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Vocalisations and taxonomy of the Sulawesi Leaf Warbler Phylloscopus sarasinorum complex, including discussion of a novel undescribed taxon from Selayar, Indonesia

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The Sulawesi Subregion was traditionally thought to be home to a single, resident Phylloscopusleaf warbler. However, recent exploration has revealed an additional three species, two of which have only very recently been described: Taliabu Leaf Warbler Phylloscopus emilsalimi and Peleng Leaf Warbler P. suaramerdu from the outlying islands of Taliabu and Peleng, respectively. The third, ‘Selayar Leaf Warbler’, remains undescribed, but here we provide the first bioacoustical documentation of its unique song, along with recommending that Sulawesi Leaf Warbler P. sarasinorum sensu lato should be regarded as two species: Lompobattang Leaf Warbler P. sarasinorum and Sulawesi Leaf Warbler P. nesophilus, based on distinct bioacoustics and morphology
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FORKTAIL 36 (2020): 90–96
INTRODUCTION
Phylloscopus, typically referred to as the leaf warblers, is a widespread
genus with a vexed taxonomy. Many species-groups are cryptic,
differing only subtly in plumage and morphometrics, but more
substantially vocally and genetically (Alström & Olsson 1990, 1992,
1997, Helbig et al. 1995, 1996, Olsson et al. 2005, Rheindt 2006,
Saitoh et al. 2008, Päckert et al. 2009, Martens 2010, Alström et al.
2010, 2011, Eaton et al. 2016, Rheindt et al. 2020). The latter two
sources of information are increasingly used to elucidate species limits,
such that the number of recognised Phylloscopus species has increased
substantially in recent years. In addition, continued exploration of
remote regions and islands has led to the discovery of numerous new
species (e.g. Alström et al. 2010, Ng et al. 2018, Rheindt et al. 2020).
The leaf warblers were traditionally split into two genera:
Phylloscopus (thetypical leaf warblers’) and Seicercus (the ‘spectacled
warblers’). Phylogenetic studies (Alström et al. 2013, 2018) have
since shown traditional Seicercus to comprise two non-sister clades
nestled within Phylloscopus. To resolve this paraphyly, three solutions
are available: 1) to substantially break up Phylloscopus and Seicercus
into smaller genera (e.g. Boyd (2017) recognised nine genera in the
complex); 2) to greatly expand Seicercus to include many traditional
Phylloscopus, including all resident Indonesian leaf warblers (e.g. Eaton
et al. 2016); or 3) to synonymise Phylloscopus and Seicercus to create
a monogeneric family, as advocated by del Hoyo & Collar (2016)
and Alström et al. (2018). For the purposes of this study, we follow
the major global taxonomic checklists (del Hoyo & Collar 2016,
Clements et al. 2019, Gill et al. 2020) in adopting option 3, with the
justification given in Alström et al. (2018) that large genera are not
inherently problematic, providing they are monophyletic.
Traditionally, the Sulawesi Subregion of Indonesia was thought to
be inhabited by a single, widely distributed resident leaf warbler species,
Sulawesi Leaf Warbler Phylloscopus sarasinorum (see Figure 1) [treated
as a Seicercus by Eaton et al. (2016) and Dickinson & Christidis (2014),
and as a Cryptigata by Boyd (2017)]. However, recent exploration has
revealed additional species, two of which have only recently been
described (Rheindt et al. 2020): Taliabu Leaf Warbler P. emilsalimi
and Peleng Leaf Warbler P. suaramerdu from the outlying islands
of Taliabu and Peleng, respectively, several years after being first
documented (Rheindt 2010, Rheindt et al. 2010).
Located in South Sulawesi Province, Selayar lies off the
southernmost tip of the south-west Sulawesi leg, separated by a 16km
deep-water strait that reaches a minimum depth of 250m, such that
even during glacial maxima (when sea levels were up to 120m lower
than the present day), the two landmasses have never been connected.
