upjerk

plural upjerks

1. An upward jerk.

   He continues — "There was the same rear up, with the head bent down, followed by an upjerk of the hind parts; the long sickle-shaped tertials, so noticeable in this species, seemed little if at all expanded, […]

   1923, Arthur Cleveland Bent, Life Histories of North American Birds: Wild Fowl, page 76

   1 more example

   […] rocky pinnacles, from whence he sends forth a sort of choking chattering song, if such it can be called, or, with an upjerk of the tail, hops away with a loud musical whistle, very much after the manner of the Blackbird.

   1877, Thomas Caverhill Jerdon, The Birds of India, page 500