Whereas nectar bats have clearly evolved some impressive morphological adaptations to optimize nectar feeding, many species also show behavioral modifications to support obligate nectarivory.
The most widespread behavioral adaptation in nectar bats is the ability to hover over (rather than landing on) flowers, much like hummingbirds do while feeding. While hovering is an energetically expensive behavior, it allows nectar bats to visit a greater number of flowers per night and thus improves foraging efficiency. In addition, bats that feed by hovering can visit a larger range of plant types, including less robust flowers that could otherwise not be visiting by bats that land to feed on fruit or nectar (Tschapka and Dressler 2002). Nectar extraction by hovering bats is quick and effective, and thus allows the bat to consume as much as 135% of its total body weight in nectar each night (Tschapka and Dressler 2002).
Figure 1. Melton, C. Mexican long-tongued bat (Choeronycteris mexicana) hovering and extracting nectar from agave flowers. http://www.nearfamous.com/Pages/NectarBats.html; retrieved 12/4/2015.
In addition to hovering behaviors, nectar bats show a particular curiosity superior to other bat species. Nectar bats in Central America are known to inspect emerging branches and mist net poles for potential flowers to feed on. Nectar bats born in captivity also readily investigate protruding objects in the hope of finding a food source (Tschapka and Dressler 2002).
The aforementioned behaviors are examples of adaptations the developed from a long history of coevolution between nectar bats and plants. A particularly intriguing example of behavioral/physiological coevolution can be found in the case of nectar bats and the tropical plant Mucuna holtonii, which will be discussed in detail in a future blog post.
References
TSCHAPKA, M. and DRESSLER, S., 2002. Chiropterophily: On Bat–Flowers and Flower
Bats. Curtis's Botanical Magazine, 19(2), pp. 114
Interesting post. You mention that the behaviours suggest coevolution between nectarivorous bats and plants, but is this always the case? Could it be that these bats have evolved in response to provision of a resource that is accessible at a different time or do we actually see the evolution of co-adapted gene complexes between plants and bats that signifies coevolution?
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