Invasive alien species are organisms that have been introduced somewhere new by humans, either by accident or on purpose, which have negative impacts on the local ecological character, human health or economy. Since European colonisation, a large number of invasive alien species have become established in Barbados. Many have arrived on island accidentally via human travel routes in containers, luggage, potting soil and plant imports. Some were purposely introduced by humans in an attempt to manage agricultural and household pests. Following is a short list of some impactful invasive alien species in Barbados.

Small Indian mongoose (Urva auropunctata)

The small Indian mongoose is considered to be among the top 10 most serious invasive species globally. This species originates from Iraq to northern India and has been introduced to the Caribbean around the 1800s, in an attempt to manage rats around plantations. Unfortunately, mongooses are active in the day, and rats are most active at night, and so the introductions were not successful. 

They are voracious, opportunistic predators; feeding on small invertebrates, mammals, birds and reptiles. This aggressive generalism has had devastating impacts on many species of reptile in the region, directly being linked to lizards and snake extinctions. Now the endemic reptiles that mongooses preyed on are rare or gone, but the rats remain.

Soon after its introduction in the 1870s, the mongoose was linked to the decline of the endemic Barbados skink (Alinea lanceolata) and Barbados racer (Erythrolamprus perfuscus). Their impacts on native species continue as they prey on endangered sea turtle nests, eating the eggs and hatchlings; often excavating entire nests. Mongooses are also a threat to poultry and are vectors of diseases harmful to humans, including leptospirosis, murine typhus and rabies in some Caribbean countries. Since they pose a threat to agriculture, human health and biodiversity, mongooses fulfil all criteria of an invasive species.

Jungle centipede (Scolopendra subspinipes)

The jungle centipede is a voracious predator of both invertebrates and small vertebrates, like lizards and even mice. The species has a global distribution and not much is known about where it originates from, but it is theorized to have originated in Vietnam and been spread throughout the tropical areas of the globe through anthropogenic means, such as the plant trade. It subdues prey by seizing it with its back legs, coiling around the prey item and injecting venom using its toxicognaths. It is known to cause declines in native reptiles where it is introduced; on Christmas Island, it contributed to the decline of five endemic and one native lizard. It is not known when the centipede was first introduced to Barbados, however, it has certainly been on the island for centuries. Rev. Griffith Hughes in his 1750 “The Natural History of Barbados in Ten Books” mentions them, even referring to them by their still-used Bajan name “forty legger”. In Barbados, it is known to prey on the Critically Endangered and endemic Barbados leaf-toed gecko (Phyllodactylus pulcher), and likely the Barbados threadsnake (Tetracheilostoma carlae).

African house gecko (Hemidactylus mabouia)

The African house gecko is a common sight in Barbados in urban environments, often hiding behind paintings and other objects mounted on or near walls. They are medium sized, with scales that vary in colour from dark brown to light grey; their tails have dark rings and their fingers have long claws for gripping. Their slender bodies are mostly covered in black/brown bands. These geckos have the ability to change colour based on physiological conditions like temperature and light.

The house gecko typically can be seen using artificial lights, such as those that illuminate roads at night, to catch insects that are lured towards them. They are not picky eaters and will consume any prey that they can reliably take down, even going for insects as large as centipedes like Scolopendra. They are also known to eat other species of gecko.

The African house gecko is native to sub-Saharan Africa and is thought to have been introduced into the Caribbean via the slave trade from the 15th to 19th century, where it stowed away on ships crossing the Atlantic. It is thought that this is what led to creation of its local common name in Barbados and some other Caribbean countries, The Wood Slave. There are varying cultural perceptions of the gecko with some seeing it as a good omen within houses that eat cockroaches, while others view it as bad luck.  The African house gecko is invasive in most of its introduced range across the Caribbean and South America. Within this introduced range it outcompetes native species of geckos, such as the Barbados Leaf toed gecko (Phyllodactylus pulcher), by aggressively displacing them from their territories, often eating them in the process. Their generalist diet also contributes to declines in native species as they lose access to their preferred food sources. The only reprieve most native gecko species have from the house gecko is due to their preference for urban environments; this does not stop them entirely from invading natural areas though.

