Does the Pied Cuckoo herald the monsoon?

This entry was posted Thursday, 4 April, 2013 at 9:49 am

Pied Cuckoo-4yrs

Does the arrival of the Pied Cuckoo herald the onset of the monsoon? The Pied Cuckoo Campaign was launched in 2009 to collect information to assess this age-old belief.

More than 600 sightings of this wonderful migrant have been contributed by over 200 MigrantWatchers so far; the first sighting dates among these were compared to monsoon arrival, as available with the Indian Meteorological Department (see the graph alongside). Each dot shows the earliest Pied Cuckoo report (after 1 May) for a broad location (an area roughly 200 Km across).

The results are fairly clear: Pied Cuckoos arrive before the monsoon in most parts of central and northern India (they are resident in southern India). You can see this from the pattern that most dots in the picture to the right are below the dotted horizontal line.

But the degree to which the arrival of the Pied Cuckoo precedes the monsoon varies from place to place, as can be seen from the scatter of the dots within each year. And even for the same general location, this varies from year to year (see how the coloured dots are in different places in different years).

What appears to be happening is that, where the monsoon arrives early, Pied Cuckoos arrive a few days before monsoon onset; but where the monsoon arrives late, the cuckoos arrive well in advance of monsoon onset.

So, overall, the old belief is true, and Pied Cuckoos tend to arrive before the monsoon — but to different degrees, depending on when the monsoon begins at each place.

Also see this article on Pied Cuckoo migration.

4 Comments to Does the Pied Cuckoo herald the monsoon?

  1. Prashanth says:

    April 10th, 2013 at 1:34 pm

    Hmm…nice. My reading on this topic is quite old. Is it not the case that their “migration” to India is somehow aided by the Somali Jet, which in turn (Wikipedia tells me) is influenced by the monsoon. So, if first arrival dates of the Cuckoo are because/related to the monsoon winds themselves, then how can we say “…depending on when the monsoon begins at each place.” It seems its arrival itself is determined by the monsoons, no?

  2. migrantwatch says:

    April 12th, 2013 at 6:06 am

    Good question, Prashanth. Our understanding/reasoning goes somewhat as follows. We don’t know exactly how Pied Cuckoos make it across the Arabian Sea to India from Africa. But it seems reasonable to speculate that the ocean crossing is aided by monsoon winds that blow from (roughly) the Horn of Africa towards us. If those winds are set up late (or early), the timing of arrival of the first African Pied Cuckoos to India might also change accordingly.

    But, after landfall, Pied Cuckoos may be able to move relatively independently of the vagaries of the progression of the monsoon over land. Thus if the monsoon “stalls”, cuckoos may be able to fly well ahead of it because they are not dependent on the wind at their backs. So Pied Cuckoos may herald the onset of the monsoon more precisely (and closely) where the monsoon arrives early, and less precisely (and far in advance) where the monsoon arrives late.

    Of course, there is no direct evidence for all of this; it’s just a plausible (to us) story. It would be wonderful to put satellite transmitters on a few Pied Cuckoos, also to examine their return journey. But that would cost a fair bit of money..

    Thanks again – Suhel (for MigrantWatch)

  3. Jaydev Nansey, CE says:

    June 2nd, 2013 at 7:30 pm

    I am very impressed by this consistent study of five years. I wish to assist in furthering this study with some solid scientific research. Is there anyone from the academics or research institutions on this network who would be willing to take this study further? Now there are possibilities of satellite tracking, ringing and trans national coordination. Comments and remarks welcomed

  4. Parth Parikh says:

    June 5th, 2013 at 4:17 pm

    I saw it on 24th May at Dholka, Ahmedabad. we got our first rains on 4th June.

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