As a small woodland bird with cryptic plumage and a quiet call, the Eurasian treecreeper is easily overlooked as it hops mouse-like up a vertical trunk, progressing in short hops, using its stiff tail and widely splayed feet as support. Nevertheless, it is not wary, and is largely indifferent to the presence of humans.[1] It has a distinctive erratic and undulating flight, alternating fluttering butterfly-like wing beats with side-slips and tumbles. Migrating birds may fly by day or night, but the extent of movements is usually masked by resident populations.