Quantity
A few coffee grounds can contain enough caffeine to be lethal to a small songbird. Don't scatter coffee grounds in areas where ground-feeding birds forage. If you compost coffee grounds, bury them under a thick layer of other material.
Notes
The biggest garden risk is coffee grounds. Many gardeners scatter used coffee grounds around plants as fertilizer or slug deterrent. Birds foraging on the ground — robins, blackbirds, thrushes, towhees — will peck through the grounds looking for insects and ingest caffeine in the process. Tea bags left on the compost heap are another common source.
Negative Signs
* Extreme restlessness and agitation
* Rapid, labored breathing
* Tremors and wing twitching
* Loss of coordination — unable to perch or fly straight
* Seizures
* Cardiac arrest
FAQ
Q: I scatter coffee grounds in my flower beds for the soil. Is that harming the birds?
A: It could be. Ground-feeding birds like robins and blackbirds scratch through soil and mulch looking for insects, and they'll pick up coffee grounds in the process. Either bury the grounds deeply or compost them in a sealed bin before adding to the garden.
Q: Are tea leaves as dangerous as coffee?
A: Tea contains less caffeine than coffee, but it's still enough to harm a small bird. Don't toss tea bags onto the compost heap where birds can reach them.
Alternatives
If you want to deter slugs without caffeine, try copper tape around pots, crushed eggshells (which birds can actually benefit from for calcium), or beer traps set flush with the ground where birds can't reach.
Risks & Disclaimer
Caffeine poisoning in wild birds is almost always fatal by the time you notice symptoms. Prevention is the only realistic option. Keep coffee grounds, tea bags, and caffeinated drinks away from areas where birds feed.
