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Density, Distribution, and Attributes of Tree Cavities in an Old-Growth Tropical Rain Forest

Authors

  • W. Alice Boyle,

    Corresponding author
    1. Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, U.S.A.
      Corresponding author; current address: Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada; e-mail: alboyle@email.arizona.edu
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  • Carissa N. Ganong,

    Corresponding author
    1. Department of Biology, Mansfield University, Mansfield, PA 16933, U.S.A.
      Current address: Department of Biology, University of Central Arkansas, Conway, AR 72035, U.S.A.
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  • David B. Clark,

    1. Department of Biology, University of Missouri-St. Louis, St. Louis, MO 61321, U.S.A.
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  • Marisa A. Hast

    Corresponding author
    1. Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, U.S.A.
      Current address: 3840 Cloverleaf Dr., Boulder, CO 80304, U.S.A.
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Corresponding author; current address: Department of Biology, University of Western Ontario, London, ON N6A 5B7, Canada; e-mail: alboyle@email.arizona.edu

Current address: Department of Biology, University of Central Arkansas, Conway, AR 72035, U.S.A.

Current address: 3840 Cloverleaf Dr., Boulder, CO 80304, U.S.A.

ABSTRACT

Tree cavities are a critical resource for many animals, especially as nesting sites for birds. Patterns of cavity distribution in temperate forests are well studied, yet little is known of cavities in tropical forests, despite a hypothesized decrease in cavity availability with decreasing latitude. We studied cavity density and distribution in a wet lowland tropical forest in Costa Rica and compared our results with estimates from forests around the world. Cavities at our site were common, occurred frequently in living trees, and were often formed by damage or decay rather than by woodpeckers. Most cavities had small openings, and woodpecker-created cavities were nonrandomly oriented. Contrary to prediction, cavity density appears to increase from the poles to the tropics. We suggest potential mechanisms to explain these patterns.

RESUMEN

Las cavidades en los árboles son recursos críticos para muchos animales, especialmente como sitios de nidificación para aves. Los patrones de distribución de cavidades en bosques templados son bien conocidos, pero se sabe poco sobre cavidades en bosques tropicales, a pesar que se ha hipotetizado que la abundancia de cavidades disponibles disminuye en latitudes bajas. Estudiamos la densidad y distribución de cavidades en tierras bajas de un bosque muy húmedo tropical en Costa Rica y comparamos nuestros resultados con datos alrededor del mundo. Las cavidades son abundantes en nuestro sitio de estudio, ocurren con mayor frecuencia en árboles vivos y se forman producto de daños o enfermedades en los árboles más que de pájaros carpinteros. La mayoría de las cavidades tienen entradas pequeñas y las que fueron hechas por pájaros carpinteros no tuvieron una orientación aleatoria. Al contrario de lo que predecimos, la densidad de cavidades aumenta desde los polos hacia los trópicos. Sugerimos unos mecanismos potenciales que podrían explicar estos patrones.

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