Sula dactylatra ssp. tasmani (Tasman Booby)

[another specialist]

Sula tasmani
van Tets, Meredith, Fullagar & Davidson 1988
Holocene of Lord Howe Island and Norfolk Islands, off e Australia
Primary materials: Holotypes: partial skeleton with maxilla, cranium, mandibula, quadratum, cervical and thoracal vertebrae, sternum, ulna, carpometacarpus
Secondary materials: Paratypes: partial juvenile skeleton with maxilla, cranium, mandibula, quadratum, cervical and thoracal vertebrae, ribben, sternum, pelvis, coracoïd, scapula, humerus, radius, ulna, carpometacarpus, phalanges, femur, tibiotarsus, fibula, tarsometatarsus, pedal phalanges

Gerard F. Van Tets, Charles W. Meredith, Peter J. Fullagar & Peter M. Davidson,
Osteological differences between Sula and Morus, and a description of an extinct new species of Sula from Lord Howe and Norfolk Islands, Tasman Sea
Notornis 35 (1988): 35-57

[dysmorodrepanis]

According to Holdaway, S. tasmani is invalid, as it is simply large individuals of the extant Sula dactylatra fullagari (Tasman Sea Masked Booby):
web.archive.org/web/20060115110918/http://www.amonline.net.au/pdf/publications/1343_complete.pdf

tinyurl.com/q9kzh9

[another specialist]

Yes, you may be right - this is an ongoing problem with fossils which are not complete. Some will say its valid and some will say its invalid - it's an ongoing debate

[dysmorodrepanis]

In this case, the matter is quite clear, however. The fullagari ssp. was not described until 2 years after the presumed species tasmani was set up. Until then, it was believed that size variation in SW Pacific Masked Boobies was clinal. As all tasmani specimens were large and its appearance was not known, it was believed to be a distinct speecies. However, it turned out that the Tasman Sea population was distinctly larger - see the original description here: www.marineornithology.org/PDF/18/MO_1990_01.pdf and nicely fits the tasmani taxon. The description of fullagari makes brief mention of the description of tasmani, but it seems that the autors have not read that paper, merely cited it for completeness (they do not compare these taxa).

Actually, since tasmani was described before fullagari, the ssp. is properly named Sula dactylatra tasmani:http://www.publish.csiro.au/paper/MU04028.htm where more info on the tasmani-fullagari relationship is probably given (can't access the paper, but what Google gives looks promising).

It might even be given species status (it is very distinct), in which case it would again be called Sula tasmani. Anyways, the case for identity of these two birds is quite convincing. Thus, Sula (dactylatra) tasmani should be moved to 'Rediscovered Birds' - it somewhat parallels the New Zealand Storm-petrel, which also was known only from bones and a few specimens, until it was seen again very much alive recently.

[another specialist]

here is the link that dysmorodrepanis supplied above just made it clickable so you don't have to copy and past it

www.publish.csiro.au/paper/MU04028.htm

[another specialist]

The pdf file includes Sula tasmani in section named movements page 5 as a species in its own right and extinct seperate from the new subspecies your mentioning is the same? the paper doesn't say there the same or confirm it in any other way.

[another specialist]

The html page about Sula dactylatra tasmani is more convincing being they use the same scientific name tasmani.

This page i found says/confirms? sula tasmani as a subspecies of Sula dactylatra so links well with what you have supplied the html webpage link

But this is not excepted by all at present may still say its a full species.

www.bsc-eoc.org/avibase/avibase.jsp?pg=summary&lang=EN&id=842FA9ECA549C773&ts=1122178993827

This page says/confirms that its not the same as the new subspecies

Masked Booby (Sula dactylatra)
ssp.: Fou masqué (Sula dactylatra dactylatra)
ssp.: Indian Ocean Masked Booby (Sula dactylatra melanops)
ssp.: (Sula dactylatra personata)
ssp.: (Sula dactylatra fullagari)
ssp.: (Sula dactylatra bedouti)
ssp.: (Sula dactylatra californica)
fossil: Tasman Booby (Sula tasmani)

www.bsc-eoc.org/avibase/avibase.jsp?pg=search&fam=16.0&lang=EN

also here includes as a seperate

worldbirdinfo.net/search_results.asp?sibleymonroefamilyname=SULIDAE:Boobies,Gannets

[another specialist]

so dysmorodrepanis what you say may be correct as there is bits here and there that help to make it convincing but haven't found anything on the web at present to connect everything together and give us a straight answer.


It does seem that they are one and the same - does anyone have any other information to add to this debate?

[dysmorodrepanis]

anotherspecialist said:

The pdf file includes Sula tasmani in section named movements page 5 as a species in its own right and extinct seperate from the new subspecies your mentioning is the same? the paper doesn't say there the same or confirm it in any other way.

Yes, the description of fullagari assumes that tasmani was a distinct species now extinct, but it is obvious that they didn't question its status. Only in the Emu paper, for which I unfortunately have only the abstract (see above: the 'www.publish.csiro.au' link) are they compared. The name change from fullagari to tasmani is due to the rule that the first species/subspecies name linked to a taxon holds (if it was not unused for centuries or similar caveats, which do not apply here). So we have Sula dactylatra tasmani or if given full species status, Sula tasmani (The Nazca booby has been split from the Masked because of traits which are equally distinct in the Lord Howe booby).

