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Bird Rarity in Terra Firme Forest: Reality or Imperfect Detection?

Do ornithologists accurately perceive bird commonness and rarity in forest patches? This study explores the correlation between occupancy and abundance of bird species, highlighting the implications for conservation efforts. Using a comprehensive methodology involving field surveys and statistical analysis, the research assesses detection probabilities and estimates occupancy for various bird species in a terra firme forest habitat. By scrutinizing observer skills and playback techniques, the study aims to unveil the accuracy of rarity assessments in bird conservation.

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Bird Rarity in Terra Firme Forest: Reality or Imperfect Detection?

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  1. Bird rarity in terra-firme forest: reality or imperfect detection? Marconi Campos Cerqueira Gonçalo Ferraz, Claudeir Vargas, Christian Borges, Thiago Vernucci, Angela Midori, Marcelo Santos, Monica Ribas, Mario Conh-Haft Fotos:Erik Johnson

  2. “Rare species play such a central role in conservation biology that the discipline has been defined as the science of scarcity and diversity “Soulé, 1986 • Hypothesis: - The ornithologist`s perception of commonness and rarity reflect the truth about forest patch occupancy by birds. • Conservation implications: - some common species may be mistakenly classified as rare.

  3. Rarity as occupancy : • Proportion of occupied sites, or occupancy, instead of abundance. • Positive interspecific correlation between occupancy and abundance – not only obvious but well documented (Gaston and Blackburn 1999) • Locally abundant species tend to occupy more places than rare ones. -

  4. Fiuí fiu fiitri

  5. Detection is not perfect ? ? ?

  6. Ovenbirds Trogons Woodcreepers Jacamars Puffbirds

  7. Antwrens Antshrikes Wrens Antthrushes Vireos

  8. Study area

  9. Methodology • 2 weeks of survey: • 1st week – Ten trained researches make 3-minute point counts in ten different trails simultaneously. • 660 point counts • 1980 min of observation • 330 km collective walk • 2nd week- playback of 16 species` songs in one more visit per point by one observer.

  10. Improve and measure observer skills • Prior training in the field • Memory training with ‘electronic flashcards’ • Memory retention test -> observer score • Observer score as covariate of detection

  11. Analysis • Parameter estimation(Occupancy and detection) Maximum likelihood • Hypothesis testing Models selection AIC the model with lowest AIC value provides the most parsimonious and best approximation of information contained in the data1 1(Burnham e Anderson 1998)

  12. Detection probabilities Example: Bucco tamatia p(playback+time) Naive estimate = 0,25 Estimated occupancy = 0,38 ±0.09

  13. Time of the day × detection (given presence)

  14. Observer score × detection (given presence)

  15. Playback ×detection (given presence)

  16. Occupancy for 20 species – final estimate

  17. So… are the birders getting it?

  18. So… are the birders getting it?

  19. Rarity team Sure they are getting it!

  20. Apoio

  21. Obrigado,thanks! marconi_cerqueira@yahoo.com.br

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