To land a career as an ecologist, a bachelor's degree in a life science is a must. Biology and chemistry are common choices, but these days more undergraduate programs are branching out (pun intended) and offering degrees specifically in environmental science. Getting even more specific, some of these degrees also come with an emphasis in a particular field like soil science, climatology, zoology, or anthropology. These degrees will come with their fair share of math and statistics courses, but crunching numbers in your sleep will come in handy, as a lot of data collected in the field needs to be plugged into various fun formulas and algorithms to make predictions. Those of you that break out in hives at the sight of a calculator need not apply.
Beyond the schooling, the right experience will play a helping hand in finding that perfect starting job. Recent graduates who already have field experience will have the upper hand. Not only does prior experience prove that you can cut it on the job, it also shows that you love nature in all its gritty glory.
Most undergraduate programs will have research opportunities for their students, working on some project alongside a professor. This sort of work will give you valuable experience for both the hands-on parts of an ecology career, but will let you peek behind the curtain and learn about the methods behind research itself. Students studying abroad could even use the opportunity to learn more about nature in truly exotic locales. Beyond the academic stratosphere, environmental organizations are always open to volunteers for certain environmental or policy projects.
Getting to work before graduating can get you dirt under your fingernails and mud in your ears—and in this field, that's a plus. Your mom was right—any experience is good experience, so keep your eyes peeled and ears open for those opportunities to get down and dirty in the field.