|Hello from the Critique Club!
I have studied your image and have the following to offer:
Composition/perspective the amount of area covered by your shot is good. The relative placement of the subjects is also quite good. They are even throughout the shot while not being crowded or too spread out. I like the mix of base elements in the shot water, plants, stone wall. The crop may be a little tight on the right side, but the birds are not cut off so that helps it there a bit. The focus seems a little off. This may be more camera shake than focus though, hard to tell. Your relative position to the subjects is nice not too much above or below. This really works with the combination of birds flying, swimming, walking/standing. Very nice mix and one of the stronger elements of the shot. The size of the shot is one of the weaker points (see below) and can be corrected. Some sharpening applied to the shot would help to define more of the textures in the scene the stone wall, reeds in the background, feather definition on the foreground birds and wing detail of the flying birds.
Color adjustments in contrast and saturation would help to separate the like colored elements. The lighter green of the reeds would contrast better against the dark green water. This would also help with the top standing bird to not blend so much into the stone wall.
Lighting natural light, dealt with fairly well. The two flying birds appear to be blown out a bit in the white areas much brighter than the rest of the image. Some of this can be seen as well on the neck of the swimming pelican. Some adjustment in levels may have eliminated this.
Challenge requirements although this is a nice group of birds, it doesnt really meet the requirements of Collections except in the very broadest sense. It may have lost some with the voters in this area.
Overall/my opinion a nice scene that with some adjustments or slightly different adjusts made in post processing could help to strengthen it. I noticed in your comments you said they were small to make the 150k limit. There are many ways to resize and compress an image to make the limit and still have a larger image 640 x 640. If this is something you are unsure how to do or would like to learn other methods, you can search the forums and find many threads about this. Also, posting a question in the forums will definitely get you helpful responses. If you PM me I will also help as much as I can.