A feather hydrogen (δ(2)H) isoscape for Brazil

Spatial patterns of stable isotopes in animal tissues or “isoscapes” can be used to investigate animal origins in a range of ecological and forensic investigations. Here, we developed a feather hydrogen isotope (δ(2)H(f)) isoscape for Brazil based on 192 samples of feathers from the family Thraupidae from scientific collections. Raw values of δ(2)H(f) ranged from -107.3 to +5.0‰, with higher values at the Caatinga biome (northeast Brazil) and lower values at the Amazon and Pantanal. A Random Forest (RF) method was used to model the spatial surface, using a range of environmental data as auxiliary variables. The RF model indicated a negative relationship between δ(2)H(f) and Mean Annual Precipitation, Precipitation in the Warmest Quarter, and Annual Temperature Range and positive relationships for amount-weighted February-April precipitation δ(2)H (δ(2)H(p(Feb-April))) and Mean Annual Solar Radiation. Modelled δ(2)H(f) values ranged from -85.7 to -13.6‰. Ours is the first δ(2)H(f) isoscape for Brazil that can greatly assist our understanding of both ecological and biogeochemical processes controlling spatial variation in δ(2)H for this region. This isoscape can be used with caution, due to its poor predictive power (as found in other tropical regions) and can benefit from new sample input, new GNIP data, ecological and physiological studies, and keratin standard material better encompassing the range in feather samples from Brazil. So, we encourage new attempts to build more precise feather H isoscapes, as well as isoscapes based on other elements.