Saccopteryx bilineata
Silhouette: T. Michael Keesey · PhyloPic
In 3 days ~40% in a week ~70%
The greater sac-winged bat (Saccopteryx bilineata) is a bat of the family Emballonuridae native to Central and South America. They are common bats seen in the rainforest, as they often roost on the outside of large trees. They are insectivores and use echolocation calls through the mouth to track their prey, which includes flies, beetles, butterflies and moths. The long nose and upper lip are highly mobile and can shift upward to enlarge the mouth opening.
The term "sac-winged" refers to small pouches on the wings. These sacs are used by males to attract females and to mark their harem territory. During daily grooming, males will fill these sacs with drops of urine and glandular secretions. During displays for females, the male will hover in front of the female and fan her vigorously to expose her to the scent of the mixture in the wing sacs. Males will also shake the contents of the sac towards bats outside of the male's harem territory to warn off intruders. Microbial fermentation in the sac may produce identifiable scent signals.
Sac-wing pups have been recorded making various calls in a jumbled context. For example, a female pup will give the male trill of courting followed by echolocation clicks then adult territorial challenges. These mixed-up vocalizations have been equated with human infant babbling and mispronounced songs of young birds. This is the first example of mammal babbling outside of the primate order. Wikipedia →
Recording0:37
Costa Rica · 2024
© sea-kangaroo · iNaturalist · CC BY-NC 4.0
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Calakmul Biosphere Reserve | 🇲🇽 Mexico | |
| 2 | Carara National Park | 🇨🇷 Costa Rica | |
| 3 | Celestún Biosphere Reserve | 🇲🇽 Mexico | |
| 4 | Piedras Blancas National Park | 🇨🇷 Costa Rica | |
| 5 | Yasuní National Park | 🇪🇨 Ecuador | |
| 6 | Braulio Carrillo National Park | 🇨🇷 Costa Rica | |
| 7 | Soberanía National Park | 🇵🇦 Panama | |
| 8 | Corcovado National Park | 🇨🇷 Costa Rica | |
| 9 | Arenal Volcano National Park | 🇨🇷 Costa Rica |
No species of the same family or order lives in Celestún Biosphere Reserve, so these are its closest relatives here: other mammals.
Possible
About 20% of wildlife watchers report a Greater Sac-winged Bat sighting in Celestún Biosphere Reserve on a given day, based on 7 verified sightings from GBIF citizen-science data from 2019 to 2026. Over three days the chance rises to about 40%, and over a week to about 70%, if each day is a fresh chance.
October
In that month about 40% of wildlife watchers report a Greater Sac-winged Bat in Celestún Biosphere Reserve on a given day, against under 5% in March, May, July–September and December–January, the lowest months. That is one of Celestún Biosphere Reserve's wettest months, with about 100 mm of rain against 10 mm in February.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Greater Sac-winged Bat sightings with a recorded time, and about 8 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
Among the best
Of the 9 parks where we can rate Greater Sac-winged Bat sightings, Celestún Biosphere Reserve ranks 3rd at about 20%, level with the leaders once rounded. The best odds are in Calakmul Biosphere Reserve (Mexico, about 20%) and Carara National Park (Costa Rica, about 20%).
GBIF citizen-science records
It is estimated from how often the Greater Sac-winged Bat is recorded against all the mammals logged in Celestún Biosphere Reserve (7 verified sightings from 2019 to 2026), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
