Livestock guardian dogs are often large enough (100-200 lbs.) and strong enough to attack and drive away livestock predators. Some smaller breeds (such as Keeshonds and Tibetan Terriers) are excellent watchdogs, but not guard dogs, because they bark loudly to alert their masters of intruders, but are physically small and not given to assertive behavior. Guard dogs will bark to alert their master and to warn off an approaching animal or human threat prior to their interception of the trespasser. They are different from the smaller watchdogs in that they do not continue barking; they take action. Specifically, livestock guardian dogs such as the Kangal use loud alarm barks as a first line of defense against presumed threats; if these do not deter a perceived foe (either human or animal predators), other displays such as bluffing and charging are employed. For livestock guardians, proactive forms of defense such as bites are only used if all other forms of deterrence fail.