When spring was over and summer was beginning, I noticed that some of the bees still remained red in colour. They didn't behave like killer bees, (they were just like normal bees) and they were named as normal bees when examining them.
There was a Goose attacking some bees and some hives during spring. The hives were destroyed. I didn't stay to witness the whole battle, but I don't think any bees survived the attack. I'm not even sure if that was the cause.
Summer came and some bees still remained red in colour when they were supposed to be yellow. None of the bees were aggressive.