by Rahul J
Our seasonal guests, from over 29 countries, come to India every year during the winter.  For most of us, a day’s long flight is enough to tire and bore us down. But for these birds, taking flight paths that can go over 1000kms long is not a choice, it is an act of survival. And as ecologists, we have all wondered how, and in particular, why- birds choose specific locations to migrate to, and that is what I’ll cover in this blog.
Why do they migrate?
Firstly, it is important to recognize that certain bird species can live and prosper only in certain conditions that their species consider ideal (similar to most wildlife). For instance, an arctic tern travels over 30,000 kilometers in its round-trip journey and moves from the arctic circle to the Antarctic circle. It is not a bird that resides in the equatorial region.  And when a certain region becomes unfavorable due to a season, it migrates to another more favorable region for breeding, food, and shelter. Hence it is an adaptation mechanism that we identify in them and the health of ecosystems can also be judged based on this metric.
Why are they important?
Migrant birds play an especially important role in enriching the ecosystems that they cross and settle in. For starters, they act as pest controls in the areas they reside in, by eating insects that might harm crops and even prevent locust attacks which have been known to occur in seasons with reduced migration.
Bird droppings on the other hand are rich in nitrogen and act as fertilizers. Finally, they have a deep-rooted ecological impact and the absence of any one of the species can negatively disturb the food chain in multiple areas.
Why are the wetlands in Chennai especially important?
If we look at where Chennai is located, we can see that it is a coastal city, and the proximity to sea is very important for birds and gives security over lake conditions ( alkalinity/acidity )and food.
Moreover, Chennai being a metro-city, one of the advantages is the lack of poaching, compared to rural areas where awareness over ecological issues is very less and to top it all off certain wetland regions such as Pallikaranai are given the status of protected hotspots.
In the absence of the above reasons, the biggest deciding factor for birds to migrate to Chennai is simply the fact that they have multiple wetlands to choose from. Having been a large wetland city, even with considerable urbanization, Chennai has multiple pockets of areas where birds can settle down, such as — Pallikaranai, Adyar estuary, Muttukadu, Pulicat lake, Kelambakkam backwaters, etc.
But why is this choice very important?
Birdwatchers and naturalists will know that birds love to come back to the same regions every year at a certain point in time, so even in the worst scenario when water levels seem to be too low in one wetland, having a choice to move somewhere close by is essential when you are travelling across continents to come to one specific area.
Birds also like to stop in multiple regions that are favourable to them in their round-trip for rest, and Chennai is a favourable location before they take off again to cross a longer flight path without other rest locations.
Wetlands here are also favourable in terms of weather conditions. Compared to severe winters abroad, and the western ghats which do not share the same climate as their neighbours, Chennai wetlands are milder and better for shelter and mating activities.
Having said all of this, the focus then turns to sustaining these habitats so that our visitors have a nice stay.
Preservation of wetlands
To begin with, the bare minimum should be maintaining a clean environment for these species. This can be done by clearly demarcating waste areas, disposal sites and wetlands ( which are often used as dump yards, unfortunately ).
Then would be rejuvenating water bodies themselves, and increasing the green cover in them. For instance, croton plants are said to be an ideal plant for this activity.
At the end of the day, we need society to understand the importance of wetlands and be mindful, if not this burden rests disproportionately on the few who volunteer and take interest.