Photos: Lesser Goldfinches ravaging sunflower plants

[Donkees]

3. It's part of their balanced diet as they prepare to breed :)

From an earlier post of mine today:

The leaves are rich in minerals such as calcium, and some leaves are also collected for nest building. Here in the east, Goldfinches are also late breeders and have their own unique behaviors.

There are several other flowering plants whose leaves Lesser Goldfinches prefer. You might plant those in the same flower-bed to minimize the damage to the sunflower plants.