Environmental causes of regional variations in Upland Goose (Chloephaga picta) color morphs

The color morphs in the Upland Goose, an endemic bird of Argentina and Chile, refer to variations in the plumage coloration in males, displaying either barred, white, or intermediate combinations of the two. These color variations can be influenced by environmental factors and, consequently, may be associated with specific geographical regions. The aim of this work was to determine the extent of Upland Goose color morphs during the breeding season and to identify potential environmental factors contributing to their differences. We compiled data from citizen science platforms and personal observations, identifying 880 records spanning from 2000-2023, covering the entire Upland Goose breeding area. Environmental variables, such as temperature, precipitation, and NDVI, and the maximum entropy modeling method were used to predict the distribution of different color morphs based on the occurrence data. Upland Goose color morphs were not uniformly distributed during the breeding season. The white morph occupied the broadest habitat suitability range, followed by the intermediate morph and, finally, by the barred morph, primarily found in the southern part of Tierra del Fuego and exhibiting allopatry with the white morph. Habitat suitability predictions suggest that barred and intermediate morphs occupy colder and more humid regions with higher precipitation compared to the white morph. These results are particularly valuable for this species given its “threatened” status in Argentina and its current global population showing a declining trend, as morphs may represent genetic variants with potential unique local adaptations and preserving this intraespecific variability is crucial for the species' conservation.