Atomic Heart

Owl's can be found throughout the game and are first discovered within the Seed Bank, moving boxes from A to B. This would be your first opportunity to get the achievement by throwing boxes at them as they go about their business.

To use Telekinesis, simply tap to pickup an object then once in your hand hold down to charge the Telekinesis shot. Let go of to throw the object.

It'll take you 2-3 hits on an Owl to down it and unlock the achievement. Don't worry if you've missed them at the Seed Bank, theres plenty more opportunities to do this. Such as my example in the video below:

The first Owl's you come across are flying near the ceiling in the seed bank.

Grab a cardboard box and take it up the elevator so your throw can reach the owls., then just wait for an owl to come near and throw it at them to take them down.

I had to hit the owl twice - Once to drop it's box, and once to kill it, but you can probably just shoot the box it's carrying around away first, and then throw your cardboard box at them.

EDIT:

Pick up an item by tapping RB

Press and Hold RB to charge, Release to throw.

There aren't many items you can pick up. Books, Cardboard Boxes, and Lamps are about the only things you will find at this point in the story.

Some items (Large Chairs for example) seem to be too heavy and won't let you charge up to throw them.

The best way to get this achievement is in your first encounter with the Owls and in the exact location of the video since there will be a drone that passes very close to us making it easier to take it down.
Use telekinesis to grab the boxes (RB) around the area and wait for it to pass to throw the first one (Hold RB and release to throw).
When it passes again throw the second box or you can try to shoot like me, strangely enough I got the achievement this way

I got this in the 8th training ground.
In the very early part of the level there is this big room with a water tank in the center.
Two Owls fly in the area.
I recommend you save prior to getting this achievement.
The Owls fly around but at a more lower altitude without too much hassle. Try this on lowest difficulty.

Instead of the cardboard boxes use the small fire extinguishers as they pack a bit more punch. You can pick them up but for some reason it will not always work. Took me two throws, the Owl exploded and the cheevo popped.