You probably cut into the quick, which will make it bleed but is not a serious injury. Just keep it clean and it should heal without a problem. Next time you trim his nails, don't cut as far back as you did this time. If he has dark nails, it is nearly impossible to tell where the quick is. If he has white nails, look for the pink vein near the back and make sure you do not cut it.

Birds can easily bleed to death from an improperly cut nail. You should always have a little baggie of corn starch handy when doing nail cutting - just in case. Dip the nail in the corn starch or push it against the bleeding nail and it will quickly help the nail to clot and stop the bleeding.

You cut too far, like if you were cutting your fingernail and cut off part of the finger. Only time will tell if it will heal.