This is a process for removing an unwanted object in a photo without using the clone tool, developed by Robert O'Tool. It gives a very clean look.

Before


After


Although the process sounds complicated, after doing it a few times it is fairly easy. It took me about a minute remove the bird. This is what I did:

In the tool bar set the foreground color to black. Press Q to enter the Quick Mask mode. Press B to access a brush, and set the brush to 0% Hardness and 100% for each of Opacity and Flow. Paint a patch (mask) in an area next to the object to be removed, with a similar background, large enough to cover up the object. Exit the Quick Mask mode by pressing Q. The painted area is selected. The selection lines are visible but the mask is invisible. Inverse the selection using Select/Inverse. Open a new layer by pressing Ctrl J (Command J on the Mac). The selection lines become invisible. Access the Move tool on the tool bar or by pressing V. Left click the cursor over the area that was painted (which is now not visible), and move it while holding down the left click over the object to be removed, aligning the background. Merge the layers by pressing Ctrl E (Command E on the Mac).