Let’s start at the beginning with chicks in the brooder. Chicks don’t just peck each other for lack of something to do. There is an underlying problem causing them stress and/or aggravation. As with any living creature, the first and foremost necessity for well-being is comfort.
Providing chick starter crumbles and fresh water is a given, so we can certainly rule out hunger as the stress factor. It is my opinion there are two other very important factors to consider. Living environment and lighting, with significant emphasis on the latter. Overcrowding may or may not be the culprit in their acquired pecking behavior. However, if ample space is not provided away from a bright light heat source, their comfort may be compromised.
Always provide more than one feeder so weaker birds are not bullied. Also, by week 3, keep them busy with offerings of green grass, especially when you witness aggression.
You may want to make the switch from a heat lamp and switch to radiant heat from a heat plate brooder. This will solve your fluctuating temperature problem, and providing you have a good number of chicks, it will be sufficient in keeping them warm.
Note: If you feel they are too cold you can supplement with a low-wattage red heat lamp. Low-wattage heat bulbs are sold for reptiles, I usually use a 50, or 100, depending on how cold it is.
I’m convinced that happy and content chickens start in the brooder. It’s easy to tell if the brooder has comfort zones. You should see some birds huddled together under the heat source, some resting alone, some scratching in the litter, and some eating. Watch your chicks, their behavior says it all.
TBN Ranch Chicken Keeping Resources 