Why are the kangaroos in Australia, and only in Australia? We know that all things were created in or near the Garden of Eden and migrated from there throughout the world. We know this from the scriptures: Adam named all of the animals (Genesis 2:19). Then, later, after the flood, the animals migrated again, this time from the “mountains of Ararat” (Genesis 8:4). Quite a bit is known about present-day animal migration, so it is logical that the animals knew, instinctively, where to go after their disembarkation from the Ark. The details and mechanisms of migration are not fully understood, but it is a fact that even now many animals possess this instinct.
It is not just the kangaroos who migrated to Australia, but also the zebras to Africa, the American buffalo to North America, tigers to Siberia, and the jaguar to South America, etc. Consider the personality of God; He is the master creator of life and beauty. When He created the world, it is logical that He did not want the animal kingdom to be one homogenous mixture throughout the world, but rather He designed the Earth to declare His creative power: cold climates, warm climates, low elevations and high elevations, arid climates, humid climates, all with different mixtures of animals, plants and insects. Consider the world to be like a canvas that was painted by God, each color a different ecosystem, a masterpiece of beauty and diversity.
One can observe the present-day migration of hummingbirds, geese, salmon, butterflies, and many other migratory animals and insects: they have a powerful urge to go where God hardwired them to go. It appears that this hardwired mechanism uses magnetic flux, or scent, or celestial markers, etc., but, science has yet to identify the exact mechanism. It really doesn’t matter, we know that migration happens and we know it is hardwired. For example, the migration of the monarch butterfly takes four generations to complete one cycle. Each generation undergoes metamorphosis; these generations have no way of passing on information to their eggs other than by DNA, yet they return to the identical spot in Mexico each year. There are also mysteries with others who migrate, salmon, whales, many birds, and even zooplankton. Migration is a powerful instinct.
Just recently the Nobel Prize for physiology/medicine was awarded to three scientists (J. O’Keefe, M.B. Moser and E. Moser) who discovered that the brain has a built-in GPS system. They discovered that the brain has grid cells that are similar to lines of longitude and latitude. This allows the brain to have access to its own nautical chart. Modern science is converging with the Bible by showing the complexity and perfection of the creation.
So, in conclusion, the kangaroo migrated to Australia twice: once after he was given a name by Adam and once after his journey on the Ark. For each of these migrations, the kangaroo journeyed to his destination; he had everything he needed including a guidance system and a strong desire to be where he belonged: in his Australian home.
Note: It is generally accepted that the sea level after the creation and also after the flood, during the ice age, was significantly lower than present sea level; this allowed passage to and from Australia on dry land. We believe that both the physical evidence (elevations of ancient civilizations) and Biblical evidence (Genesis 10:25, 1 Chronicles 1:19) support this idea.