Urban Birds as Miners' Canaries

Don't be surprised at the kinds of birds found in our cities. The cumulative list for Bangalore alone is about 340 species, which is more than half the number of species found in Peninsular India. Likewise, most other Indian cities also play host to a good percentage of the zonal species. Delhi has well over 400 species, and many others likewise have a good representation of the regional avifauna.  In fact a free software called BirdSpot, written by a Bangalore birdwatcher, allows one to draw a freehand shape over a map of India and get a list of species found there. One has to just get the software downloaded from the internet, install it, and check the various towns and cities for the number of species found in and around those towns. The results would surely surprise you.  

One may begin to wonder why is it that cities have so many species. When we think of cities, we normally picture overcrowded and congested lanes with shops touching wall to wall, dusty, dirty, noisy streets and the only green visible in the paint used. But, what we tend to forget is that for every such overcrowded part, we have the beautiful boulevards, the mall and the high value shopping areas, the industrial suburbs and open spaces. At the other end of the 'green street' we have the avenues, the gardens, parks and the residential areas. We also have water flowing in the valleys, impounded as lakes here and there by an embankment. We of course also tend to have irrigated cultivation downriver of these lakes. We have in many cases the hummocky and hilly country, as in Bangalore. And then of course, we have the airspace over a city! 

The city is in fact a mosaic, a cosmopolitan mix of many habitats that birds make use of. When we talk of city birds, we are of course talking about all those which could be visiting or living in the habitats mentioned earlier.  There are some interesting facts though. There are no urban birds which are exclusive to an urban area. All are from neighbouring rural areas. A study done by Frances Bonier at Virginia Tech examined data from many cities of the world and assessed whether urban birds were more tolerant of different environmental conditions. She found that urban birds have a broader environmental tolerance than the rural congeners, and had a wider distribution. It is a fact that if a species' range is wider, the variation in the environmental conditions that it can live in is also greater. Hence, such species make it better in an urban environment. 

Not all birds found in a city are common. About a third can be considered as wandering or those which have lost their way. Birds are highly mobile and many individuals of different kinds keep moving out of their usual haunts and land up at new places. It is technically called dispersal. Some of these birds could even colonise a new area.  Many of the birds found in our cities are migratory. All our cities are visited in winter by migratory birds from the distant north. We have many birds from central and north Eurasia spending their time here from September to April. Some are from just across the Himalaya. Many of these are small, and some like the Greenish Leaf Warblers that come to our gardens are much smaller than a sparrow! Wetlands in and near cities receive thousands of migratory birds, though this is reducing with ill-planned development. Ducks like Garganey, Shoveller and Pintail come in thousands. Likewise, shorebirds like the Green, the Spotted and Common Sandpipers come in large numbers, as do their larger relatives like the Greenhsank. Then there are the stints, especially the Little Stint, having a breeding range well across near the Arctic Circle and beyond. And how big are these stints? Around the size of a sparrow! Whether it is the ducks, or the sandpipers, or the geese, or the plovers, all are fast flying birds. They just would not be able to clear the kind of distances that they do flying at the speed of our herons and egrets (which are residents here).  

Many birds in our environs are quite visible. Take the Small Green Barbet for example. A dumpy green fruit eating bird with a white and brown head and a green body, which makes a hole in a tree for a nest, like a woodpecker does. Ask anybody who has ever looked at the life around him in Bangalore, and he would perhaps even tell you that it calls with its mouth closed, like a frog does, with the throat inflating and deflating, acting as a resonating chamber. It is found only in Peninsular India, and nowhere else in the world. This species is not even found in central India, let alone the north.  Then there are others which are nearly global – the Barn Owl  and our ubiquitous Blue Rock Pigeon. Both have gone global along with human beings, and do extremely well wherever we have multi-storeyed buildings. They are essentially birds which roost and breed on ledges in cuttings and cliffs. For them, our multi-storeyed buildings are similar to the artificial cliffs with ledges to roost and breed on! So, you have a building and you get these birds. 

One would wonder what is happening to the common birds of yesterday: the crows, the sparrows, the pigeons, the doves, the mynas… We still have them in our cities, though they are not found in the same numbers that we used to find them in. Habitat loss, increased number of man-made chemicals in the environment to contend with, noise, have all kept the pressure on. 

There is one thing to remember though. Birds are the highest metabolising powerhouses in the living world. Per unit body weight, they burn up food at a much higher rate than any other animal. That is because, flight requires power. Power to not only take forward, but to fly. So any toxin in the environment affects them earlier than it does to us. If birds suffer, we would not be far behind. Remember the miner's canary that used to be carried down into the mine shaft, until Davy invented his safety lamp? Until we discover a warning device for every chemical that we dump into the environment,  and every habitat that we destroy, we would require birds to sound the alarm.

KRISHNA MB & SUNIL KUMAR M   

September 2008

[Miner' Canary in the Tehelka Magazine]