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Animals Cooling Down (What Time is it in Nature)

June 20, 2015

It’s been quite warm in the Triangle recently with temperatures approaching 100 degrees several days last week.  While we might see a bit of a decline in the number of visitors at Prairie Ridge on very hot days, the animals that use the grounds don’t have the luxury of choosing to stay indoors.  For this week’s What Time is it in Nature, let’s explore some of the many ways that animals deal with high temperatures!

Let’s start with some of the endothermic animals we have here, also known as “warm blooded” animals.  Check out the long ears on this Eastern Cottontail:

eastern cottontail ears

You can clearly see the blood vessels running along the length of the ears under the very thin skin.  By moving blood through their ears, Cottontails expose their hot blood to cooler air, cooling the blood before it moves to other parts of their bodies.  This helps bring their temperature down.  Cottontails will also seek shady places to rest and tend to sleep during the hottest part of the day.

Another animal that tends to hide during the day is the Eastern Gray Squirrel:

Eastern gray squirrel cooling

Like the rabbits, Gray Squirrels tend to sleep during the day and are most active during the early morning and early evening.  (This is called a crepuscular lifestyle!)  If they do have to be out and about during the main part of the day, you may see them do one of three things to cool down.  They seek shade, staying out of the sun when they can.  When they’re not moving, they will flip their tail up over their backs to shade their bodies.  On really hot days, you may see Gray Squirrels flatten their bodies against the ground in a shady spot.  This brings as much of their belly’s surface into contact with the cool ground as possible and helps cool the blood passing through the area, which in turn helps cool the entire animal.  The squirrel in the photo above was enjoying a cool down on top of a shady post after a quick midday meal.

Mammals aren’t the only endothermic animals, however!  Birds also need to cool down from time to time.  They often seek shade during very hot parts of the day, but they open their beaks and pant to help cool themselves down even more.  The Purple Martins at Prairie Ridge have been panting a lot recently:

purple martin panting

You may see some birds splashing around in the pond to cool off as well.  If you hear a vigorous splashing, sneak quietly up to the sound and you’re likely to find a bird taking a refreshing bath.

Though people tend to think of endothermic animals when they hear the word “animal,” most animals are actually ectothermic, or “cold blooded.”   Ectothermic animals are almost wholly dependent on the environment for their heat and their body temperatures go up and down according to the environmental conditions.  However, that doesn’t mean that an ectothermic animal is automatically the same temperature as the air temperature.  Like endothermic animals, ectothermic animals can change their behaviors to help push their temperature above or below the air temperature.  Take this Eastern Rat Snake:

rat snake basking

It was out on the trail in the sun this morning, stretched out and sitting in place.  You will often find snakes basking in sunny patches during the cooler parts of the day as the sun helps warm them up.  However, all ectothermic animals have an upper temperature threshold; they can die if their body temperature exceeds it.  During the hot part of the day, snakes, lizards, and other reptiles will seek shady places and rest to help keep themselves cool.  Some reptiles may retreat to underground burrows to cool down.  Still others will swim into a pond or stream and wait out the hottest part of the day in the relatively cool water.

Insects are ectothermic animals too, and they exhibit a huge range of behaviors that help regulate their temperatures in hot weather.  Dragonflies will seek shade and rest on the very hottest days to prevent their body temperatures from exceeding their maximum temperature, but you will often see them sitting in strange positions, such as displayed by this Blue Dasher:

blue dasher obelisking

This behavior is called obelisking and it works because the dragonfly orients its body to minimize the amount of surface area exposed to the sun.  By pointing their abdomen straight at the sun, the sun’s rays hit only the very tip of the abdomen  rather than the entire upper surface.  This helps keep the dragonfly cool.  Conversely, on cool days, dragonflies will bask like snakes by flattening their bodies out so the sun hits as much surface area as possible.

Even though many people choose to stay home during hot days like we’ve had this week, you can see some very interesting behaviors if you’re willing to brave the heat.  On your next visit to Prairie Ridge, hop from shady spot to shady spot to stay cool, but look around as you go.  You may see animals doing a variety of bizarre or interesting things to cool themselves down!

What Time is it in Nature is a weekly feature highlighting the current plants, animals, and other wildlife at the Museum’s public outdoor facility, Prairie Ridge EcostationFind out more about the natural happenings at Prairie Ridge at our What Time is it in Nature Archive!

(Photos by Chris Goforth)

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