Which Plant Has Evolved To Repel Mammals But Attracts Birds?
Answer: Chile Peppers
There is no shortage of unique adaptations in plants. Some plants grow long thorns to avoid being bothered by anyone. Some plants secrete bitter sap to avoid becoming an herbivore’s lunch. Other plants evolve to repel the creatures least useful to them and attract the creatures most helpful.
Peppers fall into the latter category. Chile peppers are a seed bearing vegetable that require the intervention of external factors to properly propagate their seeds. The best way to spread your seeds far and wide is to be delicious, so animals will eat you and excrete your seeds in a nice nutrient-rich pile of dung. The only problem is that not all creature are equally gentle with their food. Rodents and other small mammals that eat seeds will usually chew up the seeds and leave them in an infertile state upon excreting them. Birds, however, will eat large volumes of seeds and, more often than not, those seeds will pass through their bodies intact and fertile.
Chile peppers evolved to take advantage of this. Mammals are put off by the spice of the capsicum in the peppers, whereas birds can’t taste it at all. In tasting unpleasant to mammals and delicious to birds, peppers assure that they are widely propagated under ideal conditions.
Bonus Trivia: If you’re having trouble keeping squirrels out of your bird feeders, you can taint your bird seed with chile pepper powder. The squirrels and other mammals will avoid it and the birds won’t even notice it.