The material is organized into several sections that include material from a 1972 investigation and from current activities
Between Puerto Rico and the Dominican Republic lies Mona Passage, a major gateway of the Caribbean. Deep, and some 90 miles wide, it is a natural outlet into the Atlantic for waters whmh enter the Caribbean far to the east. Near the middle of the Passage, some 42 miles west from Puerto Rico, lie two extraordinary islands, Mona and Monito. Although located 5 miles closer to the Dominican Republic, their history has attached them politically to Puerto Rico.
Mona and Monito are very different from the rest of Puerto Rico. They appear as great flat white slabs floating on the sea. They are bounded almost entirely by high cliffs rising vertically out of the water. Mona, twice as large as Culebra, has about 14,000 cuerdas of land area and is shaped like a lima bean. Monito, about 3 miles northwest of Mona, is comparatively tiny, only 40 cuerdas in area. It looks like a squarish chunk of Mona which broke off and drifted until it ran aground.
Because of the expanse and depth of Mona Passage and its changeable currents, which often run counter to the winds and swells, these islands are almost continuously battered by high seas. At sea level the cliffs are undercut by the pounding waves. Huge boulders , former sections of the cliffs, lie in the surf where they have fallen. Deep cracks on the upper surface of the island near the cliffs mark the next rocks to cede to the relentless force of the sea.
Only on the more protected sides of these islands is the sea sufficiently shallow for the development of coral reefs . These separate turquoise water near the shore from the deep indigo of the open Passage. On Mona they protect a narrow coastal plain partially fringed with sandy beaches.
Isolation and smallness make these islands spectacular for the visitor from Puerto Rico. Completely out of sight over the horizon, they are much farther from Puerto Rico than its other offshore islands. They are much more intimately a part of the sea than is the main island. Unlike Puerto Rico they are too small to generate daytime showers or a nocturnal land breeze, so their weather is essentially that which would prevail over the sea at this location if they didn't exist, much drier than that of most of Puerto Rico.
Isla de Mona is a tectonically uplifted Mio-Pliocene carbonate island located in the Mona Passage approximately half way between Puerto Rico and Hispanola. The kidney-shaped island is 12 kilometers long and 5 kilometers wide and covers 55 km2. The bulk of the island forms a flat-topped, raised platform, or meseta, that dips gently to the south. This meseta is bounded on all sides by vertical to near vertical cliffs.
The waters which surround these islands are far cleaner than those near Puerto Rico ever were. Drifting from the eastern Caribbean south of Puerto Rico, they receive no pollution from any land surface for more than 300 miles, and are not so affected by these two small dry islands. Intimacy with the sea makes these islands and their surrounding waters the home of a large number of pelagic animals which seldom visit Puerto Rico. The Passage attracts many such species which are migratory.
During the winter humpback whales, usually several at a time with their young, are regular visitors. Among the larger migrant fishes in this season are sailfish, dorado, flying fishes and, less frequently, bluefin tuna. Sea birds at this time of the year include petrels and shearwaters not found in Puerto Rico. With the spring come dolphins, white marlin, silky sharks, and blackfin tuna. Sea birds include petrels, sooty terns, frigatebirds, and tropic birds, the latter three nesting in large numbers at this time. In the summer months appear pilot whales, white-tip shark, blue marlin, yellowfin tuna, and bonito. Noddy and bridled terns and laughing gulls nest on the islands during this season. In the autumn dolphins are again common, as are whales, sharks sailfish, large tuna, and dorado. Hawksbill turtles commonly nest on the beaches of Mona during summer and fall, as do other species occasionally. Thousands of boobies (3 species) nest on these islands almost throughout the year.
The underwater world along the coasts of these islands is more spectacular than any other area around Puerto Rico. Horizontal visibility underwater may reach 200 feet. Below the cliffs of Mona the wall generally descends vertically to depths of 100 feet or more. Beneath the sone of wave action and down to the sea floor gorgonian corals and huge basket sponges stand out horizontally from the walls, waving to and fro in the current. Among them is a diversity and abundance of fish life that must be still as it was when Columbus visited the island; red snappers, yellowtail, angelfish, parrotfish, groupers, barracudas, and many others. In all, more than 270 species of fish have been found near these two islands.
The clear water makes the reefs of these islands equal to the best that ever existed around Puerto Rico. Economically important reef species now rare elsewhere but still found commonly in some areas near Mona include spiny lobsters, queen conch, and the West Indian topshell.
The beaches of Mona, some 5 miles in total length, are whiter than those of Puerto Rico. Because of their location and isolation they generally bear interesting shells and other natural products of the sea, some of them from points as distant as the Amazon and Africa.
The coastal plain of Mona, relatively protected from the winds and waves, supports a diverse terrestrial life system. Some 800 cuerdas in area, it is mostly forested. More than 600 terrestrial plant species are known to grow on Mona, most of them in this area. Hermit crabs rare in most of Puerto Rico, are common throughout Mona, where thousands migrate from the plateau to the beaches of the coastal plain on certain days each year to release their young into the sea. In all, nearly 700 known species of land animals, including land snails, spiders, insects, snakes, lizards, and birds, live together on Mona. Nearly all of them depend upon the coastal plain during at least a part of their lives.
