The bird that is said to forecast the rains, and the forests that light up when they arrive

Before weather apps, radar and satellite forecasts, the clearest signal a farmer in much of India had of the monsoon was a bird. The Jacobin cuckoo, also called the pied cuckoo and known widely as the Chatak, arrives just before the southwest monsoon and has carried the reputation of a rain forecaster for as long as anyone has been keeping records.

Naturalist and author Jennifer Nandi, quoted in The Indian Express, is careful about how much that reputation deserves. People noticed the Chatak appearing just before the monsoon, she said, and the observation became embedded in folklore and rural tradition — which is why the bird came to be called the monsoon bird. Modern ornithology supports the timing of the arrival, she noted, but not the idea that the bird can forecast weather. Satellite tracking and ringing records show that many Jacobin cuckoos reach India from eastern and southern Africa, timing the journey to the country's wet season rather than to any particular forecast.

The cuckoo does not predict the monsoon. It migrates in response to the same large-scale seasonal changes in atmospheric circulation that eventually produce the monsoon. In other words, the bird and the rains are responding to the same environmental clock.

The other seasonal event worth planning around

The same rains produce the other event that draws visitors into the Indian forest in June and July. Thousands of fireflies emerge from the undergrowth after sunset, and in a few places the density is high enough that the forest appears lit from below.

• Purushwadi, Maharashtra: a small tribal village near the Western Ghats, described as India's most famous firefly destination.
• Timing: the insects gather in the weeks before the monsoon peaks, for their mating season.
• Conditions that suit them: high humidity, moderate temperatures, lush vegetation and minimal light pollution.
• Several local communities around Purushwadi organise firefly festivals, with guided night walks and camping.
• Named alongside it: Rajmachi, Bhimashankar Wildlife Sanctuary and Anamalai Tiger Reserve.
• Viewing etiquette: no flash photography, no bright torches, and stay on the marked trails.

There is an obvious connection between the two stories and it is the one most people already know. Both the bird and the insects are responding to the same signal — the seasonal reversal that ends the pre-monsoon heat. The Chatak arrives because the air is changing; the fireflies emerge because the damp has arrived. Neither is keeping a weather record. Both are useful precisely because they are reliable indicators of a system that is not, which is a different thing from being a forecast. Nandi is sceptical of how much longer that reliability holds: as climates warm, birds are arriving earlier or later, breeding at different times and shifting range, and a mismatch between breeding cycles and food is a growing concern.