Odonata of the Osa Peninsula - Frontier

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A B C D E F Figure 1: the survey sites. A) OBC; B) Ocelotte stream; C) Piro river; D) Piro trail; E) Swamp (February) and F) Swamp (April). Notice the stick in pictures E and F indicating the same location in both pictures.
Methods To account for both seasonal and daily activity patterns, each site was surveyed 16 times in 4 different time slots between January 30 th and May 17 th 2012. Over the course of a month (4 weeks), each site was visited in the early morning (8 AM – 10 AM), late morning (10 AM – 12 AM), early afternoon (1.30 PM – 3.30 PM) and late afternoon (3.30 PM – 5.30 PM). Because it was not possible to establish transects of equal length, sampling was standardized by 30 minutes of intense sampling (excluding the time needed for analysis). Adult dragonflies were netted, measured, photographed and released. For each individual, notes were taken on time of capture, sex, behavior, height of perching and whether it was found in the sun or in the shade. Because two species of the genus Uracis (U. imbuta and U. fastigiata) were found to be extremely abundant and it was feared that capturing these species would severely underestimate their abundance, I decided to tally them when they were encountered on a survey. With the help of the pictures, each individual was later identified to genus and where possible to species with the help of Esquivel (2006), Garrison et al. (2006 and 2010) and Haber and Wagner (2011). Bill Haber kindly provided help in identifying difficult species. Some species can only be identified with full confidence by examination of their genitalia or appendages, which was out of the scope of this project. I have identified each individual to the best of my ability and within the limitations of a field survey but mistakes could have been made for species that look very alike or are not formally described. The females of two species of the genus Argia (A. frequentula and A. pulla) were hard to distinguish in the field. To avoid misidentification, I decided to group these two species together as Argia aggregation (Argia agg.). Some species were encountered outside of the systematic surveys (between January 2010 and June 2012). For the completeness of this study, they are included in the species list (Appendix I) and phenology table (Appendix II). Analysis Species accumulation curves were made to test whether the five surveyed sites were adequately sampled. Two non-parametric estimators of species richness were generated with the freeware application EstimateS version 8.2.0 (Colwell, 2006). Both parameters are incidence based (i.e. they rely on presence-absence data) and estimate the number of species that are yet to be collected based on a quantification of rarity. In the case of Chao 2 rarity is quantified as the number of species that occur in only one (uniques) or two samples (duplicates) whereas the first order jackknife only looks at uniques (Colwell and Coddington, 1994). For each site, a Coleman curve was created, which is the incidence-based alternative to a rarefaction curve that allows more heterogeneity (e.g. temporal and spatial variation in
Page 1 and 2: Odonata of the Osa Peninsula Brenda
Page 3: Site description Even though Costa
Page 7 and 8: Species distribution patterns For t
Page 9 and 10: Abundance and Richness Comparisons
Page 11 and 12: Discussion 268 species of Odonata h
Page 13 and 14: Appendix I: Odonata Species checkli
Page 15 and 16: Appendix II: Phenology of Odonata o
Page 17 and 18: Appendix III: Odonata of the Osa Pe
Page 19 and 20: Leptobasis vacillans ♂ © W.A. Ha
Page 21 and 22: Protoneura sulfurata ♂ Protoneura
Page 23 and 24: Erythemis vesiculosa ♂ Erythemis
Page 25 and 26: Orthemis schmidti ♂ Unknown speci

Odonata of the Osa Peninsula - Frontier

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