Animal migration is not just a journey in search of food
Every year at the fag end of the extended monsoon season, birds start migrating to the wetland areas in my hometown. They come from far and near and more species of birds have been coming with each passing year, especially after protection of migrating birds has been strictly imposed.
Why do birds migrate?
The common answer is for food. Seasonal changes in the areas they are endemic to forces them to leave their homes in search of food. This is true but not entirely. There are more troubling questions here. Why do they travel so far? But what is more incomprehensible is their mortality rates. As they cross oceans and continents, many die due to predators, diseases, injuries and many other reasons. Why travel so far which exposes them to higher mortality rates? Why no self preservation?
All the above questions have changed my understanding of animal migration in general. To understand the mortality rates during migration, we need to look what happens after migration. Migrating animals return to their home regions and what they do next is reproduce. Procreation is the reason why migration is so important. The weaker ones in the herds and flocks have to die. Some will die due to predation, some by diseases, some due to injuries and eventually the ones that return will be the strongest ones, physically and genetically. Migration is a natural population filter. The farther they travel the better the filter works. I came across a research on Arctic Terns flying all the way to Antarctica and back during their migrating season. The fascinating part was, they travel a longer distance during their onward journey but return by a faster route with less stopovers. Then it all became clear to me. The return journey is all about preserving themselves – feeding for enough fuel to burn to reach home so that the stored fat in the body is not depleted and reaching home quickly with less mortality to begin reproduction.
It’s the same with the now renowned yearly migration of Wildebeest across the Masai Mara plains and river, known as the Masai Mara migration. Of the 1 million odd that migrate, just 1–2% die. Even if consider the worst case scenario and take the total mortality rate to be 5%, that’s just 50,000 deaths.
So why such a population filter?
Because of Nature’s rule of Survival of the Fittest. Every living being within nature’s ecosystem is being continuously tested. Only the ones that survive predation, diseases, injuries and natural disasters need to survive. Nature retains only the best. From eating their own infants to starving them to death to pushing the chicks outside the nest so that only the ones that fly survive, nature’s filters are cruel but keeps it’s ecosystem free of genetic diseases. This is why there is only nurturing and no love in nature. This is one critical difference between us and them. We suffer from so many genetic diseases because of the complex emotions we have for our children.
But there is a filter inside our mother’s womb which gets activated as soon as we are conceived. A series of tests are run inside the womb to determine if the zygote can be harmful to the mother or to any zygotes conceived in future by the mother. This is critical since the umbilical cord connects to the blood stream of the mother through which DNA of the child is passed on to the mother which can cause health issues to the mother or to future children. This is why the first 3 months are critical for the mother as well as the baby, why the mother’s health weakens and why chances of abortion are highest in this time frame.
Nature seems to work in mysterious and incomprehensible ways but it appears so because of it’s order and discipline. Specific mating & migrating seasons are why we get to photograph them in different times in different colors, plumage and behavior. If animals were to photograph us based on mating and migrating seasons they would get thoroughly confused because we don’t have any of both. We can have children any time and we travel wherever we want when we feel like. There is no order and discipline in our lives. The fact that we do not adhere to most of nature’s laws is the reason why we are no longer part of nature’s ecosystem.
