Why do snapping turtles often build their nests quite a long walk from the water, instead of right next to it? Also, why do the babies hatch now, instead of in spring like so many other baby animals?

– Avi, 4, Portland

Great to hear from a young inquisitive naturalist! Snapping turtles are a great species to study throughout our warmer months because they are fairly common, and their slow movements and large size make them easy to find and observe over time. I’ve been tracking one of the snapping turtles at Maine Audubon’s Gilsland Farm in Falmouth for years. It lays eggs every spring, which gives us a few exciting days every fall when the babies hatch.

Female snapping turtles are predictable when it comes to laying eggs in the late spring. AP photo

We can almost set our clocks to when the female snapping turtle will wander up from the pond to find a spot to lay her eggs. Every year that we’ve found her, it has been during the first week of June. As Avi notes, she makes the 400- to 500-foot journey from the pond to find someplace that will be safe to lay the eggs. In most cases, I see turtles moving uphill to find dry sandy areas to dig a hole for their eggs. If they lay them too close to the pond or body of water that they live in, they may risk getting the eggs wet or too cold. Temperature is critical for development, and actually determines the sex of the hatchlings: warmer temperatures during embryo development will result in females, colder temperatures result in males.

Predation is also a big problem for snapping turtles, with studies showing that over 80 percent of nests are raided by predators. Many of the animals that would make a meal of a turtle’s eggs, including raccoons and mink, are likely to be found around the waters or riparian habitats that the turtle lives in. So perhaps moving away from the water could also help lower predation risks.

Just as we can predict the early June laying of eggs, we almost always see baby turtles hatching out during the second week of September. This has varied over the years, with Oct. 10 being our latest hatch date, despite the same June lay day. Unlike the other “spring babies” that we see with other animals, especially mammals, snapping turtles have a narrower window to reproduce. They can only start mating once they’ve emerged from the mud in the spring (we often see turtles mating during our Spring Warbler Walks at Evergreen Cemetery in mid-May). So by the time females lay eggs, the eggs incubate, and then hatch, we find ourselves in September.

There are sometimes reports of eggs that have overwintered in northern regions, probably because they didn’t have enough time to incubate, that then hatch out in the spring. Still others can hatch, overwinter underground, and emerge from their nests in spring. Good questions, Avi!

CAN SOLAR PANELS AND BIRDS COEXIST?

Since reading that Paris and Oxford have approved a 30 acre solar panel farm, I have been worrying. Is it true that birds flying over such projects can get fried?

– Cynthia Burmeister, Paris, Maine

With climate change arguably the greatest threat to wildlife, human health, and even habitability on this planet, we need to transition to renewable energies as quickly as possible. Acting fast does not mean we should act improperly, and this is where we need to evaluate the different options for a sustainable future, as not all are equal.

The sun sends us energy in the form of solar radiation, and we have several technologies (and more coming) for harnessing this hopefully infinite source of energy. One of those is used in concentrated power facilities, and it has been known to be harmful to birds. These facilities essentially use mirrors to reflect light back to a single point, on a tower, and convert that heat into energy. These systems can heat water to produce steam, or even efficiently store heat in molten salts.

The problem with concentrated solar power facilities is that they use lots, often thousands, of specialized mirrors (heliostats) that essentially create a “heat ray.” This is practically the same technology that Archimedes used to burn attacking Roman ships during the Siege of Syracuse (213–212 BC). Scale up that Greek’s science project, and you can imagine how effective these modern facilities are. They can, unfortunately, “fry” birds that fly through the hot beams. However, to allay Cynthia’s concerns, concentrated solar power is not very common, and Maine is far from suitable for this technology.

The solar technology that we are seeing a big push for in Maine is generating electricity through photovoltaics. This is basically a plan to scale up the solar panels you see collecting sunlight directly on rooftops and ground-mounted platforms. Photovoltaics represent the cheapest solar electricity source, and Maine is a great place for them, especially for homeowners thanks to the restoration of net-metering by Gov. Janet Mills in 2019. From an environmental impact perspective, photovoltaics are great: they don’t produce any pollution or green-house gases. Yes, manufacturing of anything will produce some waste and carbon emissions, but the longevity and efficiency of photovoltaic cells make them one of our best options. And from a bird’s perspective, there is virtually no harm from photovoltaics themselves.

There is potential for adverse impacts, however, as my colleague Eliza Donahue wrote about in August. Photovoltaic technology is great, and placing them on rooftops or brownfields are ideal, but we need to be cautious in large-scale adoption. Proposals for large solar farms on grasslands, woodlands, or other ecologically productive sites need to be thoughtfully sited and evaluated for long-term impacts to the species that rely on those areas — including humans.

Do you have a nature question for Doug? Email questions to [email protected] and visit www.maineaudubon.org to learn more about virtual and backyard birding, online classes, and other programs about Maine wildlife and habitat.


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