The Blue Whales off Timor in a changing world
A blue whale dives off the coast of East Timor
Every year, hundreds of blue whales migrate southwest along the coast towards Australia
However, the migrations are becoming increasingly unpredictable
Every year, one of our tours takes us to the largely unknown Southeast Asian country of East Timor. Just a few meters from the coast, hundreds of blue whales migrate from the mating grounds in the Banda Sea to South Australia and Antarctica every year. The encounters with blue whales are probably the best in the world. Seeing these animals in the water is simply indescribable... However, the migration tends to become more and more unpredictable. The animals are migrating more and more inconsistently and later and later. How and why does the migration of this population of around 1500 animals shift?
First of all, it should be noted that we still have no long-term records of blue whale migrations in this region of the world. Twenty years ago, hardly anyone was aware of the natural spectacle that takes place every year on the coasts of East Timor. Whale watching and swimming with whales only developed in the 2-3 years before the coronavirus pandemic.
However, the main blue whale migration season has already shifted during this time alone. 7-8 years ago, most whales could be observed at the end of September - mid-October. In the last two years, this has tended to be the case in early to mid-November. These are shifts of several weeks (!) in a relatively short period of time. There were also interesting interruptions in the migration. In 2022, there was a constant flow of whales in October with a few animals per day. Then suddenly there was a 10-day lull and no more animals appeared. But from one day to the next, the floodgates opened and up to 25 whales a day migrated along the coast. An even more drastic phenomenon in 2023: Hardly a whale was sighted until the beginning of November. After that, the numbers rose briefly but sharply. Groups of up to 7 whales were observed.
What could be the reasons for the above developments? As so often, we know little for sure, but we have our theories.
Short-term interruptions in migration patterns as described above are probably strongly related to wind & currents. The blue whales use a strong current that connects the Pacific Ocean with the Indian Ocean for their migration. If this current changes temporarily or the wind blows in the opposite direction, this can be a reason for the whales to stop their migration. Why fight the elements when they will carry you towards Australia a short time later? In addition, wind and currents can cause food (aka krill) to gather in specific places, which can cause whales to fill their bellies for a few days. In the animal kingdom, food is often a very strong motivator anyway.
For the stronger migration shifts of several weeks, however, we have to look at more significant developments. The climate emergency has reached tremendous speeds and effects. Especially the sea is increasingly becoming a heat reservoir. In the last twelve months alone, the average global temperature has been higher every day than ever before. Although these are small changes in absolute terms (around 1 degree Celsius), this has a massive impact on ecosystems. These habitats are fragile and sensitive to even small changes. In 2024, the whales arrived late, but were better saturated than in previous years. Apparently, thanks in part to the El Nino phenomenon, they found more food and therefore delayed their migration.