How Does Temperature Affect Turtle Gender?

One of my close friends, Rahik, asked me about turtle’s reproduction and gender determination. When I told him about the temperature-dependent sex determination process in turtles, he first asked how temperature affects turtle gender?

The sand temperature during the hatchling or egg incubation period determines the gender of the turtles. In short, high temperature develops the eggs as female turtles, and low temperature develops the eggs as male turtles. This process can cause gender imbalance in sea turtles.

But why does a turtle’s gender imbalance occur only in the ocean? Is there any temperature chart to follow to control the gender ratio of turtles? 

I know there are more queries about this topic, so I came up with this article to explain the effects of temperature on a turtle’s gender.

Key Highlights

• The turtle’s gender depends on their egg incubation temperature.
• Warm temperatures led to female turtles, and cool temperatures led to male turtles.
• Environmental warming causes temperature fluctuations, and it creates a gender imbalance in sea turtles.
• Around 99% of sea turtles are born female.
• The feminization of sea turtles is increasing day by day due to frequent climate change.
• Climate change not only influences the gender ratio, but it also affects their nesting zones and reproductive system.

How Does Temperature Affect Turtle Gender?

According to scientist Camryn Allen, the sand temperature where sea turtles keep their eggs for incubation determines the turtle’s gender.

The temperature influences their gender during the embryo’s development of turtles.

If their incubation temperature is high and warm more than 31° Celsius, the eggs develop as female turtles. On the other hand, when the temperature is cool and calm, less than 27.7° Celsius, they grow as male turtles.

It’s common in all sea turtles and some freshwater turtles. From the research report of Duke University, I’ve learned that most sea turtles are born female in present times due to the high sand temperature.

The higher the temperature rises, the more feminization will occur in these turtles. This study also states that the reproduction of pre-eggs or germ cells and the number of female turtles are also increasing.

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Why Are Higher Temperatures Causing This Male-Female Imbalance In Sea Turtles?

While studying about the turtle’s gender, I’ve found that climate change affects sea turtles. Additionally, global warming is the reason for frequent climate change. It happens because of the unkindness of humans towards nature.

Nevertheless, it’s not only damaging human lives but also spoiling nature and other living beings. The temperature of this world is rising higher and warmer day by day. It’s a life-threatening condition for sea turtles.

In addition to that, environmental warming is one of the significant causes of male-female imbalance in sea turtles. 

Warmer temperatures are the major reason that around 99% of sea turtles are turning into females.

What Is Temperature-dependent Sex Determination (TSD) In Turtles?

The process of determining a turtle’s gender by temperature is called temperature-dependent sex determination.

As I’ve mentioned earlier, the gender of turtles depends on the sand temperature during embryo development.

However, TSD is a common term in the biological lifecycle of different species of reptiles, including green sea turtles, loggerhead sea turtles, and leatherback turtles. It can be found in some freshwater turtles like snapping turtles, map turtles, painted turtles, and red-eared sliders.

Temperature-dependent Sex Determination (TSD) Vs. Genotypic Sex Determination (GSD)

The gender of some turtle species can be determined by the genotypic method. But most of their gender determination depends on the temperature. There are several differences between both sex determination methods.

Here are the features of both gender determination methods to understand the difference.

Features	TSD	GSD
Sex determination method	According to the temperature during embryo development	According to the combination of sex chromosomes
Influence on gender ratio	Depends on the temperature fluctuations	Depends on reproduction capabilities
Visibility	Mostly found in reptiles such as turtles and crocodiles	Mostly found in birds, mammals, and other animals
Gender reversal	Chances of reversing the gender are higher due to temperature	They can’t reverse gender because it includes stable hormones
Hormonal connection	No hormonal connection	Highly connected to a hormonal condition

Temperature Chart Of Determining the Gender Of Sea Turtles

After in-depth research, I’ve got a complete temperature chart for the gender determination of sea turtles. This temperature is based on several scientific tests on the lifestyle of sea turtles.

Species	Male-producing Temperature	Mixed temperature range	Female-producing temperature
Loggerhead Turtles	Less than 28.8°C	29.8°C to 31.7°C	More than 32.7°C
Green Sea Turtles	Less than 26.9°C	27.9°C to 31.7°C	More than 32.7°C
Leatherback Turtles	Less than 29.4°C	29.4°C to 30.0°C	More than 31.0°C
Hawksbill Turtles	Less than 29.0°C	29.0°C to 29.5°C	More than 30.0°C

Got questions about Shell + Turtle Anatomy & Physical Traits? This post has the basics, turtle-style. Are Turtles Born With Shells?

How Can You Control The Incubation Temperature For Pet Turtles?

Controlling the sand temperature for sea turtles is quite tough. But we can control the incubation temperature for our pet turtles.

In my experience, I found it a little bit tricky because it requires proper knowledge of the turtle’s egg incubation.

After talking to the vet, I’ve followed this temperature range during my pet turtle’s hatchling period.

Temperature range	Incubation duration	Final Outcome
27.8°C to 30°C	50 to 60 days	Mostly male turtles
30.6°C to 31.7°C	45 to 50 days	Balanced or mixed gender ratio
32°C to 33.3°C	40 to 45 days	Mostly female turtles

The temperature range varies with different turtle species. However, it’s mandatory to keep a consistent temperature throughout their incubation period.

Apart from that, I’ve kept the eggs in a safe place. Using a reliable thermometer is also important for making the process more convenient.

What Are The Effects Of Climate Change On Sea Turtles?

Besides gender imbalance, climate change can affect the sea turtles in other ways as well. These effects make sea turtle’s life intolerable and have a negative impact on their reproduction system. 

• Climate change increases sea heat levels, and beach erosion deeply affects turtles’ reproduction. Also, the erosion reduces the sources of suitable nesting zones.
• When the temperature range gets higher, it alters food availability for turtles and influences their migratory movements.
• The increasing temperature range can cause ocean acidification. It affects the turtle’s health and reproduction abilities.
• Natural disasters can harm turtles’ nesting zones and egg incubation areas. 

Before You Go

After reading thousands of research studies and consulting the experts, I’ve understood the strong impact of temperature on turtles’ gender. Generally, a turtle’s gender depends on the sand temperature in their pre-egg condition and embryo development.

However, you can balance the gender ratio for your pet turtles. To control the gender imbalance of sea turtles, we all need to make the world environment-friendly and restore the natural temperature. If you are interested in learning more about a turtle’s gender, have a look at the article below.

How To Tell Turtle Gender Infographic?