Bats: The Night Workers

Shiwani

As the sun goes down, the nightwalker, or rather, I would say, night fliers come out, one can see colonies of bats flying in the sky and sometimes wandering near a tree or plant. On one such night, as I stood on the balcony, sipping a cup of tea, I observed some bats visiting a tree next to my balcony. After watching them hovering around the flowers on the tree for a while, I realised that bats were actually sucking nectar from the flower on the tree and thus, pollinating the flower. As soon as we hear the word pollination, the picture of different insects, which are the primary pollinators, come to our minds.  Bees, flies, birds, butterflies, and moths are the main pollinators. It is very rare that one would imagine a flying mammal to be a pollinator, especially one that is active primarily at night, thus, making our night fliers – bats – even more interesting and fascinating.

The world’s only flying mammal acts as an important pollinator. Pollination by bats is termed as Chiropterophily. They belong to 18 different families of the same order, and of those 18, only two families: Leaf-nosed bats (Phyllostomidae) and Fruit bats (Pteropidae) are morphologically specialised for nectar feeding. Worldwide, it pollinates 528 species in 67 families and 28 orders of angiosperms (Kunz et al., 2011). As stated by Faegri & van der Pijl (1979), there are specific kinds of characteristics associated with different kind of pollinators. And for bats, the classic ones are “nocturnal anthesis, drab coloration (i.e. white or green), musty smell, flowers often located on branches or tree trunks (cauliflory) or suspended on long stalks (flagelliflory), and tubular or radially symmetrical flowers, often of the ‘shaving brush’ type” (Faegri & van der Pijl, 1979; Howe & Westley, 1988). These similarities among the plants for bat pollination is termed as chiropterophilous syndrome.

Image: Bat feeding on flowers of Katsagan (Haplofragma adenophyllum)

Although some plant species, such as Oroxylum indicum, which are specialist species, depend completely on bats for the pollination process, there are many, which are generalists species and do not depend on bats alone for the pollination process. These generalists are visited by bats as well as other species, which may or may not have these particular characterising traits. Thus, bat is known to be an opportunistic flower visitor. The tree mentioned at the beginning which was visited by bats is one such example of a generalist species known as Haplofragma adenophyllum commonly known as Katsagon. Most of these bat pollinated flowers can be morphologically categorised into pincushion-type flowers and  bell-shaped flowers.

Bats are larger in size, as compared to other pollinators, specifically insects, and make more reliable visitations, giving them an advantage to carry large pollen loads to longer distances. Thus, they are considered to be great in promoting outcrossing (i.e. crossing between different breeds) (Cruden, 1972). Apart from their role as pollinators, they are also great seed dispersers, making them prime examples of “Double Mutualists”. Double mutualism is a rarely recorded phenomenon, and according to a review done by Fuster et al. (2019), there are only 302 recorded observations of the same, occurring most commonly on islands (Olesen et al., 2018; Fuster et al., 2019 as cited in Aziz S.A et al., 2021). As stated by Bascompte (2007), these plant-pollinator relationships form complex interdependence networks leading to dynamic stability in particular habitats (as cited in Beltran et al., 2017) Bats also act as an important biological indicator species of any change in the biodiversity, as different important roles are played by them. For example, they keep a check on certain insect populations in an area. They can also be representative of a poorly managed or destroyed habitat. In other words, a decline in the bat population is seen with the destruction of foraging habitats (Rainho & Palmerim, 2011).

Even though bats are of Ecological and economic importance, several negative connotations have been associated with them. Such as in many western cultures they are associated with blood-sucking, vampires and are often used to symbolize evil (Rocha et al., 2021). Apart from that, they are considered pests and undesirable neighbors. Such attitudes towards bats have been further augmented in recent times with the current COVID-19 pandemic, raising more disease-related concerns.

To conclude, even though bats may have superstitious and unpleasant connotations attached to them and may be socially unwanted creatures, their ecological importance cannot be overlooked and rather, it possibly overrules their otherwise negative perceptions. They sustain certain specialist plant species with their pollination and are also seen as an important bio-indicator as their presence and activity in any area signals a healthy-functioning ecosystem. Therefore, the relationship between humans and other nonhuman species, bats in this case, is intricate, multidimensional, and complex.


References

  • Aziz SA, McConkey KR, Tanalgo K, Sritongchuay T, Low M-R, Yong JY, Mildenstein TL, Nuevo-Diego CE, Lim VC and Racey PA (2021) The Critical Importance of Old World Fruit Bats for Healthy Ecosystems and Economies. Front. Ecol. Evol. 9:641411. doi: 10.3389/fevo.2021.641411
  • Theodore H. Fleming, Cullen Geiselman, W. John Kress, The evolution of bat pollination: a phylogenetic perspective, Annals of Botany, Volume 104, Issue 6, November 2009, Pages 1017–1043, https://doi.org/10.1093/aob/mcp197
  • Rainho A, Palmeirim JM (2011) The Importance of Distance to Resources in the Spatial Modelling of Bat Foraging Habitat. PLoS ONE 6(4): e19227. https://doi.org/10.1371/journal.pone.0019227
  • T. Sritongchuay, C.A. Hughes, S. Bumrungsri The role of bats in pollination networks is influenced by landscape structure. Global Ecol. Conserv., 20 (2019), Article e00702
  • Ricardo Rocha, Adrià López-Baucells, Álvaro Fernández-Llamazares “Ethnobiology of Bats: Exploring Human-Bat Inter-Relationships in a Rapidly Changing World,” Journal of Ethnobiology, 41(1), 3-17, (19 March 2021)

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