Speaking as a living creature, I think a gull is no more worth saving than any other living creature. There are plenty of gulls and there are plenty of people.
Rather than rush around in circles trying to save the odd stray dog from a fate worse than death I wonder if people drawn to the RSPCA shouldn't consider dealing with the problems rather than the symptoms. We do a lot more damage through blind thoughtlessness than we do through deliberate cruelty. The kids kicking the gull around are the next generation of 'consumers' who will rape the planet with their insatiable wants without even knowing that they're doing it.
The main problem is that there are too many of us. We all know how Mother Nature deals with that kind of thing. For some strange reason most people seem to think that Nature's laws don't apply to people, and that we can do what we like where we like when we like as much as we like with absolute impunity. Of course that isn't true. Nature's laws apply just as much to us as they do to a gull.
We would do a great service to the rest of the species on the planet and not a small one to ourselves if we would just reduce the population to something sensible. Say about ten percent of what it is now as a target.
If we don't do something about it ourselves, then Mother Nature will do it for us. As every one of us here knows, she treats wayward children like us very harshly.