@Needs native check:
Wouldn't it be better to say 'the hedgehog' rather than just 'hedgehog'?

How's this:
A hedgehog is a proud bird. If you never kick it, it will never fly.

There is a crude attempt at humour, since a hedgehog is a more or less inoffensive mammal and not a bird at all. And I believe one reason we seem to have more serial killers and mass shooters nowadays than we ever had 50 years ago is that children are not routinely learning empathy in childhood.Someone who is habituated to behave cruelly to small animals can readily extend his cruelty to fellow humans later.

Being too much a friend to small animals, I don't like this saying one bit. But if we are to have it, I think it should be grammatical. Probably you should also tag it as "Russian proverb."

I always regarded it as a metaphor (some things/people won't get/be done until and unless you 'kick' them to give them a shake).

@objectivesea
That is so true. Can you please make some good example sentence that would remain here as a reminder of those wise words. Love is something that is learned, and if one fail to learn that, in proper time, it hardly can be compensated. How is possible for a person who does not love animals, to love other human being, and to know what is the love, at all.

So to love other people, one must love animals first, you say, but evidently it is very possible to love animals while being quite a misanthrope. What's that supposed to mean, that love for animals is greater that love for people?

ps. "You keep using that word. I do not think it means what you think it means."

Well, I didn't say that (I have to use it:) ) the loving animals is a prerequisite for all loves. Just try to say that love is learned, in many "areas" (animal, whole nature, neighbours,...) and developed over time. If you missed the train, it is gone. So, if one never had a pet, probably isn't a loving person. That doesn't mean the opposite. You turned the logic a little bit upside down.

I will try to check that "that" for proper usage, thanks.

I won't have a pet because I'm not up for taking complete responsibility for a living being. Human love needn't involve that level of dependency; you could be occasionally forgetful without great consequences.

@neron

I've now added eight English sentences on the theme of kindness, empathy, cruelty and criminality.

[#3504510] Witnessing cruelty to animals, children may become cruel.
[#3504511] Parents shouldn't let children be cruel to animals.
[#3504512] By example, parents should teach their children kindness.
[#3504513] Young children ought to learn empathy for animals.
[#3504516] Callous, unemotional children can sometimes become adult sociopaths.
[#3504517] Violent criminals were often bullies in childhood.
[#3504518] Troubled children often lack any sense of guilt.
[#3504519] In childhood, many violent criminals wantonly abused animals.

@Objectivesea
Thank you very much. Those are really nice examples of sentences by itself, if I may say so. I've really enjoyed translating them. And, at the same time, they seem as a proper response to this sentence on which we are commenting.

considering all the discussion, what do native English speakers say about the article? a, the or none?

I always was translating this joke shorter: The hedgehog is a proud bird. It doesn't fly without a kick.

And Ooneykcall is 100% correct. I am that hedgehog time to time myself. Sometimes I need a good shake to start doing something.

And guys. What it has to do with the cruelty towards animals?

Hedgehogs are proud birds.
The hedgehog is a proud bird.