I love using my Nikkor 3oomm f/4 lens for chasing birds. It is a great compact, light and portable outfit when it is being used with a monopod.
It is not difficult finding birds when they are feeding, if you can find their feeding source then sure enough you will find the birds nearby. I always find that if the birds are totally absorbed in chasing their food then it can take their attention away from the photographer as their attention can be totally focused on their feeding and you may get much closer to them to capture their image.
In the case of the Noisy Minor below the birds were totally absorbed on chasing the insects which were flying around the truck of the tree. Several birds spent quite a bit of time chasing and catching these insects.
I also think a bird engaged in some action, such as here the bird chasing the insect, is better than an image of a bird just sitting on a branch, it adds some more interest to the image.
In this second image below I have captured a pair of Galahs feeding on seeds close to the ground. The two Galahs are totally engrossed in looking for food and not concerned about the photographer slowly approaching.
The last image below, is a capture of a Brown Honey-eater busy looking for nectar in a bottle brush tree. This results in a nice colourfull image with the beautiful bird and the bright bottle brush flower together.
Some of the equipment I use for my photography is shown below if you are interested.