In urban areas, the number of pigeons and crows are exploding. Sometimes, local bird pests also join in.
For example in this part of India, the population of cuckoos is exploding.
Cuckoos are an egg-parasite, which also means that they destroy local birds, via their eggs.
So, why does this all happen?
1 Due to massive urbanization, the natural predators of these pesky birds have disappeared.
So,now the pesky birds fly without fear,
2 Secondly, the birds are not really scared of humans any more.
If you notice, these birds are just above where humans usually reach or are in some obscure place, where humans don’t venture.
But, they fly low enough so that they can take advantage of humans (food, nesting, etc.)
3. Smaller birds and also predators of the pests have nowhere to go because of loss of habitat.
Trees are cut down for buildings, roads, etc. and the green cover is disappearing and so are the predators