By: Teresa Kearney – Curator: Vertebrate Department, Small Mammals, DITSONG: National Museum of Natural History (DNMNH)

Earlier this year I joined AfricanBats NPC in Unguja to survey bats along the length of the island. Unguja is one of the Zanzibar islands in an archipelago off the coast of Tanzania and is part of the United Republic of Tanzania. Unguja island, which is just south of the equator has also been called the spice island in reference to the productive plantations of spices such as nutmeg, clove, cinnamon, vanilla, cardamon and pepper.

Unguja island is also awash with tropical fruits including coconuts from the many palm trees.

The palm trees proved quite useful at some of the netting sites, as tall points from which to secure the ropes onto which the nets were strung.

Nets strung from ropes secured in trees were set at 10 different places along the length of the island to try and capture free flying bats.

The 10 sites were sampled twice, before and after the 20 March 2023 equinox, to give a summer and autumn sample. Fortuitously it rained between the two samples, and sites that were previously dry and dusty, were damp and greener with new growth on the second visit. On the second visit some areas had been ploughed in preparation for the longer rains and to sow rice.

It was exciting to catch so many bat species we had never caught before, like Nycticeinops grandidieri, Nycteris hispida, and Lavia frons. There is an element of randomness to captures of free flying bats. One does not necessarily know when one sets the net in a particular way whether it is near a roost, or a flight path used by a certain species. Free-tail molossid bats, which fly high out in the open sky are unlikely to be caught in nets that are set away from their roost sites, so any patterns in the data collected need to be considered with caveats such as this in mind.

Nycteris hispida (left) and Lavia frons (right).