Proposal (1059) to South American Classification Committee

Recognize Patagona gigas and Patagona peruviana as separate species, with revised nomenclature

This proposal would split the Giant Hummingbird (Patagona gigas) into two species, the Northern Giant Hummingbird (Patagona peruviana) and Southern Giant Hummingbird (Patagona gigas).

Background:

The giant hummingbird genus Patagona has historically been treated as a single species, Patagona gigas, with two subspecies: P. g. peruviana (thought to range from Ecuador through NW Argentina) and P. g. gigas (thought to range throughout Chile and to central Argentina, primarily). Multiple recent studies have now provided strong, integrative evidence––including genomic, morphological, ecological, biogeographic, and vocal data––supporting full species status for these taxa; these studies additionally clarify the ranges of each giant hummingbird form. A brief summary is provided by Schulenberg et al. (2025).

New Information:

This history of the taxonomy and nomenclature of the giant hummingbirds was reviewed in detail by Williamson et al. 2025, Zoological Journal of the Linnean Society. Williamson et al. 2024, PNAS provided comprehensive genomic, morphological, and ecological evidence of species-level divergence. Newly available bioacoustic data analyzing songs across the ranges of both lineages (Robinson et al., In Review; bioRxiv preprint: https://www.biorxiv.org/content/10.1101/2025.06.30.662449v1) documents striking vocal divergence, providing additional decisive support.

Specifically, these new data include:

Divergent genomes:

- Genome-wide divergence between peruviana and gigas populations was high (F_ST ≈ 0.6), with estimated divergence times of ~2.1–3.4 Mya, based on separate estimates from nuclear DNA and mitochondrial DNA, respectively (Fig 1A; Williamson et al. 2024).

- Admixture and PCA analyses of the nuclear genome showed clear population clusters with no evidence of ongoing gene flow. The lack of gene flow over time was corroborated by ABBA/BABA tests (Fig 1B–D).

Hybridization:

- The one hybrid individual that was detected among 101 sampled individuals was an F1 (from the non-breeding season zone of range overlap in Peru). This finding indicates that there is nearly complete post-zygotic reproductive isolation (Williamson et al. 2024), despite incomplete pre-zygotic isolation and occasional hybridization between the two species.

- There is no evidence of ongoing backcrossing or introgression. If inter-species gene flow were occurring, backcrossed individuals of mixed ancestry would outnumber F1s, but the population genomic data presented in Williamson et al. (2024) clearly refute that possibility.

Figure 1. Genomic divergence of the giant hummingbirds. A) Time-calibrated phylogenies estimated divergence of northern (peruviana) and southern (gigas) giant hummingbirds ~2.1–3.4 million years ago (Mya). B–C) Principal Components Analysis (4,416 SNPS from ultra-conserved elements of 70 individuals) illustrated strong species differentiation and structure within each northern and southern forms. D) Admixture analysis (with sNMF) of 35 whole genomes illustrated clear population structure between northern and southern forms. No admixed individuals were detected between northern and southern lineages. Country labels denote sampling origin; colors correspond to ancestry. Modified from Williamson et al. 2024.

Morphology & plumage differences:

- peruviana averages larger in bill, wing, tail, and tarsus length. It has a whiter throat and chin with darker black streaks and a brighter white post-ocular spot (Fig. 2).

- gigas averages slightly smaller in all measurements. It has a browner, sometimes reddish chin and throat, with almost greenish streaks (Fig. 2).

- Despite these differences, extensive overlap exists in morphological measurements; discriminant analyses based on morphology can only correctly classify ~65–85% of individuals when evaluating solely adults, and when examining sexes separately (Williamson et al. 2024, Williamson et al. 2025).

Figure 2. Plate for distinguishing between northern (peruviana) and southern (gigas) giant hummingbirds, highlighting important plumage and morphological characteristics. Modified from Williamson et al. 2025.

Song divergence:

- A comprehensive analysis of 217 recordings spanning 49 years (1976–2025), >36° latitude, and >4,300 m in elevation has revealed that the songs of peruviana and gigas differ significantly in all measured traits: peruviana songs are >2x longer in duration with significantly higher minimum (mean ~4.5 kHz) and maximum (mean ~5.6 kHz) frequencies. The frequency range of gigas songs is 2x greater than that of peruviana (Fig. 3A–D; Robinson et al., In Review).

- A linear discriminant model based on song traits correctly classified individuals as peruviana or gigas with 100% accuracy when trained on breeding season data. When applied to full annual data as a tool to identify individuals across the range and during periods of non-breeding season overlap, the model had 98.7% accuracy (1.28% error rate; one individual mis-identified).

- Spectrogram shapes are highly diagnostic: peruviana songs appear as an upward-sloping note leading to a short, horizontal segment. By ear, songs are recognizable as a high-pitched, dry and thin 'tsee!'. In contrast, gigas songs have the shape of a candy cane (i.e., an inverted capital letter ‘J’; long and straight on one end, with a tight, curved bend at the top). By ear, they are recognizable as a loud ‘tsiP!’ with an abrupt ending.

