Invasive Fauna
Based on documents from the Department of Natural and Environmental Resources and information obtained, we provide a brief description of invasive and exotic species, specifically fauna. We detail how they arrived, the damage they cause to biodiversity, and even the risks they pose to public health in Puerto Rico. You will also find images of each species to allow for easy identification.
Rhesus macaque (Macaca mulatta)
The rhesus macaque (Macaca mulatta) is one of the exotic primate
species that escaped from the Guayacán istlets and caves in
southwestern Puerto Rico between the 1960s and 1980s…
This species became established mainly in dense forest areas and
at higher elevations, especially within the limestone formations
of Cabo Rojo and San Germán. It can transmit serious diseases
such as herpes B, tuberculosis, hepatitis A and B,
salmonellosis, intestinal parasites, and simian immunodeficiency
virus (SIV). Its presence threatens biodiversity in sensitive
areas such as the limestone forests of Cabo Rojo and San Germán.
It competes with native species for food, alters habitats by
damaging vegetation, and promotes the spread of invasive plants
through seed dispersal.
Patas monkey (Erythrocebus patas)
During the 1960s to 1980s, the patas monkey (Erythrocebus patas)
escaped from captivity in southwestern Puerto Rico and became
established in the dry savannas of Lajas and Cabo Rojo…
Adapted to open and arid environments, it formed stable
populations that are now considered invasive. It can transmit
several diseases, such as simian hemorrhagic fever virus (SHFV),
herpes B, and SIV, a virus related to HIV. It can also carry
parasites such as Streptopharagus armatus, Toxoplasma gondii,
and possibly Mansonella ozzardi. The patas monkey affects local
flora by consuming fruits and plants, altering vegetation, and
digging in the soil, which disrupts the natural balance of dry
ecosystems.
Rat (Rattus norvegicus) and House mouse (Mus musculus)
These animals arrived on the island accidentally during the
colonial period, transported by ships…
They feed on chicks and bird eggs, particularly affecting
endangered species such as the Puerto Rican parrot, as they
occupy artificial nests created for its recovery in El Yunque
and the Río Abajo Forest. In addition, they can transmit rabies
to humans and domestic animals, and infect cats and pigs with
the parasite *Toxoplasma gondii*, which causes toxoplasmosis, a
disease that can be severe or even fatal in humans.
Shiny Cowbird (Molothrus bonariensis)
The shiny cowbird (Molothrus bonariensis)is an invasive species
in Puerto Rico that negatively affects native birds, especially
the Puerto Rican yellow-shouldered blackbird…
Instead of building its own nest, this bird lays its eggs in the
nests of other birds, which reduces the survival of native
chicks because they must compete for the parents’ attention and
food. Although the shiny cowbird has not been shown to transmit
specific diseases to humans, it can carry certain microorganisms
that may affect human health, such as bacteria that cause
gastrointestinal infections or fungi that affect the lungs.
However, to date, there is no clear evidence that it poses a
significant health risk in Puerto Rico.
Green iguana (Iguana iguana)
The green iguana (Iguana iguana) is an invasive species in
Puerto Rico that has caused significant problems in local
ecosystems…
This iguana feeds primarily on plants, including trees, shrubs,
and crops, which can alter natural vegetation and affect other
species that depend on these plants for survival. In addition,
its large size and digging habits can damage natural habitats
and human structures. Regarding health, green iguanas can carry
bacteria such as Salmonella, which can be transmitted to humans,
especially if handled carelessly. Although direct transmission
is uncommon, it is important to exercise caution when
interacting with these reptiles.
Reticulated Python (Malayopython reticulatus)
The reticulated python (*Malayopython reticulatus*), native to
Southeast Asia, has been introduced to Puerto Rico through the
illegal pet trade and now reproduces in the wild in several
regions of the island…
It is a large predatory species (up to 20 feet) that poses a
threat to native wildlife such as birds, rodents, pets, and the
Puerto Rican boa, seriously affecting ecological balance. It can
carry bacteria such as Salmonella and other pathogens, and also
represents a physical risk to humans and animals, which has led
the Department of Natural and Environmental Resources (DRNA) to
allow unrestricted hunting of this species.
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Boa Constrictor (Boa constrictor)
The boa constrictor is a non-native snake introduced to Puerto
Rico, likely through the pet trade. It now reproduces in the
wild, especially in western areas such as Mayagüez, Cabo Rojo,
and San Germán, where dozens of captures have already been
reported…
It is a large snake, up to 10 feet long, that feeds on birds,
rodents, bats, and even pets, posing a threat to native wildlife
and protected species such as the Puerto Rican parrot and
certain pollinating bats. In addition to its ecological impact,
it can carry pathogens such as Salmonella and viruses that
affect other snakes. Due to its environmental and health risks,
the Department of Natural and Environmental Resources (DRNA)
considers it a harmful species, authorizing its capture and
removal without restrictions. It also competes with the Puerto
Rican boa (Chilabothrus inornatus), an endemic protected
species.
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Mongoose (Herpestes javanicus)
The mongoose was brought to Puerto Rico to control rats and
mice, but this attempt failed because it is diurnal, while the
rodents are nocturnal…
Instead of controlling pests, the mongoose has caused
significant damage by feeding on native and endemic species,
such as birds (including Puerto Rican parrot chicks that fall
from the nest), lizards, iguanas, snakes, and insects.
