Habitat change and trade explain the bird assemblage from the La Chimba archaeological site in the northeastern Andes of Ecuador

Abstract

The nature of tree‐line habitats in the Andes has long been a contentious topic in the ecological literature. Palynological studies suggest that a combination of anthropogenic and natural processes throughout the Holocene contributed to its present form and species composition. This is the first study to use zooarchaeological evidence to reconstruct possible prehistoric changes in these alpine habitats. I analysed the remains of birds from the La Chimba archaeological site in northern Ecuador to assess changes in the bird tree‐line community over three distinct phases (Early, 2640–2390 year BP; Middle, 2390–1994 year BP; Late, 1994–1700 year BP) of this prehistoric settlement. The elevation of this site (3200 m) places it near a steep elevational gradient in vegetation, with the modern tree‐line here at 3500–3600 m. Therefore, non‐local specimens of birds from the lowlands would hint at long‐distance trade. The composition of birds changes through time: species associated with high montane forest and shrubby páramos decrease and species from dry or open montane habitats increase. This trend is dominated by the decrease of Curve‐billed Tinamous Nothoprocta curvirostris (current elevational range 3000–3900 m) and a corresponding increase of specimens of Andean Tinamous Nothoprocta pentlandii (current elevational range 1000–2300 m). The large number of Andean Tinamous is surprising given that presently it occurs no closer than 300 km to the south of the La Chimba site. Overall, 18 of the 43 species of birds identified from La Chimba are likely to be the result of trade. This includes species from the eastern and western lowlands of Ecuador and one possible long‐distance transport from Peru. Prehistoric trade of birds and bird parts was probably common, and prehistoric anthropogenic landscape change and trade in birds should be considered as alternative explanations for species with disjunct populations in and across the Andes.