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Rare or elusive? A test of expert knowledge about rarity of Amazon forest birds

Authors

  • Marconi C. Cerqueira,

    1. Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
    2. Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia/Smithsonian Tropical Research Institute, Amazonas, Brazil
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  • Mario Cohn-Haft,

    1. Scientific Collections – Birds, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
    2. Department of Biodiversity, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
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  • Claudeir F. Vargas,

    1. Scientific Collections – Birds, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
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  • Carlos E. Nader,

    1. Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
    2. Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia/Smithsonian Tropical Research Institute, Amazonas, Brazil
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  • Christian B. Andretti,

    1. Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
    2. Scientific Collections – Birds, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
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  • Thiago V. V. Costa,

    1. Scientific Collections – Birds, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
    2. Departamento de Zoologia, Instituto de Biociências and Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil
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  • Monica Sberze,

    1. Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
    2. Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia/Smithsonian Tropical Research Institute, Amazonas, Brazil
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  • James E. Hines,

    1. Patuxent Wildlife Research Center, U. S. Geological Survey, MA, USA
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  • Gonçalo Ferraz

    Corresponding author
    1. Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia/Smithsonian Tropical Research Institute, Amazonas, Brazil
    2. Smithsonian Tropical Research Institute, Panama, Panama
    • Graduate Program in Ecology, Instituto Nacional de Pesquisas da Amazônia, Amazonas, Brazil
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Correspondence: Gonçalo Ferraz, Biological Dynamics of Forest Fragments Project, Instituto Nacional de Pesquisas da Amazônia, CP 478, Av. André Araújo, 2936 69083 Manaus AM, Brazil.

E-mail: ferrazg@si.edu

Abstract

Aim

To offer a test of expert knowledge about rarity of twenty Amazon forest bird species following an approach that equates rarity with low site occupancy and formally accounts for imperfect species detection. We define ten pairs of closely related species, each pair with one hypothetically common and one hypothetically rare species. Our null hypothesis is that members of each pair have similar occupancy, with hypothesized differences due to detection errors alone.

Location

A 1000-ha plot of primary rainforest in the central Brazilian Amazon.

Methods

We visited each of 55 sampling sites multiple times per season for three field seasons and estimated the probability of site occupancy by each species following a maximum likelihood state-space approach that also estimates the probability that a species is present yet undetected at a site. To maximize detection and account for its variation, we employed three different sampling techniques while systematically training and testing observer's ability to recognize species.

Results

Occupancy estimates agree with expert predictions in all but two species pairs and show no evidence of clear temporal variation in occupancy between sampling seasons. Detection probability had a positive relation with observer ability, a strong relation to time of day across species, and a strong relation with the use of playback for some species. Detection with point counts and with autonomous recorders varied between species pairs.

Main conclusions

We reject the null hypothesis of equal occupancy within pairs, concluding that expert knowledge on species rarity is useful and worth eliciting. Our results replace qualitative ratings of rarity with statistical estimates of occupancy, establishing a reliable baseline for future comparisons. Besides illustrating the relevance of expert knowledge, this application to Amazonian birds illustrates a flexible approach that can be used for testing knowledge about rarity for a variety of species groups and spatial scales.

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