The Honduran fisherman bat (Noctilio leporinus Linnaeus, 1758)

This note was written by Josue Galdamez

email: josueramos002@gmail.com

Since primary school, we are taught that in Spanish, the word for bat (“murciélago”) contains all five vowels of the alphabet; in high school, we are taught that vampire bats exist, and when we grow up, there are movies where the bat is the villain of the story. To top it off, the COVID-19 pandemic is attributed to them. Are bats really as bad as they are portrayed? On this occasion, Honduras Neotropical brings you a note about a bat species you may not have heard of, one that can help broaden your knowledge about this wonderful group.

Not many people know this, but the diet of the vast majority of bats (Order Chiroptera) is not based on blood, but on fruits, insects, and even flower nectar; some even feed on fish. This is the case of the genus Noctilio, which inhabits the tropical and subtropical regions of the Americas, from western and eastern Mexico (Sinaloa and Veracruz) to northern Argentina, and is even found in the Caribbean Islands.

The name Noctilio is derived from the Latin “Noctis,” meaning night, although it is also related to the French “Noctilion,” meaning bat (Smith, 2008). Noctilio is the only genus of the family Noctilionidae, a sister family to mustached bats (family Mormoopidae) and leaf-nosed bats (family Phyllostomidae).

There are two species of fishing bats found in Honduras: Noctilio albiventris (Figure 1a) and Noctilio leporinus (Figure 1b), the latter being the larger (Figure 2). The fishing bat (Noctilio leporinus Linnaeus 1758) was first recorded in Honduras in 1942, thanks to the collections made by Cecil F. Underwood between 1932–1938 (Goodwin, 1942). Initially recorded in Gracias a Dios, it has now been documented in Atlántida, Choluteca, Cortés, El Paraíso, Islas de la Bahía, Lempira, Olancho, Santa Bárbara, Valle, and Yoro (Marineros and Martínez-Gallegos, 1998; Rivas, 2013; Mora et al., 2018; Hernandez and Elvir, 2019; PCMH, personal communication, 2020; Kanahau, personal communication, 2020) (Figure 3).

Figura 1. A: Noctilio albiventris and B: Noctilio leporinus. the two species of the family Noctilionidae found mainly in the lowlands of Honduras. They differ in size, diet, and foraging hours. Photos by Josué Ramos..

Figure 2. Adult specimen of Noctilio leporinus with wings extended; it can measure up to 60 cm from tip to tip with wings spread. Photo: Josué Ramos.

Figure 3. Known distribution of Noctilio leporinus in Honduras, based on literature data, personal observations, and data provided by PCMH (Programa de conservación de los murciélagos de Honduras).

It is also known as the “bulldog bat” due to its resemblance to that dog breed. The similarity lies in their split, drooping upper lip, forming a “V” like a cleft lip (Medina-Fitoria, 2014). They have a large, wrinkled chin. The ears are separated, pointy, and highly mobile (they tend to fold them backward when stressed during capture). The toes and claws are considerably large (Figure 4). They have short fur with noticeable variations in brown, copper, and/or orange, as well as a pale stripe down the middle of the back (Lewis-Oritt et al., 2001).

Figura 4. Detail of the toes of Noctilio leporinus, which are considerably large—an adaptation that optimizes the capture of prey associated with water surfaces. Photo by Josué Ramos.

The fishing bat is associated with rivers, streams, estuaries, and coasts, where it captures its food—in some lagoons, several individuals can be observed “fishing.” Foraging begins early at dusk and continues throughout the night. They seem unaffected by artificial light from bulbs and flashlights, as in places like Laguna del Cacao in Atlántida (Figure 5b) and localities in La Mosquitia (Figure 5a), where they approach beams of light (probably attracted by insects drawn to the light).

Figure 5. Two locations where foraging activity has been observed for several hours. A: medium-flow river in La Mosquitia. B: Estero de Las Mujeres, on the coast of Atlántida, Nombre de Dios National Park, recorded by Bocanegra et al. (2017). Photos by Josué Ramos.