Selayar hosts two endemic avian taxa: subspecies of Sulawesi Blue
Flycatcher Cyornis omissus peromissus and Rusty-breasted Whistler
Vocalisations and taxonomy of the Sulawesi Leaf Warbler
Phylloscopus sarasinorum complex, including discussion
of a novel undescribed taxon from Selayar, Indonesia
ALEX J. BERRYMAN & JAMES A. EATON
The Sulawesi Subregion was traditionally thought to be home to a single, resident Phylloscopus leaf warbler. However, recent exploration has
revealed an additional three species, two of which have only very recently been described: Taliabu Leaf Warbler Phylloscopus emi lsalimi and
Peleng Leaf Warbler P. suaramer du from the outlying islands of Taliabu and Peleng, respectively. The third, ‘Selayar Leaf Warbler’, remains
undescribed, but here we provide the first bioacoustical documentation of its unique song, along with recommending that Sulawesi Leaf
Warbler P. sarasinorum sensu lato should be regarded as two species: Lompobattang Leaf Warbler P. sarasinoru m and Sulawesi Leaf Warbler
P. nesophilus, based on distinc t bioacoustics and morphology.
Pachycephala fulotincta teysmanni, the latter given species rank,
Selayar Whistler, by del Hoyo & Collar (2016). A form (saleyerensis)
of Sahul Sunbird Cinnyris clementiae is currently synonymised
with the widespread plateni by all major global taxonomies (e.g. del
Hoyo & Collar 2016, Clements et al. 2019, Gill et al. 2020), but
probably deserves recognition as a third endemic subspecies (Eaton
& Rheindt 2017). Selayar was first ornithologically explored by
Teysmann in 1878—which included, among others, the collection
of Selayar Whistler (Büttikofer 1893)—and again in 1889 and 1895
by Professor Max Weber and Alfred H. Everett respectively (Hartert
1896). Although Everett collected an Arctic Warbler P. borealis sensu
lato (AMNH 449898; specimen checked), neither he nor Weber are
known to have procured any other Phylloscopus on the island. Further
explorations, in 1927 (von Plessen 1929) and 1993 (Dutson 1995) also
make no mention of a resident leaf warbler on the island.
On 30 November 2017, JAE discovered a singing Phylloscopus
warbler in an area of mixed second growth forest at an elevation of
220m on Selayar (6.211°S 120.500°E), and noted its unique plumage
compared to other Wallacean leaf warblers (Eaton & Rheindt 2017).
Figure 1. Distribution of resident Phylloscopus in the Sulawesi subregion,
Indonesia.
Forktail 36 (2020) Vocalisations and taxonomy of the Sulawesi Leaf Warbler Phylloscopus sarasinorum complex 91
Between 22–24 January 2020, AJB visited Selayar and at the same
locality found a minimum of six leaf warblers showing the same
plumage traits as those identified in 2017, as well as a lone bird at
a different location further south, at 200m asl. To the best of our
knowledge no one has published, either in peer-reviewed literature
or on popular online sources, any other sighting or documentation
of the novel taxon.
Sulawesi Leaf Warbler is a common (sub)montane species, not
found below 600m, endemic to the island of Sulawesi (White & Bruce
1986, Coates & Bishop 1997). Traditionally (Dickinson & Christidis
2014, del Hoyo & Collar 2016, Clements et al. 2019, Gill et al. 2020),
it is considered to comprise two subspecies: (i) nominate sarasinorum,
endemic to the Lompobattang Massif, South Sulawesi; and (ii)
nesophilus, found in montane forest throughout the rest of Sulawesi
(Figure 1). Eaton et al. (2016) split the two taxa, as ‘Lompobattang
Leaf Warbler’ and ‘Sulawesi Leaf Warbler’ respectively, on account
of ‘extensive vocal and plumage differences greater in magnitude
than between many other leaf warbler species’. Here, we describe the
bioacoustical and morphological distinctiveness of the two Sulawesi
and single Selayar taxa, and propose species status for all three.
METHODS
Acoustic analysis
In January 2020, the first sound recordings of Selayar Leaf Warbler
song were obtained from four individuals. These are compared
herein to other Wallacean Phylloscopus species. Recordings of songs
were compiled from online repositories: AVoCet (https://avocet.
integrativebiology.natsci.msu.edu/), xeno-canto (https://www.
xeno-canto.org/) and the Macaulay Library (http://macaulaylibrary.
org/); recordings that were too poor quality to extract data were
removed. Sonograms were visualised and analysed with Raven
Lite v2.0 (Bioacoustics Research Program, Cornell Laboratory of
Ornithology, Ithaca, New York, USA). Contrast and brightness
were equalised across all recordings. Elements were defined as an
unbroken vocal segment within a strophe; a strophe is defined as
a series of elements with a discrete beginning and end. Parameters
measured were: 1) number of elements per strophe; 2) duration
of strophe; 3) lowest frequency of strophe; 4) highest frequency
of strophe; 5) bandwidth of strophe (Table 1). The means of all
parameters were calculated for each individual. Data for P. presbytes
and P. rotiensis were taken from Ng et al. (2018).
