The reproduction of the blue lacerta~
Male and female blue lacertas are fully mature at around 1500 years of age, meaning that they are able to reproduce at the same time. The breeding season occurs during early winter to late spring and usually lasts for about 3 - 6 months. During this time, females who have not reproduced for fifty years will produce one egg cell, however females that have recently reproduced (say, in the last 10 years or so) will not.
Blue lacertas will bond, pair, and mate for life with the same partner for the rest of their lives. A blue lacerta can select a mate anytime of the year, although the most popular time is during the breeding season. During this time, matured males will begin to start showing off to females either by flashing or flaring their fins, or showing off their aquatic expertise by leaping, diving and twirling in the water. Males may also begin to be more aggressive with each other as the breeding season nears.
Females may also become increasingly grouchy and picky with other females, especially with younger or newer females to an area. Nipping and slapping is common, especially when there are other males in the vicinity.
Once a suitable mate has been selected, both blue lacertas will follow each other about, hunting together, sleeping near each other, nuzzling and occasionally soft-tackling. They will spend almost everyday with each other, bonding and becoming used to one another as the breeding season approaches. After days of bonding, the female will then start producing a single egg cell, (providing she has not reproduced in the last fifty years) and will begin releasing pheromones. The male will then sense her chemical messages through the air, and shortly afterwards, both will begin to travel further and further away from their small territory, in search for the best site for building a nest for the female to lay her single egg in. Nest mounds made in planted areas (close to water), river banks, and ocean shores are perfect for blue lacerta eggs, providing they are very close to water and have plenty of air. Mound nests are also efficient for blue lacerta eggs, as they build up useful amounts of moisture, creating the perfect environment for developing and hatching. Moisture is very important for eggs as not only will it be useful for developing, but if there is not enough moisture in the air when hatching, the shell membrane will dry out, consequently causing the young hatchling to stick to its' tough shell.
After a suitable nesting spot has been selected, a small yolk would have been formed within the female, ready for fertilization. Mating always takes place in shallow water, usually on ocean shores, or upon shallow river banks. Beforehand, the male will court her, nuzzling and nudging her as he walks around her, clicking gently. The female will then stand still, occasionally clicking as she awaits the male's next move. The male will then approach her side, before mounting her and sliding his paddle shaped tail beneath hers, so both cloacas are touching. He will grip onto her scaled sides with his small claws, holding himself in position for a few minutes, until he eventually slides off. The female will usually remain still directly after mating, whilst the male will plod out of the water, leaving her alone for a few minutes. After a minute or so after lying still in the water, the female will then plod off, before joining her mate once more. Mating may commence more than once between a pair, to achieve effective fertilization.
After the yolk is fertilized, the egg will then pass throughout the female, layers of shell encasing the yolk. Inner and outer shell membranes, mineral salts, and water are added first, before albumen (the 'whites' of the egg) is secreted and layered around the soft yolk as well as more water, and then finally layers of hard shell encase the yolk (the shell is mainly made of calcium carbonate). This whole process takes an average of around a week, before the egg passes through the cloaca.
Around a week or two after being mated, a slight bulge will be just noticeable around the abdominal area on the female. At this stage, the egg is nearly ready to be laid, and the pair will be off again, travelling back to their chosen nest site. Once arrived, the female will begin to make herself comfortable, creating a large mound nest on either soil, amongst foliage, or sand. Both parents will forage around for branches, twigs, leaves, bark, and even mud or sand, to make a suitable mound for the egg to be laid in. The mound will be draught proof (as quick icy changes can kill a developing embryo), as well as reasonably hidden amongst other vegetation so predators cannot easily spot and consume an egg. The mound nest will also be quite close to water, (at least a metre or two away) as it is important for the hatchling to get to the water quickly, so they do not die of either predators, lack of food, or protection.
After a suitable mound nest has been created, the egg forming throughout the female should be ready to be laid. The female will then crouch over the nest, making sure there is an opening in the mound where the egg can slip into easily. The male will stand a little way from the female, guarding the two until the egg has been laid.
She will then begin to push the egg out, her back slightly arched in the process. She may emit several distressed clicks, as egg laying can be a painful process for first time females. After a few minutes of pushing, the egg will eventually slip out from the cloaca, landing into the mound nest. The egg is grey-blue in colour, and is around 30cm long. The female may take a few moments to recover, before she and her mate will cover the egg with a thin layer of leaves, sand and dirt, before covering the whole nest completely.
After the egg laying process is complete and the mound nest is suitable, both parents will leave the egg to hatch by itself. The blue lacerta pair will return back to their daily lives, hunting, sleeping, and interacting with each other, just like before. Reproduction is complete for both blue lacertas, although the egg is still yet to form and grow..
Male courting the female - female left, male right.
A male blue lacerta approaching a female after courting. - female left, male right.
The Growing Egg~
A hatchling nearly ready to squeeze out of the shell
A hatchling nearly completely free of its tigh confines of its shell