150-400mm on swallows

Lovely shots. I'm so jealous of your lens!
Are the blue backs and green backs just effects of the different angle of light on the same bird, or are these different species?
... 631 is also nice but a bit out of place with all these swallow (?) shots.

Maybe it's a Swallow Duck?

Very nice photos. That's apparently a great lens that I'll never own; the 100-400mm is enough for me especially with the 1.4X teleconverter.

Thanks, I think they are different species, and yes the duck is out of place.

Not something we have here, so quick search and it looks like it could be a violet green swallow. We only have the welcome swallow here.

We have barn swallows and I have never been able to catch them, they are so fast! And I have had shutter speeds higher than you. Very impressive!

Thanks, just with lots of patience and lots of shots(over a thousand), can I find only a few acceptable ones

Phew, that does seem excessive. I would probably get 1 in 10 maybe 15 at the most. I'm not sure with AF on m4/3 but try wide focus area if you are not using it. I tried zone on Sony and it picks up the water background too easily. Wide or full works well. Different camera though. Still as long as you get them, that's all that counts. Fine work either way, not easy.

Danny.

As nzmacro guessed, the green swallows are indeed violet-green swallows. They're incredibly fast and maneuver unpredictably - they make for delightfully challenging subjects compared to barn swallows or cliff swallows (also found here). They are my absolute favourite species of bird! I look forward to shooting them every year.

All violet-greens shared by OP are females (juveniles also look the same but it's too early in the year for them). The males are a lot more vividly coloured. The green on their heads is a deep emerald green instead of a fainter jade of the females, and they have a distinctive 'mickey mouse' pattern on their faces.

Here are a couple of my older shots to illustrate the colours of the male and the face pattern (seen on the blurred male in the background, chasing after the female in the foreground). Both shots were taken with my E-M1ii and 300mm Pro. The OM-1 is of course a lot more consistent but these are the ones I have on hand - I'm too lazy to process most of my shots. 😀

The blue swallows are tree swallows (both genders look identical). The duck is a bufflehead - that's a great shot because these ducks are small and it's hard to fill the frame with them.

Nice shots! Really like that photo where they danced with each other