Morphological comparison
Photographs of Wallacean Phylloscopus species were compiled from
online depositories, as well as the authors’ private collections, to check
for a range of plumage and bare part characteristics. Discounting
poor quality photographs and duplicates between depositories, 184
photographs were analysed (including Macaulay Library n = 70;
Flickr n = 55; Oriental Bird Images n = 16, see Appendix 1). For
‘Selayar Leaf Warbler’, P. s. sarasinorum and P. s. nesophilus, these
consisted of at least 5, 28 and 26 individual birds, respectively.
RESULTS
Selayar Leaf Warbler Phylloscopus sp.
The song of this undescribed taxon is characterised by the repetition
of short stereotypic strophes (0.8–2 seconds; mean 1.23), spaced
by 1.6–3.1 seconds (Figure 2). Each strophe is audible as a distinct
rattle (sometimes with a simple introduction), with little complexity
and a relatively high minimum frequency. Compared to both
sarasinorum (Figure 3) and nesophilus (Figure 4), the song of this
undescribed taxon is much simpler, with no rambling or squeaky
quality to its strophes. Among the four individuals recorded, there
was little variation away from the recording visualised in Figure
2. Structurally, the song is most similar to that of sarasinorum
(cf. Figure 3A)—which it is geographically closest to—however,
the latter has longer strophes (Kruskal-Wallis Test: χ2(1) = 4.127,
p<0.05) with more elements (χ2(1) = 6.585, p = 0.01) and exhibits
considerably more complexity, with fewer repetitions or rattles.
Sulawesi Leaf Warbler Phylloscopus sarasinorum
As first reported in Eaton et al. (2016), the song of P. s. sarasinorum
is strikingly different to that of P. s. nesophilus, although both exhibit
considerable variation with much overlap. The song of nesophilus has
Table 1. Univariate summary statistics (mean ± standard deviation) of selected vocal parameters for the six Wallacean Phylloscopus taxa,
including the novel taxon from Selayar.
Figure 2. Sonogram of the song of Selayar Leaf Warbler Phylloscopus
sp., Selayar, Indonesia [XC585653, AJB].
Taxon/island
Vocal para meter
Selayar L eaf Warbler
(P. sp.)
(n = 4)
P. s. sarasinorum
(south-wes t Sulawesi)
(n = 6)
P. s. nesophilus
(rest of Sul awesi)
(n = 16)
P. p. presbytes
(Timor)
(n = 33)
P. p. oresianus
(Flores)
(n = 17)
P. rotiensis
(Rote)
(n = 30)
Number of e lements
per stro phe 7.83 ± 0.67 11.33 ± 2.07 13.87 ± 2.19 7.8 ± 2.16 7.15 ± 1.26 5. 58 ± 0.66
Duratio n of
stroph e (seconds) 1.23 ± 0.19 1.90 ± 0.61 3.58 ± 2.77 1.14 ± 0.25 1.05 ± 0.23 1.39 ± 0.11
Lowest fr equency of
stroph e (Hz) 3214.71 ± 307.95 2944.73 ± 307.83 2141.70 ± 623.38 2764.24 ± 345.68 2 953.7 ± 358.37 3075.28 ± 392.21
Highest f requency o f
stroph e (Hz) 6975.89 ± 480.14 6650.76 ± 393.8 6858.06 ± 67 2.37 7953.98 ± 533.67 7920.88 ± 537.86 8103.1 ± 490.37
Bandwi dth of
stroph e (Hz) 4127.3 8 ± 924.4 3390.2 ± 601.7 4737.57 ± 9 94.5 5189.74 ± 705.94 4967.17 ± 445.89 5027.82 ± 685. 93
92 ALEX J. BERRYMAN et al. Forktail 36 (2020)
a peculiar squeaky quality unmatched by sarasinorum, principally a
result of its significantly greater bandwidth 2(1) = 5.918, p = 0.015).
