According to the Cornell Lab of Ornithology, birds quickly get used to seeing the same thing day after day, and no longer fear it because it is not moving and thus seems less threatening. When this happens the birds will return, sometimes after just a few days. Visit Site http://www.fickity.net/how-owls-scare-birds/

1. HOW DO OWLS SCARE BIRDS?
Fake, molded plastic “decoy” owls are a popular way of deterring common pest species of
bird, such as woodpeckers and pigeons. Per the New York Times, fake owls are even used to
deter birds near airport runways. Decoy owls work, at least temporarily, because owls prey
on many species of birds.
Predator Intimidation
The idea behind decoy owls is a straightforward one. Several species of owl’s prey upon other
bird species, and so their mere presence deters those birds from remaining in the area if they
think they have spotted an owl. When a prey sees an owl-like figure, they will usually find
somewhere else to be.
Short-term Solution
Although decoy owls can be effective at deterring many species of birds, they are only a
temporary fix. Per the Cornell Lab of Ornithology, birds quickly get used to seeing the same
thing day after day, and no longer fear it because it is not moving and thus seems less
threatening. When this happens, the birds will return, sometimes after just a few days.