On Pern, barring occasional variations, female @Dragons and @Fire-Lizard are either green or gold in color, and males are blue, brown or bronze. The larger a color is, the less common it is. For instance, there are more blues than browns, and more browns than bronzes. Half the dragon population is female, with green dragons being roughly fifty percent of the population and golds being one percent or slightly less. Riding a larger color of dragon confers higher social status in Pern's hierarchy, following the dragons own instinctual hierarchy based on color that they inherited from fire lizards. Perhaps as a result of this, it is commonly believed that the larger colors are more intelligent, although recent novels implied that this may not be true.
Gold dragons, also called Queens, are the largest dragons, being 70-80 feet long. They are notable for being the only draconic females that can reproduce of the species, having strong maternal instincts and producing larger, stronger clutches than a green could, as greens are sterile from chewing firestone. Gold dragons are by far the rarest dragons on Pern, at just less than 1% of the population. They range in color from pale yellow to dark, antique gold. They are dominant over all other colors; any non-gold dragon will invariably obey a queen's orders, even against the wishes of its own rider. Queens are not able to chew firestone. As a result, Queens cannot breathe flame. However, they do fight Thread - they fly in the lowest wing, with their riders armed with specially designed flamethrowers to flame any Thread missed by the wings above. This reduces the danger to both rider and dragon, as well as greatly reducing the number of times they have to go between, which could result in a pregnant queen aborting. An egg that is going to hatch a gold dragon is very distinct, developing a gold color a short time after being laid and being larger than other eggs. The mother will also separate it from the others and is often much more possessive of it. A gold dragon will always Impress a heterosexual female and most Weyrfolk believe they prefer young women who were not raised in the Weyr.
Bronze dragons are the largest males (55-65 feet long), although they are significantly smaller than the queens. Bronzes only comprise of about 5% of all dragons. Their color is described as golden-green, but some are dark enough to be nearly considered brown. They are almost always the ones to mate with queens, as the smaller colors generally lack the stamina to chase and catch the gold dragons when they rise to mate. Due to the 5-1 bronze/gold ratio and the infrequency of gold mating flights, they often mate with greens, but their size often put them at a disadvantage in chasing the smaller, more agile females. The senior bronze of a Weyr is determined by which bronze won the mating flight of the senior gold. The rider of a bronze dragon is always a heterosexual male.
Brown dragons comprise about 15% of the draconic population and are 50-60 feet long. They range in color from tan to chocolate. They will occasionally mate with queens, although this is rare, and became even more rare as the dragons increased in size; by Ramoth's time in the Ninth Pass, it is unheard of, although some are willing to try. All riders of brown dragons are male.
Blue dragons are the smallest males (35-45 feet long) and make up about a third (30%) of all dragons on Pern. Their color range encompasses nearly the whole blue spectrum. They are nearly as agile as greens, but unlike the greens, they often have enough stamina to last for an entire Threadfall. They are noted to be some of the fastest straight-line flyers and often Impress similarly quick riders. They mate only with greens, as they are simply too small to keep up with a massive queen over a long mating flight. Some assume the position of teaching the new riders after their Impression. Blue riders are male though there has been known to be rare exceptions.
Green dragons are the smallest normal color (30-40 feet long) and make up about half of all dragons on Pern (50%). Their color range encompasses nearly the whole green spectrum. They are female, but unlike the queens, they can chew firestone and therefore produce flame, although this has the (helpful) side effect of sterilizing them. They are extremely valuable in Threadfall because of their agility, but they lack the stamina to last an entire Fall and generally fly in two or three shifts. Riders of green dragons are typically female, though there has been known to be rare exceptions
Ruth is the only known white dragon, whose rider was Lord Jaxom of @Ruatha Hold. He was not an albino, as his hide contained very faint patches of all the normal dragon colors, visible on close examination when Ruth was very clean. Ruth's egg would not have hatched if Jaxom had not forced it open and released the dragonet from an unusually tough shell; thus, it seems likely that white coloration in dragons is normally a lethal mutation, as it is tradition not to assist dragonets who cannot hatch on their own. It appears that a white dragonet is unable to break out of their own egg, perhaps due to possibly inadequate strength of the dragonet or the unusually tough shell of a white's egg such as Ruth's, or a combination of both. Although his parents are the largest queen (Ramoth) and largest bronze (Mnementh) in the history of Pern, Ruth is smaller than even a normal green dragon in his time; he is only slightly larger than the largest dragons of the first generation. He stands higher than a runnerbeast (horse) at the shoulder and is roughly eighteen feet long. He is male or neuter (undetermined), and assumed sterile, with no urge to mate. Ruth also has the unusual ability to intuitively orient himself in time and space.