In addition, it is usually more varied, with a greater number of elements
per strophe (χ2(1) = 5.273, p = 0.022), and more rambling, often
lacking any structure or repetition (although the latter character is
somewhat variable). Recordings of nesophilus song from throughout
Sulawesi were analysed (north: n = 4; south-east: n = 6; central: n =
6), with no variation noticed between subpopulations.
Morphological dierences
Selayar Leaf Warbler Phylloscopus sp.
All birds observed (n = 7) matched the phenotype described
by Eaton & Rheindt (2017). Specifically, birds on Selayar are
characterised by very dull olive-green upperparts with almost no
yellowish hue, a broad, whitish crown-stripe, a long supercilium
extending to rear crown, unmarked ear-coverts, and whitish
underparts (including contrasting undertail-coverts). While Eaton
& Rheindt (2017) noted a ‘narrow but distinct greater covert
wingbar’, this appeared to be variable: only three individuals
displayed it, which was likely due to the worn plumages displayed on
some individuals. Birds showed extensive white in the tail, seemingly
at least equal to that shown by sarasinorum. While comparisons
must await accurate measurements, all individuals also appeared to
exhibit a conspicuously large bill. Qualitative plumage data (Table 2)
Figure 3. Sonogram of Lompobattang Leaf Warbler Phylloscopus sarasinorum sarasinorum, from the Lompobattang Massif, South Sulawesi
[XC393126, Jonas Nordin].
Taxon/island
Plumage f eature ‘Selaya r Leaf Warbler ’
(P. sp.)
P. s. sarasinorum
(south-wes t Sulawesi)
P. s. nesophilus
(rest of Sul awesi)
P. p. presbytes
(Timor)
P. p. oresianus
(Flores)
P. rotiensis
(Rote)
Crown-stripe Yes: whi tish Yes: broad, pa le
yellowish Ab sent Yes: dull, greyish Indistin ct Yes: pale yellowis h
Crown Oli ve-green Dark brown Brownish Ol ive-grey Grey Olive -grey
Supercilium Bro ad, whitish Broad, pale y ellowish Narrow, pale yell owish Pale yellowis h Whitish Pale yellowish
Underparts Whitish Whitis h, yellow wash
on breast Yellow-washed Variably pal e yellowish Bright yellow Pale yellow
Upperparts Dul l olive-green Olive-b rown Olive-b rown Olive- green Ol ive-green Olive-brown
Wingbar
Present on a t least some
individu als (absent on
worn birds)
Yes: pale tips to gr eater
coverts A bsent Variably pr esent Variably p resent Yes: pale cre am tips to
greater cover ts
White in ou tertail Yes: seemingly s imilar
extent to sarasinorum
Yes: extensi ve white on
inner webs of t wo outer
rectr ices
Absent
Yes: inner webs of ou ter
three feat hers entirely
white
Yes: inner webs of ou ter
three feat hers entirely
white
Yes: inner vanes o n
outermos t feathers enti rely
white
Undertail-coverts Whi tish Yellowi sh Yellowish Pale yel low Yellowish Pale yell ow
Bill Grey; di stinctly long er
than sarasinorum
Dark with or ange lower
mandible ba sally Dark Dark w ith orange lower
mandible ba sally
Dark with or ange lower
mandible ba sally
Pinkish- orange mandible;
very larg e (15% l onger than
P. presbytes)
Legs Slate-grey Blackish Slate-grey Slate-grey Slate-grey Slate-grey
Table 2. Qualitative summary characteristics of plumage and bare-part dierences using photographs (see Appendix 1) between some
taxa in the Wallacean Phylloscopus complex.
Forktail 36 (2020) Vocalisations and taxonomy of the Sulawesi Leaf Warbler Phylloscopus sarasinorum complex 93
undoubtedly align Selayar birds as most similar to P. s. sarasinorum,
but the former differ clearly in their whiter underparts, supercilium,
crown-stripe and undertail-coverts, greenish, not brownish lateral
crown-stripes, lack of any yellow plumage tones, and perhaps larger
bill (cf. photographs in Plate 1).
