How lakes become hostile for birds

Lakes in Bengaluru are where most birders flock. Though home to many birds and urban wildlife, lakes are neglected without proper ecological plans. Many lakes have lost many types of birds due to such deterioration.

Take, for example, the case of Yediyur Lake, situated in Bengaluru South and considered one of the city’s oldest lakes. It is home to around 40 bird species, including several resident birds and migratory birds, such as the Ultramarine Flycatcher and Paradise Flycatcher, during the winter season.

However, the lake has problems when it comes to the conservation of birds. Gopal, a morning walker at the lake for two years, feels the number of birds has decreased compared to 2021. He feels there is a need for concerted action.

Like several other lakes in the city, Yediyur Lake has an island, but there is no space to place logs on it, depriving smaller birds of perches to rest on.

Environmentalist and wildlife conservator Vallish V Kaushik explains the proactive steps taken by activists and residents in the vicinity. “We place fallen logs inside the lake water. These act as perches for birds, helping them to survive inside the lake and thrive on marine food,” he says.

Similarly, boxes with holes have been placed in various parts to help smaller birds build their nests, away from the prying eyes of other predatory birds like Shikra or Sparrow Hawk. Pots filled with water in suitable locations help the birds that cannot enter the lake directly.

However, not all citizens are interested in doing these or know the utility of such measures.

Problem of dogs

Kaushik feels the clash of interests between protecting dogs and saving birds is a critical issue at the lake. “A ruling by the Supreme Court prevents us from removing dogs from the lakes. However, their presence harms birds as many of them are eaten by the dogs,” he says.

He points out that this has led to fights between animal conservation groups and bird lovers across the city. “I am not against dogs, but it shouldn’t come in the way of the birds’ habitat,” he adds.

This is a problem in many lakes. In Doddakallasandra Lake, the bund is barricaded, but the gap between the ground and barricade easily allows dogs to slip into the lake premises. Lighting on the walking path is another problem that disturbs birds.

Lack of holistic vision

Not all the lakes are rejuvenated with a perspective on biodiversity. The survey of existing plants is not conducted often. Any rejuvenation attempt must build on the existing ecology, says Raghavendra B Pachhapur, Senior Lead Project, ActionAid Association, Bengaluru.

Trees to be planted should not be of one species alone. More fruiting trees should be planted in addition to the existing flora and fauna. But sometimes, some lakes end up getting ornamental plants instead of creepers and other plants that can help nurture biodiversity, he says. 

Many walkers and residents who do not respect the presence of birds on the lake premises demand manicured surroundings. But, a tree considered waste by humans, such as Acacia arabica, a thorny tree, can be an excellent habitat for various birds.

When an existing tree comes in the path of planned work, contractors use crude methods to make way, such as improperly cutting branches or digging the earth closer to roots, ultimately killing the tree.

Presence of wetlands

The area with shallow water is important in any lake. The vegetation growth in such areas is a natural phenomenon crucial for birds. But it is treated as an eyesore by many. “Genesys of ecology is in plants. With plants, smaller insects will start living, which will be eaten by bigger insects that come searching for them, which birds eat,” Raghavendra explains how vegetation helps birds. Not all birds eat fish, and many eat insects and molluscs.

He adds that the shallow region required for the growth of such natural vegetation is absent in many lakes inside Bengaluru. “We don’t need to look at Ranganthittu, etc.; we can create our own thittus (shallow wetlands) here,” he says, adding that BBMP needs an environmental perspective while planning civil works around lakes.

The bund is constructed around the lake generally. “If your lake bed is flat and the bund is created across the lake, the lake will resemble a tank that does not help the ecological diversity,” he says. He says the presence of humans in such bunds and walking paths drives away birds.

Planting grass species that thrive on nitrate content in water serves two purposes. They host insects and absorb the excess nutrients in the water, thus cleaning the lake in the process. “Some birds lay their eggs in such grass habitats to ensure protection from other birds and wildlife,” Raghavendra adds.

Planning for water

Lakes need to plan for tapping rainwater, which does not happen, “In Doddakallasandra lake, two roads and four drains are directly connected to the lake. As a result, the lake will get rainwater,” says Raghavendra, underlining that BBMP does not plan this for many lakes, and only sewage-mixed stormwater becomes the source of water.

During a sewage spillage into stormwater, this becomes a problem. When sewage enters the lake in large amounts, it starts decaying, using up the dissolved oxygen in the water. As a result, the Biochemical Oxygen Demand (BOD) becomes higher, indicating low water quality and killing fish. Many birds feed on fish.

Karnataka State Pollution Control Board (KSPCB) compiles pollution data for all lakes every month, but the data does not show the parameters. “If this is displayed publicly, anyone can check them and come to know what’s happening to the water and alert the concerned authority,” says Raghavendra.

Nothing official about it

Lakes in Bengaluru are managed by the Bangalore Development Authority (BDA), the Forest Department (four lakes), Bangalore Metro Rail Corporation Limited (BMRCL) (one lake) and the Bruhat Bengaluru Mahanagara Palike (BBMP). 

The BBMP handles about 200 lakes — most lakes in the city are in BBMP’s purview. These lakes do not get a holistic plan for managing biodiversity, though the BBMP plans civil works.

BBMP officials, who prefer anonymity, say that each lake gets a customised, detailed project report after surveys conducted by the consultant. The DPR contains details of civil works, including sewage diversion and stormwater management. However, it does not lay out an ecology management plan.

Sources in BBMP’s lake division say BBMP’s forest wing plans what to plant in a lake territory. In addition, the horticulture department plants ornamental plants using local funds. Thus, officials say BBMP’s lake division has no control over what is planted.

Sources in BBMP’s forest wing are not aware of this. They say the lake division is responsible for planning and planting the various tree species inside the lake premises, while the forest wing takes care of other areas. 

Horticulture wing, sources say, plants ornamental plants inside the premises, close to walking tracks etc. In some of the lakes, they undertake tree planting as well. However, sources DH spoke to did not confirm the presence of any single department solely responsible for planting fruiting species.

Violation: Nobody’s business

Officials say every DPR for any lake in the state, including BBMP-managed ones, goes through the Karnataka Tank Conservation and Development Authority (KTCDA), the state regulatory board, which checks and approves the plan.

However, sources in the know say that KTCDA checks the lake revival plans for encroachment removal, adherence to the hydrology of the place by way of water sources and stormwater drains, and structural issues such as checking the weirs (used to control the flow of water for outlets of lakes), sluices (a type of lock to manage the water flow and water level) and aprons (basins of rocks which also help control the speed of incoming water) and core activity infrastructure such as walking path, gazebos, gyms, drinking water etc.

However, KTDCA has no authority to enforce the rules when they are violated during the construction stage or later. They alert the concerned body, BBMP, in case of lakes managed by the BBMP, to take action.

For example, the walking path on lake bunds must only be made using red gravel. There are many lakes where the walking paths are tiled with interlocks or even cemented or concreted, but the KTCDA cannot do anything other than submit facts in court in case any such project is questioned.