I often see comments from people who are completely shocked on my posts and videos that feature a turtle or tortoise laying eggs. It's because they're utterly blown away by both the size of the eggs coming out of them and by the intricate work the mother displays.
Tortoises can lay eggs that are truly remarkable in size compared to the body size of the
animal itself. It’s incredible how these females can develop, carry and then successfully pass these huge eggs once they’ve dug a nest. Small tortoise species like smaller Greeks, pancakes, Egyptians, and western Hermann’s to name a few, typically produce just a few very large eggs in one clutch (sometimes only 1) as opposed species like Burmese star, marginated or leopard tortoises which may lay many eggs in one clutch that are still big but less shocking when compared to the body size of these bigger tortoise species.
Tortoise and turtle species lay eggs at different times during the year depending on where they’re from in the world but most commonly, they nest in spring and summer like this diamondback terrapin at one of our study sites. Although we have some winter layers (as we like to call them) in the Garden State Tortoise collection, it's April through July when things get pretty busy around our property with our hard working moms. From dawn until dusk and even sometimes later at night, females of various species begin pacing their enclosures to find the right nesting spot with some choosing the same ones each and every year.
During this time, these focused moms have one thing on their mind which is in their genetic make up. They must migrate to the best places to lay their eggs. They become restless, sometimes even frantic and this need to migrate is not stopped just because of enclosure walls. This is yet another reason why a spacious, naturalistic enclosure is so important, even indoors. In addition to this restlessness, lot of moms to be will refuse food for weeks until after the body cavity is free of eggs. This often tricks a keeper into thinking their female tortoise(s) may be sick when in fact, they won't necessarily be hungry enough to eat until they've passed eggs.
For the diamondback terrapins we work with in the wild through our Terrapin Conservation Initiative, this is a dangerous time because females are forced to cross busy roadways in order to make it to the places they will dig their nests. You can see just how close to the road this female is as she works herself into exhaustion to safely get her eggs into the ground for incubation. Lucky for her, I was right there to make sure no one disturbed her.
Throughout the course of oviposition (which means to lay eggs), the mother becomes solely focused on digging the nest with her hind legs, pushing the eggs out once labor contractions set in, situating them just right inside the nest chamber and then covering them up with the earth. She may even pull pieces of debris like twigs or pebbles to help disguise the nest from predators and pack it all down. Sometimes it looks like they’re doing a funny dance. Mothers have no concerns or care for their offspring, they just do their best to secure their nests so they evade predation and hatch.
Interestingly, Asian forest tortoises such as the brown and black varieties, scientifically known as the Manouria emys subspecies, go against what is typical for nesting behavior in chelonians. These large tortoises will actually build a nesting mound as high as 2 feet out of sticks, debris, leaves, dead grasses and anything else suitable. They then climb up into it, dig down with their front limbs only to turn around and back into the hole to deposit large clutches of eggs. They then cover the eggs and fully guard the nest for a few weeks before leaving them to finish out incubation and hatch on their own.
For tortoises and box turtles, once the exhausting act of nesting is finished, they may haul themselves underneath a nearby bush or fallen tree to cool off and relax. For aquatic turtles, work is far from over as they must now make it back to the water safely. Some travel impressive distances from their watery homes to nest and that means the journey is only half over once oviposition is complete. Some species will lay more than one clutch in a given season so this means these daring moms have to make the treacherous trek more than once, round trip each time.
It’s always a great idea to be fully aware of when local tortoises or turtles nest in your area so you can keep a look out when driving during peak times. It can’t be stressed enough how dangerous of a time this is for mother turtles. So many never even get to nest because vehicles claim their lives as they attempt to cross roads to get to nesting grounds.
Females of some species like box turtles can actually store sperm from a single mating for several years and continue to lay fertile eggs each year until another mating is required. For other species, females may attempt to nest just 4 to 6 weeks after mating in the spring.
Mother turtles and tortoises may not play a role in raising their young but they certainly work hard to prolong the existence of their kind and hard work is what it takes to save this very threatened group of vertebrates overall. The removal of just one female from a wild population can certainly have its effects on the future of the species in a given area. Turtles and tortoises take years to reach sexual maturity, some taking nearly 2 decades, so a female that is mature and reproductive is a true, irreplaceable treasure.
All this hard work and life risking is to ensure ultimate survival. It's something these animals have done for millions of years. Each year, female chelonians set out to plant the seed for future generations. Although it's nothing new for them, it's a good idea to keep in mind that we are the ones that have gotten in their way now. Nesting treks weren't always so dangerous. Human encroachment costs all kinds of wildlife their lives at a staggering rate but it's vertebrates like turtles and tortoises that suffer immensely. They simply cannot bounce back fast enough like mammals for example. So, sure, maybe a female box turtle isn't exactly packing lunches or helping her kiddies get on the bus, but she leaves the comfort of her woodland home each spring to begin a journey into uncertainty. Every time she does this she is putting her life on the line and in today's world the odds are greatly against her. She may never return home but that's not what's on her mind. She has a job to do and it'll take all she's got. To me, that's pretty epic for a mom.
Chris