Population ecology is the study of these and other questions about what factors affect population and how and why a population changes over time. Population ecology has its deepest historic roots, and its richest development, in the study of population growth, regulation, and dynamics, or demography.
While running, the neck of a giraffe moves backward and forward to keep the animal balanced. Giraffes have a top speed of about 56 kilometres per hour (35 miles per hour), however, because its legs are so long a galloping giraffe does not appear to be going very fast.
But they do it very rarely. A giraf has a lot of legs and neck to coordinate when he gets up, By that time the hyenas or lions already got it. So keep yourselve in a start position, it saves your life. Just like horses giraffes can lock their legs and sleep standing u whitout faling down.