Seed Dispersal by Geochelone carbonaria and Geochelone denticulata in Northwestern Brazil1

Authors

  • Joel N. Strong,

    Corresponding author
    1. 241 Illick Hall, Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210, U.S.A.
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  • José M. V. Fragoso

    1. Botany Department, University of Hawaii at Manoa, 3190 Maile Way, Honolulu, HI 96822, U.S.A.
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  • 1

    Received 30 September 2005; revision accepted 5 December 2005.

Corresponding author; e-mail: joelstrong78@yahoo.com

Present address: Zoology Department, University of Hawaii at Manoa, 2538 McCarthy Mall, Honolulu, HI 96822, U.S.A.

ABSTRACT

The role of red-footed tortoises (Geochelone carbonaria) and yellow-footed tortoises (G. denticulata) as seed dispersal agents was investigated in northwestern Brazil from 5 to 26 January 2002 by analyzing fecal samples for frequency and viability of seed species and estimating daily displacement of tortoises from recaptured and thread-trailed individuals. Fourteen of 19 fecal samples contained a total of 646 seeds represented by 11 plant species. The most abundant species was Ficus sp. (N= 400) with 100 percent of seeds viable, followed by Aechmea sp. (N = 88) with 93 percent of seeds viable, and Genipa americana (N= 59) with 91 percent of seeds viable. Mean minimum retention time of seeds was 1.6 d and mean daily displacement of tortoises based on recaptured (N= 7) and thread-trailed tortoises (N= 2) was 57 m. Thus, the diversity and proportion of viable seeds consumed by tortoises, combined with the seed retention times and daily movements, suggest they may be effective dispersal agents. These preliminary findings warrant further investigation into the ecological role of these tortoises in Neotropical ecosystems and their contribution to the maintenance of species diversity and forest structure.

RESUMEN

O papel do jabuti-piranga (Geochelone carbonaria) e do jabuti-tinga (G. denticulata) como agentes dispersores de sementes foi investigado no noroeste do Brasil de 5 de janeiro a 26 de janeiro de 2002, analisando amostras fecais pela freqüência e viabilidade das espécies de sementes e estimando o deslocamento diário dos jabutis através da recaptura de indivíduos e técnica de carretel. Quatorze das 19 amostras fecais continham um total de 646 sementes representadas por 11 espécies de plantas. As espécies mais abundantes foram o Ficus sp. (N= 400) com 100% de sementes viáveis, seguida por Aechmea sp. (N= 88) com 93% de sementes viáveis, e Genipa americana (N= 59) com 91% de sementes viáveis. O tempo mínimo médio de retenção das sementes foi de 1.6 dias e a média diária de deslocamento dos jabutis baseado na recaptura (N= 7) e na técnica do carretel (N= 2) foi de 57 m. Assim, a diversidade e a proporção das sementes viáveis consumidas pelos jabutis, combinada com o tempo de retenção de sementes e movimentos diários desses animais, sugerem que eles devem ser efetivamente, agentes dispersores. Estas descobertas preliminares indicam que pesquisas futuras sobre o papel ecológico dos jabutis em ecossistemas Neotropicais contribuem para a manutenção da diversidade de espécies e estrutura florestal.

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