Invasive Species
Background: a form of biological pollution
What are they?
Invasive species are non-native animals or plants introduced to an ecosystem.
Where do they come from?
Invasive species are introduced either accidentally or intentionally.
What harm do they cause?
Invasive species threaten the native species in an ecosystem, impacting the food chain and competing for habitat and other resources. They have the ability to reduce the biodiversity in an ecosystem when they compete with native species (General Information about Invasive Species).
Invasive species are non-native animals or plants introduced to an ecosystem.
Where do they come from?
Invasive species are introduced either accidentally or intentionally.
What harm do they cause?
Invasive species threaten the native species in an ecosystem, impacting the food chain and competing for habitat and other resources. They have the ability to reduce the biodiversity in an ecosystem when they compete with native species (General Information about Invasive Species).
West Indian Mongoose
How did it get to Puerto RIco?
The West Indian Mongoose was intentionally brought to Puerto Rico in 1877 to "prey" on black rats living on sugarcane plantations in Puerto Rico. The black rat arrived in the 1500s accidentally, arriving as a stowaway with Ponce de Leon. Unfortunately, the rat population grew after finding food water and shelter throughout urban, rural and natural environments. Over time it has become clear that mongooses cannot control the rat population, and once they were in Puerto Rico, they began to change the ecosystem.
Description:
The mongoose has a thin body with a long tail; the body is 9 to 25 inches and it has a tail extending another 9 to 20 inches. Their weights vary from one to 30 pounds. In Puerto Rico, they are grayish brown, with long and coarse fur.
Habits:
The mongoose is terrestrial and agile, able to climb using its 5 digits on each limb and sharp and curved fore claws. They are both nocturnal and diurnal. The mongoose is a threat to many species in El Yunque as a tertiary consumer, preying on insects, frogs, snakes, birds, insects and other small animals. Breeding takes place throughout the year, with a female having up to 5 litters in 18 months. With each litter having 1 to 4 young, and a short gestation period of 42 days, the mongoose population can grow quickly. They can live up to 20 years.
Habitat:
The mongoose lives in hollow logs or trees and holes in the ground. Eventually, his nesting in tree trunks kills the trees, eliminating them as a possible habitat for other animals.
Their home range is approximately one mile. They easily adapt to new surroundings and are able to survive given the wide range of food which it eats.
(Cruz, Welcome to El Yunque)
Threats:
They prey on birds, including the Puerto Rican parrot, small mammals and reptiles. The IUCN includes the mongoose as one of the top 100 of the world's worst invaders, and the threat is especially seen on islands where new predators are rarely introduced. The mongoose changes the ecosystem as he is an additional consumer which can cause extinction of other species and overpopulation of others.
(Gannon)
The control of mongooses has been one of the most challenging obstacles for El Yunque Forest. Studies show that the mongoose and rats have populations throughout the Forest that will rise and fall with local migration of other species. Mongooses adapt to their environments easily and move around. Public education is needed as the mongoose carries rabies, which is a threat to human health. Mongooses destroy young Puerto Rican parrots that are not able to fly and are attacked on the ground. The loss of a young endangered birds hurts the recovery program of the endangered species. The current humane trapping and processing of mongooses remains the most responsive pest control program in the Forest. In 2008, 95 mongoose were "live-trapped". There is no information available as to how many mongoose exist in the Forest.
Control Methods:
The most common control method is trapping, although poison is also used. In El Yunque, the US Forest Service spends approximately $10,000 per year for two people who trap the mongooses. The exact impact of these efforts is not known.
(Barun; Cruz, Monitoring and Evaluation Report 13)
The West Indian Mongoose was intentionally brought to Puerto Rico in 1877 to "prey" on black rats living on sugarcane plantations in Puerto Rico. The black rat arrived in the 1500s accidentally, arriving as a stowaway with Ponce de Leon. Unfortunately, the rat population grew after finding food water and shelter throughout urban, rural and natural environments. Over time it has become clear that mongooses cannot control the rat population, and once they were in Puerto Rico, they began to change the ecosystem.
Description:
The mongoose has a thin body with a long tail; the body is 9 to 25 inches and it has a tail extending another 9 to 20 inches. Their weights vary from one to 30 pounds. In Puerto Rico, they are grayish brown, with long and coarse fur.
