A closer look at Cave Nectar Bats visiting banana flowers

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Two earlier posts documented the visits by Cave Nectar Bats (Eonycteris spelaea) to banana flowers (Musa cultivars) for their nectar LINK 1 and LINK 2.

The bat usually circles around the plant before landing on the flowers. It uses its sharp claw at the end of each thumb to cling onto the inflorescence bud.

It then proceeds to probe into the flowers (above). This involves pushing its narrow snout between the two perianths (the larger upper and the smaller lower to get at the nectar – see below.

It uses its long red tongue to lick up the nectar (below). And it knows exactly which flowers to probe and which to ignore.

In this post we specifically look at the frequency of visits and the number of male flowers probed for their nectar during each visit. Visits usually come between 2200 hours onwards at intervals of 30 to 60 minutes or so.

Observations were made when the banana inflorescence was at the male-flowers stage (see HERE for detaiis) and actively producing male flowers. During each visit, the bat sometimes systematically probed the flowers from one end to the other, starting with the upper row and ending with the lower. At other times it selectively probed the flowers, possibly targeting only those with sufficient nectar.

On the night of 15th January 2015, between 2130-0100 hours, two visits were recorded (video below) – it is not known whether the visits were by the same bat or different bats. The first visit took 32 seconds and the bat probed 18 male flowers for their nectar – note that there were about 18-19 flowers per hand. The second visit, about a hour later, lasted 25 seconds when 13 flowers were probed.

On the night of 18th January, between 2130-2300 hours, there were three visits. The last visit lasted five seconds and the bat probed only two flowers for their nectar (video below). This is compared to the earlier two visits when it spent 20-25 seconds probing 13-15 flowers.

Obviously after each visit the flowers will have less nectar left. Revisiting the flowers after 30-60 minutes will allow them to replenish their supply.

YC Wee
Singapore
February 2015

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