Ring-necked parakeet (Psittacula krameri)

The ring-necked parakeet is well known here in Barbados. They can be easily spotted in flight with their vivid green colouration, long pointed blue tails, red beaks, and distinct loud squawks. This bird species is native to the Indian subcontinent and Sub-Saharan Africa, with introduction to Barbados occurring from the pet trade. It is quite popular due to their ability to repeat words, phrases, and songs very clearly. They are also different colours they are bred for in captivity, like blue, yellow, and white.

They pose a threat to agricultural production and various native and endemic bird species. They are herbivorous birds that often feed on many fruit crops around the island. They may also compete for nesting spots with the native species like the Orange-winged Amazon, Amazona amazonica, which are not seen as commonly on the island anymore. This bird can also act as a host or vector for diseases such as the Psittacine Beak and Feather Disease Virus, which can be contracted from infected birds and contaminated surfaces, affecting wild and captive avian species and even human health.

Mother-in-law’s tongue (Dracaena hyacinthoides)

Dracaena hyacinthoides, famously known as mother-in-law’s or snake plant, is a popular indoor and outdoor plant often said to be a good air purifier. It is an evergreen from the Agave family, and it is native to Africa, Madagascar, and southern Asia. 

This plant is characterised by its rigid, upright, sword-like leaves. It has a network of creeping rhizomes underground, with hard basal leaves coming from the base of the plant. 

Dracaena hyacinthoides has leaves of various colours, ranging from green to brown, with different types of spots or stripes. The leaves can be arranged in a circular pattern or upright and erect, with either an elongated and narrow shape or a broad, spear-like shape. 

Mother-in-law’s tongue plants can be incredibly invasive because they spread aggressively through their underground rhizomes, which crowd out other plants. New plants can also grow very easily from even small pieces of the plants, including leaves. This is why it is recommended to keep them potted to prevent their invasiveness.

Flamboyant tree (Delonix regia)

Delonix regia, or the flamboyant tree, is a species of flowering plant that is native to Madagascar. They are widely distributed in tropical and subtropical regions of the world, including the Caribbean, Central and South America, Africa, and parts of the United States. 

The Flamboyant tree is highly recognised for its brilliant display of vibrant red-orange flowers. Its leaves are compound and feathery, with numerous small leaflets which contribute to its elegant appearance. Flamboyant trees can be found in abundance all across the island, in both urban and rural landscapes. They are planted in parks, along the street, in car parks and are even present in gullies. 

Delonix regia was introduced into the Caribbean and Barbados sometime during the 19th century. It was brought for its ornamental value and as a shade tree. In certain regions, such as Australia, Christmas Island, and several Pacific islands, Delonix regia is considered an invasive species due to its ability to outcompete native species in the area, thereby disrupting local ecosystems. In deforested areas, it can prevent the regeneration of native species. The dense canopy of flamboyant trees excludes native plants and grasses, restricting their growth. The roots can also cause damage to concrete structures, sidewalks and footpaths. 

MacArthur palm (Ptychosperma macarthurii)

Ptychosperma macarthurii, commonly known as the Macarthur palm, is  a species of palm native to tropical regions of Oceania and Australia. Macarthur palms are often found near watercourses or in areas with consistent moisture. This species grows in clumps that get to approximately 10 meters tall, with multiple slim, ringed trunks and prominent leaf scars. The leaves are green, feathery, flat, and broad, with jagged tips. 

These palms are thought to have been brought to the Caribbean sometime during the 19th century after they were first described by Sir William Macarthur in 1884. Macarthur palms are widely used ornamental plants and many of the specimens found in the wild outside their native range are escapees from gardens, with their seeds easily spread by birds on the island that feed on their fruit. In places where it is invasive, the MacArthur palm threatens local ecosystems by outcompeting native species for limited resources, altering habitats and disrupting the balance within plant communities.