eBird checklist data used to analyze temporal patterns of occurrence of Fox Sparrows in the northeastern United States
These data are a filtered version of the 2016 eBird Reference Dataset (https://ebird.org/data/download), which includes only complete checklists and is zero-filled. As such species are treated as absent from any checklist without a positive record of the species. This download consisted of 14,728,627 checklists.
The dataset was created by filtering the 2016 eBird Reference Dataset to include only checklists from June and July. I further reduced the dataset by including only checklists from counties in the northern halves of Maine (Aroostook, Penobscot, Piscataquis, Somerset, Franklin, and Oxford) and New Hampshire (Coos and Grafton). Next, I filtered out any checklists associated with survey protocols not compatible with detection of Fox Sparrows during the breeding season, in particular checklists with count types identified as "Yard Count", "Loon Watch", "My Yard eBird", and "Pelagic" (although the former should be unnecessary given the geographic filters applied). Finally, I removed duplicate checklists generated by multiple observers birding together, first verifying that the number of Fox Sparrows recorded on each checklist matched. In 3 cases, Fox Sparrows were observed by only 1 member of a birding group (in all 3 cases, on the primary checklist) and in these cases I retained the checklist that included the observation of Fox Sparrow, the logic being that the bird was present even if only recorded on one of the group checklists. After applying these filters, I was left with 74,881 checklists, which are included here. I then removed column data for all species except the 3 included in analyses: Fox Sparrow (Passerella iliaca) Bicknell's Thrush (Catharus bicknelli), and Blackpoll Warbler (Setophaga striata) and added 3 columns that transformed count data into a binary presence/absence variable for each of the 3 species.
This dataset can be described as counts of Blackpoll Warbler, Bicknell's Thrush, and Fox Sparrow from all unique complete checklists submitted to eBird using the historical, stationary, traveling, area, or random protocols and included in the 2016 eBird Reference Dataset from Aroostook, Penobscot, Piscataquis, Somerset, Franklin, and Oxford counties in Maine, USA and Coos and Grafton counties in New Hampshire, USA.
