NATURE WATCH
Tracking the cuckoo
MARIANNE DE NAZARETH
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The Pied Cuckoo's arrival on the Indian coast is said to herald the onset of the monsoon. How true is this legend?
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Photo: Nitin Srinivasamurthy
“The first migratory Pied Cuckoos from Africa will soon be among us,” say Suhel Quader and Uttara Mendiratta from the MigrantWatch team, a group of ornithologists who track migratory bird movement in India. In preparation, they have summarised the data collected by MigrantWatch's Pied Cuckoo Campaign over the last two years. Legend has it that the arrival of the Pied Cuckoo heralds the onset of the monsoon but MigrantWatch's data shows that this is not really true.
The Pied Cuckoo ( Clamator jacobinus) is a species of Cuculiformes that belongs to the Cuckoo family. A fairly large bird of around 33 cm, the adult bird has a noticeable crest with a long tail. Being an insectivore, its diet consists of caterpillars and various insects. Its breeding grounds are in Africa, beyond the Sahara desert and closer to India, Sri Lanka and Burma. Unlike other species, the distance it travels is shorter. It migrates to India only in the summer where it is warmer and wetter. The bird lays a single egg mainly in the nests of Turdoides Babblers, which nurture the cuckoo along with its own young. The areas where it is commonly found are scrub, wetlands and agricultural areas.
Indian literature and poetry are full of references to the bird and most of us are familiar with its loud and persistent pipew-pipew-pipew call, which to us heralds the rain.
According to Suhel, the Pied Cuckoo campaign was begun in 2009 to gather data that would help understand the association between the southwest monsoon and arrival of the migratory population of the Pied Cuckoo to the Indian subcontinent from Africa. Many people believe that the arrival of the Pied Cuckoo precedes the onset of the monsoon by a couple of weeks. Is this indeed the case? “The Pied Cuckoo campaign was started precisely to answer this question,” says Suhel. Mousumi Dutta, a MigrantWatch participant who works for the Indian Meteorological Department, presented an analysis of the 2010 Pied Cuckoo data. She then summarised the 2009 and 2010 sightings of this species in relation to the monsoon onset in those years. The ‘normal' onset of the monsoon on the Kerala coast is June 1. In 2009, the monsoon arrived nine days early; and one day early in 2010. After the onset, cyclones disrupted the monsoon's normal progress in both years. In 2009, a cyclone in the Bay of Bengal slowed the monsoon's progress despite an early start across southernmost India, West Bengal, and the northeastern States. In the beginning of June 2010, cyclone ‘Phet' in the Arabian Sea brought rain to parts of western India, but delayed the northward progress of the southwest monsoon.
Between May 1 and July 15, the number of Pied Cuckoo sightings reported to the MigrantWatch database was 28 in 2009 and 25 in 2010. Despite the early arrival of the monsoon in 2009, the first sightings were on similar dates in both years (May 17 and 18 from Kolkata and Alibag respectively in 2009; and May 16 and 17 from Bhubaneswar and Jalpaiguri respectively in 2010).
Maps and scatterplots created by MigrantWatch suggest that the degree to which the arrival of Pied Cuckoos precedes the monsoon is highly variable. Sometimes the earliest sighting is no more than a few days earlier; at others the earliest sighting precedes the monsoon by more than 30 days. So Pied Cuckoos often do arrive at a location before the monsoon does but their regularity varies with location and year.
What the actual data shows: Out of 12 locations for which there is information, the cuckoos appear to show no consistent differences in arrival date with differences in the onset of the monsoons! Proof shows that there is more fiction than fact in that dearly held belief!
The writer is a media fellow with UNFCCC, UNEP and Robert Bosch Stiftung and is adjunct faculty in St Joseph's PG College, Bangalore.
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