Ankarana Special Reserve is a protected area in northern Madagascar that was created in 1956. It is a small, partly covered with plants plateau made of limestone that is 150 million years old, from the Middle Jurassic period. The area receives about 2,000 millimeters (79 inches) of rain each year. This rainfall has eroded the rocks below, forming caves and underground rivers, which create a type of landscape called karst topography. The rough and uneven land, along with thick vegetation, have helped keep the region safe from people entering or using it. The Ankarana Massif is the setting for a wildlife-rich adventure story for children.
The southern entrance to the Ankarana National Park is located in Mahamasina, part of the Tanambao Marivorahona commune, on Route nationale 6. This entrance is about 108 kilometers southwest of Antsiranana and 29 kilometers (18 miles) northeast of Ambilobe. There are hotels near the park headquarters at the entrance.
Geology
The plateau slopes gently toward the east, but on the west, it ends suddenly at the "Wall of Ankarana," a steep cliff that stretches 25 kilometers (16 miles) from north to south and rises as high as 280 meters (920 feet). To the south, the limestone forms separate tall rock pillars called tower karst. In the middle of the plateau, shaking from earthquakes and long-term rainfall have worn away the limestone, creating deep canyons and flowing mineral deposits called flowstone. In areas where the top layer of calcified rock has completely eroded, the harder rock below has been carved into channels and ridges known in Malagasy as tsingy, which means "where one cannot walk barefoot." The area is covered with basalt rocks, and basalt has also filled deep into the canyons that cut through the landmass.
Exploration
Starting in the 1960s, a French person living abroad named Jean Duflos (who later changed his name to Jean Radofilao) did a lot of exploration of the cave systems and underground rivers in the massif. Much of this work was done alone or with visiting cave experts. About 100 kilometers (62 miles) of cave passages in the massif have been mapped. La Grotte d'Andrafiabe, one of the most easily reached caves, has at least 8.035 kilometers (4.993 miles) of horizontal passages. The massif contains the longest cave systems in Madagascar and likely in all of Africa.
Fauna
In the 1980s, expeditions began recording the animals and plants of the Ankarana Special Reserve. These efforts are described in Dr. Jane Wilson-Howarth’s book Lemurs of the Lost World and in scientific articles. Scientists found unexpected remains of large extinct lemurs, as well as living but previously unknown species of blind fish, shrimp, and other small animals. Some members of the expeditions contributed photos to an illustrated guide about Madagascar, which includes information about the Crocodile Caves of Ankarana.
During the 1986 expedition, Phil Chapman and Jean-Elie Randriamasy created a list of bird species in the reserve. They recorded 65 bird species from 32 families, which represents nearly one-third of all bird species that nest in Madagascar. They also observed a unique behavior among small insect-eating songbirds. These birds, such as the paradise flycatcher (Terpsiphone mutata), common jery (Neomixis tenella), greenbuls (Xanthomixis zosterops and Bernieria madagascariensis), bulbul (Hypsipetes madagascariensis), sunbird (Nectarinia souimanga), and vangas (Lepopterus madagascarinus and Xenopirostris polleni), often foraged together in groups. Within each group, different species focused on different areas to find insects. Some searched tree trunks and branches, others looked on thin twigs, and some searched under leaves. By working together, these birds likely found food more easily and were safer from predators because the group could spot dangers more quickly.
The Ankarana Reserve is an important home for large numbers of the crowned lemur (Eulemur coronatus), Sanford’s brown lemur (Eulemur sanfordi), and other mammals. Other lemurs found in the area include the northern sportive lemur (Lepilemur septentrionalis), brown mouse lemur (Microcebus rufus), fat-tailed dwarf lemur (Cheirogalus medius), fork-marked lemur (Phaner furcifer), eastern woolly lemur (Avahi laniger), Perrier’s sifaka (Propithicus diadema perrieri), aye-aye (Daubentonia madagascariensis), and the western lesser bamboo lemur (Hapalemur griseus occidentalis).
Scientists have also found subfossil remains of several lemur species at Ankarana, including the greater bamboo lemur (Prolemur simus), indri (Indri indri), sloth lemur (Babakotia radofilai), Mesopropithicus dolichobrachion, Palaeopropithicus cf ingens, Pachylemur sp., the large Megaladapis cf madagascariensis/grandidieri, and the baboon lemur Archaeolemur sp..