El Verde Grid long-term invertebrate data

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The data set consists of 41 files: (1) abundance data for the walking stick, Lamponius portoricensis, (2) estimates of abundance (Minimum Number Known Alive) for 17 species of terrestrial snails, and (3) 39 files containing data on size and mark-recapture estimates of population size for the snails Caracolus caracolla and Nenia tridens from the Wet Season of 1995 to the Wet Season of 2016 (no dry season data for 1995 or after 2012). Note: MNKA estimates are not always identical to the number of individuals indicated in the Mark-Recapture data, because some individuals (e.g., those that were lost before being marked) had to be excluded from calculations for Mark-Recapture estimates of abundance.

Date Range: 
1991-06-01 00:00:00 to 2016-07-31 00:00:00

Publication Date: 

2011-04-04 00:00:00

Additional Project roles: 

Name: Eda Melendez-Colom Role: Data Manager
Name: Stephen Cox Role: Associated Researcher


One hundred sixty points were selected on the Hurricane Recovery Plot at El Verde. Circular quadrats (r = 3 m) were established at each point. From June 1991 to present, 40 points were sampled four times seasonally for the presence of terrestrial snails and walking sticks, with the following exceptions: (1) in 1995, 1996, and 1997, the wet season surveys comprised 160 points, (2) in 1998, the wet season survey comprised 100 points, (3) walking stick surveys began in the wet season of 1992, (4) walking sticks were sampled only twice per season until 1994, (5) snails were sampled only once in Dry season 1991, twice in Wet season 1991, Wet and Dry seasons 1992, and Wet and Dry seasons of 1993, and three times in Wet and Dry seasons 1994. Sampling at each point consisted of a minimum of two individuals searching all available surfaces within a quadrat (e.g., vegetation, litter, rock, soil) for the presence of snails and walking sticks. Walking sticks were identified to sex whenever possible, with immature or unidentifiable individuals being classified as "juveniles." Exceptions to this classification system are Dry season 1993, Dry season 1996, and Wet season 1996, when no walking sticks were classified to sex. In these cases, all walking sticks are listed in the data file as "juveniles." Beginning in 1995, individuals of C. caracolla and N. tridens were marked with a numbered plastic dot affixed to the shell and measured to the nearest 0.1 mm using dial calipers. All surveys occurred between 19:30 and 03:00 hours to coincide with peak snail activity. Population densities were estimated as Minimum Number Known Alive (MNKA), the maximum number of individuals of each species recorded for a site in each season, and from Wet Season 1995 onward, using the Lincoln-Peterson, Modified Lincoln-Peterson, and Schnabel estimators.



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