“index”
Numerical index used for ordering

“sample”
This is the record number. e.g. ND19J03 = The first letter refers to the year (N = 14th letter; these samples were collected in 2014), the second letter refers to the month (D = 4th letter; these samples were collected. The number (“19”) refers to the day of the month. The third letter (“J”) refers to the collector (“Julian” in this case) and the final number was the individual bird it was collected from. Therefore, two feathers were collected from the individual ND19J03.

“dH”
Raw hydrogen value

“pair”
Indicates whether the sample is paired with another from the same individual

“species”
M - myrtle; A - Audubon’s, as identified by plumage

“feather”
This identifies the feather mold, alternate versus basic (see manuscript for additional details)

“Hp”
This is the inferred precipitation hydrogen value as estimated using the Hf:Hp transformation function ( see manuscript for additional details).

“Isomap_job_key”
Isomap retains all of the assignment modelling jobs and this refers to the specific run using the precipitation model for each feather assignment.

“wing_chord”
The length of the unflattened wing

“tail_length”
The leather of the tail

“wing_tail”
The additive measure of “wing_chord” and “tail_length”