Sulawesi Leaf Warbler Phylloscopus sarasinorum
In addition to significant bioacoustic differences between the two
taxa, sarasinorum and nesophilus are also morphologically distinct
(Table 2). Comparing photographs from online repositories,
sarasinorum (n = 26) always showed pale tips to the greater coverts
(even in moulting individuals), forming a single narrow wingbar,
while this always appeared absent in nesophilus across their range (n
= 30). Moreover, sarasinorum has a darker crown, with much greater
contrast between that and the mantle (concolorous in nesophilus), a
broad pale crown-stripe (absent in nesophilus), and white in the inner
webs of the two outer rectrices (absent in nesophilus; Riley 1918)—
for the latter feature, compare the undertail visible on the bottom
row of Plates 1B and 1C. These differences greatly exceed those of
other taxa traditionally treated as species (compare, for example, the
differences between P. presbytes and P. rotiensis in Table 2).
DISCUSSION AND TAXONOMIC
RECOMMENDATIONS
As is typical for small island taxa (Kroodsma 1985, Baker et al.
2006, Morinay et al. 2013), the song of Selayar Leaf Warbler is much
simplified when compared to its mainland congeners, comprising
shorter strophes with fewer elements. These differences are probably
a result of founder effects given Selayar’s likely colonisation by
Phylloscopus via south-west Sulawesi (further evidenced by Selayar
Leaf Warbler’s morphological and bioacoustic affinity to sarasinorum).
Nonetheless, these differences are substantial. The fact that evidence
A
B
Figure 4. Sonograms of Sulawesi Leaf Warbler Phylloscopus sarasinorum nesophilus from [A] the Mekongga Mountains, Southeast Sulawesi (JAE);
and [B] Gunung Ambang, North Sulawesi [XC152065, Mike Nelson].
94 ALEX J. BERRYMAN et al. Forktail 36 (2020)
Plate 1. Photographs of Sulawesi Phylloscopus leaf warblers: (top two images) Selayar Leaf Warbler, Selayar [November 2017, JAE]; (left lower three
images) P. sarasinorum sarasinorum, Lompobattang [top and middle, November 2017, JAE; bottom, November 2017, MIKE NELSON]; (right lower
three images) P. s. nesophilus [top, Lore Lindu NP, September 2013, YANN MUZIKA; middle, Lore Lindu NP, November 2017, MIKE NELSON; bottom,
Gunung Ambang, September 2018, SCOTT BAKER].
Forktail 36 (2020) Vocalisations and taxonomy of the Sulawesi Leaf Warbler Phylloscopus sarasinorum complex 95
comes from two independent lines of enquiry—morphology and
bioacoustics—provides strong support for the view that Selayar Leaf
Warbler represents a unique lineage that is likely to be both diagnosably
distinct and reproductively isolated. This interpretation is consistent
with the principles of integrative taxonomy (Sangster 2018): the
existence of morphological differences rules out the possibility that the
vocal differences merely represent a local ‘dialect’ and, conversely, the
differences in song rule out the possibility that the plumage differences
represent a local ‘ecotype’. Thus, while formal taxonomic recognition
must await the procurement of specimen material, we recommend that
Selayar Leaf Warbler is given species rank when described.
The plumage and bioacoustic differences between P. s. nesophilus
and P. s. sarasinorum are, arguably, even more pronounced. While it is
widely acknowledged that plumage differences in leaf warbler species
can be subtle (Irwin et al. 2001), P. s. sarasinorum differs significantly
from birds elsewhere on Sulawesi in plumage and song, such that their
position as conspecifics—as adopted by all global taxonomies—is
unjustified, especially given the absence of discernible plumage
and bioacoustic variation in P. s. nesophilus throughout the rest of
Sulawesi. The plumage differences between the two taxa are far more
salient than in near-identical Phylloscopus species on the continent
that are otherwise deeply divergent vocally and phylogenetically
(e.g. the Arctic Warbler complex; Alström et al. 2011), while the
vocal differences also exceed those of other Wallacean leaf warblers:
for example the differences between P. presbytes and P. rotiensis, the
latter having been afforded species rank by global taxonomies (e.g.
Clements et al. 2019, Gill et al. 2020, BirdLife International 2020).
