It depends on the tone/PoV of the setting. Some scenes can get away with longer descriptions of animals in the background, while others demand faster descriptions of sounds. This is determined by what feel you're trying to accomplish, primarily, and how your PoV character is likely to notice the animals. If they wouldn't, then only mention animals when they notice them.
Usually, the slower the scene, the more time you can spend on background noise. That tends to get blocked out in times of stress, unless the PoV character wold be actively looking for the sounds of animals and every single one just makes him more nervous. But, still, that would determine the length of each sentence and the way sounds are described.
A writer is a world trapped in a person— Victor Hugo
Ink is blood. Paper is bandages. The wounded press books to their heart to know they're not alone.
