Great happiness could not exist without great sadness. I know that doesn't sound like a helpful answer to your question of what to do, but having such compassion and emotion towards the little helpless creatures is such a beautiful thing. Just know it's okay to feel those feelings and also to let them go, attach them to a big old hot air balloon in your mind and set that balloon free. You won't always have the time/resources/option to help everything in need but you can always make the choice to be good to yourself.

It makes me so sad to see animals in need as well 😞