Rise in glory,
Bronze and gold.
Dive entwined,
Enhance the Hold.

Count three months and more
And five heated weeks,
A day of glory and
In a month who seeks?
A strand of silver
In the sky...
With heat, all quickens
And all times fly.

  I believe this teaching ballad interprets as three months or longer being the time between mating and clutching. Five heated weeks is the time the eggs gestate on the hot sands of the hatching ground. A possible translation: "Three weeks or more, and up to five weeks for the eggs to gestate on the sand. The eggs are laid and hatch about a month later." The bit: "A day of glory and in a month who seeks" could be reiterating that the eggs hatch roughly a month after being laid.

So dragon gestation would most likely be: 
Mating to clutching - twelve weeks or longer.
Gestation on the sands - four to five weeks.

 

Eggs:

  Clutches normally range between 20 and 40 eggs, with larger queens producing larger clutches. The eggs are laid with thick leathery hides, which are slightly pliable. They are mixed creamy shades of dragon colors. Bronze eggs can have distinct markings, and I suspect it is because the colors and stretching of pigments relate to the size of the egg. As they mature they harden and tighten, causing stretch-marks to become visible. As evidenced in the books brooding queens will constantly fuss over and turn the eggs. This may be to maintain their spherical shape as they transition from soft to hard. By the time the eggs are fully brittle, the yolk - which is actually a padding evenly coating the egg walls - is fully absorbed. 

 

 

 

 

 

 

 

 

 

 

 

Hatching:

  By the time the entire clutch has fully absorbed their yolks and are becoming hungry, an unknown cue will trigger them to simultaneously break through their shells. Synchronized hatching is not outside of logic, considering that dragons are psychic. The maternal crooning of the queen signifies hatching is imminent, which is joined by the hum of the other dragons, gaining intensity until the instant the shells crack. There is little time at this point, for the Candidates in the weyr to don the traditional white robe and gather around the rocking eggs on the hatching ground. Lower cavern's staff race to begin preparation for the celebratory meal that will take place after the hatching.

  Once in a while, an egg fails to hatch. Necropsies revealed handicaps that prevented the dragon from being able to escape it's shell, and in other cases, the dragons were formed with no discernible flaws. The Weyrleader would promptly dispose of unhatched eggs between by the second Pass. Another possible cause for unhatching eggs is a speculated fail-safe.  This proposed fail-safe will activate if a certain part of the genetic code is compromized/altered, resulting in an unnaturally thick shell and membrane which prevents any fetus that is aberrant from escape. This more or less happened in the case of the white dragon, Ruth, who was apparently intended by Anne to be the only one of his kind. (Dragonquest, The White Dragon, and following chronological novels.)

Mating and Sexual Maturity:

  Queens mate as often as every 2-5 years, and reach sexual maturity at about three years of age during the 9th Pass. We can assume it doesn't take as long for previous passes, when the queens didn't grow to such enormous sizes. Greens will mate as often as a few times in one year and likely become sexually active a little earlier. 

Dragons mate on the wing, and altitude is critical. If dragons have to break apart because they met the ground too soon, fertilization could be weak. Worse, the dragons could be so distracted that they fail to react in time and are injured or killed. This is one of the main reasons a female's instinct is to fly as high as possible as quickly as possible, before she is caught. Dragon mating can also be referred to as "twining necks" though dragons can also twine necks on the ground out of simple affection, so  with this term, context is key.

  If it were not for greens, who frequently have an urge to mate, the weyr would be full of frustrated virgin male dragons. If it were not for greens, small agile dragons would not be able to fight thread in place of the larger and more cumbersome colors. Despite being sterile, greens serve a vital purpose in the spectrum. 

  Dragons reach sexual maturity at less than two years of age for greens and males, and up to three for Queens, (Dragonflight). In Dragonseye (beginning of the Second Pass) Zulaya mentions that greens hatched in the tenth month would fly no sooner than the fourth month of the next year. That is only six months! I would think that size and time spent growing has a bearing on this. Dragons don't mate until it is "time." For greens this can be as frequent as every few months. For the Queen it only happens every other year to every three years or more... It all depends on the position of the Red Star. At the beginning of a Pass Queens lay larger clutches and more often. 

  The mating urge is completely overwhelming to female dragons. They are irresistibly compelled to eat, while the males gather and watch tensely. Once sated the queen takes to flight, and the males will pursue her. Her body has saved reserves for this flight. Charged with vigor impressive even among the powerful bronzes, she gives the males a run for their money. Flying closer then diving away to leave them far behind... the male that handles the game with the best intelligence, reflexes and stamina is the one she will allow to catch her. Some inexperienced females get caught before they've made up their minds. 

  Because of the telepathic bonds, the human counterpart of the dragon is nearly incapacitated by the dragon's mental images and emotions. The lust is potent enough that the telepathic green or gold can share these signals to any living thing around her, but fortunately these third parties can  remain in control of their actions. For the rider it is an out of body experience, and if they do not "follow" their dragon at this crucial time, the bond can swing just as far the other way, leaving them farther apart than ever... not healthy for the symbiotic pair. (Particularly implied in Dragonflight as well as other books, when queenriders are urged to stay with the dragon or else she may go between.)

  In the Weyr, chambers are set aside just for the event, so the riders of the mating dragons can have privacy as their dragon's urges completely overtake them.  They can be arranged together or with their significant others instead if they have them. Unfortunately (or fortunately) for other colors, the experience is not exclusive to Queens and bronzes.

 

Population Growth:

The fact that they have a large number of infertile offspring makes them an ideal soldier race. A large population is needed to throw at thread, but if 50% of that population were fertile females, the multiplication of the population would overwhelm Pern. Thus a handful of fertile queens who produce large clutches when the red star is near is the solution. Because the survival rate of dragons is so good, realistically, each queen should only produce only one or two other queens in her lifetime, and a few more during a Pass. Fertility might be hindered by, not only passes, but crowding in weyrs, making it more realistic that Ramoth produced a queen egg in her very first clutch.

 

As sad as it is, this also explains why queens kill each other when they rise at the same time. As crowding occurs, the likelihood of queens rising at the same time grows. If queens who rise at the same time eliminate each-other, then the population will balance it'self. 

 

 

Growth Rate and Life Span:

  Over the course of 18 months, a dragon can grow from the size of a dog or small pony, to the size of a jet plane, and young dragons must eat copious amounts to facilitate this feat. Dragon life-spans are comparable to human's, although, if their death were not synonymous with their human bonded, they may greatly outlive any human. Please refer to the "Dragon Growth Chart," under the "Dragons" category at the top of the page.