat on humans. Although they may be capable of carrying and transmitting rabies, no cases have been confirmed in Spix’s disk-winged bats and serum sample tests on 2 individuals were negative. (de Almeida, et al., 2019)

Conservation Status

Spix's disk-winged bats are listed as a species of “Least Concern” on the IUCN Red List. They have no special status on other national or international conservation lists.

There is growing concern about the conservation status of Spix’s disk-winged bats as climate change and anthropogenic development continue to disrupt or destroy their habitat. Globally, 24% of bat species are under threat from human activities, and highly specialized species, such as Spix's disk-winged bats, are under greater threat compared to generalist species. They primarily roost in young, rolled-up leaves of Heliconia plants, which puts them at risk of future endangerment if the availability of these roost sites decreases.

There are populations of Spix’s disk-winged bats in national parks in South America, providing them some level of protection by the conservation laws associated with national parks. However, no species-specific conservations efforts are currently in place. (Chaverri and Kunz, 2011; Tavares and Mantilla, 2015)

Contributors

Waitta Jarso (author), Radford University, Sierra Felty (editor), Radford University, Karen Powers (editor), Radford University, Galen Burrell (editor), Special Projects.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

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.

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

cryptic

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.

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).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

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

nocturnal

active during the night

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

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

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

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.

References

Boada, C., D. Tirira, M. Camacho, S. Burneo. 2010. Mammalia, Chiroptera, Thyropteridae, Thyroptera tricolor Spix, 1823: Distribution extension in Ecuador. Check List, 6/2: 227-229.

Boerma, D., J. Barrantes, C. Chung, G. Chaverri, S. Swartz. 2019. Specialized landing maneuvers in Spix’s disk-winged bats (Thyroptera tricolor) reveal linkage between roosting ecology and landing biomechanics. Journal of Experimental Biology, 222/20: 1-9.

Buchalski, M. 2013. Population Demographics and Genetics of Spix's Disk-Winged Bat: Insights Regarding Survival, Mate Choice, Gene Flow and Effective Population Size (Ph.D. Dissertation). West Michigan: West Michigan University.

Chaverri, G., E. Gillam. 2010. Cooperative signaling behavior of roost location in a leaf-roosting bat. Communicative & Integrative Biology, 3/6: 599-601.

Chaverri, G., T. Kunz. 2011. Response of a specialist bat to the loss of a critical resource. PLoS One, 6/12: e28821. Accessed October 04, 2022 at https://doi.org/10.1371/journal.pone.0028821.

Chaverri, G., M. Vonhof. 2011. Reproduction and growth in a neurotropical insectivorous bat. Acta Chiropterologica, 13/1: 147-155.

Dechmann, D., K. Safi, M. Vonhof. 2006. Matching morphology and diet in the disc-winged bat Thyroptera tricolor (Chiroptera). Journal of Mammalogy, 87/5: 1013-1019.

Fenton, M., J. Rydell, M. Vonhof, J. Eklöf, W. Lancaster. 1999. Constant-frequency and frequency-modulated components in the echolocation calls of three species of small bats (Emballonuridae, Thyropteridae, Vespertilionidae). Canadian Journal of Zoology, 77/12: 1891-1900.

Findley, J., D. Wilson. 1974. Observations on the neotropical disk-winged bat, Thyroptera tricolor Spix. Journal of Mammalogy, 55/3: 562-571.

Gillam, E., G. Chaverri. 2012. Strong individual signatures and weaker group signatures in contact calls of Spix’s disc-winged bat, Thyroptera tricolor. Animal Behaviour, 83/1: 269-276.

Gillam, E., M. Fenton. 2016. Bat Bioacoustics. New York, NY: Springer Handbook of Auditory Research.

Hernández-Pinson, H., S. Chaves-Ramírez, G. Chaverri. 2021. Seasonality in the emission of contact calls in Spix's disc-winged bats (Thyroptera tricolor) suggests a potential role in mate attraction. Acta Chiropterologica, 23.2: 413-420.

Montero, B. 2015. Social and Acoustic Behavior of the Leaf-Roosting Bat Thyroptera Tricolor (Ph.D. Dissertation). Fargo, North Dakota: North Dakota State University of Agriculture and Applied Science.

Pape, T., D. Dechmann, M. Vonhof. 2010. A new species of Sarcofahrtiopsis Hall (Diptera: Sarcophagidae) living in roosts of Spix's disk-winged bat Thyroptera tricolor Spix (Chiroptera) in Costa Rica. Journal of Natural History, 36/8: 991-998.

Riskin, D., M. Fenton. 2001. Sticking ability in Spix's disk-winged bat, Thyroptera tricolor (Microchiroptera: Thyropteridae). Canadian Journal of Zoology, 79/12: 2261-2267.

Sagot, M., C. Schöner, A. Jago, I. Razik, G. Chaverri. 2018. The importance of group vocal behaviour in roost finding. Animal Behaviour, 142: 157-164.

Solano-Quesada, M., L. Sandoval. 2010. Requirements of the roost used by Spix’s disk-winged Bat (Thyroptera tricolor). Chiroptera Neotropical, 16/2: 786-788.

Tavares, V., H. Mantilla. 2015. "The IUCN Red List of Threatened Species 2015: e.T21879A97207863" (On-line). Thyroptera tricolor (errata version published in 2016). Accessed September 05, 2022 at https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T21879A21985559.en.

Velazco, P., R. Gregorin, R. Voss, N. Simmons. 2014. Extraordinary local diversity of disk-winged bats (Thyropteridae: Thyroptera) in northeastern Peru, with the description of a new species and comments on roosting behavior. American Museum Novitates, 3795: 1-28.

Vonhof, M. 2003. Habitat Availability, Population Size, and the Composition, Stability, and Genetic Structure of Social Groups of Spix's Disk-Winged Bat, Thyroptera Tricolor (Ph.D. Dissertation). Toronto, Ontario, Canada: York University.

Vonhof, M., C. Davis, C. Strobeck, M. Fenton. 2001. Characterization of microsatellite loci in Spix's disk-winged bats (Thyroptera tricolor). Molecular Ecology Notes, 1/1-2: 73-75.

Vonhof, M., H. Whitehead, M. Fenton. 2004. Analysis of Spix’s disc-winged bat association patterns and roosting home ranges reveal a novel social structure among bats. Animal Behaviour, 68/3: 507-520.

Whitaker, J., J. Findley. 1980. Foods eaten by some bats from Costa Rica and Panama. Journal of Mammalogy, 61/3: 540-544.

Wilson, D., J. Findley. 1977. Thyroptera tricolor. Mammalian Species, 71: 1-3.

de Almeida, M., A. da Rosa, L. Alves Martorelli, A. Geraldes Kataoka, C. Cotrim Aires. 2019. Rabies virus monitoring in bat populations in Rondônia state, Brazil. Journal of the Brazilian Society of Tropical Medicine, 52: 1-6.

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