How to Help a Sick or Injured Bird
Always be quiet and gentle around a sick or injured bird, as it may be in shock, dehydrated, exhausted, and/or suffering from trauma.
While the bird may appear very calm, this is often a survival response and the bird is probably very stressed (some species can die simply from stress alone).
A stressed bird will have its mouth open and be panting. It is not happy and doesn't know it is being rescued.
What to Do Next
Try to catch the bird without risking your own safety (i.e. avoid sharp beaks and claws, and be mindful of traffic, dangerous terrain, waves, etc).
Hold the wings to the body to prevent any further injury.
Take the bird to the nearest vet or Wildlife Rehabilitator (see Who to Call). To transport the bird, ideally place it in a cardboard box with a towel. Keep it warm and don't put any water in with it, as it might spill and make the bird cold.
Do NOT attempt to give the bird food or water. The anatomy of birds is different from that of mammals, and even small drips of water into a bird's mouth can result in its death, as there is a high risk that the water will get into its lungs.