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P oposal o Sou h Ame ican Classi ica ion Commi ee (SACC)
Recognize Pa agona gigas and Pa agona pe u iana as sepa a e species, wi h e ised
nomencla u e
This p oposal would spli he Gian Hummingbi d (Pa agona gigas) in o wo species, he
No he n Gian Hummingbi d (Pa agona pe u iana) and Sou he n Gian Hummingbi d
(Pa agona gigas).
Backg ound:
The gian hummingbi d genus Pa agona has his o ically been ea ed as a single species,
Pa agona gigas, wi h wo subspecies: P. g. pe u ian a ( hough o ange om Ecuado h ough
NW A gen ina) and P. g. gigas ( hough o ange h oughou Chile and o cen al A gen ina,
p ima ily). Mul iple ecen s udies ha e now p o ided s ong, in eg a i e e idence––including
genomic, mo phological, ecological, biogeog aphic, and ocal da a––suppo ing ull species
s a us o hese axa; hese s udies addi ionally cla i y he anges o each gian hummingbi d
o m. A b ie summa y is p o ided by Schulenbe g e al. 2025.
New In o ma ion:
This his o y o he axonomy and nomencla u e o he gian hummingbi ds was e iewed in
de ail by Williamson e al. 2025, Zoological Jou nal o he Linnean Socie y. Williamson e al.
2024, PNAS p o ided comp ehensi e genomic, mo phological, and ecological e idence o
species-le el di e gence. Newly a ailable bioacous ic da a analyzing songs ac oss he anges
o bo h lineages (Robinson e al., In Re iew; bioRxi p ep in :
h ps://www.bio xi .o g/con en /10.1101/2025.06.30.662449 1) documen s s iking ocal
di e gence, p o iding addi ional decisi e suppo .
Speci ically, hese new da a include:
Di e gen genomes:
- Genome-wide di e gence be ween pe u iana and gigas popula ions was high (FST ≈ 0.6), wi h
es ima ed di e gence imes o ~2.1–3.4 Mya, based on sepa a e es ima es om nuclea DNA
and mi ochond ial DNA, espec i ely (Fig 1A; Williamson e al. 2024).
- Admix u e and PCA analyses o he nuclea genome showed clea popula ion clus e s wi h no
e idence o ongoing gene low. The lack o gene low o e ime was co obo a ed by
ABBA/BABA es s (Fig 1B–D).
Hyb idiza ion:
- The one hyb id indi idual ha was de ec ed among 101 sampled indi iduals was an F1 ( om
he non-b eeding season zone o ange o e lap in Pe u). This inding indica es ha he e is
nea ly comple e pos -zygo ic ep oduc i e isola ion (Williamson e al. 2024), despi e incomple e
p e-zygo ic isola ion and occasional hyb idiza ion be ween he wo species.
- The e is no e idence o ongoing backc ossing o in og ession. I in e -species gene low we e
occu ing, backc ossed indi iduals o mixed ances y would ou numbe F1s, bu he popula ion
genomic da a p esen ed in Williamson e al. (2024) clea ly e u e ha possibili y.
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Figu e 1. Genomic di e gence o he gian hummingbi ds. A) Time-calib a ed phylogenies
es ima ed di e gence o no he n (pe u iana) and sou he n (gigas) gian hummingbi ds ~2.1–
3.4 million yea s ago (Mya). B–C) P incipal Componen s Analysis (4,416 SNPS om ul a-
conse ed elemen s o 70 indi iduals) illus a ed s ong species di e en ia ion and s uc u e
wi hin each no he n and sou he n o ms. D) Admix u e analysis (wi h sNMF) o 35 whole
genomes illus a ed clea popula ion s uc u e be ween no he n and sou he n o ms. No
admixed indi iduals we e de ec ed be ween no he n and sou he n lineages. Coun y labels
deno e sampling o igin; colo s co espond o ances y. Modi ied om Williamson e al. 2024.
Mo phology & plumage di e ences:
- pe u iana a e ages la ge in bill, wing, ail, and a sus leng h. I has a whi e h oa and chin
wi h da ke black s eaks and a b igh e whi e pos -ocula spo (Fig. 2).
- gigas a e ages sligh ly smalle in all measu emen s. I has a b owne , some imes eddish chin
and h oa , wi h almos g eenish s eaks (Fig. 2).
- Despi e hese di e ences, ex ensi e o e lap exis s in mo phological measu emen s;
disc iminan analyses based on mo phology can only co ec ly classi y ~65–85% o indi iduals
when e alua ing solely adul s, and when examining sexes sepa a ely (Williamson e al. 2024,
Williamson e al. 2025).
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Figu e 2. Pla e o dis inguishing be ween no he n (pe u iana) and sou he n (gigas) gian
hummingbi ds, highligh ing impo an plumage and mo phological cha ac e is ics. Modi ied om
Williamson e al. 2025.
Song di e gence:
- A comp ehensi e analysis o 217 eco dings spanning 49 yea s (1976–2025), >36° la i ude,
and >4,300 m in ele a ion has e ealed ha he songs o pe u iana and gigas di e signi ican ly
in all measu ed ai s: pe u iana songs a e >2x longe in du a ion wi h signi ican ly highe
minimum (mean ~4.5 kHz) and maximum (mean ~5.6 kHz) equencies. The equency ange o
gigas songs is 2x g ea e han ha o pe u iana (Fig. 3A–D; Robinson e al., In Re iew).
