Safe environment — Place the animal(s) in a cardboard box or plastic carrier with plenty of air holes for ventilation. Use soft bedding such as towels, old t-shirts, or you can line the bottom with newspaper for adults. Do not use grass clippings or wood chips/shaving. Keep the box inside in a quiet, dark area away from pets and people. Handle the animal as little as possible — wild animals can easily get stressed by captivity and over handling.
A bowl of water can be placed inside the enclosure. Most wild animals are much too stressed initially to eat or drink so placing food in the enclosure is not necessary. However, if you feel you must offer food, cracked corn, duck/goose grower (available at farm and garden stores), or insects (not bees/wasps) may be offered. Bread can also be offered however it has little nutritional value. Do NOT feed whole kernel corn or other large seeds (sunflower) or nuts as this can lead to a crop impaction (blockage). Seagulls may be offered canned dog or cat food or dry food soaked in water to soften.
DO NOT give any medical treatment or medications, including flea sprays etc. Many medications that are safe for use in your pets or humans are not safe in wild animals and can have severe to life threatening adverse effects.
Get the animal to a licensed wildlife rehabilitator or facility as soon as possible in the morning. Injuries need professional medical attention as soon as possible to increase the likelihood of successful treatment. It is against the law and not in the animal’s best interest to keep wildlife without the proper permits and education.
Always wash hands thoroughly after handling a wild animal.