Conservation status
A search of intact native forest at the southernmost end of Selayar (all
< 180m) in January 2020 failed to locate Selayar Leaf Warbler, despite
extensive playback of newly acquired sound recordings, suggesting the
species may be restricted to elevations above 200 m. Selayar is densely
populated on its west coast, while small patches of native forest remain
along its more rugged eastern half, reaching a maximum elevation
of approximately 597m (Google Earth); widespread clearance for
cashew Anacardium occidentale plantations has resulted in very little
native forest remaining. In total, 146km2 of forest cover remains
above 200m (Global Forest Watch 2020), suggesting that Selayar
Leaf Warbler, if described as a species, may qualify for categorisation
as Vulnerable or Endangered under IUCN criteria B1 and B2 (IUCN
2020). Future ornithological surveys on the island should prioritise
quantifying this species’ abundance and density, as well as assessing
the extent to which it is threatened by habitat loss.
Lompobattang Leaf Warbler is confined to the Lompobattang
Massif, occupying the same habitat and range as the forest-dwelling
Lompobatta ng Flycatcher Ficedula bonthaina and Southern
Hylocitrea Hylocitrea bonthaina, both of which are regarded
as Endangered under criteria A2c+3c+4c; B1ab(ii,iii,v) and
B1ab(ii,iii,v), respectively (BirdLife International 2020). Due to its
small range and extensive habitat loss, with an extent of occurrence
likely to be under 1,200km2, we would recommend the same threat
category for Lompobattang Leaf Warbler, highlighting the need for
stronger enforcement to halt the continued, extensive habitat loss
and encroachment throughout the Lompobattang Massif.
Sulawesi Leaf Warbler (sensu stricto) occupies much of the rest
of Sulawesi, where extensive montane forest remains and is unlikely
to be under any immediate threat. We would recommend the status
Least Concern.
CONCLUSION
The increasing use of acoustic signals to differentiate between
Phylloscopus warblers is beginning to elucidate their diversity across
Wallacea, such that more species are now recognised than ever
before. Further research should focus on other island complexes
currently treated as ‘wastebasket species’, in particular those of
Island Leaf Warbler P. maforensis and Mountain Leaf Warbler P.
trivirgatus, which exhibit substantial plumage and vocal variation
among populations across their range (Eaton et al. 2016).
ACKNOWLEDGEMENTS
We thank all recordists and photographers, too numerous to
mention individually, who deposited their sound recordings
and photographs on online depositories, including xeno-canto,
Macaulay, Avocet, Flickr and Oriental Bird Images. We thank Yann
Muzika, Mike Nelson and Scott Baker for permission to reproduce
their photographs in this manuscript. We also thank Paul Sweet
and Peter Capainolo (AMNH) for their assistance in locating and
photographing Everett’s Selayar Phylloscopus borealis specimen.
AJB thanks Nathan Ruser for his help with mapping and accessing
appropriate forest cover data. JAE thanks Frank E. Rheindt for
discussion on the birding potential prior to his visit to Selayar.
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Appendix 1. Photographs used for morphological comparison as
catalogued on online depositories: ML = Macaulay Library, OBI =
Oriental Bird Images.
‘Selayar Lea f Warbler’ Phylloscopus sp. [18 image s, comprising at leas t 5 individuals]
JAE private co llection (x 10); AJB pri vate collectio n (x 8).
Phylloscopus sarasinor um nesophilus [33 image s, comprising at leas t 28 individuals]
ML205509781; ML205255961; ML205222171; ML199370131; ML199360 931; ML199360921;
ML199360901; ML174585391; ML174316661; ML174316631; ML118972811; ML109173191;
ML109173161; ML104572251; ML71039881; ML71039851; ML70689211; ML 70689211; O BI81051;
OBI53550; OBI53549; OBI39541; OBI30387; Flickr 14021907098; Fli ckr 10821818; Flickr 5591072369;
Flickr 21246837114; Oiseaux.net f rpe252267; Oiseaux. net frpe252264; A JB private collec tion (x 4).
Phylloscopus sarasinor um sarasinorum [40 images , comprising at leas t 26 individuals]
ML205767801; ML185364511; ML183583761; ML258916211; ML 258916181; ML 258916071; Flickr
23882528717; Flickr 32334 009348; Flickr 37768893965; Fli ckr 49202524198; Flickr 49203218357;
Flickr 21246837114; Flickr 21682719209; Oiseaux. net pava277364; JAE priv ate collection ( x 20);
AJB priv ate collection (x 6).
