With motion-triggered DSLR bluebird images, I've been prefocusing and hoping for the best. I set the f-stop between 8 and 11 to get some depth of field, but that means I either have to use a high ISO or a slow shutter speed. I got a new flash, but I've still got the problem of it powering down long before it get triggered. The hardware solution to the flash falling asleep seems to be a second Camtraptions wireless receiver, which costs £20 plus shipping from England.
Until I get that, I will have to experiment with being "artistic." This image is perfectly in focus, but the bird is motion-blurred. 5D Mark III, 300mm lens, 1/125 at f/11, ISO 250.
If the bird stands perfectly still, no problem. 1D Mark II, 35mm lens, 1/250 at f/7.1, ISO 250.
And this one combines a relatively-static bird on the right with an artistic blur on the left. 1D Mark II, 35mm lens, 1/320 at f/9, ISO 250.