The Collaborative International Dictionary of English v.0.48:

Gaggle \Gag"gle\ (g[a^]g"g'l), v. i. [imp. & p. p. Gaggled; p.
   pr. & vb. n. Gaggling.] [Of imitative origin; cf. D.
   gaggelen, gagelen, G. gackeln, gackern, MHG. g[=a]gen, E.
   giggle, cackle.]
   To make a noise like a goose; to cackle. --Bacon.
   [1913 Webster]