Habits:
The mongoose is terrestrial and agile, able to climb using its 5 digits on each limb and sharp and curved fore claws. They are both nocturnal and diurnal. The mongoose is a threat to many species in El Yunque as a tertiary consumer, preying on insects, frogs, snakes, birds, insects and other small animals. Breeding takes place throughout the year, with a female having up to 5 litters in 18 months. With each litter having 1 to 4 young, and a short gestation period of 42 days, the mongoose population can grow quickly. They can live up to 20 years.
Habitat:
The mongoose lives in hollow logs or trees and holes in the ground. Eventually, his nesting in tree trunks kills the trees, eliminating them as a possible habitat for other animals.
Their home range is approximately one mile. They easily adapt to new surroundings and are able to survive given the wide range of food which it eats.
(Cruz, Welcome to El Yunque)
Threats:
They prey on birds, including the Puerto Rican parrot, small mammals and reptiles. The IUCN includes the mongoose as one of the top 100 of the world's worst invaders, and the threat is especially seen on islands where new predators are rarely introduced. The mongoose changes the ecosystem as he is an additional consumer which can cause extinction of other species and overpopulation of others.
(Gannon)
The control of mongooses has been one of the most challenging obstacles for El Yunque Forest. Studies show that the mongoose and rats have populations throughout the Forest that will rise and fall with local migration of other species. Mongooses adapt to their environments easily and move around. Public education is needed as the mongoose carries rabies, which is a threat to human health. Mongooses destroy young Puerto Rican parrots that are not able to fly and are attacked on the ground. The loss of a young endangered birds hurts the recovery program of the endangered species. The current humane trapping and processing of mongooses remains the most responsive pest control program in the Forest. In 2008, 95 mongoose were "live-trapped". There is no information available as to how many mongoose exist in the Forest.
Control Methods:
The most common control method is trapping, although poison is also used. In El Yunque, the US Forest Service spends approximately $10,000 per year for two people who trap the mongooses. The exact impact of these efforts is not known.
(Barun; Cruz, Monitoring and Evaluation Report 13)
Invasive Plants
Overview
Even in a rain forest there are plants which were not intended to be there. A section on Invasive Species should at least point that out.
In addition to the mongoose, there are also many kinds of invasive plants in the El Yunque Forest. Invasive species of plants could detract from the Forest as a tourist attraction, hurting Puerto Rico's economy. In addition, from an ecological perspective, the ecosystem is damaged by invasive plants that do not help to hold soil in place, and by those that take important nutrients from other plants that are needed in the food chain. When an invasive plant takes over in a location, the animals which had relied on other plants in that region, will have to move elsewhere for their food, a clear indicaiton of the negative impact on the food chain.
As the lower levels of the Forest warm due to urbanization in the buffer zone, weedier plants will increase throughout the Forest, as they can survive in different climates. This will further spread invasive plant species.
Control Methods
The 2008 Monitoring and Evaluation Report cited 81 invasive plant species in El Yunque National Forest and 19 top priority species that are a threat to the wilderness. Alternatives were evaluated and recommended. They include: no treatment; manual removal; and chemical controls.
Even in a rain forest there are plants which were not intended to be there. A section on Invasive Species should at least point that out.
In addition to the mongoose, there are also many kinds of invasive plants in the El Yunque Forest. Invasive species of plants could detract from the Forest as a tourist attraction, hurting Puerto Rico's economy. In addition, from an ecological perspective, the ecosystem is damaged by invasive plants that do not help to hold soil in place, and by those that take important nutrients from other plants that are needed in the food chain. When an invasive plant takes over in a location, the animals which had relied on other plants in that region, will have to move elsewhere for their food, a clear indicaiton of the negative impact on the food chain.
As the lower levels of the Forest warm due to urbanization in the buffer zone, weedier plants will increase throughout the Forest, as they can survive in different climates. This will further spread invasive plant species.
Control Methods
The 2008 Monitoring and Evaluation Report cited 81 invasive plant species in El Yunque National Forest and 19 top priority species that are a threat to the wilderness. Alternatives were evaluated and recommended. They include: no treatment; manual removal; and chemical controls.
(Source: Cruz, Monitoring and Evaluation Report 14)