I do not know that a term has been established since the common (and incorrect)
notion is that hedgehogs are solitary animals. On the hedgehog list server,
groups of hedgehogs have been referred to as a "whump," (a term apparently
suggested by a hedgehog specialist veterinarian) and subdivided into a small
group "whumpie" (two to five hedgehogs), medium group "whump" (six to 24
hedgehogs), and large group "grootwhump" (over 24 hedgehogs), the suffix and
prefix being in Afrikaans.
Best wishes, Z. G. Standing Bear at The Flash and Thelma Memorial Hedgehog
Rescue (northern Colorado)(
http://hedgieflash.org)