Why butterflies are sometimes attracted to cow dung: The science behind ‘puddling’

Butterflies, often associated with flowers and nectar, can sometimes be found congregating around cow dung, a behaviour known as puddling. This unusual activity is not a result of the butterflies seeking out a new food source, nor is it due to a sudden change in taste preferences. Instead, cow dung provides butterflies with crucial nutrients they might not obtain in sufficient quantities from nectar alone.

The primary nutrients found in dung, such as sodium and nitrogen, are essential for the butterflies' overall health and reproductive success. The phenomenon is particularly common among male butterflies, as the nutrients obtained through puddling can aid in both nutrition and reproduction. In some species, males may even transfer these nutrients to females during mating through a package called a nuptial gift.

India is home to numerous documented examples of butterflies engaging in puddling behaviour. A 2023 study conducted in the Western Ghats recorded 26 butterfly species from five different families puddling on elephant dung. This finding suggests that elephant dung, like cow dung, can offer mineral supplementation that contributes to butterflies' fitness and reproductive physiology.

In addition to dung, butterflies in India have also been observed puddling on animal urine, bird excreta, and damp soil, all of which can provide valuable nutrients like amino acids and minerals not readily available from nectar. The clustering of butterflies around a single patch of dung is not due to a shared preference for the same food source, unlike birds gathering around a feeding spot.

Instead, the moisture and concentration of nutrients at a particular site make it attractive to multiple butterflies. The preferences for different puddling substrates can vary among butterfly species, with sodium concentration being a significant factor influencing these choices. Temperature also plays a role, with butterflies showing a preference for particular temperature conditions during puddling activity.

So, the next time you observe a colourful group of butterflies hanging around animal dung, it's essential to recognize that they are not abandoning flowers for something unpleasant. Instead, they are efficiently utilizing a resource that many other creatures would overlook.