These terrestrial plants and animals reached Mona and Monito by crossing the water, since there is no indication that these islands were ever connected to any other land area. Pigeons come annually from Hispaniola, but how did most of the other animals and plants reach the islands? It apparently took tens of thousands of years. At least 58 of them have been on Mona so long that they are no longer like they were when they came and have thus become species endemic to Mona, found nowhere else, not even on Puerto Rico. Of these, 46 species are animals and 8 are vertebrates. At least another 75 species on Mona evidently arrived from sources other than Puerto Rico, because they have never been found on that island. This means that 133 species of plants and animals of Mona and Monito are not found on Puerto Rico. At least another 29 species of Mona and Monito, including many sea birds, are so rare or endangered elsewhere on Puerto Rico that these islands can be considered their last significant refuge.
The whitish color of the two islands is a result of their rock structure, limestone on the surface, underlain by dolomite, both derived from deposits of marine animals beneath the sea before the islands rose above the surface. At the horizontal level between the two rock layers are dozens of caves which open out on the cliffs or, if their roofs have collapsed, on the top of the plateau. These caves contain attractive dripstone formations, stalactites, columns, and basins.
The plateau of Mona is unlike any part of Puerto Rico. Although apparently nearly level, its surface is actually rough, much of it exposed limestone which is pitted and sharp. Where there is little or no soil or where wind exposure is extreme, vegetation is either absent or made up of low cacti and shrubs. In the depressions, where soil accumulates to depths of two feet or more, low forests grow.
The Mona ground iguana , found nowhere else in the world, and looking like a relic of some ancient era, is the most spectacular single form of life on the island. It attains four feet in length but is harmless. Iguanas live on both the plateau and the coast. Their nests, consisting of a tunnel burrowed into the soil, are commonly on the coastal plain. Their food is vegetable matter.
The isolation of these islands has prevented their modification by human activities to the degree characteristic of nearly all of Puerto Rico and its other island possessions. It is doubtful that since discovery more than 100 persons have successfully clambered up the rocky cliffs onto Monito. The continuous inhabitation of Mona ceased 400 years ago. Human use of the island since that time has been temporary and mostly confined to small areas. The islands are among the few places in the Caribbean where the mongoose, that implacable foe of native animals, was not introduced.
As a consequence of the less modified condition of these islands, their natural life is more abundant, accessible, and tame than elsewhere. Whales come in close to the shore. In some of the largest sea bird rookeries in the eastern Caribbean on Monito and the northern cliffs of Mona, thousands of nestlings remain directly on the ground, helpless, for months. Rare turtles nest commonly on the beaches, a thing of the past in nearly all the rest of Puerto Rico.
Notwithstanding the relatively unmodified character of these islands there exists much evidence of a long and interesting history. Remains from the Taino village visited by both Columbus and Ponce de Leon are still to be found in the soil at Sardinera. Pottery relics, some with affinities with Hispaniola, are much more common than in Puerto Rico. They have been found in all parts of Mona, but especially near the cave mouths. What appear to be Taino inscriptions, petroglyphs, and even pictographs remain within the caves. Two Taino ball courts are still visible on the. plateau. Evidence of history since the end of the Taino culture on Mona is equally interesting. Inscriptions in some of the caves apparently were made by explorers as long as 200 years ago. Skeletons, bottles, and other relics buried on the coastal plain tie back to the three centuries of pirate history on the island. Mining railroads, equipment, and processing machinery used to extract bat guano from the caves nearly 100 years ago also remain. The ruins of historic cabins, stone walls, graves, old trails , and an abandoned lighthouse also are to be found. Some nine shipwrecks have been located around the coast of Mona, and historical records suggest there may be many others.
More recent historical remains include the ruins of the Forest Service dock and the CCC camp at Sardinera, the wings of aircraft which crashed at the island during World War II, and flotsam on the beach from unknown but probably distant sources.
Living historical remains are to be found in plants and animals introduced by man. Plants include the casuarina and mahogany trees, coconut palms, papayas, sisal, guinea grass, quenepas, and limes.
Introduced animals include goats, pigs, cats, rats, mice, and chickens. The most prominent feature of the plateau of Mona is the lighthouse , near Punta Este. For some 70 years, it has guarded the eastern channel of the Passage, and its tower provides an excellent view of nearly the entire island and the sea to the east and south.
An attachment to the natural beauty of these two islands is human. The water is colorful and clear, the marine life exceptional, the beaches are outstanding, the cliffs are unique, and the spectre of the varied living things surviving together on this small isolated area of land arouses interest. Added depth to the scene not equalled elsewhere is provided in the historical remains. An encounter with any of these features stimulates the search for more. The more completely the islands are known the more sharply are their extraordinary qualities manifest. These islands, purely as something unique, produce an inescapable positive emotional response.
Even were these islands devoid of other attractions they would still appeal to man's adventuresome spirit. Their isolation and relative size give the islands promise of being unusual simply because they are less frequented by man. The need to cross an expanse of water beyond the horizon to reach them foretells a differentness greater than that of any location contiguous to familiar places. The smallness of the islands brings them entirely within the compass of visual perception. The whole island of Mona can be "mastered" or at least become well known to one within a practical period of exploration. The process of mastering it can be predominantly a matter of unrestrained personal decisions, a degree of freedom unequalled in more populated surroundings.
The beauty of Mona and Monito is awe-inspiring, their life is unique, and their colorful history is still in evidence. They are among Puerto Rico's greatest remaining natural treasures.