Additionally, it is one of the main carriers of rabies on the
island, posing a danger to humans, pets, and wildlife.
Australian blue crayfish (Cherax quadricarinatus)
This invasive crustacean competes for food with native fish and
can feed on small fish, altering aquatic food chains…
It carries fungi and parasites that are not native to the local
ecosystem, putting native species at risk that have no defenses
against these pathogens. By digging and undermining the edges of
rivers and bodies of water, it destabilizes the banks and
contributes to erosion, affecting the quality and structure of
the aquatic ecosystem.
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Lionfish(Pterois volitans)
Native to the Indo-Pacific, the lionfish is an invasive species
that threatens coral reef ecosystems in Puerto Rico and the
Caribbean…
It feeds on juvenile fish, crustaceans, and other small species,
causing a significant reduction in local marine biodiversity and
affecting key species vital to reef health. It reproduces
explosively; each female can release up to 2 million eggs per
year, which are easily dispersed by currents. With no natural
predators in the Caribbean, its population grows rapidly,
invading reefs, mangroves, and both deep and shallow coastal
areas. For protection, it has dorsal spines that contain venom
capable of causing extreme pain, inflammation, and, in severe
cases, medical complications. As a management measure, fishing
campaigns, tournaments, and promotion of its consumption as food
are organized to help reduce its population.
Asian clam (Corbicula fluminea)
The Asian clam competes with native freshwater species for food
and space, altering the aquatic ecosystems of rivers and
reservoirs in Puerto Rico…
Its microscopic larvae can travel with currents or attach to
boats and equipment, allowing rapid expansion into new areas. It
accumulates in large quantities inside pipes, clogging cooling
systems and water intakes in power plants and industries,
resulting in high cleaning and maintenance costs.
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Koi (Cyprinus carpio)
It alters aquatic ecosystems by digging the bottom in search of
food, disturbing sediments and causing water turbidity, which
reduces habitat quality…
It damages submerged vegetation because its destructive behavior
uproots or buries aquatic plants, affecting fish and birds that
rely on that vegetation for shelter or food. It impacts
biodiversity, as by altering the environment, it can displace
native species, disrupt food chains, and contribute to the
degradation of freshwater bodies in Puerto Rico.
Pleco (Pterygoplichthys multiradiatus)
It is a type of armored catfish native to South America that now
inhabits rivers and reservoirs in Puerto Rico after escaping
from the aquarium trade…
This species digs burrows along riverbanks, causing erosion,
damaging infrastructure, and altering aquatic habitats.
Additionally, it competes with native fish for food and space,
negatively affecting local fisheries by displacing species of
ecological and economic value. It can also carry parasites such
as nematodes and protozoa that impact the health of other fish
species, and in rare cases, it could pose a risk to humans by
contaminating water bodies or fishing equipment if not handled
properly.
Cichlids (Herichthys spp.), Jack Dempseys (Amphilophus spp.), Convict cichlid (Archocentrus nigrofasciatus)
Like plecos, these cichlid species were mainly introduced
through the aquarium trade; they fiercely compete with our
native fish for spawning space and food resources, displacing
them from their natural habitats and altering their population
dynamics…
These fish are territorial and predatory species that consume
eggs and juveniles of local fish, limiting the ability of native
populations to regenerate and threatening aquatic biodiversity.
Moreover, some of these fish, such as the Convict cichlid, have
been found to carry flatworms like Bothriocephalus acheilognathi
in other regions. These infections can be transmitted to local
fish, creating indirect impacts on the health of aquatic
ecosystems.
Cuban tree frog (Osteopilus septentrionalis)
The Cuban tree frog, native to Cuba and the Cayman Islands, has
become established in Puerto Rico over the past two decades…
It preys on native species such as coquí frogs, lizards,
scorpions, and other frogs, causing imbalances in the local
ecological structure. This frog secretes an irritating mucus
from its sebaceous glands, which can cause skin irritation and
vision problems if it comes into contact with the eyes.
Additionally, it enters homes, can obstruct electrical systems,
and adapts surprisingly well to urban areas. Although no
concrete cases have been documented on the island, studies in
the United States have found that this frog can transmit
parasites such as the rat lungworm, suggesting a potential risk
to the health of wildlife and humans.
Caiman (Caiman)
They are an invasive species established in Puerto Rico since the 1950s–60s, with sightings reported in at
least 58 municipalities...
Concentrated in areas such as Carolina, Vega Baja, Aguada, and Barceloneta.
Although they are not aggressive by nature, they pose a danger to human safety and native wildlife in rivers,
lakes, and mangroves when defending nests or due to hunger. They can transmit salmonellosis, along with
infections caused by Edwardsiella, parasites (Spirometra), and potential viruses such as West Nile virus.
Tarantulas (Theraphosidae)
The introduction of these exotic tarantulas represents a direct threat to endemic fauna
such as the Puerto Rican Brown Tarantula (Cyrtopholis portoricae)...
and the Pink Arboreal Tarantula (Caribeana
laeta), due to competition for habitat and resources. They also pose a risk to human safety, as many of the
introduced tarantulas are venomous and there are currently no local antivenoms available to treat their bites.
They are commonly seen in the western part of the island, as well as in mountainous and northern areas.