Field Notes Society

How to understand bird behaviour better...

When an issue has an in-built complexity as big as the size of a paw, the prudent course would be to avoid trying to put a finger on it. The explanation is likely to be inadequate, and sometimes grossly misleading. In some of its facets, bird migration is one such issue. The question on most birders’ lips in Chennai today is: “Why have the migratory birds not arrived in impressive numbers this season, despite a good monsoon?”

We have zoomed past mid-January, and wintering birds are thin on the ground. Some species even seem to have stood us up. The situation is starkly evident in the prominent birding spots in Chennai, especially the Kelambakkam backwaters and the Perumbakkam wetland. Some of those I know are heading to far-flung spots to catch a glimpse of their favourite winter visitors. Trying to tackle the afore-mentioned question without a larger perspective, can lead to answers that are both plausible and fallacious at the same time.

Recently, when I discussed this issue with Hopeland P, an independent wildlife researcher, he said while trying to analyse local factors, it is absolutely necessary to factor in the global perspective.

“That is why larger regional bird counts such as the Asian Waterbird Census are a valuable tool in understanding bird migration patterns, and a seeming break in them. Local results should always be interpreted in the global context, understanding the various dynamics impacting a species across its home and wintering range. In the current scenario involving Chennai, a multiplicity of governing factors fusing the global and the local can be at play. Widespread availability of resources, such as the availability of food, can scatter bird populations. Environmental regulators, such as wind, can also have a role in migration.”

So, it seems to boil down to the fact that birders from across the globe have to be more connected to understand some blind spots in migratory patterns. Such knowledge sharing has helped us understand bird behaviour better.

Here is an example. Now, you will see whimbrels and common curlews in the shallow Kelambakkam backwaters, running their bills — longer, the common curlew’s bill is a walking symbol for the kinked-demand curve theory — through the muddy brackish waters for crustaceans like crabs. Now, there are any number of omnivorous birds that have a varied diet plan. But to think of the whimbrel having a frugivorous diet as an add-on, while in its breeding habitat, is quite something to chew on. From crabs to a combo of “cranberries and crabs” seems like quite a switch, though in reality not unusual at all. We know this about the whimbrel because of what gets reported from its breeding grounds. Similarly, our understanding of bird migration and its occasional vagaries will be more reality-centred, if there is greater reporting of periodic changes in known patterns.

This is a fortnightly column on the resident and migratory birds of Chennai

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Printable version | Jul 27, 2021 5:49:51 PM |

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