What Animal Is This? Identify It From a Photo or Its Sign

The quickest way to find out what animal you are looking at is to photograph it and run the photo through an identification tool. Google describes how Lens works: it compares objects in your picture with other images and ranks them by similarity, then shows the most likely match. Dedicated nature apps, NatureLens included, do the same thing against wildlife data and then point to the features that support the answer.

What makes the difference is the photo:

• Whole animal, side-on. Body shape, legs and tail matter more than a close-up of the face.
• Something for scale. A fence post, a step or a hand in the frame tells the tool whether it is looking at a mouse or a rat.
• More than one frame. Burst mode catches a moment when the animal is not blurred.
• Where and when. Location, habitat and time of day remove animals that could not be there.

Photo identification only works for animals the model has learned. iNaturalist, whose model powers its app and Seek, publishes its rule: a species is included only when there are at least 100 photos and 60 observations of it, and the model uses no more than 5 photos from any one observation. Rare animals, local subspecies and juveniles that look unlike adults can fall outside what a model knows.

When that happens a good tool gives you a broader group, such as "a weasel" or "a vole", rather than a confident wrong species. Treat a genus- or family-level answer as useful: it tells you which features to check next. Google's own example of Lens results is a ranked set of possibilities with probabilities, not a single certainty.

Many animals are never seen, only their tracks and droppings are. Both can be identified.

• Toe count and claws. Missouri Department of Conservation describes coyotes, foxes and dogs as having four toes, a three-lobed heel pad and visible claw marks, while bobcats, house cats and mountain lions show four toes and no claw marks. Raccoons have five toes on both front and hind feet, and the front print looks like a tiny human hand.
• The opossum's thumb. Wildlife Illinois notes that an opossum's hind track resembles a baby's handprint because the inner toe is a clawless, thumb-like toe.
• Scat shape. The Internet Center for Wildlife Damage Management sorts droppings into pellets (deer, elk), plops (bear, cattle), large tubes (dogs, coyotes, foxes, raccoons, cats) and small tubes (rodents, bats, birds, reptiles).

Our animal track identification guide, animal poop identification chart and species pages for 32 animals go further.

If the tool is unsure, decide the group yourself first; each group has its own shortcut.

• Birds you can only hear. Image tools such as Lens work on pictures. For birdsong, the Cornell Lab of Ornithology's Merlin app has a Sound ID feature that listens and suggests the singer.
• Spiders. Count the eyes and look at the web; see what spider is this.
• Flying insects. Bees, wasps and hoverflies are separated by wings and antennae; see telling bees, wasps and hoverflies apart.
• Mammals seen at night. Note the size against something nearby, the tail and how it moved; then check the tracks the next morning.

Identification never requires handling a wild animal. The CDC's advice is to keep your distance from wildlife and never approach animals that appear injured, sick or dead, especially animals out in daytime that are normally active at night, such as bats and raccoons. It also asks people to note any sign that an animal is not acting normally and report it to a healthcare provider or public health professional.

If you are bitten or scratched, the CDC says to wash the wound immediately with soap and water for 15 minutes and to talk with a healthcare or public health professional about whether you need rabies-related care. A photo taken from a distance is enough for an identification.