There are these days when birds show up in numbers I only dream of normally but and this is the big but they are either in the wrong place or/and the light is so horrible that taking pictures of them is no pleasure.
This is the reason why I never leave the house without flash. To be honest I always take two of my 580EX II with me. Call me paranoid but I had a flash fail in the field and this was on a day when this little helper would have saved the day. Needless to say I missed some species I was looking for; for years. The Blue-naped Chlorophonia above is another example for how using fill-flash rescued the photographer. If you move the mouse over the picture you will see the same bird, same situation just this time no flash was used. Only a little spotlight on the bird and this very patchy, the background really bright and not very inspiring. The other opportunity for the background would have been a large window of the hotel I was staying at this time. Neither a good background without flash and even worse with flash. I would have gotten all kind of strange reflections. High speed fill-flash was the way to go. As I was pretty close this was powerful enough to bring back the colors and details of the bird.
Usually -depending on the ambient light- I deal in a minus compensation around -0,7 too -1.3 but in this case I knew that the short exposure time and the high-speed fill-flash will be okay at it’s default settings. High-speed fill-flash gets less powerful the shorter the exposure-time.
I nearly always use my flash on the Wimberley flash bracket. With this bracket it doesn’t matter whether I take a vertical or horizontal picture the flash stays in the correct position. Very often I use an extension arm to get the flash a little bit higher which helps tremendously to avoid the infamous steel- eyes.
And with a second socket it works nearly perfect on the beanbag as a very good shooting platform. Wimberley products are not cheap; neither is a good flash but in both cases it pays to get the best what the market offers.
Good luck and good light and may the creatures show up on these perfect days ... but if not get your flash out and keep going.