Monday, November 04, 2013

Warm Autumn Impacting Tortoise Hibernation

There are signs of autumn all around. The leaves of the peach tree are daily turning red and golden.

The toyon fruit (aka California holly) is turning red and attracting the attention of the hungry hermit thrush.

But the on-again, off-again autumn weather is making someone grumpy. The angle of the sunlight signals autumn–time to hibernate–but the warm days keep tempting the desert tortoise to stay up.

As you can tell from the photo, this guy is not asleep. His son, has gone in for the winter. Typically, the old guy is in by mid-October, but this year he can't seem to commit to hibernation. He comes out, sits in the sun, takes a few bites of food then grumbles back into his den. Today he stuck his head out and immediately turned around.

He wants to be asleep, but the warm weather is confusing. Some of the migrating birds have been off in their annual cycles as well. For this desert tortoise who has been in captivity, since the mid-1970s, fluctuating climate is an irritation, but for desert tortoises in the wild there can be serious consequences. If they miss time hibernation, they can get caught away from a protective den when the weather does turn cold. They could use up food reserves before they hibernate.

They do not digest food well without basking in the sun and having hot temperatures. They need to stop eating and completely digest what is in their stomachs before going into a deep sleep. Undigested food in their system can rot while they are hibernating, causing them problems. When tortoises awaken in the spring they have expectations of flowering plants and new greenery that they depend on to replenish themselves after months of not eating or drinking. Changing climate can impact all of the timing in this delicate dance making survival even more of a challenge for wild tortoises.

This grumpy guy has us as caretakers to make sure he has food and vitamin supplements. Wild desert tortoises are on their own. Tortoises around the world need our help. They are important members of their ecosystems and all too frequently they are taken out of the wild, both to their detriment and that of the other plants and animals that depend on them.

Tortoises in Turkey
I recommend book Life in a Shell