- Song appears to be the most reliable and diagnostic trait for field identification in zones of sympatry. Unlike plumage and morphology, this characteristic is applicable to both adults and juveniles (Fig. 3E).

Figure 3. The songs of northern (peruviana) and southern (gigas) giant hummingbirds differ in all measured characteristics. A) Minimum frequency was 2x higher in peruviana songs. B) Maximum frequency was 1.3x higher in peruviana songs. C) peruviana songs are 2x longer. D) Frequency range was 2.41x greater in gigas. E) Spectrograms illustrate vocal differences between peruviana (top) and gigas (bottom) songs; these differences diagnose the two with high confidence. Modified from Robinson et al., In Review.

Biogeography & contact zone:

- peruviana is resident at high elevations (1,800–4,300 m) from SW Colombia through Ecuador, Peru, northern Chile, and into northern Bolivia.

- gigas is a migratory breeder in central Chile (0–2,500 m) and NW Argentina (typically above ~2,500 m) that spends the non-breeding season at high elevations (>2,500 m) in central and southern Peru. It also breeds throughout Bolivia, where there are no data yet on seasonal movements.

- New field data documented a previously unrecognized sympatry around Copacabana, Bolivia (Lake Titicaca), where both species co-occur at high elevations (Robinson et al., In Review).

- Songs are fully diagnostic, even in the putative zone of sympatry.

Recommendations:

This proposal has three parts:

A. Species Recognition: Recognize the giant hummingbirds as two species based on concordant genomic, morphological, ecological, biogeographic, and vocal evidence (Robinson et al., In Review; Williamson et al. 2024; Williamson et al. 2025).

B. Scientific Names: Following the recommendations outlined in Williamson et al. 2025, use the scientific name Patagona peruviana (Boucard 1893; priority name, Areta et al. 2024) for the northern species and the name Patagona gigas (Vieillot 1824) for the southern species. The name Patagona chaski (sensu Williamson et al. 2024) is a junior synonym of P. peruviana (Williamson et al. 2025).

C. English Names: Following recommendations by Williamson et al. 2024 and Williamson et al. 2025, use the English names Northern Giant Hummingbird (Patagona peruviana) and Southern Giant Hummingbird (Patagona gigas).

Literature Cited:

Areta, J.I., Halley, M.R., Kirwan, G.M., Norambuena, H.V., Krabbe, N.K., Piacentini, V.Q., 2024. The world’s largest hummingbird was described 131 years ago. Bulletin of the British Ornithologists’ Club 144. https://doi.org/10.25226/bboc.v144i3.2024.a14

Boucard, A., 1893. Genera of Humming Birds. Pardy & Co. Printers, London, UK.

Robinson, B.W., Zucker, R.J., Witt, C.C., Valqui, T., Williamson, J.L., In Review. Songs distinguish the cryptic giant hummingbird species and clarify range limits. bioRxiv. https://doi.org/10.1101/2025.06.30.662449

Schulenberg, T.S., 2025. Splits, lumps and shuffles. Neotropical Birding 36, 66–69.

Vieillot, L.P., 1824. La Galerie des Oiseaux. Constant-Chantpie, Paris, France.

Williamson, J., Gyllenhaal, E.F., Bauernfeind, S.M., Bautista, E., Baumann, M.J., Gadek, C.R., Marra, P.P., Ricote, N., Valqui, T., Bozinovic, F., Singh, N.D., Witt, C.C., 2024. Extreme elevational migration spurred cryptic speciation in giant hummingbirds. Proceedings of the National Academy of Sciences 121, 1–11. https://doi.org/10.1073/pnas.2313599121

Williamson, J.L., Gadek, C.R., Robinson, B.W., Bautista, E., Bauernfeind, S.M., Baumann, M.J., Gyllenhaal, E.F., Marra, P.P., Ricote, N., Singh, N.D., Valqui, T., Witt, C.C., 2025. Taxonomy, nomenclature, and identification of the giant hummingbirds (Patagona spp.) (Aves: Trochilidae). Zoological Journal of the Linnean Society 204, 1–16. https://doi.org/doi.org/10.1093/zoolinnean/zlaf036

Jessie L. Williamson, Thomas Valqui, and Christopher C. Witt, July 2025

Vote tracking chart: https://www.museum.lsu.edu/~Remsen/SACCPropChart1044+.htm

Comments from Donsker (voting for Bonaccorso):

“C. Should Proposal 1059 pass I would support the English names proposed by the authors:
Patagona peruviana: Northern Giant Hummingbird

Patagona gigas: Southern Giant Hummingbird”

Comments from Stiles: “YES to recognize 2 species: solid evidence from morphology voice, distributions, and genetics.”