Long distance documentary photos

Allen

I keep running into this, a rare/uncommon bird, duck, gull, etc., out there
at least 150 yards or farther. The best I can do is add a 2x to the 500L
and sometimes also a 1.4X. This is strictly for documentation although
would be nice to get a decent photo especially showing the field marks.

This is the latest, Long-tailed Duck at a quarter of a mile amongst the Ruddy Ducks.


It looked like the raft was on the other side of the lake but going over
there, they also looked like on the other side. The lake is 1/2+ miles wide.

Here's another from the other day, Black Scoters at 900+ yards.



Does anyone have any suggestions on how to solve the long distance shots?
* distances measured on GoogleEarth
* these are huge crops 7D 500L+2X

Harryb

Allen the first one who solves the long distance problem will become a hero to all wildlife photographers around the world.

I swear those damn birds choose their distance based on the lens I'm using. They usually will find a way just to be outside the usable range of whatever lens I'm using. Some of those evil creatures will even wait until I'm using the 500mm with the 1.7TC. Then they will fly in real close, closer than my minimum focusing range. :bash

Seriously the only way I know is through observation of their habits and patterns and trying to find a spot within shooting range.