The Collaborative International Dictionary of English v.0.48:

Dabchick \Dab"chick`\ (d[a^]b"ch[i^]k`), n. [For dabchick. See
   Dap, Dip, cf. Dipchick.] (Zool.)
   A small water bird (Podilymbus podiceps), allied to the
   grebes, remarkable for its quickness in diving; -- called
   also dapchick, dobchick, dipchick, didapper,
   dobber, devil-diver, hell-diver, and pied-billed
   grebe.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Didapper \Di"dap`per\, n. [For divedapper. See Dive, Dap,
   Dip, and cf. Dabchick.] (Zool.)
   See Dabchick.
   [1913 Webster]