Crab for Dinner

I've been wanting a telephoto lens for awhile now, but I held off because my shooting style lends itself to more wide angle lenses.  Today's photo is a case for a good telephoto.  I saw this bird with a small crab in its beak and I really wanted to capture it with the ocean in the background.  Now, you're looking at this and perhaps saying, "Dave, you got a decent shot of the bird with its dinner, why are you getting so caught up on the telephoto lens?" The problem with this shot is it is extremely cropped.  I used my 24-105 4.0 lens to get this photo and the bird was fairly cooperative in letting me carefully approach to within 10 meters or so.  If I had the telephoto, I could:

1.  Get a closer view of the bird and not have to crop it so much

2.  Because I couldn't zoom in as far as I wanted, I couldn't get the background to blur as much as I wanted (shallow depth of field).

3.  If the bird is far away, then it is very small and the camera doesn't have as much information to get a sharp focus.

Now with all that said, I stil have some time before I drop a couple grand for a solid telephoto lens, but these moments bring out the gear lust to an extreme.  In the meantime, I'll just have to find a way to make these photos work.