Tracing the Bird Populations of the Eastern Ghats

E&E professor shares observations from the field

Professor Trevor Price traveled on a Fulbright Fellowship in India for January and February of 2024. Between visiting various universities, he conducted field research in both the western and eastern ghats, mountain ranges on the west side and east side of the Indian peninsula. He sent this dispatch from the eastern ghats on a plateau at about 800 meters, where he compared current bird populations with those he surveyed in the same place in the 1970s. The remaining forest is essentially an enormous coffee grove, and the area is rapidly developing into a tourist center.

Field Dispatch

In both the 70s and more recently, we have censused the birds using two methods, first through the number we capture in mist nets, and second through visual and acoustic surveys. It will require a fairly-complex analysis to unequivocally demonstrate changes in bird diversity (all Bayesian experts please step forward). Some species, which were rare in the 1970s, have not been seen, but perhaps this represents the relatively short duration of our recent visits. Further, climate varies a lot from one year to the next and the birds change with it; we’ve visited in 2018, 2022, as well as this year, and in 2022 we experienced a cyclone with much rain. It never rained at all in January in the 1970s.

So what can we say? We can obviously conclude that loss of forest, which has declined by about 20% since the 1970s (according to both GIS estimates and our photographs) has led to forest bird declines. Only a few birds, such as the Blyth’s reed warbler, which love secondary growth, appear to have increased (but even in this case, more were present in 2022 than 2024, for reasons we are still trying to work out).

Blyth’s reed warbler
Blyth’s reed warbler. This bird was banded by Kristen Wacker in 2018 (of 9UP fame in the photo gallery above) and caught by us in late February 2024. It is therefore at least 6.5 years old. The species breeds in the marshes of Siberia, and birds return to the same winter territory every year. It inhabits secondary growth and is flourishing in the area.

Within the forest we see much land use change as well: coffee below the canopy has increased from 10% in the 1970s to 95% now. Some, likely commercially grown, is clearly sprayed with pesticide, having no insect leaf damage. Some, likely planted by local villagers, does not appear to have been sprayed as intensively. Assessment of what has happened to the birds is difficult, because, given a thick canopy, undergrowth in natural forest was always sparse and capture rates have always been low. Tentatively, we see little evidence for species declines in the canopy, or in the coffee plantations, but it may well be that some species, such as the fantastic Malabar trogon, which was always uncommon and lived in the understory, has disappeared, for we have not recorded it in recent visits. Other species really do seem to have declined, for example the Tree pipit, like the reed warbler a winter visitor, is now rare and was once more common.

Abbott’s babbler.
Abbott’s babbler. This species breeds in the Himalaya but is also found in the eastern ghats, albeit not at our long-term study site, but a short distance away. Based on some subtle plumage differences it was described as a different subspecies in the 1980s. Its full scientific name is Malacocincla abbotti krishnarajui, with the subspecies identifier named after Krishna Raju (who is pictured above in 1978). We caught the bird above this year and will conduct a genetic analysis to determine how different it is from the Himalayan subspecies.

Beyond our evaluation of changes in bird numbers, we are invested in studying some populations which have limited distributions in the eastern ghats. This mountain range is of interest because some species are held in common with the Himalaya, presumably representing relict populations from more continuous distributions, e.g. during the ice ages. Some may be different enough to be considered different species, and we are assessing this using both genomics and studies of songs. One such example is the Abbott’s babbler (see picture on left).

Endemic forms help us make a stronger case for conservation. It is important to do so, because there are no protected areas on the plateau, and as we have seen, no natural forest to speak of. If coffee plantations are converted to non-shade, as has happened in many places in South America, the eastern ghats populations will be seriously threatened. Even if the coffee plantations remain with canopy, we remain unsure of the impacts of coffee, especially when sprayed, on birds and other animals.