after seeing the original, you are asking way too much of this lens if you're expecting that bird to look like it was taken with another lens
why would you set the f stop to f15? there's no need to really do that at all...even f10 wasn't neccesary for this...if it's dark and gloomy, open up the lens to f5.6...you'll get a faster shutter speed, which will make it better
birds will need a faster shutter...but they also require more reach, and getting closer...the 18-55mm isn't the lens for birds
the lens should be able to perform close to your nifty fifty...you just need to use it right
landscapes would be a good use, basically any time you want to go wider than 50mm