Since 2007 MigrantWatch has brought together hundreds of birders across India to pool their observations of migratory birds. Over the years, our enthusiastic participants have collectively contributed more than 20,000 records of nearly 250 bird species. The idea of collecting all this information in one place is to document patterns of bird migration in the Indian subcontinent.

To mark the completion of 5 years of MigrantWatch, we have put together a brief summary of the migration patterns that are emerging. We hope you will enjoy it, and will tell your other birding friends about it too.

You can download a soft copy of the summary here [PDF, 2.9 MB; right-click to save it]. We have also printed a set of copies, and if you would like a hardcopy of the summary, just mail your postal address to us at mw@migrantwatch.in, and we will be happy to send you a copy.

A big ‘Thank You!’ to all participants and contributors, and we look forward to working with you for the next five years!

First arrival of the Pied Cuckoo in 2010 in relation to the onset of the Southwest Monsoon

by Mousumi Dutta

Mousumi Dutta is a frequent contributor to the MigrantWatch database. She is an avid birder, and spends her spare time on bird and wildlife conservation. She works with the Indian Meteorological Department, and so has a particular interest in bird migration. Mousumi’s MigrantWatch sightings page is here.

India’s climate is dominated by monsoons. Most of its annual rainfall (86%) occurs during the Southwest monsoon months. The monsoon is a key influence on agricultural output as well as the overall economic growth of India. From ancient times it has been believed that the onset of the monsoon is associated with the appearance of the Pied Cuckoo Clamator jacobinus.

The Southwest monsoon normally sets in over Southeast Bay of Bengal on 20 May and then over Kerala on 1 June. An analysis of the first sighting dates of the Pied Cuckoo and the onset of the Southwest monsoon for the year 2010 (see figure below) shows a fairly systematic pattern. In general, the first sighting of this species in a State is 20-25 days in advance of the onset of the monsoon in that State. This appears to be earlier, relative to the monsoon, than reported for last year.

These patterns indicate an interesting relation between the onset of the monsoon and the arrival of Pied Cuckoos. Long term studies are needed to clarify the details of the relationship between the monsoon winds and Pied Cuckoo migration.

Methods
First sighting dates (after January 2010) for Pied Cuckoos for each State were taken from the MigrantWatch database. (Maharashtra and the four southern States were excluded.) Dates of the onset of the monsoon for each State are taken from the Indian Meteorological Department’s monsoon pages (click on “Northern Limits of Monsoon”). The data used to generate the figure are given below. The links under “Reported by” point to the sighting page on MigrantWatch.

If you would like to make your own visualisation and analysis of Pied Cuckoo sightings, you can download all 300+ records here. Please share your findings with everyone at MigrantWatch – send us (mw@migrantwatch.in) a small blog post and we will put it up.