Each plant, animal, rock, and other entity has a spirit. This can be found in many religions: Wicca, Paganism, Witchcraft, Buddhism, Native American, Shamanism, and many others. These Nature spirits are psychically powerful, and are much less abstract and controllable than the Elementals that many who perform all of their rituals indoors are familiar with. Nature Spirits can be extremely powerful allies. It is possible to sense nature spirits, to determine if they are receptive to a ritual planned, and to have them actively participate in magickal workings if they are.
For example, birds may join the rituals, flying around the circle when energy was being raised, specifically invocations dealing with Air. Nature spirits often channel great amounts of power into the magick being performed. Let Nature channel her power into the magick in her own way. Do not approach them with disrespect, or by attempting to command them rather than listening to them. The Nature Spirits may flee or attack. Besides, the goal is to honor and harmonize nature with your magickal workings.
Working with Nature Spirits can also bring a deep sense of partnership with Nature, and bring new levels of attunement. As always, respect Nature, Mother Earth, and all her creatures. It is sometimes a good idea to find your own personal Nature Spirit, or animal guide, but it is not necessary.