The eBird Basic Dataset (EBD) includes both true species and every other
field-identifiable taxon that could be relevant for birders to report. This
includes taxa not identifiable to a species (e.g. hybrids) and taxa reported
below the species level (e.g. subspecies). This function produces a list of
observations of true species, by removing the former and rolling the latter
up to the species level. In the resulting EBD data.frame,
category will be
"species" for all records and the subspecies fields will
be dropped. By default,
ebd_rollup() when importing an
eBird data file.
auk_rollup(x, taxonomy_version, drop_higher = TRUE)
data.frame; data frame of eBird data, typically as imported by
integer; the version (i.e. year) of the taxonomy. In
most cases, this should be left empty to use the version of the taxonomy
included in the package. See
logical; whether to remove taxa above species during the rollup process, e.g. "spuhs" like "duck sp.".
A data frame of the eBird data with taxonomic rollup applied.
When rolling observations up to species level the observed counts are summed across any taxa that resolve to the same species. However, if any of these taxa have a count of "X" (i.e. the observer did not enter a count), then the rolled up record will get an "X" as well. For example, if an observer saw 3 Myrtle and 2 Audubon's Warblers, this will roll up to 5 Yellow-rumped Warblers. However, if an "X" was entered for Myrtle, this would roll up to "X" for Yellow-rumped Warbler.
The eBird taxonomy groups taxa into eight different categories. These
categories, and the way they are treated by
auk_rollup() are as follows:
Species: e.g., Mallard. Combined with lower level taxa if present on the same checklist.
ISSF or Identifiable Sub-specific Group: Identifiable subspecies or group of subspecies, e.g., Mallard (Mexican). Rolled-up to species level.
Intergrade: Hybrid between two ISSF (subspecies or subspecies groups), e.g., Mallard (Mexican intergrade. Rolled-up to species level.
Form: Miscellaneous other taxa, including recently-described species yet to be accepted or distinctive forms that are not universally accepted (Red-tailed Hawk (Northern), Upland Goose (Bar-breasted)). If the checklist contains multiple taxa corresponding to the same species, the lower level taxa are rolled up, otherwise these records are left as is.
Spuh: Genus or identification at broad level -- e.g., duck sp.,
dabbling duck sp.. Dropped by
Slash: Identification to Species-pair e.g., American Black
Duck/Mallard). Dropped by
Hybrid: Hybrid between two species, e.g., American Black Duck x
Mallard (hybrid). Dropped by
Domestic: Distinctly-plumaged domesticated varieties that may be
free-flying (these do not count on personal lists) e.g., Mallard (Domestic
type). Dropped by
The rollup process is based on the eBird taxonomy, which is updated once a
year in August. The
auk package includes a copy of the eBird taxonomy,
current at the time of release; however, if the EBD and
auk versions are
not aligned, you may need to explicitly specify which version of the
taxonomy to use, in which case the eBird API will be queried to get the
correct version of the taxonomy.
Consult the eBird taxonomy page for further details.
# get the path to the example data included in the package # in practice, provide path to ebd, e.g. f <- "data/ebd_relFeb-2018.txt f <- system.file("extdata/ebd-rollup-ex.txt", package = "auk") # read in data without rolling up ebd <- read_ebd(f, rollup = FALSE) # rollup ebd_ru <- auk_rollup(ebd) # keep higher taxa ebd_higher <- auk_rollup(ebd, drop_higher = FALSE) # all taxa not identifiable to species are dropped unique(ebd$category)#>  "domestic" "form" "hybrid" "intergrade" "slash" #>  "spuh" "species" "issf"unique(ebd_ru$category)#>  "species"unique(ebd_higher$category)#>  "species" "hybrid" "slash" "spuh"# yellow-rump warbler subspecies rollup library(dplyr)#> #>#>#> #>#>#> #># without rollup, there are three observations ebd %>% filter(common_name == "Yellow-rumped Warbler") %>% select(checklist_id, category, common_name, subspecies_common_name, observation_count)#> # A tibble: 3 x 5 #> checklist_id category common_name subspecies_common_name observation_cou… #> <chr> <chr> <chr> <chr> <chr> #> 1 S8949407 species Yellow-rumped … <NA> 1 #> 2 S8949407 issf Yellow-rumped … Yellow-rumped Warbler … 13 #> 3 S8949407 issf Yellow-rumped … Yellow-rumped Warbler … 17# with rollup, they have been combined ebd_ru %>% filter(common_name == "Yellow-rumped Warbler") %>% select(checklist_id, category, common_name, observation_count)#> # A tibble: 1 x 4 #> checklist_id category common_name observation_count #> <chr> <chr> <chr> <chr> #> 1 S8949407 species Yellow-rumped Warbler 31