hey ralph!  there are several reasons for neutering / spaying rabbits aside from population control.  i probably don’t even know all of them myself but a big reason is for the longevity of your bunny.  spayed / neutered rabbits are way less likely to develope cancer.  another huge reason is to reduce all of the hormonal behaviours such as marking with pee & poops, and agressive behaviour like you mention.  if you’re weighing the cost it makes sense to alter your rabbit versus paying for vet bills for cancer treatment.  i just went through this last year when i had a nasty looking, protruding mass removed from my rabbit’s belly.  or even the cost of cleaning up lots of pee spots over the years.  not to mention the cost of your patience and the happiness of the bunny who will be more relaxed without all the hormones.  my unspayed rabbit is 7 yrs old and unfortunately spaying is not an option anymore.  how old is your bun? 

good question!  babybunsmum summed it up very well,but to see it from another point of view also, i attached the House Rabbit Society page on spaying and neutering.

http://www.rabbit.org/health/spay.html

thats a great article… thanks beka!  ralph, forgot to add, when buns lick its usually grooming… showing affection in rabbit speak.  my girl does this when she wants head pets from me.  it can also be a pre-cursor to sexual behaviour, i think.  the pic of your bun is very cute

Ralph – in addition to all the good info that babybunsmum shared – that growl is a territorial sign. These kind of aggressive territorial behaviors are common in rabbits before they’ve been neutered. Neutering will calm him down, and he’s likely to be happier too. An intact male rabbit is also at risk for testicular cancer. Litter box habits generally improve post neuter and it stops territorial spraying.

I feel like the hormones kind of make them a bit crazed – it’s such an overwhelming thing that really has a strong impact on their behavior.