"A good tracking dog must posses a very strong urge to chase, play with and carry objects, with vitality and intensity. The intensity of which a dog chases the ball or tug is important however, it’s the determination of which the dog clamps down with his mouth, holds and resists in giving up the object that is desirable. "
Really? Do you really believe so? Toy driven and possessive is a MUST for tracking success? Dogfolk I've worked with in the past would primarily use food, via Joanne's methods. The above description seems like a limited training methodology as any (IOW, specialized), perhaps geared primarily for sport tracking, and excluding particular breeds such as bloodhounds.
"to me the key to her tracking drive was that she just HAD to have her nose into EVERYTHING! Telling her 'no sniff!' was like asking her not to breathe. "
Now that, I can wholly agree with! The matter then becomes, how to communicate your directives, guiding the behavior.
Well then, I hope you can both clearly understand my failure to see drive and possessiveness for objects as somehow being a direct correlation of their aptitude for tracking, and instead are really just a means for motivating. What that implies, is that it's OK to select for a specialized behavior that's conducive to one's training limitations.