Tuesday, July 14, 2015

Summer Sleep: The Wonders of Aestivation

By Sandi Funke, Education Director

Newt at Pepperwood, photo by Joel Cervantes
When traveling in Spain over 20 years ago, I experienced some of the hottest driest days of my life. I remember sitting on a train swooning, feeling light-headed and wishing for more, much more water to drink. I also experienced Siesta - an almost mandated time lapse in the “busy-ness” of the day when folks take a break, close shops, and rest. As it was particularly hot during this trip, I really appreciated some time to sleep and wait for the sun to go down.

Imagine you are one of Pepperwood’s salamanders. As you may know, these amphibians need water to reproduce. They also need to keep their bodies moist. In addition, their food supplies may be low in the drier months. As summer arrives, places of moisture such as Pepperwood’s Turtle Pond and Double Ponds begin to dry up. How would you cope with California’s hot and dry summers?

Pacific chorus frog photographed by TeenNat intern Henry O'Donnell
Amphibians as well as many other animals undergo aestivation. Aestivation is a period of animal dormancy, similar to hibernation. It is characterized by inactivity in which animals lower their metabolism. Aestivation takes place during times of heat and dryness, the hot dry season, which in California is during the summer months. Animals that aestivate undergo very similar physiological changes as animals that hibernate. However, when conditions are right, aestivating animals can arouse more quickly than animals which hibernate.

So where do animals hide when they are aestivating? Well, it depends on the animal. Some creatures seek solace underground, often in burrows, other bury themselves in leaf litter and rubble. Some creatures even climb trees or man-made structures to hang on during the hot times of the year.

Newts aestivating under a rock, photo by Celeste Dodge
Several types of animals at Pepperwood aestivate. Last year Preserve Technician Celeste Dodge captured this incredible picture (left) of California Newts aestivating under a rock near turtle pond. Arboreal Salamanders commonly aestivate in the holes of large oaks especially, and are more tolerant of arid conditions than most amphibians. They adapt by curling their body and tightly coiling their tails! California Tiger Salamanders aestivate nine out of twelve months of the year. Turtles, salamanders, and frogs also avoid much movement during the hot summer months, as do some invertebrates including worms, snails, and even beetles. So as another California summer begins to embrace us with its wide, languid arms, maybe we should take a cue from the animals of Pepperwood? Relax and take time for a long nap!

An alligator lizard hides in leaf litter
Learn more about amphibians:

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