Sentence 1: Tim's dog like to chase things. 
 Sentence 3: One day the bird started to fight back 
 Sentence 4:  It started to peck and poke at the dog when it came near 
 Sentence 5:  Tim's dog doesn't chase the bird anymore 
 Option 1: Including a pet rabbit Tim had. 
 Option 2: Including a pet bird Tim had.