Crested Pigeons (or Topknots as they are sometimes called) have been in my yard ever since I moved here. I think they have been nesting in some thick shrubs in my neighbor's yard. They have foraged around the yard and perched up on the electricity wires. I would certainly miss seeing them if they were not here.
A few years ago a new bird started perching and foraging in the same places. It is a Spotted Turtle Dove which was introduced into Australia from the 1860s onward and is expanding its range all the time. In the last few weeks I have been seeing fewer Crested Pigeons and more Spotted Turtle Doves and it even seems that the Doves are taking over the shrubs where the Pigeons formerly nested.
Introduced species always change the balance of the environment. Unfortunately our native species don't seem to compete so well. Of course, all introduced species are more carefully managed now but we are still left with the problems created by earlier introductions which were allowed before it was realized just how delicately balanced the environment is. I hope the Doves don't push the Pigeons out of my yard!
For more bird photos visit the Bird Photography Weekly.