Pine
Siskin

Pine siskins run their metabolic rates 40% higher than normal songbirds. In extreme cold down to –94°F, they can speed up their metabolism up to five times normal for hours.

They can store seeds in their crop (part of the esophagus) totaling up to 10% of their body weight to stay warm through subzero nights.

Siskins will sit near larger birds like evening grosbeaks to eat dropped seed particles, aggressively defending their tiny spot.