Every winter, waves of migrating birds flock to India. Millions are drawn to the Western Ghats, one of the world’s premier biodiversity hot spots. Some birds, like Siberian cranes and bar-headed geese, actually fly over the Himalayas on their epic journey. Black redstarts and blue rock thrushes leave for warmer climes. Wagtails, godwits and sandpipers follow water. Pied cuckoos, ospreys, bee eaters and drongos head south.
And then there’s the greenish warbler.
They flit among tree canopies on their southward migration, heard rather than seen. The tiny leaf-warbler’s incessant chiswee chirp has the repetitive lulling of a generic meditation soundtrack.
Getting a photograph of them is out of the question, and even in a picture, the paradise flycatcher would steal the show anyway. Most birders would just pass by the warblers’ tree, searching for more aesthetically interesting species.
But warbler counts are an essential part of tracking long-term trends. The commonness of greenish warblers makes them a great candidate for bird counts. With larger numbers, statistical anomalies can be minimized and it’s easier to tease apart different factors affecting the population. Common birds can be illuminating indicator species that reflect the health of other species and ecosystems. Yet barely a handful of short-term studies have been done on the greenish warbler and its leaf-loving kin. Continue reading