Data from: Abundance models of endemic birds of the Sierra Nevada de Santa Marta, northern South America, suggest small population sizes and dependence on montane elevations
Data files
Feb 05, 2024 version files 268.32 KB
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Dataset-Abundance_models_priority_endemics_SNSM.xlsx
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README.md
Abstract
Abundance measures are almost non-existent for several bird species threatened with extinction, particularly range-restricted Neotropical taxa, for which estimating population sizes can be challenging. Here we use data collected over nine years to explore the abundance of 11 endemic birds from the Sierra Nevada de Santa Marta (SNSM), one of Earth’s most irreplaceable ecosystems. We established 99 transects in the “Cuchilla de San Lorenzo” Important Bird Area within native forest, early successional vegetation, and areas of transformed vegetation by human activities. A total of 763 bird counts were carried out covering the entire elevation range in the study area (~175–2650 m). We applied hierarchical distance-sampling models to assess elevation- and habitat-related variation in local abundance and obtain values of population density and total and effective population size. Most species were more abundant in the montane elevational range (1800–2650 m). Habitat-related differences in abundance were only detected for five species, which were more numerous in either early succession, secondary forest, or transformed areas. Inferences of effective population size indicated that at least four endemics likely maintain populations no larger than 15,000–20,000 mature individuals. Estimates of species’ area of occupancy and effective population size were lower than most values previously described, a possible consequence of increasing anthropogenic threats. At least four of the endemics exceeded criteria for threatened species listing and a thorough evaluation of their extinction risk should be conducted. Population strongholds for most of the study species were located on the northern and western slopes of the SNSM between 1500–2700 m. We highlight the urgent need for facilitating effective protection of native vegetation in premontane and montane ecosystems to safeguard critical habitats for the SNSM’s endemic avifauna. Follow-up studies collecting abundance data across the SNSM are needed to obtain precise range-wide density estimations for all species.
README: Data from: Abundance models of endemic birds of the Sierra Nevada de Santa Marta, northern South America, suggest small population sizes and dependence on montane elevations
https://doi.org/10.5061/dryad.5dv41nscw
MS Reference Number: ORNITH-APP-23-061R2
Dataset name: Abundance_models_priority_endemics_SNSM.xlsx
The whole dataset contains data for fitting hierarchical distance-sampling models for priority, endemic bird species from the Sierra Nevada de Santa Marta, northern Colombia. Models were used to assess elevation- and habitat-related variation in local abundance and obtain values of population density and total and effective population size for the study species. Details on other methods used for estimating extent of presence (EOP) and area of occupancy (AOO), and for generating abundance maps are provided in the manuscript and the supplementary material file that accompanies it. Abundance maps will be uploaded as distribution hypothesis for each species to the BioModelos online platform (Velásquez-Tibatá et al. 2019), available at http://biomodelos.humboldt.org.co. BioModelos is an initiative of the Instituto de Investigación de Recursos Biológicos Alexander von Humboldt (IAvH; http://www.humboldt.org.co/es/).
The data set is divided into twelve spreadsheets, which are explained below.
1. Transect_Info:
This spreadsheet contains all information regarding location and habitat covariates at each of the 99 transects installed throughout the study area in the "Cuchilla de San Lorenzo" IBA, Sierra Nevada de Santa Marta (Colombia).
These data matrices contain the following variables:
VARIABLE DESCRIPTION
- Location: Name of the locality where each transect is located.
- TransectID: Name of each transect.
- TLength: Length of each transect in m.
- TReps: Total number of replicated surveys in each transect.
- TDistance: Total distance surveyed for each transect during the study in m.
- TBirdRecs: Total number of records of the study species in each transect.
- Latitude: Coordinates in decimal degrees.
- Longitude: Coordinates in decimal degrees.
- Elevation: Elevation in m.
- ElevCat: Elevation category as described in the main text (Low: lowland, 171–1200 m; Pre: premontane, 1200–1800 m; Monta: montane, 1800–2650 m).
- LandCover: Land cover units considered as potential habitat for the study species.
2. Dryhel, 3. Graban, 4. Scylat, 5. Scysan, 6. Synfus, 7. Atlmel, 8. Arrbas, 9. Myicon, 10. Myifla, 11. Animel:
These spreadsheets contain ready-to-use datasets for fitting distance-sampling models in the R package unmarked (Fiske & Chandler 2011). Each spreadsheet contains data collected during bird counts for all the 11 study species.
- Dryhel: Drymophila hellmayri
- Graban: Grallaria bangsi
- Scylat: Scytalopus latebricola
- Scysan: Scytalopus sanctaemartae
- Synfus: Synallaxis fuscorufa
- Atlmel: Atlapetes melanocephalus
- Arrbas: Arremon basilicus
- Myicon: Myiothlypis conspicillata
- Myifla: Myioborus flavivertex
- Animel: Anisognathus melanogenys
These data matrices contain the following variables:
VARIABLE DESCRIPTION
- Location: Name of the locality where each transect is located.
- TransectID: Name of each transect.
- TransectID2: Unique name given to each transect for modeling purposes.
- TransectRep: Code to identify each repetition for each transect.
- Species: Species scientific name.
- CodSpecies: Short name for each species.
- NoInd: Number of individuals for every record.
- Distance: Estimated distance to each individual recorded in m.
- Record: Type of record (acoustic and/or visual).
- Date: Date of survey (d/m/y).
- Day: Day when the record was made.
- Month: Month when the record was made.
- Year: Year when the record was made.
- StartTime: Survey starting hour in min.
- Duration: Survey duration in min.
- Observer: Nick Bayly (NB) or Enrick Meza (EM).
- TDistance: Total distance surveyed for each transect during the study in m.
- Elevation: Elevation in m.
- LandCover: Land cover type where survey took place.
*NA: not available.
References:
Fiske, I., and R. Chandler (2011). “unmarked”: an R package for Fitting Hierarchical Models of Wildlife Occurrence and Abundance. Journal of Statistical Software 43:1–23.
Velásquez-Tibatá, J. I., Olaya-Rodríguez, M. H., López-Lozano, D., Gutiérrez, C., González, I., and M. C. Londoño-Murcia (2019). BioModelos: A collaborative online system to map species distributions. PLoS ONE 14:e0214522.
Contact information:
Esteban Botero-Delgadillo, Dr.Sc.
Director of Conservation Science
SELVA: Research for Conservation in the Neotropics
Diagonal 42A No 20 - 37
Barrio La Soledad, Bogotá, 111311, Colombia
https://selva.org.co/en/home/
e-mail: eboterod@gmail.com; esteban.botero@selva.org.co