Yes, squirrels are present in Puerto Rico, but they are not native to the island. The species found there is the Indian palm squirrel, an introduced species that has established populations across various habitats. This presence raises questions about their arrival and the ecological consequences for Puerto Rico’s unique environment.
Squirrels on the Island
The specific squirrel species found in Puerto Rico is the Indian palm squirrel (Funambulus palmarum). This rodent is recognizable by its grizzled grey-brown fur, a creamy-white belly, and three distinct white stripes running along its back.
Indian palm squirrels are similar in size to a large chipmunk, measuring around 20 centimeters (7.9 inches) in length, with their tail nearly as long as their body. They weigh approximately 100 grams (3.5 ounces) and can reach speeds of about 10 miles per hour. These squirrels are active during the day, known for their agility and vocal “chip chip chip” calls. They do not hibernate due to the warm climate. Their diet includes fruits, nuts, seeds, insects, and small vertebrates like eggs and chicks.
How They Arrived
The Indian palm squirrel is not indigenous to Puerto Rico, originating instead from India and Sri Lanka. Its presence on the island is due to an introduction, though the precise method and timeline are not extensively detailed. Historically, this species was introduced to several other tropical islands, including Madagascar, Réunion, Mayotte, the Comoro Islands, Mauritius, and Seychelles, predominantly in the late 19th century.
Such introductions occur through accidental escapes from the pet trade or intentional releases. Given the Indian palm squirrel’s history as an introduced species elsewhere, it is probable that individuals were brought to Puerto Rico and established a wild population. This pattern highlights a common pathway for non-native species establishing themselves in new environments.
Impact on Local Ecosystems
The presence of the non-native Indian palm squirrel in Puerto Rico raises concerns for the island’s local ecosystems. Puerto Rico has no large native terrestrial mammals; its native mammals are primarily bats and shrews. This absence makes native species vulnerable to competition and predation from introduced species like the Indian palm squirrel.
Indian palm squirrels are omnivorous, consuming fruits, nuts, and seeds. Their diet also includes bird eggs and chicks, posing a threat to native bird populations. Beyond impacts on wildlife, these squirrels can affect agricultural interests, as they are known to damage crops such as pineapple, mango, and sugarcane. They thrive in diverse habitats, including urban areas and agricultural lands, intensifying their interactions with natural and human environments. The introduction of non-native species can alter an island’s ecological balance, potentially leading to competition for resources with native fauna and changes in local food webs.