Foxes bark, yip, yowl, growl, cogh and gekker. These sounds are part of a varied repertoire of noises used on various fox communications need. Part of the odd sounds include yow-wow-wow, ack-ack-ackawoo-ack, and YAAGGAGHHGHHHHHHAHHHH!!!!!. They aso make a scream/howl that sounds like a murder mystery scream.
Foxes actually bark.
You write sizzle.
baaah
ting
squeak
BOOM!
bacock
You could write Bzzzz or Zzzz or any other buzzing sort of sound.
The sound a whistle makes is often described as "whoo" or "wee" depending on the pitch and intensity of the sound.
Squirrels make a chattering sound or the sound you make by knocking your tongue on the roof of your mouth.
"bzzftt"
dribble dribble
BWAAAAAAAAAAAAAAAAAAAAAAAAA~!!! At least that's the sound he makes around here.