Noctilio leporinus occasionally feeds on prey such as crabs, scorpions, shrimp, and tree frogs (Medina-Fitoria, 2014). The main insects they consume include ants (Solenophis sp.), mole crickets (Gryllotalpa sp.), beetles (Carabidae, Dytiscidae, Scarabeidae, Cerambycidae, Elateridae, Hydrophilidae), cockroaches (Blattidae), true bugs (Thyanta sp.), and crickets (Gryllidae) (Hood and Knox, 1984). But the reason for the fame of these voracious chiropterans is their particularly notable piscivorous diet (Figure 6), which involves numerous adaptations for detecting, capturing, and consuming prey beneath the water’s surface by detecting tiny ripples produced on the water (Suthers, 1965). This formidable ability has attracted the attention of mammalogists (mammal researchers) worldwide.

At the end of the night, bats seek shelter in tree hollows or caves in numbers ranging from a few to hundreds of individuals; they can even share these shelters with other species, such as the vampire bat (Desmodus rotundus).

Figure 6. Adult Noctilio leporinus eating a freshwater fish in the Honduran Mosquitia. Photo by Josué Ramos.

According to specialists from the International Union for Conservation of Nature (IUCN), this species’ conservation status is “Least Concern” (LC), mainly due to its wide distribution. However, in Honduras, it inhabits areas that are undergoing severe human impact, so monitoring and population studies are necessary. For this reason, alternatives and programs have been developed in Honduras for the study and conservation of these enigmatic and stigmatized nocturnal fliers. Among these is the Honduras Bat Conservation Program (PCMH), part of the Latin American and Caribbean Bat Conservation Network (RELCOM). Recently, a group of biologists formed a bat research group known as “The Big Bat Theory,” which has been carrying out activities to promote knowledge and conservation of Honduran chiropteran diversity (Figure 7).

Figure 7. A: Member of The Big Bat Theory working in the field, collecting morphometric data on Noctilio leporinus. B: In situ talk about the fishing bat with Miskito communities. C: Fieldwork by PCMH members and volunteers collecting data on Noctilio leporinus in Catacamas, Olancho. Photos A and B by Josué Ramos, C byJonathan Hernández.

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References

Bocanegra, V. D., J. E. Mérida, y G. A. Cruz. 2017. Ampliación del ámbito del murciélago Lasiurus ega (Chiroptera: Vespertilionidae) en Honduras. Cuadernos de Investigación UNED 9(1): 87-90.

Goodwin, G. G. 1942. Mammals of Honduras. Bulletin of the American Museum of Natural History 79: 107-195.

Hernández, D. J. 2015. Programa de Conservación de Murciélagos de Honduras (PCMH); en Estrategia Centroamericana para la conservación de los murciélagos, Rodriguez, B. H y R. Sánchez eds. Costa Rica. 41-55.

Hernández, D. J., Cabrera, G. y F. Elvir. 2019. Diversidad de murciélagos en el sistema insular del Golfo de Fonseca, Honduras. CODDEFFAGOLF. 20pp.

Hood, C. S., y J. K. Jones. 1984. Noctilio leporinus. Mammalian Species 216: 1-7.

Lewis-Oritt, N., R. A. Van Den Bussche, y R. J. Baker. 2001. Molecular evidence for evolution of piscivory in Noctilio (Chiroptera: Noctilionidae). Journal of Mammalogy, 82(3): 748-759.

Marineros, L. y F. Martínez-Gallegos. 1998. Guía de campo de los mamíferos de Honduras. INADES. Tegucigalpa, Honduras. 374pp.

Medina-Fitoria, A. 2014. Murciélagos de Nicaragua, guía de campo. dirección de Biodiversidad MARENA, Nicaragua. 278pp.

Mora, J. M., L. I. López, M. R. Espinal, L. Marineros, y L. A. Ruedas. 2018. Diversidad y conservación de los murciélagos de Honduras. Master Print S. del R. L., Tegucigalpa, Honduras. 284pp.

PCMH. 2016. Los murciélagos del Aarea propuesta como Parque Nacional Cuyamel/Omoa, Golfo de Honduras: un atractivo de Biodiversidad. Cuerpos de Conservación Omoa, Omoa Cortez. 14pp.

Rivas, A. M. 2013. Distribución de los murciélagos de Honduras según el uso de la tierra. Proyecto especial de graduación presentado como requisito parcial para optar al título de Ingeniería en Ambiente y Desarrollo en el grado académico de licenciatura. Escuela Agrícola Panamericana, Zamorano, Honduras, i-vi+44pp.

Smith, P. 2008. Lesser bulldog bat Noctilio albiventris. Mammals of Paraguay 22: 1-15.

Suthers, R. A. 1965. Acoustic orientation by fish-catching bat. Journal of Experimental Zoology 158: 319-348.