Hatching Plans

posted in: Local Conservation, Turtles | 0

As many of you have certainly noticed, it’s been an odd summer in terms of weather. June was off-the-charts hot; tying the all-time heat record for several different days here in Eastern Mass. On June 30th, Boston hit 100 degrees, the ninth June day that eclipsed 90 degrees…but by July 3rd, we’d plummeted to 60 degrees, and wet. By July 3rd, we’d had 1.5” more rain than we’d had in all of June, and it continued to rain: this July was officially the rainiest on record. The mercurial weather stymied a lot of vacation plans. It also led to some uncertainties in our jobs as conservation managers. High water levels led to adjusting or cancelling some projects, but the biggest impact may be on something not immediately obvious: the nesting patterns of our turtles.

Eight dirty, deflated turtle eggs on a white paper towel. Various of them are broken open to show hints of pale yolk.
It’s hard to say why some eggs fail – maybe temperature, or moisture, or they were infertile to begin with.

June is a hectic month for us: we’re feverishly tracking turtle moms, often late into the night, to protect their nests. July is a time for us to recuperate and get back on track with our other important summer projects. But while we work elsewhere, arguably the most important piece of the turtle life cycle is happening, underground and unseen: the turtle eggs are developing. Turtle moms don’t monitor their nests, and the eggs rely on thermal energy and their yolks to grow and develop, so the weather is incredibly important! Too cold, and the eggs won’t have enough energy to succeed. Too little water, and the hatchlings might desiccate, or have their shells punctured by desperate plant roots. Too hot, and the eggs will roast. Too wet, and the eggshells could get inoculated by fungus. 

And of course, it’s extremely important to these species that their young survive! We make small adjustments to increase survival probabilities in this egg stage. We protect the nests by placing hardware cloth over the top of the ground above the nest and securing the mesh with landscape stakes. This is by no means fool-proof– a truly determined predator would be able to dig around or yank up the protection– but making an easy meal into a difficult one discourages many nest thieves. We also “water” the eggs a few times a week in drought conditions (not a consideration this year.) After about 55 days of gestation, we remove the hardware cloth. For most nests, we replace it with a cage. The cage allows hatchlings to dig up and out of the nest,  and protects them once they’re aboveground from terrestrial and avian predators alike. It also allows the hatchlings to be collected and marked for future ID, and some are entered into our headstarting program, where they’ll be raised for 9 months by partnering organizations and schools! 

A gray wire mesh sheets sits stapled into the ground amidst a field of plants, pebbles, and soil. Bright flagging tape and small red and yellow landscape flags indicate the position of the nest.
Here is one of our turtle nests, flagged and screened to keep it safe from human interference and hungry predators alike. The screen is replaced with a cage shortly before hatching.

Some of the nests can’t be caged properly. For instance, this year one of our turtle moms placed a nest 1-2’ under the asphalt overhang of a driveway. In cases like these, following USFWS protocols, we carefully remove the eggs from underground, which is a great opportunity to examine the eggs themselves. The group of eggs, called a “clutch,” looks impossibly large, like the eggs shouldn’t have been able to fit inside mom at all! Healthy eggs are eggshell-white but oddly leathery, and heavy for their size. As the summer days pass, anticipation builds. We all hope for healthy hatchlings, but sometimes we dig down into a nest and find infertile, deflated eggs. It’s disappointing, but hope springs eternal– the next nest might yield an entire group of healthy eggs! The task of egg removal is akin to excavating precious antique objects from the ground.  Small digging tools and artists’ brushes are used, and each egg is meticulously removed and placed in a prepared container.

The removed eggs are incubated indoors and checked daily to ensure moisture and heat levels remain constant. And of course we look for tell-tale signs of imminent emergence. The first observed sign are tiny water droplets that develop on the egg, followed shortly by a small pip (a hole!) made by the turtle. Within 1-3 days of the first pip, the turtle fully emerges from its egg. The first turtle to pip is cause for excitement and celebration– just a few days ago, Julie sent our staff text chain the adorable picture you see below– a full clutch of healthy, tiny wood turtle offspring! At this point, the hatchling is placed in the “nursery”, a container with soil substrate, and for several days yet they are quiet and mostly bury themselves. After about 3 days they move about the enclosure and are active.  At this time, if a freshwater turtle, they are ready to be placed in a shallow aquarium and fed. Then it’s time for school! There is lots of love and labor by both the turtle mom and biologists to arrive at this point.

Eight small, brown wood turtles, each about the size of a half-dollar coin, crawling around a container with soil, mulch, and sweetfern fronds.
These tiny, healthy wood turtle hatchlings are the result of months of effort by wild turtles and dedicated humans both doing their part.

At this time of year, along with joy, there is uncertainty: how many eggs will successfully hatch? We can’t count our turtles before they hatch– and yet we try in order to organize the machinations of our headstarting projects. For species we’ve worked with for a long time, like the Blanding’s turtles, our estimates are relatively accurate. For relative newcomers, like box turtles or wood turtles, we rely on the experience of other scientists. This can be tricky because the situations are rarely completely comparable. With 25+ nests protected, our estimates for viable, healthy hatchlings range from 100 to 200 turtles. We should know in the next three weeks! Feel free to drop your estimate in the comments below, and be on the lookout for the adorable hatchling pics that are soon to grace your screen.