Three boos for Horton's friends: Boo! Boo! Boo! These little creatures really let him down in his time of greatest need:
They taunted. They teased him.
They yelled, "How absurd!
Old Horton the Elephant
Thinks he's a bird." (80-82)
This motley crew (we counted a giraffe, a hippo, a kangaroo with a joey in her pouch, and other critters we're afraid to try to identify, but which look like squirrels, a moose, a lion, and some bunnies) seem to represent a cruel, callous society which ridicules what they don't understand.
But Horton's friends help us see how strong he is. A lesser elephant would have hopped right off the egg and run away with his friends. A lesser elephant would have abandoned the egg in order to earn the acceptance of his friends. Horton has his priorities straight.
Will he forgive his friends for their terrible breach? Well, check out the snooty looks on Horton and the elephant-bird's faces in the homecoming scene. Those looks, and Horton's distance from his friends, suggests that they might have to learn a thing or two about faithfulness before they rejoin the Horton club.
The Circus Crowds
The circus crowds have the same reaction to Horton as his friends do, except these people are willing to pay for the pleasure of taunting our hero:
Sold to a circus! Then week after week
They showed him to people at ten cents a peak. (159-160)
And everywhere thousands of folks flocked to see
And laugh at the elephant up in a tree. (165-166)
Oh, cruel world. Where are all the good guys?
The circus crowds, like Horton's friends, finally do see the goodness in Horton—but only because his kid looks kind of like him. Still, maybe, just maybe, they'll be more accepting in the future.
For, while Horton sat there
So faithful, so kind,
Three hunters came sneaking
Up softly behind! (95-98)
If nothing else, these three hunters are superhumanly strong. They six-handedly uproot Horton's tree with him inside it. They even manage to get it into a pot. And into a cage. Then they push and pull it over a ten-thousand-foot mountain range. Yikes.
The hunters contribute to the transcontinental flavor we talk about in "Setting" by sending Horton on a whirlwind tour. Plus, they allow Seuss to weave all kinds of complicated issues into his story, including colonization, slavery, forced migration, and, of course, the ethics and morality of zoos and circuses.