Animal Migrations in the Amazon Rainforest

The words Amazon Rainforest conjure images of luxuriant jungle—vast and unchanging for kilometers on end. Here, where it is lush and green all year, one might predict that animals are freed from the need to migrate seasonally due to changes in temperatures or food availability. However, the Amazon actually features some of the most extraordinary migrations on Earth.

The Amazon Basin: a vast matrix of rainforest and freshwater. While it might seem like animals have no reason to leave their home ranges, the Amazon features some of the most spectacular migrations on earth. Photo by Neil Palmer Photography ©

Animal migrations are a conspicuous phenomenon, noticed even by the most casual observers. Many of us (in temperate regions) are familiar with the straggling “V”s of geese crossing the horizon as they migrate south for winter. Others may think of wildebeest moving across African savannas to follow the rains, or salmon leaping up waterfalls to spawn in the mountains. But what about in the Amazon? While it might seem like there is little reason for animals to migrate in an ecosystem so lush and full of life, scientists are beginning to understand more about animal movements in the world’s largest rainforest.

Unlike the African savannahs, the Amazon is thick with vegetation, making land-based migrations very challenging. There is only one species of mammal in the Amazon Rainforest that lives in large herds: the white-lipped peccary (Tayassu pecari). They look similar to wild boar, but live in herds numbering in the hundreds! Peccary have been shown to exhibit some local movements to take advantage of different forest types and food resources. However, no evidence has suggested that white-lipped peccary migrate seasonally. 

Contrarily, some of the Amazon’s most notable migrations happen in the water. The Amazon is the largest river basin in the world, with over 3000 species of fish, including many that migrate. The most spectacular are the Amazonian goliath catfishes (Brachyplatostoma spp.), which complete the longest freshwater fish migration on Earth! – over 11,600km (7200 miles). These fish spawn at the base of the Andes mountains, and upon hatching, casually drift down the Amazon River, all the way to the river’s mouth in Brazil. Due to the sheer vastness of the Amazon Basin, and the fact that many river stretches are turbid and hidden, biologists discovered this migration by mapping where goliath catfishes were caught, noting where different age and size classes of the fish occurred. Remarkably, except for a few places where the catfish move through rapids at certain times of year, this migration cannot be observed.  

A local fisherman in the Brazilian Amazon stands with the catch of his life: a goliath catfish. These incredible fish grow to extreme sizes, and undergo the longest freshwater migrations on Earth!

If not by river, the Amazon’s great migrations take to the sky. Some, like the Orinoco goose, migrate within the Amazon Basin. Some birds that live in the Amazon Rainforest make it as far north as the United States and Canada to breed. Scarlet tanagers, familiar to many people in the United States, spend the winter as far south as the Western Amazon. While most birds with this lifestyle migrate to places in Central and Northern South America, Eastern Kingbird, Veery, Gray-cheeked Thrush, Blackpoll Warbler, and Connecticut Warbler are a few examples of some that venture as far as the Amazon rainforest for the winter.

Tracking flying animals across the Amazon has only recently become possible. Even so, it is still fraught with difficulties. For example, researchers struggled with developing a backpack transmitter for macaws. A recent study noted that “The combination of the birds’ destructive abilities and their relatively low body mass has made it difficult to create a transmitter that is light enough for the bird to carry, tough enough to resist destruction, and with enough battery life to last through full seasonal migrations.” Nonetheless, these challenges proved to be worthwhile. The study found that, while some macaws stay put all year, others would migrate over 100 kilometers to spend the nonbreeding season in separate habitats. 

However, the most bizarre Amazonian migration may be that of black skimmers (Rynchops niger). These birds raise their young during the dry season (winter) on the beaches of the Manu river in the Peruvian Amazon. Researchers tracked some of these birds and found they crossed OVER the Andes and embarked to the Chilean coast for the summer. This bird not only migrates upside down (north to south, rather than south to north), but also breeds at the opposite time of year from other migratory birds in the Southern Hemisphere!

Black skimmers (Rynchops niger) lives up to their name, skimming along the water to eat small fish and insects. These unique birds undergo some of the wackiest and most extreme migrations, flying backwards, over the Andes, and during the opposite season!

Interestingly, insect migrations are almost completely unknown in the Amazon Rainforest. However, researchers have recently begun to document the seasonal movements of one species of butterfly. It appears that the butterflies migrate from the foothill forests of the Peruvian Andes out into the Amazon basin at the height of the dry season—a strategy to take advantage of seasonally abundant fresh leaves. This might seem counterintuitive, but the dry season is the sunniest time of year, and so many trees produce new foliage at this time of year to take advantage of the increased sunlight during this time of year. I have been fortunate enough to observe this migration and participate in some of the preliminary studies. 

One thing is for sure, as we begin to learn more about animal movement in the Amazon, we see how life moves within it as well between the Amazon and other places to survive. This illustrates the importance of conservation measures that will protect the connectivity of different ecosystems within the Amazon Rainforest.

Want to help protect the Amazon and its incredible migratory animals? Consider becoming an ARCC Member, or making a donation for a lasting impact.

References

1.  Barthem, R., Goulding, M., Leite, R. et al. Goliath catfish spawning in the far western Amazon confirmed by the distribution of mature adults, drifting larvae and migrating juveniles. Sci Rep 7, 41784 (2017). https://doi.org/10.1038/srep41784

2.  Brightsmith, D.J.; Boyd, J.D.; Hobson, E.A.; Randel, C.J. Satellite telemetry reveals complex movement patterns of large macawsin the western Amazon basin. Avian Conserv. Ecol. 2021, 16, 14.55. Roberts, J.L.; Luther, D. An exploratory analysis of behavior-based

3. Costa, H. C. M. , Peres, C. A. , & Abrahams, M. I. (2018). Seasonal dynamics of terrestrial vertebrate abundance between Amazonian flooded and unflooded forests. PeerJ, 6, e5058. 10.7717/peerj.5058 

4. Davenport LC, Goodenough KS, Haugaasen T (2016) Birds of Two Oceans? Trans-Andean and Divergent Migration of Black Skimmers (Rynchops niger cinerascens) from the Peruvian Amazon. PLoS ONE 11(1): e0144994. https://doi.org/10.1371/journal.pone.0144994

5. https://news.mongabay.com/2013/09/scientists-discover-that-threatened-bird-migrates-entirely-within-amazon-basin/