The Fran-San site linked to by [D.W.] is NOT about GSDs, it is about the deviation we sneeringly call the NAmerican Ski-Slope Dog. Among the errors in just its HISTORY page are that it claims that GSDs are "wary of strangers", and that Max renamed Hektor as "Horand v Grafeth".
You'll find nothing about being "wary" in the International Standard of the GSD, as approved by conferences of the WUSV (World Union of GSD Clubs, with about 77 member-nations):
"BEHAVIOUR / TEMPERAMENT : The German Shepherd Dog must be even tempered, well balanced (with strong nerves), self assured, totally at ease (except when provoked) and good natured, as well as attentive and easy to train. He must possess courage, combativity and toughness in order to be suitable as a companion, guard, service, herding-dog and «Schutzhund»."
The concept of "wary of strangers" is used by so-called "breeders" who need to excuse the poor character of their stock. A correct GSD is CALM and CONFIDENT and CURIOUS about everything.
As for colour changes:
With a couple of minor exceptions, it doesn't happen.
All properly-coloured GSD pups are born very dark, except if they have inherited a pair of recessives for white spotting. Although undesirable, inconspicuous white spots on chest or toes are acceptable PROVIDED the nails are black.
• Self-black pups have no tan anywhere.
• Tan-point pups (which includes those that will end up as saddle marked, or blanket-backed, or bi-colour) will have tan on their pasterns, cheeks, by their anus, and maybe as eyebrows.
• Wolf-sable pups will start the same as tan-points but once the birth-fluids dry out it will be seen that they are mostly a dark-honey colour except for those tan areas, and they have a dark brown stripe over the spine. By the time buyers see them, at 6 or 7 weeks old, they will be darkish-honey almost all over.
The adult guard hairs start emerging at about 14 weeks old, beginning as a shiny black diamond about 1/3rd of the way down the tail, and then along the spine before spreading downwards.
• Tan-point pups have the tan start spreading at about the same time. For bi-colours it spreads almost not at all. For blanket-backs it spreads to just-above the chest-line. For saddle-backs it spreads until the black covers little more than a patch resembling the saddle on a horse. Regardless of how far it spreads, it is the SAME tan that the baby puppy had. There has been NO change of colour, just a change of distribution of the tan vs the black..
• Wolf-sables have the same adult distribution of black vs tan. But whereas the adult tan-point dogs have black hairs that are black all the way from tip to root, wolf-sables have adult hairs that are black at the tip, paler at the root. Those with more gold-tan than black on each sable hair are known as gold-sables, those with more black than tan-gold are known as gray-sables. There is a variation of wolf-sable that never goes through the dark-honey phase - those are known as black-sables and are probably caused by the same modifier-genes that cause tan-points to be bi-colours - but be aware that most dogs that owners call black sables are actually just gray-sables, equivalent to the blanket-backs but with sabled guard-hairs instead of black guard-hairs.
Exceptions:
• There are undesirable genes for black-loss. These reduce the dark area over a period of about 3½ years, and can also result in so little eumelanin (the black pigment in hairs) being pumped into the black hairs that they look like the dark brown of something that has been partially burned. In extreme cases the saddle-area becomes a brown only a little darker than the tan.
• There are undesirable genes for colour-paling. These weaken the amount of phaeomelanin (tan pigment) being pumped into the hairs, so that over a period of about 3½ years the tan or gold of the baby becomes a pale fawn or cream - in extreme cases becoming almost a chalky-white.
• There are undesirable genes for what used to be called a "bit.ch-stripe". This tends to first appear after the first moult, and in some lines (such as those with many lines to Canto vd.Wienerau) affects dogs as well. It resembles a pepper-&-salt stripe above the spine, being particularly broad above the croup, and sometimes above the shoulders as well.
You can get a good idea about undesirable colour-paling possibilities by looking at the parents, as it seems to be caused by a dominant allele.
But black-loss and bit.ch-stripe are caused by either a simple recessive or a polygenic set of recessives, so can surprise you by being produced by a pair of well-coloured parents.
• Add http://pets.groups.yahoo.com/group/The_GSD_Source to your browser's Bookmarks or Favorites so that you can easily look up such as feeding, vaccinations, worming, clubs, weights, teething, neutering, disorders, genetics in the public section.
To see how pups with various coat-patterns and colourations develop, often from birth, Join the group so you ca