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Navassa Island

• Introduction
  
  
• History
  
  
• Geography
  
  
• Field Work
  
  
• Terrestrial Biota of Navassa Island
  
  
• Marine Ecosystems
  
  
• Marine Biota
  
  
• Status and health of the coral reef ecosystem of Navassa Island
  
  
• References and Information Sources
  
  

Terrestrial biota of Navassa island

	Read About: Plants Invertebrates Vertebrates Birds and mammals Evolution and endemism More photos

Plants

Approximately 120 terrestrial plant species are known to occur on Navassa (Swearingen, 1999), dominated by four species of tropical and subtropical trees: the mastic (Sideroxylon foetidissima), the short leaf fig (Ficus populnea var. brevifolia - may be a synonym of Ficus citrifolia), the pigeon plum (Coccoloba diversifolia), and the highly toxic poisonwood, Metopium brownei. Two endemic palm trees occur on the island, one found commonly, and the other, Pseudopheonix sargentti saonae var. navassana remains as the single living specimen. A number of exotic plants occur on Navassa, including the introduced popular ornamental Madagascar periwinkle, (Catharanthus roseus).
Approximately 200 acres of forest were burned by Haitians in 2000. The Haitians also planted a few acres of crops such as watermelon, corn, and squash.

The New York Botanical Society maintains a Virtual Herbarium Web site which provides an annotated checklist of vascular plants of Navassa Island.

the highly toxic poisonwood, Metopium brownei, found in the vicinity of the lighthouse (photo: New York Botanical Society)

The last Pseudopheonix sargentti saonae on Navassa (Photo: U.S. Geological Survey)

Invertebrates

Early survey collections documented 650 species of invertebrates, including over 500 new insects, 30 percent of which may be endemic. Over 100 non-insect arthropods, mostly spiders, make up the rest. Arachnologists cataloged 40 new species of spider.

Entomologists use pitfall traps and other techniques to collect insects and other terrestrial invertebrates on Navassa (Photo: Jil M. Swearingen)

A naturalist collecting insects on Navassa island (Photo: U.S. Geological Survey)

Vertebrates

Vertebrate surveys confirmed the existence and abundance of four endemic lizards: the Navassa Island galliwasp (Celestus badius), the Navassa anole (Anolis longiceps), Cochran’s croaking gecko (Aristelliger cochranae), and the Navassa dwarf gecko (Sphaerodactylus becki), all previously reported for the island. Four other known species of reptiles, including a large endemic iguana (Leiocephalus eremitus) that may now be extinct, and a small boa (Tropidophis bucculentus), could not be relocated (Powell, 2005).

Dr Robert Powell (Avila University) maintains a web site on the herpetology of Navassa. This web site contains photographs of reptiles found on Navassa, a list of reptile species reported, museum collections with herpelogical collections, and a bibliography of the island.

The endemic dwarf gecko Sphaerodactylus becki (Photo: Robert Powell, Ph.D)

An adult Cochran’s Croaking Gecko, Aristelliger cochranae (Photo: S. Blair Hedges)

Birds and mammals

Dozens of species of tropical birds inhabit Navassa. These include the white-crowned pigeon (Columba leucocephala), over 5,000 nesting red-footed booby (Sula sula), brown booby (Sula leucogaster), masked booby (Sula dactylatra), Cory’s shearwater (Calonectris diomedo), magnificent frigatebird (Fregata magnificens), cliff swallow (Hirundo pyrrhonota), Bonaparte’s gull (Larus Philadelphia), Pomarine jaeger (Stercorarius pomarinus), and several cliff-nesting birds, including the bridled tern (Sterna anaethetus). No endemic mammals are known to occur on Navassa. Goats, dogs, rats, and possibly cats, have been introduced (Swearingen, 1999).

An adult brown booby (photo: C. Addison)

The red-footed booby, Sula sula, in Navassa (Photo: Chan Robbins)

Evolution and endemism

Navassa Island gave rise to a rich diversity of terrestrial species that have been isolated long enough have evolved independently of the species on close-by land areas. The tall cliffs which surround Navassa make it difficult for invading organisms to reach the island’s high terraces, and the surrounding waters off the submarine terraces are 500 m deep, eliminating the possibility of land connections to larger islands in past times.

Fifteen species are endemics and include land snails, lizards, vascular plants, and possibly a ground dove. Two endemic reptiles, an iguana and curly tailed lizard, found on the island during the last century, may be extinct. (U.S. Geological Survey, Coastal and Marine Geology Program) (http://coastal.er.usgs.gov/navassa/)

Threats

Threats to the terrestrial ecology include the burning of forested areas by Haitian squatters and the introduction of invasive species such as rats, dogs, cats, and goats.

More photos -

Click here to view the collections of the photos.

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