El Yunque National Forest

Frequently Asked Questions

Questions most asked by visitors.

1. How much does it rain in the rain forest?

2. Where does all the water come from?

3. Are there any snakes in the El Yunque National Forest?

4. Is there any gold left in the rivers of the El Yunque National Forest?

5. Why are there no large animals in the El Yunque National Forest?

6. I have heard that it “rains frogs” in the El Yunque National Forest. Is this true?

7. Why is the Puerto Rican Parrot almost extinct?

8. Have “aliens” been seen in the forest?

How much does it rain in the rain forest?
That depends on which part of the forest you are in. Generally speaking, the higher you are in the forest, the more it will rain. Maximum amounts occurring at the forest’s highest elevations have reached over 250 inches (635 centimeters) annually, while lower elevations receive only 50-60 inches (120-150 centimeters). For the current rainfall readings at selected locations in the forest, see the USGS Rainfall Sensor Map.

Where does all the water come from?
It comes from rainfall much of which is brought to us by the Trade Winds. The Trade Winds, with their moisture laden air sweep westward across the Atlantic ocean and Caribbean sea from Africa. These constant wind currents were named the Trade Winds because they filled the sails of ships sailing from Europe and Africa that carried trade goods to and from the new world. When the Trade Wind clouds reach mountain ranges like those in the El Yunque National Forest, they are driven upward along the slopes. As the moisture laden air rises it becomes colder and condenses into raindrops which fall on the forest below. This phenomenon is known as “orographic” rainfall and it produces much of the rain the forest receives each year. It is estimated that the forest’s average rainfall (120 inches-304 centimeters/year) would yield 160 billion gallons (605 billion liters) annually, enough to supply the municipality of San Juan with a population of half a million persons for over two years!

Are there any snakes in the El Yunque National Forest?
Yes, there are 5 or 6 species of snakes that live in the forest. They are rarely seen, are non-poisonous and pose no threat to humans. The largest of these is the Puerto Rican Boa which can reach a length of 6 feet. It is a tree climbing predator, hunting at night for small animals and bird eggs. It can sometimes be seen at lower elevations coiled-up and sleeping during the day. The other snake species found in the forest are much smaller and do not climb trees and so are much harder to find. To read more about the Puerto Rican Boa check-out EYNF Wildlife Facts-November 2002.

Is there any gold left in the rivers of the El Yunque National Forest?
Yes, but don’t expect to become wealthy by searching for it; estimates vary, but at most you could expect to collect no more than US$2.00 worth for a full day’s hard work! In the early days gold was removed from the sands of rivers such as the Rio Mameyes which parallels PR 191 on the way to the El Yunque National Forest, but the source of the gold was never discovered and the work was eventually discontinued.

Why are there no large animals in the El Yunque National Forest?
The island of Puerto Rico was formed by volcanic activity during the Triassic period. Thrusting out of the Caribbean sea it had no land bridge to any continent. Consequently, the animals of Puerto Rico (and the El Yunque National Forest) originally arrived on the island by either swimming, floating or flying, and thus were smaller in size than those found on large continents. The largest mammalian animals in the forest are the rats, bats and the mongoose (see EYNF Wildlife Facts). A reptile, the Puerto Rican Boa can grow to a length of 6 feet but poses no threat to humans. None of the animals of the forest, large or small (including insects) are poisonous. The tarantulas, scorpions and centipedes found in the forest can provide a venomous bite (similar to a bee sting) but are only dangerous to those who are allergic!

I have heard that it “rains frogs” in the El Yunque National Forest. Is this true?
This interesting forest legend involving Puerto Rico’s indigenous Coqui frog Eleutherodactylus coqui is actually based on scientific fact! During those times of the year when the humidity is high, the tiny Coqui frogs will climb to the forest canopy, sometimes as high as 100 feet (30 meters). Predators such as the Tarantula anticipating this behavior, lay in wait for the frogs. Many frogs are caught by the predators during their ascent. Instead of returning to the ground by the same dangerous path, the surviving frogs prefer to launch themselves into the air, thus bypassing their predators on the way down. The tiny frogs are almost weightless so that they float to the forest floor unharmed. If you are lucky enough to be sitting under a tree when this is happening, you will indeed be “rained upon” by tiny frogs! To read more about the Coqui frog check-out EYNF Wildlife Facts

Why is the Puerto Rican Parrot almost extinct?
The Puerto Rican Parrot Amazona vittata is the only native parrot on the island. When Christopher Columbus arrived here on his second voyage of exploration in 1493, these birds were a common sight throughout the island. This parrot is a forest bird which requires large hollow tree trunks for nesting. As trees were cut-down by the original settlers to make way for farms, the parrots gradually retreated into the remaining patches of forest. During the ensuing centuries it is estimated that 85% of the island was deforested. Only in the protected El Yunque National Forest could the parrots still find the large trees that they needed for nesting. Until laws were enforced that stopped parrot hunting in the forest the parrot population decreased substantially. In 1968 the Puerto Rican Parrot was placed on the Federal Endangered Species List and cooperative effort by the USDA Forest Service, the US Fish and Wildlife Service, the Commonwealth of Puerto Rico Department of Natural and Environmental Resources and the World Wildlife Fund were begun to recover this important species. The continuing decline in the parrot population results from a number of factors; nest competition by the Pearly-eyed Thrasher, an aggressive bird that has invaded the parrot’s prime habitat; an infusion of honeybees that have taken over cavities in many of the Palo Colorado trees suitable for parrot nesting, and for various other reasons. A parrot aviary managed by the USFWS has been established in the El Yunque National Forest. Here parrot eggs are hatched and fledged in captivity, birds are prepared for living in the wild and subsequently released. The present population in the wild numbers less than 50 individual birds but captive individuals and pairs are being released into the wild on a yearly basis, and their survival rates are encouraging. For more information on the Puerto Rican Parrot check-out EYNF Wildlife Facts-August 2004 or CLICK HERE to read the amazing story of how the Puerto Rican Parrot was rescued from estinction.

Have “aliens” been seen in the forest?
There is no scientific evidence that “aliens” have “visited” the El Yunque National Forest, however local folklore has kept this story alive for years. The most reasonable explanation for any “alien sightings” in the forest is easily explained. From the early 1960’s until quite recently the US Navy maintained an Electronic Tracking Facility on Pico del Este (East Peak) a part of the El Yunque National Forest that overlooks many of Puerto Rico’s major northeastern roadways and towns. At night the lights of the facility, seen from below during military exercises cast an eerie glow over the mountain peak, which most probably added fuel to the legend. However, only the forest animals know the full story behind these supposed nocturnal “alien visits” and so far they’re not telling us!

USDA Forest Service - El Yunque National Forest
Last Modified: Tuesday, 16 December 2008 at 13:52:55 EST