If you have the Brush tool selected, hold down Opt key will quickly activate the Eyedropper tool.

Select the eyedropper tool then click somewhere on the tail, this is to get a reddish color that matches the color of the bird.

This is a much quicker method than using the Eyedropper tool to select individual colours and adding them one by one to the Swatches palette – it also works with any RGB image.