Very nice Kinich
I was looking at these two pictures and thinking that they are in some ways very similar, in others very different. So I thought I jot a few notes for anybody looking through these posts who maybe is new to or not very experienced with photography who might be interested.
Both feature birds in flight (and both over water), and both birds are in a similar pose/position. Both shots where taken on the same camera (a Canon 7D in this case).
The not some similar.
The lenses & settings:
Duck 1/160th Sec at f8 with a Sigma 150mm f2.8 Macro lens.
The Gull 1/1000th Sec at f9 with a Sigma 170-500mm f5-6.3 Zoom lens (at 500mm).
The lower shutter speed of the duck shot has meant that the background has blurred as I tracked the duck with the camera (a technique known as panning), also you can see the blur of the ducks wings as they have moved during the exposure. These effects result in a less sharp image but give a sense of movement to the shot.
The Gull shot because of the higher shutter speed has frozen the bird in flight, the result is a sharper bird but with little sense of movement.
Which you prefer is a personal choice and what you are looking to achieve, but in my opinion they both make good shots of similar subjects but with some distinct differences.