How to Tell If Sunflower Seed or Other Birdseed Is Spoiled

Sunflower seed clumps on flat green mat next to bowl and birdhouse

The Spruce / Sarah Crowley

Savvy birders often save money on birdseed by buying in bulk, but bird appetites can vary and the seed is not always eaten quickly. Over time, birdseed can become less appealing to the birds, but does sunflower seed go bad? What about other types of birdseed? Yes, birdseed can rot, and birders who understand the different ways birdseed can spoil can be better prepared to offer their backyard birds healthy, nutritious food.

Say No to Spoiled Birdseed

Birds may not be picky eaters, but spoiled birdseed can be unhealthy and unappetizing. Not only will bad birdseed be less nutritionally wholesome for birds, but also if the seed is contaminated with mold, feces, fungus, chemicals or other substances, it can actually be fatal to birds. Some types of mold and fungus can lead to different bird diseases, while other diseases are spread through contaminated feces. Seeds that are sticky or clumped may also be harder to swallow and could lead to choking in extreme cases.

Because so many birds from so many flocks may visit the same bird feeders, it is imperative that backyard birders take steps to prevent spreading diseases through spoiled or contaminated birdseed.

Ways Birdseed Goes Bad

To check for bad birdseed, watch for…

  • Clumps: Birdseed that has gotten wet or otherwise spoiled may start to form stiff, firm clumps. Clumps that break apart with barely any effort are nothing to be concerned about, but stronger clumps that must be forced apart can indicate spoiled seed. Clumps may also clog feeder ports, which can cause more seed to spoil as it stays inaccessible and uneaten.
  • Insects: Insects such as moths, worms, spiders and earwigs can infest birdseed. Look for live or dead insects, cocoons, webs and other indications of insect activity. One or two bugs will not be a problem, but several bugs or a larger swarm means the seed is spoiled and should be discarded.
  • Mold: Mold and mildew can be fatal to birds, and moldy seed can show mold or fungus growth, discoloration or a musty smell. The seed may be softer than it ought to be or could have a slimy feel that indicates the presence of mold spores.
  • Sprouts: Many types of birdseed will germinate under the right circumstances. Seeds that are swollen, split, or actively growing shoots or roots are spoiled. Birds will not eat these growing seeds, but in a bird-friendly garden are the sprouts can be left to mature and ripen into more supplies of birdseed. Birds will even help themselves from the plants once the seeds have ripened.
  • Smell: Bad seed can sometimes be detected by a simple smell. Many seeds have high oil contents, and when that oil goes bad it will generate a sharp, rancid smell. Moldy and musty odors also indicate spoiled birdseed.
  • Rodents: An infestation of rodents, such as mice and rats, can spoil seed through contaminants such as urine or feces. Check for chewed containers. Rodent tracks or visible feces can indicate contaminated seed as well as unwanted rodent populations.
  • Aging: Very old birdseed loses its nutritional value. While it may not show blatant signs of being spoiled, the seed that is dull, dusty, or dried out is less healthy for the birds and should be discarded if possible.
  • Feces: Many different wild bird diseases are spread through contaminated feces, and when bird feeders are dirty and caked with excrement, the birdseed can be infected. Birders should thoroughly clean feeders and remove any feces buildup each time feeders are refilled, or that contamination can easily spread to spoil more seed.

Keep Birdseed From Spoiling

Recognizing spoiled birdseed can help keep bad seeds from reaching bird feeders, but it is better if backyard birders take steps to keep the seed from spoiling at all. This will ensure that the seed is always suitable for the birds to eat, and it will save money by not needing to replace uneaten seed or throw away unsuitable supplies. To keep seed from spoiling:

  • Store birdseed properly in airtight containers in a cool, dry place out of reach of rodents.
  • Avoid buying more birdseed than what can be used up in a few weeks.
  • Only fill feeders with enough seed for 2-3 days so that it won't spoil in open feeders or poor weather.
  • Use the oldest seeds first and rotate seed stocks regularly to keep seed fresh.
  • Keep feeders clean and free of seed debris and feces that can spoil or contaminate refills.

By understanding how to check for spoiled birdseed and how to keep it from spoiling, birders can be sure to offer their backyard birds fresh, healthy, tasty seeds in every feeder.

Watch Now: Top 7 Bird Feeding Mistakes

Article Sources
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  1. Keep Bird Feeders Clean: Dirty Feeders Can Spread Disease to Backyard Birds. Oregon Department of Fish and Wildlife, 2017