80-90% decline in water birds’ count in last 2-3 decades in B’luru
Bengaluru Deteriorating ecology of lakes, the presence of untreated sewage, and concrete embankments that claim to help waterbody rejuvenation have led to a steady decline in the number of water birds found in Bengaluru, according to experts and environmentalists
Bengaluru

Deteriorating ecology of lakes, the presence of untreated sewage, and concrete embankments that claim to help waterbody rejuvenation have led to a steady decline in the number of water birds found in Bengaluru, according to experts and environmentalists.
Bird watchers and ornithologists say the decline could be anywhere between 80% to 90% over the last two to three decades. According to ornithologist and scientist S Subramanya, the use of civil engineering techniques for lake development has a profound impact on the water birds.
“The lakes used to be shallow water basins with varying water depths and different birds would occupy different depths of water. Now, the lakes are usually desilted uniformly and only a small section of birds benefit from that,” he explained. For instance, deep water of uniform depth discourages waders, diverse populations of which migrate to India, including the southern peninsula in winter.
Subramanya added that the lakes, which used to be seasonal have turned perennial due to the inflow of sewage water. “The structure and ecology of these lakes have changed and as a consequence, the water bird population has nosedived,” he added.
Bird watchers who update lists of various species on online platforms also noticed higher presence of birds of a single species rather than diverse ones.
According to a joint report by Council of Scientific and Industrial Research (CSIR) and National Environmental Research Institute (NEERI), 19 of the 205 extant lakes (out of an earlier estimate of 250) in and around the city are completely encroached. And only 21 have water that’s fit to drink. A report by the Karnataka State Pollution Control Board (KSPCB) in 2020 suggested that not even one lake had water fit for drinking.
Between 2008 and 2020, the BBMP claimed to have developed around 80 out of 205 lakes with another 20 under various stages of completion, but this development often refers to the building of concrete structures around the lake rather than any focus on the ecology itself.
According to State of India’s Birds 2020 , a report on the distribution and conservation of birds, there has been a “gradual decline” in the population of birds in the metro cities of Bengaluru, Chennai, Delhi, Hyderabad, Kolkata and Mumbai.
Birders and environmentalists also referred to “man-made problems” such as rapid and unplanned urbanisation that is replacing the habitats of these winged creatures. Moreover, conservation efforts by the government often refers to the legal protection of animals, they added.
The most noticeable change in Bengaluru is the disappearance and an explosion in the number of pigeons and barn owls, experts said.
“Pigeons are traditionally known to lay eggs based on the availability of food. But they breed all year now since there is feeding by humans that has altered the very nature of their reproductive structures and caused an explosion in their numbers,” Chandrakanth, formerly with the University of Agricultural Sciences (UAS) in Bengaluru, said.
Pigeons now tend to nest in every possible concrete structure, including apartments and other buildings to avoid threats from other predators as well, experts said.
Studies showed that their excreta is capable of causing multiple diseases and is extremely acidic that can cause long-term damage to structures and humans and spread salmonella germs . Similarly, Barn Owls which were a rare species of bird in the city, also nest in apartment complexes as open garbage attracts rats which are easy prey for these nocturnal birds, experts added.
The sight of walkers and joggers feeding birds with all kinds of food such as biscuits, grains, puffed rice and even bread is a common sight in areas such as Cubbon Park and Lal Bagh .
The use of chemicals and pesticides has also impacted the health of these birds who feed on seeds and insects in these areas.
The trouble in assessing the actual impact is the lack of proper studies to determine the rise in population of a few birds and disappearance of others, birders and ornithologists said.
“Of the 261 species for which long-term trends could be determined (i.e. not uncertain or data deficient), 52% have declined since 2000. In all, 43% of species showed a long-term trend that was stable and 5% showed an increasing trend,” according to the report by CSIR and NEERI.