What specific condition of a seed, even one that is normally a staple, causes House Finches to refuse it instinctively?

Answer

The seed is moldy or damp

Moldy or damp seed is universally avoided because it can harbor mycotoxins that lead to serious illness, triggering an instinctual aversion to decay.

What specific condition of a seed, even one that is normally a staple, causes House Finches to refuse it instinctively?
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