Yeah, head bobbing can mean a lot of things. Its one way beardies communicate with each other and with us. It can be a sign of dominance, or sometimes a sign of subbmission, it can be a "hello", and it can also mean "I feel scared or threatened." And, like Sara said, sometimes its hard to tell what they mean at all. All beardies are different, basically you have to get to know your beardie, and see in context what they are doing to be able to decipher exactly what they may mean
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0.1 Bearded dragon
0.1 mexican Black kingsnake
1.1 Leopard Gecko's
0.0.1 Tokay Gecko
1.0 Blue Tongue Skink
0.0.1 Reverse Okeetee Corn
0.1 Anerythristic Corn
0.0.1 Red Tegu
0.1 Bullmastiff
4.1 Cats