Now I guess nearly all wildlife photographers are used to having and using a bean bag to rest the camera and long lens on to help those awkward moments, support the weight and help when shutter speeds are low.
I bought my original double bag a number of years ago from Wildlife Watching Supplies. It has seen plenty of action and different refills from time to time. I had noticed it was starting to emit dust so time for a clean and refill. I also was most impressed when I went out on a day trip with Robbie that he had a funkyshoulder strap fitted to his. So on the basis that we needed to get another one to avoid any fights between me and Jac, I ordered another one from Kevin at WWS, this time with the strap.
This is my original bag, emptied and with the liners, after a good wash out.
New bag with shoulder strap attached
New bag filled
A nice little 'over the shoulder' number
Previously I have filled bags with a mix of rice and bird seed. Heavy and gets damp and then mouldy, and then dusty. Good stability though. Not easy for portability.
The last fill I used less rice and added some polystyrene chips and chopped up bubble wrap strands. This gave a much lighter bag for ease of carrying, but there was still dust eventually. This mix was not quite as stable as the rice/seed only, but a good compromise for the loss of weight.
The new bag is excellent with the strap for carrying so I can highly recommend this option.
So for this mix I bought a large bag of polystyrene balls from Amazon - links below for UK and USA, and used about a 50% : 50% by volume mix of rice and balls.
If you do this a word of warning - the poly balls go everwhere, so have the vacuum cleaner to hand.
Also don't put in half the rice followed by the balls or vice versa. Make sure you put in some of each in alternate quantities so you get a good mix in the liner. This provides for better stability and weight spread.