In general, you ALWAYS want more for birds...but it depends on just how far away the birds are. If you can get within about 50 feet of the bird, 200mm on your camera would be OK for getting decent closeups and details. If you're more like 100 feet away, you'll want more...300mm at least. And so on. Most people who shoot birds are using 400mm to 600mm lenses on APS-C sensor cameras like yours...and STILL wish they had more. It also depends on just how much you expect to be getting into shooting birds - if you just want the occasional snap, you don't want to invest in expensive or heavy lenses - so a cheap 55-200mm should suffice. Maybe consider a 70-300mm type zoom as it will give you more reach and can still be found cheap. Remember that the cheaper lenses usually aren't great in poor light and still won't usually have that super-sharp and crisp detail - you need to invest in more expensive lenses to get high quality, but that's only if you're going to really get into birding photography. A cheap option would be to pick up a used Minolta lens like the 75-300mm F4.5 - or the newer Sony 75-300mm...it's a good compromise between reach and size/weight...the Minoltas can be found pretty cheap used and are still pretty good quality. If you're really looking to take bird photography seriously, then you start getting into the very good and expensive lenses like the Sony 70-400mm G...much bigger, heavier, much better reach, and of course 4-figure price range.