Friday, November 21, 2008

Turtles Change Nesting Dates Due to Change in Temperature

Fred Janzen, a professor in ecology, evolution and organismal biology, has studied turtle nesting habits and also collected research going back decades in order to track the habits of the turtles to find out when they make nests and lay eggs.

He has discovered that some species are starting to nest 3 weeks earlier in comparison to ones in the 1990s and thinks this is a fastest response to climate change of any species that he knows of. Turtles young and old have changed their behavior because of the rising temperatures.

He studied various species of turtles and hopes this gives the study more credibility. He made one astonishing discovery in this study. Usually in reptilian eggs the sex is determined by temperature, he figured because of the higher temperature rgwew would be more females than males. The opposite is happening though, there seems to be a larger amount of males to females being born. He thinks because the air feels warmer that the turtles are nestinf earlier, but the ground is still cold leading to the birth of more males.

Janzen thinks that the larger amoung of males will stress the species. Combined with the adult females being forced to change nesting habits, the stresses could mean the species is under real pressure to adapt swiftly, a pace not popularly considered to characterize turtles, he said.

Article can be found here

Duy Nguyen (10)

It remains to be seen if the turtles will adapt to the ground temperatures as well, one would think they would. But with behaviors you never know.

Dr. Fred Janzen has been studying the tutrtles for some time, since the 1980s according to the article.

"Janzen thinks that the overabundance of males will stress the species. Combined with the adult females being forced to change nesting habits, the stresses could mean the species is under real pressure to adapt swiftly, a pace not popularly considered to characterize turtles, he said."- Article

I don't think Dr. Janzen has enough past data to determine if these fluctuations have occured before.


At 2:46 PM, Anonymous Anonymous said...

This is interesting, at the beginnning I thought it would be to keep a balance of sexes by trying to maintian a simialr temperature year to year. Sinc eth eground is still cold though this isnt working, do you think that the turtles will adapt to notice the ground temerature instead of air temp?

Erica Damon

At 3:41 PM, Anonymous Anonymous said...

Wow. Very interesting. I have heard of trees and flowers doing their thing earlier due to climate change, but this is the first I have heard of an animal. So they believe more males are being born because the ground is cold, so that they are not relying on just the atmospheric temperature change to dictate their adaptations. Interesting how that is occuring, and it is amazing how they are nesting three weeks early. Did the article mention how long they have been studying these turtles?

Katie Cole

At 11:20 AM, Anonymous Anonymous said...

If this continues will it eventually get to the point were there a barely any females, or is there still a good number of female offspring (just not as high in numbers as males)?
-Sasha Rogers

At 4:13 PM, Blogger PWH said...

Interesting article. I'm surprised turtles would be the first to take this step in their reproductive behavior as an effect of global warming. What advantages does the turtle laying the eggs earlier give? I wonder whether there will be an evolving of the determination of sex because global warming has led to a population of mostly males.

-Helen Thi

At 6:16 PM, Blogger PWH said...

I wonder how the turtles know to nest earlier, it cant just be the weather alone because what if there were a cold front?

Jennifer Smith

At 1:59 PM, Anonymous Anonymous said...

I never understood but found it amazing that temperature is the main source of determining the sex of the turtle's infants. What makes the turtle know that they should nest 3 weeks ahead?

- David Huynh

At 3:51 PM, Anonymous Anonymous said...

It's definitely becoming clear that we are in a climate crisis, but how have turtles adjusted to temperature fluctuations in the past?

-Jane de Verges

At 4:19 PM, Anonymous Anonymous said...

I guess this is yet another achievement of global warming. It's intersting to know that the sex determination is based not only on the atmospheric temperature but also on the ground temperature. How would an imbalance of the sex ratio affect the species?

Hanbing Guo

At 7:05 PM, Anonymous Anonymous said...

I thought it was positive that the species was able to change nesting habits that quickly in response to rising temps. It will be interesting to follow this and see what happens in the future; what kind of changes will occur in the species in response to more males?

Allan Eldridge

At 9:23 PM, Anonymous Anonymous said...

That was an interesting article. I was wondering has the lack of females to mate caused any increased aggressiveness among the male population vying for the attention of a potential mate? Has any part of their courting process changed because of this?

- Debbie Theodat

At 9:48 PM, Blogger Dan said...

That's interesting that the turtles have responded in such a way, although it is unfortunate that this will create more stress within the species. I'm wondering what the ratio of males to females are compared to previous years.

~Dan Hong

At 10:17 PM, Anonymous Anonymous said...

Very interesting. It seems like a lot of behaviors are related to the temperature. As we know from the class, this is very similar to those in robins: temperature change triggers growth/shrinkage of testicles. This may be true for humans too. we wear thicker clothes as temperature decreases.
I wonder how many more species are affected by this temperature change.

-Yi, Jeongsang

At 11:41 PM, Blogger PWH said...

With the dramatic change in climate and changes in temperatures in the ocean it is not surprising that these turtles are affected by these conditions. I would have never thought that a change in temperature would cause more production of males than females. I'm sure this has a horrible affect on the survival of the species. How can a population reproduce successfully without the proper amount of reproducing females? Nice article. I would like to know more about this study.

-Carlos Varela

At 1:13 AM, Anonymous Anonymous said...

No, the poor turtles!!! I have a male asian box turtle myself, and so this is really irritating me. Turtles are one of our oldest repiles and to lose them would be catastrophic. This isn't a part of your blog, but is there any group that is going to these nests and warming the sand after the females leave so that less males are made? Also besides reproductive stress, does the increased ratio of males to females change or threaten turtles in anything else?

Ada Marie Flores

At 11:25 PM, Anonymous Anonymous said...

this presents some challenges with respect to climate change. but overall i think they must be able to adapt.
-Matthew Sousa

At 5:58 PM, Anonymous Anonymous said...

I was intrigued by the fact the the sex of the turtle is determined by the temperature. I did not know that. Hopefully the need to adapt quickly does not do anything to deplete the species that already exitsts.

Allison Gamelli


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