Seasonality of Date Palm Sap Feeding Behavior by Bats in Bangladesh

Ausraful Islam, Clifton McKee, Probir Kumar Ghosh, Jaynal Abedin, Jonathan H. Epstein, Peter Daszak, Stephen P. Luby, Salah Uddin Khan, Emily S. Gurley

Research output: Contribution to journalArticlepeer-review


Pteropus bats are the natural reservoir for Nipah virus, and in Bangladesh, it is transmitted to people through consumption of raw or fermented date palm sap. Our objective was to understand seasonal patterns of bat feeding on date palm sap at a location where sap is collected year-round. Seven nights each month over three years, we mounted infrared cameras in four trees to observe bats’ feeding behavior at date palm trees harvested for fermented sap production. We described the frequency of bat visits, duration of bat visits, and duration of bat-sap contact by month and by year. We captured 42,873 bat visits during 256 camera-nights of observation, of which 3% were Pteropus and 94% were non-Pteropus bats. Though the frequency of Pteropus bat visits to each tree/night was much lower than non-Pteropus bat visits, Pteropus bats stayed in contact with sap longer than non-Pteropus bats. Frequency of bat visits was higher during winter compared to other seasons, which may arise as a consequence of limited availability of food sources during this period or may be related to seasonal characteristics of the sap. Seasonal alignment of sap consumption by humans and bats may have consequences for viral spillover into humans.

Original languageEnglish (US)
Pages (from-to)359-371
Number of pages13
Issue number3
StatePublished - Sep 2021


  • Date palm tree
  • Food contamination
  • Fruit bats
  • Infrared camera
  • Nipah virus
  • Non-Pteropus bats
  • Pteropus bats

ASJC Scopus subject areas

  • Ecology
  • Health, Toxicology and Mutagenesis


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