Gus: Male, born July 8, 2006 at Caldwell Zoo in Texas. He arrived at the Zoo on June 12, 2008.
Stella: Female, born May 27, 2001 at Cape May County Park Zoo in New Jersey. She arrived at the Zoo on May 21, 2003.
Abigail: Female, born July 17, 2010 at the Philadelphia Zoo to Gus and Stella. The keepers call her Abby for short.
Giraffes are best known for their long necks and the striking coat patterns of irregular brown patches on a lighter background. Each giraffe has a pattern that is unique to that individual, like a human fingerprint. This may help hide them from predators, particularly when they are young, since the bloches tend to break up their outline when they are among trees. Giraffes are divided into several subspecies depending on their geographic location, color and coat pattern. The number of subspecies is still a topic of debate among scientists and ranges from 6 to 9. The giraffes at the Philadelphia Zoo are reticulated giraffes which are identified by their rich brown, geometric spots on a white background Other subspecies include Masai and Rothschild's.
Giraffe necks have seven vertebrae, the same as humans do, and this amazing adaptation allows them to reach food in tall trees that is not accessible to other browsers. Both sexes have two short, blunt, skin-covered horns atop their heads, although some giraffes can have several more. Males in particular develop additional bumps on the skull as they get older. To increase their reach even more, giraffes have an 18 inch long tongue that they use to grasp and strip leaves from branches.
Longevity
A typical lifespan for a male giraffe in a zoo is about 13 years. Female giraffes tend to live longer and have a typical lifespan of 17 years. A very few males may live as long as 22 years, and some females can reach 30, but most individuals don’t reach these oldest ages. Lifespan in the wild is similar to that of zoos.
Reproduction
After a 14 month gestation, a giraffe gives birth to a single calf that can be 6 feet tall (1.8 meters) and 100 to 150 pounds (45 to 68 kilograms). The mother gives birth while standing up, and the newborn giraffe enters the world with a thud as it falls to the ground headfirst. Although it sounds a bit rough, the fall not only breaks the umbilical cord, it jolts the baby which helps it start to breathe. The calf is on its feet within 15 minutes and will nurse within an hour. Baby giraffes frequently lie down and remain still while the mother leaves it for up to 4 hours. After about a month the calves begin to associate with other calves in groups called creches that the mothers take turns watching over. The young giraffe is typically weaned after 12 months although it may stay near its mother for another year.
Behavior
Although giraffes are social, they do not form long lasting bonds with other giraffes. Relationships are casual and individuals come and go from a herd without any reaction from the others. They rarely group closely together unless they are browsing from the same tree or are nervous about a predator. There is no leader and little if any coordination of movement - a group of wild giraffes can barely be called a herd. They do, however, maintain visual contact with other giraffes due to their lofty vantage point, and there is some degree of communication using infrasonic sound.
Males tend to associate with other males to form bachelor groups, but as they mature they are increasingly solitary as they move from group to group searching for females. Bull giraffes will fight for the right to mate with a female in a highly ritualistic manner known as necking. They face each other and begin rubbing their heads and necks together as if to judge each others weight and strength. As the fight escalates the bulls swing their heads and necks towards each other trying to land blows that are powerful enough to knock the other male off his feet. One male will typically give up and run away, although serious injuries do sometimes occur.
Giraffe spend about half of their day browsing on leaves, although most of their feeding is done in the morning and evening when temperatures are cooler. During the heat of the day they simply stand in the shade and ruminate (chew their cud). Giraffes rarely sleep for more than a few minutes at a time, but do lie down to rest.
To learn more about the conservation efforts at the Philadelphia Zoo, click here.