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A Q&A with Expert Jim Karr

By | April 5, 2014

Q: As a specialist in tropical ecology, ornithology, and stream ecology, you have done extensive fieldwork around the world, including Central and South America, Africa, Southeast Asia, and New Guinea. What kinds of tropical ecology projects have you worked on in Central America? 

A: Most of my research in Central America focused on birds. That work led to the study of interactions between birds and vegetation structure, insects, and undergrowth microclimate (temperature and humidity). My research group also studied fishes in forest streams. The bird research began in 1967 and continued until 2001 when I last collected data in Soberania National Park in central Panama. On that trip, I captured a Rufous Motmot that I first captured 18 years earlier at the same site. Over the years, my students and I studied habitat selection, survival rates, movement patterns, site fidelity, frugivory, and predation on nests of forest birds. Another line of research involved asking why did some bird species go extinct on Barro Colorado Island, Panama, after the island's isolation in Gatun Lake, the lake formed by construction of the Panama Canal in the early 1900s. Research and teaching trips to Costa Rica and Panama have taken me to those countries dozens of times. My longest period of residence in the region was four years in the 1980s. 

Q: In all of your travels to Costa Rica, which places draw you back again and again? 

A: This question is like asking which of my children I love best. Many places draw me back. My favorite natural environments are forests, rivers, and wetlands. Costa Rica has a rich variety of forest types from lowland wet and rain forest to lowland dry forest. And how can I not cherish the beauty and mystery of cloud forest. Rivers and the wetlands and riparian forest that border rivers are centers of interest and biological activity. But human environments also intrigue me, especially the agricultural areas and the crops they produce. One of the best ways to see those products in all their diversity is in the local, typically open-air markets in many towns and villages. To see all of these special places I must also cross the larger landscapes in a region. How are the nature reserves, agricultural lands, and urban centers distributed across a region? How do they fit into the topographic and geological diversity of the region? Are there connections among the natural areas that allow migration from highland to lowland and wet to dry areas? Or are the reserves isolated, small patches of nature unconnected to other natural areas? As landscape architect D. W. Meinig observed, "Landscapes mirror and landscapes matter; they tell us much about the values we hold and at the same time affect the quality of lives that we lead." The Costa Rican people understand Meinig's observation. They lead the world in taking conservation of their landscapes seriously with more than 25 % of the country's land mass protected in national parks and preserves.

Q: Costa Rican mountains are home to extraordinary "cloud forests," of which Monteverde is one. What is a cloud forest and what makes them so special? 

A: Lower montane rain or "cloud" forest is the prevalent forest of upper middle elevations (4,000 to 6,000 ft above sea level) in the Monteverde area. Moisture-laden winds from the Caribbean ascend the mountains, forming clouds that bath the forest in nearly perpetual moisture. Measured rainfall is low in cloud forests compared with rain forest but moisture intercepted by tree canopies makes the forest wetter. The diversity of woody plants is reduced in cloud forest and tree height (up to 100 feet) is shorter than in rain forest. Leaves in cloud forest tend to be smaller and harder than lowland tree leaves. The ground is typically covered with a dense growth of mosses and tree ferns are common. Tree trunks and branches support luxuriant growth of mosses, ferns, orchids, lichens, and bromeliads. Cloud forests are home to many species found nowhere else with high diversity for groups that are especially adapted to these perpetually cool, moist environments. These include, for example, orchids, bromeliads, insectivorous plants, ovenbirds, and tanagers.

Q: A highlight of Monteverde is the Bat Jungle where visitors can observe different species of fruit-eating bats in a simulated forest environment. What other kinds of foods do Costa Rican bats consume? Have Costa Rican bat populations been affected at all by the white nose syndrome that is decimating bat populations in North America and Europe? 

A: More than 200 species of bats live in Costa Rica. The Bat Jungle's interactive displays, exhibits, and simulated forest environment are designed to give a new appreciation for these often misunderstood but important and intriguing creatures of the night. Live bats in the simulated forest are all fruit eaters and visitors normally see them flying around and feeding on bananas and other fruit. The high diversity of bats in Costa Rica is possible because each species specializes on different foods: fruit, nectar, insects, frogs, fish, birds, lizards, blood, or mice. In addition to discussing foods eaten by bats, Bat Jungle guides discuss echolocation, where bats roost, how bats care for and carry their young, and bat conservation. Fortunately, Costa Rican bats are not yet threatened by the white nose syndrome, an infectious and lethal cold-loving fungus that threatens so many of the cave dwelling bats of North America. 

Q: How is it that Palo Verde can be both wetland and tropical dry forest? What range of habitats will Smithsonian travelers see on the float safari on the Tempisque River? 

A: Palo Verde National Park is in the lowlands of the Tempisque River, Guanacaste Province, in the Pacific Northwest region of Costa Rica. The region receives more rain each year (70 inches) than most regions of North America. But most of that rain falls in the seven-month wet season (May-Nov), leaving an extended dry season with little or no rain. The region's dry tropical forest survives by dropping most leaves during the dry season, much as temperate deciduous forests lose their leaves during the northern temperate winter. The lack of rain in the dry season contrasts with the substantial rainfall (6 to 12 inches) each month during the 6-month rainy season. Water accumulates in marshes, seasonal pools, and the Tempisque River floodplain during the rainy season, creating massive seasonal wetlands that are prime breeding areas for thousands of wetland birds. Smithsonian travelers motor upstream on the Tempisque River and along a small tributary. You experience the tidal changes of the lower river, as well as pass through adjacent mangrove forest, dry tropical forest, and areas cleared for pasture and agriculture. Birds (black hawk, egrets, and herons) and howler and white-faced monkeys are common during the float safari. Palo Verde National Park is on the list of wetlands of international importance because of the diversity of plants and animals and the large number of breeding birds. The park also protects one of the most endangered Central American ecosystems, tropical dry forests that once covered much of Pacific coastal Central America.


Jim Karr

Smithsonian Study Leader Jim Karr is Professor Emeritus of Ecology at the University of Washington, Seattle, specializing in tropical ecology, ornithology, water resources, and environmental policy. He also served as deputy director of Smithsonian Tropical Research Institute in Panama for four years in the 1980s.

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