If you notice that your bird seed is disappearing quickly, it could be due to various animals or pests. Some common culprits include birds, squirrels, mice, rats, and even raccoons. To identify the specific animal, you can set up a camera or observe the area during the day to see who is consuming the bird seed. Once you determine the culprit, you can take appropriate measures to address the issue, such as using squirrel-proof feeders or placing bird seeds in containers that are inaccessible to other animals.