Galápagos tortoises are natural migrators. The Galapagos Tortoise Movement Ecology Program specialize in tracking the migration routes and behaviors of these reptiles on Santa Cruz Island. Much of this research involves tagging several giant tortoises with GPS devices and then documenting their behavior.
Over the course of a two to three weeks, the slow but steady tortoise traverses 3.7 miles, sometimes more, starting in the highlands before moving to the lowlands, they return to a higher altitude in the summer months.
Galapagos tortoises are known to repeat this behavior every year, basing their journeys on the times where there was the most food. Recent research has suggested climate change to pose the risk of drastically influencing this routine behavior for the worse.
Increasingly rising sea temperatures may impact the amount of rain and, consequently, the abundance of food and resources for the tortoises in their migratory periods.
Cedrela odorata is vulnerable to extinction, just like the tortoise itself which is critically endangered.
Now there is a new evolutionary barrier for Galapagos giant tortoises: the Spanish cedar tree, known as Cedrela odorata. These rapidly growing patches of forest pose a great obstacle for the tortoise, who must already journey uphill for weeks at a time.
The well shaded forests make it harder for the tortoises to stay warm, and the lack of vegetation creates a dangerous and barren wasteland for the tortoises to crawl through for almost two weeks.
Published in Ecology and Evolution, a new study collated all data on the migratory behavior of tortoises since 2009, focusing on the routes of 25 tortoises who, in some cases, would filter through the small gaps in Cedrela strands and brambles.
This slows down the already lengthy and arduous journey of the tortoise, with some of them being unable to maneuver through the strands and ending their quest to the highland region of the island altogether.
The gradually growing forests pose the risk of entirely closing off certain migration routes for tortoises, forcing them to adapt to their heavily routinised behaviour or relent to feeding within the sub-optimal conditions of the cedar forests.
Countering the threat of the forest is a moral quandary, as Cedrela Odorata is vulnerable to extinction, just like the tortoise itself which is critically endangered.
The journey of the Galapagos giant tortoise is one of peril, scale, and determination, in which geographical and climatized barriers have become a notable obstacle over the recent years. Further research is vital for understanding the gravity of the cedar barriers and if there are any effective preventative measures to stifle its spread.
