Saturday, February 11, 2012

Eating Habits and Foraging Behavior


Are you ready to digest more information on giraffes?!

Giraffes are herbivores, meaning they only eat plant-based foods.  More specifically, giraffes are classified as browsers because their diet consists more of trees, and less of grasses.  Because they rely on only leaves to energize their bodies, they must eat large quantities.  Their daily intake can be up to 65 pounds, but they only need 15 pounds to survive.  Giraffes usually live in environments such as the savannas, woodlands, and grasslands that provide sufficient resources for their eating habits.


Acacia trees form the bulk of a giraffes diet. From these trees giraffes are able to eat the leaves and twigs using their strong, long tongues.  The Acacia tree leaves contain a lot of water, which allows them to attain water from resources other than lakes or streams.  The advantage of having high-water content leaves as a food source allows the giraffe to go many days without drinking water.  If they do drink from a water source such as a lake, they can drink up to 12 gallons.


Since both males and females feed from the same type of plants, it is important to not create competition among their own species.  Males often feed on leaves higher on the trees than females, thus reducing competition for food.  Because males feed on higher parts of the tree, their diets contain more fiber while the female’s diet is more nutritious due to eating from lower parts of the tree. For both females and males, eating can take up to 75% of their day, especially during dry season when resources are limited, which requires longer browsing time.

One characteristic that is important to a giraffe’s diet is their unique tongues.  They are about 18 inches long.  Having this long of a tongue allows the giraffe to reach leaves and break branches.  Their tongues are also extremely strong, allowing them to maneuver through and deal with thorny branches. Another important characteristic of a giraffe’s mouth is their thick salvia.  It is produced in large quantities during eating times, allowing them additional break down of food particles.  It also protects the giraffe’s throat from the possibility of being harmed by swallowed thorns.


Additional important foraging behaviors include the way in which they obtain water from lakes and streams.  Because their legs are longer than their necks, they must spread their legs far enough apart to allow their necks to reach the water.  They also have very flexible necks, allowing them to reach high parts of a tree for leaves and also, low level streams for water

After giraffes eat their large amounts of leaves and branches, it is important for them to digest these nutrients properly.  Their ruminant stomach allows them to do this.  After swallowing their food, a giraffe then regurgitates it back up into its mouth for additional grinding and break down of the food.  When giraffes drink water from watering holes, they almost always travel in packs.  This allows them to guard each other from predators while the others drink from the water hole in a vulnerable position (legs extended out). 


Interesting fact of the week: Giraffes have a dark colored tongue, which prevents it from getting sunburnt while reaching for leaves!

"Giraffe - The Facts." GCF. Giraffe Conservation Foundation. Web. 11 Feb. 2012. <http://www.giraffeconservation.org/giraffe_facts.php?pgid=39>. 
"Giraffe Fact Sheet." San Diego Zoo. Global. Web. 11 Feb. 2012. <http://library.sandiegozoo.org/factsheets/giraffe/giraffe.htm>. 
"Giraffe." San Diego Zoo's Animal Bytes. San Diego Zoo. Web. 11 Feb. 2012. <http://www.sandiegozoo.org/animalbytes/t-giraffe.html>. 

4 comments:

  1. I like how creative your blog is! You do an amazing job in representing such a fascinating animal. I thought it was interesting that there exists a difference in what males and females eat. Why do you suppose that males tend to go for the higher part of the Acacia tree? Is it because male giraffes are more taller? or is it because females need a particular type of diet in order to produce healthy offspring? I wonder in what ways the higher fiber diet is better for the males. I also wonder how this type of behavior adapted... great blog and keep up the good work!

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  2. I thought it was really cool that males and females kind of eat separately. I guess it is really good for the female giraffes to have more nutrients because they are the ones that bear young while the males are for stamina to protect their mate and young ones and even to mate! I also thought it was really cool that they store water. I wonder if they are related to camels at all or if they are just like camels because they live in that sort of dry condition.

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  3. This is a really cool blog! I also think the height of the tree that the giraffe eats at is super interesting. Just thinking logically it seems that it would be super important for females to have diets high in fiber, for childbirth and rearing. The dark tongue is also interesting, I wonder if that is something that has developed over time or if they had always had it?

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  4. In our Animal Behavior book by Dugatkin (2009), it mentions the optimal foraging theory and how it was used to determine whether how animals optimize their foraging behavior. I'm guessing that giraffes eat mostly Acacia trees because it is the food source that is most profitable for them. While it would be difficult, it would be interesting to do an experiment like Kreb's tit bird study, but with giraffes. Controlling how often a giraffe encounters, how much energy is provided by, and how long the giraffe gets to handle either the Acacia leaves or another type of leaf would be necessary to see when the giraffes should take the most profitable leaves and when they should take both leaves. Perhaps the prey choice model would provide a good prediction of how giraffes forage for leaves under certain circumstances.

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