I have a very friendly Partridge Rock Hen and every time I open the tractor she flies up to roost right in front of me ( she likes being petted). Lately she will be roosting on top of the tractor and when she sees the dog will fly into its mouth. The dog doesn't hurt her- he just kinda holds her until I get her. I put her up and then she will do it again! Any ideas on this strange behavior?