New Species Of Bird Killing Trees Were Just Discovered In Puerto Rico

Pisonia horneae. Image by Rosimar Rivera Colón. Acquired from phys.org

Thoughts of the Caribbean generally conjures up beaches, all inclusive hotels, and sunny weather. Besides being a great choice for a relaxing holiday from the hustle and bustle of life, the Caribbean is also a haven for biodiversity that spans from the microscopic to the towering. There are numerous rainforests that hold exotic plants and animals.

Their rivers and waters are filled with aquatic life that rivals anywhere on Earth. There are always new things to find in the Caribbean. In 2012, 24 new species of lizards were found in the Caribbean. Just recently in January 2017, a new species of hermit crab was also found in the Caribbean. These are just a few of the many new species in the Caribbean. But not all species found are harmless. Some can be dangerous to other animals by intent or accident.

Killer Plants and Trees

Deadly plants and trees come in all shapes, sizes, and levels of fatality. There are many different kinds of poisonous plants that can hurt you or your pets and some can even be fatal. A commonly known poisonous plant is the nightshade, which results in paralysis of various parts of your body including the heart. The apple, a very common household fruit, holds a dark secret that makes it join the list of poisonous plants. The seeds of apples contain very small amounts of amygdalin, which can be fatal if consumed in very large quantities because amygdalin breaks down into cyanide. Among the most poisonous trees in the world are the manchineel trees, located in Central and North America. The fruits, sap, bark, and many other bits of the manchineel trees are all toxic to humans and animals. Even when you burn them, toxic fumes are released.

Besides poison, there are also carnivorous plants, like the Venus flytrap or pitcher plants. For trees, besides poison, there are also stinging trees. These deliver very dangerous neurotoxins that cause allergic reactions in humans and animals. They cause intense pain and discomfort. Among the most painful is the species Dendrocnide moroides, which is located in Australia.

The Killer Tree

The bird catcher trees that were discovered in Puerto Rico are Pisonia horneae and Pisonia roqueae. They were discovered by Marcos A. Caraballo-Ortiz, a doctoral candidate at Pennsylvania State University, US and Jorge C. Trejo-Torres, a researcher at The Institute for Regional Conservation in Florida, US. Both trees were named to honor the achievements of women in the past. P. horneae was named to honor Frances W. Horne (1873–1967), an American illustrator who painted numerous plants and birds in Puerto Rico. P. roqueae was named in honor of Dr. Ana Roqué de Duprey (1853-1933), a Puerto Rican writer, suffragist, and amateur botanist.

The trunk if Pisonia roqueae. Image by Fabiola Areces. Acquired from phytokeys.pensoft.net

As their common name implies, these trees target birds. The trees produce very sticky fruits that become stuck in birds that pass by the trees or land on it. The purpose of this is to disperse the seeds within the fruits across long distances to further propagate the species.

The ripe and sticky fruits of the bird-catcher trees. Image from phytokeys.pensoft.net Credit: Jorge C. Trejo-Torres

The deadly aspect of these trees is unintentional. Sometimes, the sticky fruits stick too tightly on the birds, which restricts their movement and their ability to fly. This leads to birds dying near the trees, which the two researchers noted by the few small bones that surrounded both species. It is not only birds that are flying by that gets trapped. As the ripe fruits fall on the ground they attract insects, which gets stuck in the fruit, and this attracts other birds that are hungry. They end up getting stuck on the ground and cannot do much until they become lunch for any other hungry animals. Because it is an unintentional act that kills the birds, the trees derive no benefit from their deaths. It is simply a byproduct of the trees trying to ensure their survival.

While these two species are new, the genus Pisonia is not. Other tree species of this genus are found throughout many parts of the Pacific, like Hawaii and New Zealand. Like those found in Puerto Rico, the other trees also have the stick fruits and result in birds dying because of it. Despite the deadly relationship that trees of Pisonia have with birds, they continue to survive because there are birds that love these trees. Beth Flint, a biologist from the U.S Fish and Wildlife Service, noted that regions with both seabirds and bird-catcher trees always have seabirds flocking around the bird-catcher trees.

Abundance In Nature

As these two species are endemic to Puerto Rico, which is a fairly small island, they are rare and in need of protection. P. horneae is considered a vulnerable species and it is also designated as a crucial part of the flora and fauna of Puerto Rico by the Department of Natural and Environmental Resources of Puerto Rico. This is important because it is a species in limited number and any designation or recognition would go along way in bringing awareness of its existence and its need for conservation. The other Pisonia species are also rare and in need of conservation efforts as well because, like these two, they are on relatively small landscapes that limits their seed dispersal.

One crucial aspect of conservation that is needed to be considered in order for these trees to survive and thrive is the birds that flock to them. As the climate changes and mass animal deaths continue to rise, many bird species, like seabirds, are facing many disruptions to their food sources, habitats, genetic stability, and they also face an increase in mass deaths. This needs to be addressed along with addressing how the changing environment, due to climate change, agriculture pressures, and other forces, affects the continued survival of the trees themselves.

As we continue to explore deeper into the forests and landscapes of the Caribbean, hopefully, we can find more new species to excite and enlighten the world. Not only would they be important in the local ecosystems they thrive in, they would also teach us more about the complexity and diversity that exists in our natural world.

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