Phylloscopus presbytes p resbytes [26 images, com prising at least 18 indi viduals]
ML205145401; ML205769851; ML237611271; ML124032171; ML217828731; ML124 032191;
ML217828781; ML237611571; ML217828701; ML 217828671; ML217828621; ML217681711;
ML215389801; ML192843711; ML179258561; ML124032251; ML124032241; ML124 032221;
ML124032211; ML124032181; ML123174101; ML217681741; OBI159142; OBI120791; Fl ickr
2175011794; Flickr 22185847148.
Phylloscopus presbytes  oris [32 images, compr ising at least 25 indi viduals]
ML205960301; ML204 043871; ML207119431; ML43770351; ML 209277481; ML67252981;
ML67252931; ML43848721; ML43769881; ML43769831; ML94246721; ML94057171; ML179258561;
ML122432271; ML122432251; ML115922701; ML115922491; M L117014411; ML117014401;
ML117012351; ML2566 41951; OBI175278; OBI36481; OBI14007; Flick r 41429761931; Flickr
22440254905; Flic kr 36854433481; Flickr 36185954 073; Flickr 45308958281; Flickr 45260610442;
Flickr 42429093181; Flickr 22239152329.
Phylloscopus rotiensis [35 im ages, comprising at l east 23 individu als]
ML205762241; ML191671191; ML191671211; OBI16524 0; OBI160829; OBI160828; OBI160827;
OBI143812; OBI82127; Flickr 44908930114; Flickr 15118754623; Flickr 44908932534; Fl ickr
15738133735; Flickr 44908399104; Flick r 15736065441; Flickr 15738135425; Flickr 15738134425;
Flickr 15552258499; Fl ickr 44908931604; Flick r 15118751173; Flickr 15736212211; Fli ckr
23529577338; Flickr 297 76037086; Flickr 37381462581; Flickr 49032656631; Flickr 4229 4320855;
Flickr 36186212043; Flickr 368 23398512; Flickr 29832039654; Flickr 45294322 565; Flickr
36597866550; Flick r 29829923743; Flickr 36597866880; Fli ckr 28556240608; Flick r 41526 642165.
... split Sulawesi Leaf Warbler P. sarasinorum (sensu lato) into two species, Lompobattang Leaf Warbler P. sarasinorum of the Lompobattang massif, south-western Sulawesi, and Sulawesi Leaf Warbler P. nesophilus of the rest of Sulawesi, on the basis of consistent differences in song and plumage. Berryman & Eaton (2020) confirm these differences, showing that, although there is overlap, the song of P. nesophilus has 'a pec u l ia r squea k y qua l it y u n matched by sarasinorum, principally a result of its significantly greater bandwidth'. Comparison of photographs of the two forms confirm that they are consistently different in appearance: for example, P. nesophilus lacks a central crown-stripe, a pale wing-bar and white in the tail (all prominent features in P. sarasinorum). ...
... 'Selayar Leaf Warbler', for which no scientific name is available, appears to differ from other Wallacean Phylloscopus, including P. sarasinorum of southwestern Sulawesi, the nearest congeneric species, in its very dull olive-green upperparts with almost no yellowish hue, a broad, whitish crown-stripe, a long supercilium extending to the rear crown, unmarked ear-coverts, and whitish underparts. Berryman & Eaton (2020) provide further evidence for the recognition of the Selayar warbler as a new species by showing that its song differs from those of all other Phylloscopus species in the region. Its song is most similar to that of P. sarasinorum but is simpler (as is typical for small island taxa) and lacks that species' rambling or squeaky quality. ...
... It is very difficult to determine the precise diversity of these song birds due to having a large number of cryptic species in the genus Phylloscopus, exhibiting morphologically similar or identical natural populations [28]. Modern methods such as molecular genetics and song spectrogram analysis both are needed for their accurate identification and classification [3,29]. However, being astonishingly species-rich, the genus has remained a focus of evolutionary studies to better understand ecological and evolutionary traits in the leaf warbler assemblage [30]. ...
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