Fig 1.
Study area showing surveyed points along an elevational gradient in the Aroma/Chiapa basin, Dry Tropical Andes of Northern Chile.
Circles show the 118 surveyed points, and the striped polygon indicates the western boundary of the Volcán Isluga National Park. Source: Base map from Natural Earth.
Table 1.
Candidate covariates for detectability and density estimations used in the analysis.
Fig 2.
Elevational range sizes for 49 species occurring along an altitudinal gradient in the Dry Tropical Andes of northern Chile, between November 2016 and August 2017.
Lines indicate the maximum and minimum elevational limits of each species range, and species are ordered along the abscissa by ranked elevational midpoints (range average). See “S1 Appendix” for codes of bird species.
Table 2.
Top five ranking models used to estimate the effect of environmental covariates(a) on species richness along an elevational gradient in the Dry Tropical Andes of northern Chile, between November 2016 and August 2017.
The models are ranked in descending order according to AICc.
Fig 3.
Relationship between (a) elevation and alpha diversity, (b) heterogeneity and alpha diversity, (c) elevation and density (individuals/ha), and (d) heterogeneity and density (individuals/ha) along an altitudinal gradient in the Dry Tropical Andes of northern Chile.
Fig 4.
(a) Alpha diversity by habitat type and (b) bird density (individuals/ha) by habitat type, along an elevational gradient in the Dry Tropical Andes of northern Chile. Agr: Agricultural habitat; Arb: Arboreal shrubland habitat; Col: Columnar cactus habitat; Des: Desert habitat; HiS: Highland steppe habitat; Rip: Riparian habitat. Dotted lines indicate mean alpha diversity and mean density, respectively. Significant codes: <0.0001 ‘****’; <0.001 ‘***’; <0.01 ‘**’.
Table 3.
Environmental characteristics, alpha diversity, beta diversity and estimated density for 19 elevational intervals (118 surveys points), surveyed between November 2016 and August 2017, in the Dry Tropical Andes of northern Chile.
Fig 5.
Cluster analyses based on the composition (presence/absence) of bird species across 19 elevational intervals in the northern Andes of Chile, using the Sørensen index of dissimilarity and the Unweighted Pair-Group Method (UPGMA).
The yellow clusters indicate desert belt intervals, the green cluster indicates Pre-Puna belt intervals, and the brown cluster indicates Puna and High Andean belts intervals. Agr: Agricultural habitat; Arb: Arboreal shrubland habitat; Col: Columnar cactus habitat; Des: Desert habitat; HiS: Highland steppe habitat; Rip: Riparian habitat.