- A linea disc iminan model based on song ai s co ec ly classi ied indi iduals as pe u iana o
gigas wi h 100% accu acy when ained on b eeding season da a. When applied o ull annual
da a as a ool o iden i y indi iduals ac oss he ange and du ing pe iods o non-b eeding
season o e lap, he model had 98.7% accu acy (1.28% e o a e; one indi idual mis-iden i ied).
- Spec og am shapes a e highly diagnos ic: pe u iana songs appea as an upwa d-sloping no e
leading o a sho , ho izon al segmen . By ea , songs a e ecognizable as a high-pi ched, d y
and hin ' see!'. In con as , gigas songs ha e he shape o a candy cane (i.e., an in e ed
capi al le e ‘J’; long and s aigh on one end, wi h a igh , cu ed bend a he op). By ea , hey
a e ecognizable as a loud ‘ siP!’ wi h an ab up ending.
- Song appea s o be he mos eliable and diagnos ic ai o ield iden i ica ion in zones o
sympa y. Unlike plumage and mo phology, his cha ac e is ic is applicable o bo h adul s and
ju eniles (Fig. 3E).
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Figu e 3. The songs o no he n (pe u iana) and sou he n (gigas) gian hummingbi ds di e in
all measu ed cha ac e is ics. A) Minimum equency was 2x highe in pe u iana songs. B)
Maximum equency was 1.3x highe in pe u iana songs. C) pe u iana songs a e 2x longe . D)
F equency ange was 2.41x g ea e in gigas. E) Spec og ams illus a e ocal di e ences
be ween pe u iana ( op) and gigas (bo om) songs; hese di e ences diagnose he wo wi h
high con idence. Modi ied om Robinson e al., In Re iew.
Biogeog aphy & con ac zone:
- pe u iana is esiden a high ele a ions (1,800–4,300 m) om SW Colombia h ough Ecuado ,
Pe u, no he n Chile, and in o no he n Boli ia.
- gigas is a mig a o y b eede in cen al Chile (0–2,500 m) and NW A gen ina ( ypically abo e
~2,500 m) ha spends he non-b eeding season a high ele a ions (>2,500 m) in cen al and
sou he n Pe u. I also b eeds h oughou Boli ia, whe e he e a e no da a ye on seasonal
mo emen s.
- New ield da a documen ed a p e iously un ecognized sympa y a ound Copacabana, Boli ia
(Lake Ti icaca), whe e bo h species co-occu a high ele a ions (Robinson e al., In Re iew).
- Songs a e ully diagnos ic, e en in he pu a i e zone o sympa y.
Recommenda ions:
This p oposal has h ee pa s:
A. Species Recogni ion: Recognize he gian hummingbi ds as wo species based on
conco dan genomic, mo phological, ecological, biogeog aphic, and ocal e idence (Robinson
e al., In Re iew; Williamson e al. 2024; Williamson e al. 2025).
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B. Scien i ic Names: Following he ecommenda ions ou lined in Williamson e al. 2025, use he
scien i ic name Pa agona pe u iana (Bouca d 1893; p io i y name, A e a e al. 2024) o he
no he n species and he name Pa agona gigas (Vieillo 1824) o he sou he n species. The
name Pa agona chaski (sensu Williamson e al. 2024) is a junio synonym o P. p e u ia na
(Williamson e al. 2025).
C. English Names: Following ecommenda ions by Williamson e al. 2024 and Williamson e al.
2025, use he English names No he n Gian Hummingbi d (Pa agona pe u iana) and Sou he n
Gian Hummingbi d (Pa agona gigas).
Li e a u e Ci ed:
A e a, J.I., Halley, M.R., Ki wan, G.M., No ambuena, H.V., K abbe, N.K., Piacen ini, V.Q., 2024.
The wo ld’s la ges hummingbi d was desc ibed 131 yea s ago. Bulle in o he B i ish
O ni hologis s’ Club 144. h ps://doi.o g/10.25226/bboc. 144i3.2024.a14
Bouca d, A., 1893. Gene a o Humming Bi ds. Pa dy & Co. P in e s, London, UK.
Robinson, B.W., Zucke , R.J., Wi , C.C., Valqui, T., Williamson, J.L., In Re iew. Songs
dis inguish he c yp ic gian hummingbi d species and cla i y ange limi s. bioRxi .
h ps://doi.o g/10.1101/2025.06.30.662449
Schulenbe g, T.S., 2025. Spli s, lumps and shu les. Neo opical Bi ding 36, 66–69.
Vieillo , L.P., 1824. La Gale ie des Oiseaux. Cons an -Chan pie, Pa is, F ance.
Williamson, J., Gyllenhaal, E.F., Baue n eind, S.M., Bau is a, E., Baumann, M.J., Gadek, C.R.,
Ma a, P.P., Rico e, N., Valqui, T., Bozino ic, F., Singh, N.D., Wi , C.C., 2024. Ex eme
ele a ional mig a ion spu ed c yp ic specia ion in gian hummingbi ds. P oceedings o
he Na ional Academy o Sciences 121, 1–11. h ps://doi.o g/10.1073/pnas.2313599121
Williamson, J.L., Gadek, C.R., Robinson, B.W., Bau is a, E., Baue n eind, S.M., Baumann, M.J.,
Gyllenhaal, E.F., Ma a, P.P., Rico e, N., Singh, N.D., Valqui, T., Wi , C.C., 2025.
Taxonomy, nomencla u e, and iden i ica ion o he gian hummingbi ds (Pa agona spp.)
(A es: T ochilidae). Zoological Jou nal o he Linnean Socie y 204, 1–16.
h ps://doi.o g/doi.o g/10.1093/zoolinnean/zla 036
Jessie L. Williamson, Thomas Valqui, and Ch is ophe C. Wi , July 2025
