How to take a sharp nice looking photo for a flying bird "not to appear blurry" with a canon t4i 18-135 STM lens
As already mentioned, one method is to get the shutter speed up high.
Another method could be to use a strobe/flash. The 'lower' the power setting on the strobe, the 'faster' the flash rate, so it can be beneficial to get the strobe quite close to the bird as this will allow you to keep the power low. Many flashes actually fire at much faster speeds that your camera shutter could ever reach, so they offer a great way of freezing the image.
Here is an example of an image I took using the flash rather than camera to 'freeze the action'.
This was a one flashgun setup with the flash being about 1.5 metres from a bird table. I pre-focused manually on an area where I saw the birds used a lot, and waited. I had the advantage of knowing where the birds were likely to be, and therefore could easily plan for the shot. It is much more difficult if you are doing 'sporadic' shots of BIF.
I didn't use any modifier on the flash as I knew that my settings would 'blacken' the background, therefore wasn't bothered about any shadows, or effect on surroundings as I was aware that they wouldn't show up in the photo. All settings in the camera and flash were done manually so I could get the result I was hoping for. There is a bit of blur on the bird's tail (left hand one), but otherwise I was happy with the results.