Adaptive foraging tactics of greater short-nosed fruit bats on a spiny shrub and its effect on seed dispersal
2021
Sangavi, Dhanapal | Murugan, Chinnaperamanoor Madhappan | Mahandran, Valliyappan | Marimuthu, Ganapathy | Thiruchenthil Nathan, Parthasarathy
Many plant species have seeds embedded in their fleshy pulp to attract frugivores, which enhances the chance of seed dispersal. However, some tropical plants are evolved with sharp spines to avoid herbivores and/or to prevent water loss, which makes foraging by frugivores difficult. Such plants receive frugivores’ attention, either because of resource scarcity or adaptive behavioural plasticity. We have a limited understanding of how fruit-eating animals access fruits protected by spines. In this 1-year study, we describe bat foraging on a spiny tropical shrub, Ziziphus mauritiana (Rhamnaceae) whose dried branches are often used by the local people to capture bats in caves that inevitably damage their wing membranes. The greater short-nosed fruit bat, Cynopterus sphinx was the only visitor to this spiny plant during its fruiting season and predominantly extracted fruits using a hovering tactic (on 81% observations) without damaging wing membranes. The hovering enabled them to extract fruits quicker than when alighting on the tree. Bats carried all the fruits away from the parent tree to feeding roosts for consumption. Bat foraging has thus effectuated short-distance seed dispersal (range 11–70 m radii) in which most seeds (30.73%) were found at the distance of 31–40 m in our search up to 150 m. Although bats extracted both ripe and unripe fruits, ripe-fruit extraction was 4.5 × higher than the unripe fruits. This study shows the tradeoff between getting a good meal and contending with spines in a resource-scarce habitat. Besides, this study describes the adaptive foraging tactics of greater short-nosed fruit bats that facilitate short-distance seed dispersal.
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