It's interesting you ask what the motivation behind the shot was as this version is different to how I originally imagined it!
What caught my eye was the symmetry of the way the birds are perched and the soft light from above. On the day, it was also tipping down with rain and version 2 is one of the shots with lots of rain, splashes off the beak etc. but after trying different processing options I went for this. One of the reasons is that "legit" rain in photos can often look like photoshopped rain.
After making the decision to do away with the rain I was left with the blurred background and the birds - plus some tidying up tweaks. It was trial and error that led to this result, with just the light and the birds. The background as you'll see later was "generic tree bokeh". I like Scott Kelby's advice that anything not adding to the scene is taking away and in this case the rain + background wasn't adding any context and took away from the simplicity.
One of the reasons for this kind of look and feel is that it contrasts to this -
Purple Bird by
David, on Flickr
This is a clean, sharp & minimally processed bird. No distractions. But it's basically a record shot, it only is slightly different because of the vivid colours of the bird.
I could have taken a record shot that had a perfectly normalised histogram, pushed the shadows at the bottom and showed you everything you wanted to see about the pelicans... but then it would be just a technically competent image of some pelicans. Here, I wanted to show an image of two pelicans huddled together against the driving rain (in a fortuitous symmetrical position) but when the rain didn't "work" I focused instead on how the soft light made the birds look.
Once I get home I'll share the original image and a WIP on my "how to make real rain not look like fake rain" version

On the techie side, there's no subject movement at all, which part(s) of the body look motion blurred?