From the Migratory Bird Center in the USA:
Tool Use by Chestnut-backed Chickadee
by Sandy Salmons and Gregory Gough (April 2007)
In late February of 2007, Sandy Salmons observed a chestnut-backed chickadee visiting her backyard suet feeder for about two weeks in Nanoose Bay, Vancouver Island, British Columbia, Canada.
She was amazed to see the bird use a stick or thorn to pry seeds from the surrounding suet.
Chestnut-backed chickadees are found from southern Alaska to central California, mostly along the coast.
They often come to bird feeders to eat seed and frequently lay their eggs in backyard bird boxes.