This change of name paper was only published 1 month ago. Unfortunately, it does not seem that I have access to Emu papers, but I will try to check out whether Wuppertal University has, as I have a friend there whom I will visit this weekend. I don't think so, however, as The Emu is a specialist journal. University of Frankfurt should have access, but I know nobody there.

At any rate, this Emu paper should answer most questions about tasmani's status - at the very least, it should provide references. It should clear up the 'Holdaway' reference I mentioned on June 22nd, which is not further elaborated upon in the file.

So what we have as a good reference of synonymizing tasmani and fullagari is only this Emu paper, which is too recent for any Web page to comment upon.

[another specialist]

thanks for the info

[Melanie]

Common Name/s TASMAN BOOBY (E)
Species Authority van Tets, Meredith, Fullagar & Davidson, 1988
Assessment Information
Red List Category & Criteria EX ver 3.1 (2001)
Year Assessed 2006
Assessor/s BirdLife International
Evaluator/s Butchart, S. & Pilgrim, J. (BirdLife International Red List Authority)
Justification Sula tasmani is known from bones found in aeolian coral sand, from Lord Howe and Norfolk Islands, Australia. Bones on Norfolk Island were found with those of the Polynesian Rat Rattus exulans, which was presumably introduced to the islands by Polynesians. Sula tasmani was apparently not present by 1774, so was presumably eradicated directly by the Polynesians for food, or indirectly by invasive species brought with them. On the contrary, the species appears to have survived until at least 1788 on Lord Howe Island, at which time it was still nesting in the "thousands" on the sandy shores of the lagoon. In this year, this large sulid and its eggs were collected for food in some numbers by visiting sailors, from whom the last records come. It is not clear how much longer it survived, or what eventually caused its extinction, but it seems likely that overexploitation and/or invasive species were to blame.
Distribution
Country Names Australia [RE] (Lord Howe I. [RE])
Norfolk Island [RE]
Summary Documentation
System Terrestrial; Marine
Major Habitat/s
(terms) 9.1 Sea - Open
10.2 Coastline - Sand, Shingle or Pebble Shores

Major Threat/s
(terms) 2.2 Invasive alien species (directly affecting the species) - Predators (past)
3.1.1 Harvesting (hunting/gathering) - Food - Subsistence use/local trade (past)

www.redlist.org/search/details.php?species=61927&tab=all

[dysmorodrepanis]

Right, I have the reference from the Emu sorted out:

RICHARD N. HOLDAWAY AND ATHOLL ANDERSON:
Avifauna from the Emily Bay Settlement Site, Norfolk Island-A Preliminary Account
Records of the Australian Museum, Supplement 27 (2001): 85–100.
www.amonline.net.au/pdf/publications/1343.pdf

"Sulids. The sulid presently breeding in the Norfolk Island group is the Masked Booby Sula dactylatra. An apparently extinct species of booby (Sula tasmani) has been described from fossil remains collected on Norfolk and Lord Howe Islands (van Tets et al., 1988). The material in the present collection is attributed to S. dactylatra because the mensural differences listed by van Tets et al. (1988) are not sufficient to support recognition of a separate taxon and instead represent the upper size range of S. dactylatra (Holdaway and Anderson, unpubl. data).
Other differences proposed included choice of nesting habitat, S. tasmani apparently differing from S. dactylatra in nesting on sand beaches where they were vulnerable to predation by humans (van Tets et al., 1988). When undisturbed by humans, even Australasian Gannets (Morus serrator), which typically nest on or above high sea cliffs, nest on sand dunes at sea level (Hawkins, 1988)."

So, two things can be noted:

1) The Norfolk population was a subspecies of dactylatra that was replaced with fullagari after its extinction by the latter, or dactylatra fullagari all the time. In the former case, tasmani and dactylatra (which ranges throughout the region) must have been sympatric for considerable time.

2) The answer lies in the van Tets paper. Notornis is not online, but they provide PDFs to authors, at least as of recently. Still, I think one can only get the descriptiopn of S. tasmani as a hardcopy.
The question is how the morphometrics of tasmani fide van Tets et al compare to those of tasmani fide Holdaway et al = fullagari (available here www.marineornithology.org/PDF/18/MO_1990_01.pdf).
When they are continuous, tasmani = fullagari. Consider the example of Atlantic fishes which have become smaller during the last 100 years or so because of human predation pressure. Exactly the same would likely happen in a seabird population: bigger birds have MUCH reduced fitness due to being more tempting prey (more meat, need longer for takeoff). Incidentially, the extant Kermadec population of "fullagari" seems to be about the same size as the original tasmani, whereas the extant Lord Howe population is smaller. The two locations are around the same latitude, so things like Bergmann's Rule won't noticeably apply.

However, the nesting habit argument does not really fly. Just because it is so in M. serrator (the parallel-evolution cousin of S. dactylatra, but still, only a cousin), does not necessarily imply anything about dactylatra. If tasmani fide van Tets was a distinct, ground-nesting subspecies, it could have evolved parallel to fullagari. In such a case, one would expect that there are signs of such a process. As the bones are subfossil, molecular analysis could easily determine if the prehistoric population was distinct.

At any rate, there is no reason to believe it was a distinct species. If it had been, how did it evolve in the first place? "fullagari"'s area of occurrence overlays the one of tasmani fide van Tets entirely.

(The Nullarbor Plains Cave Owl, Tyto novaehollandiae "troughtoni", is a similar example. It is today not even accepted as a subspecies, but it was a geographical isolate that differed in nesting habit. If anything, its case to distinct ssp. status is stronger than that of tasmani fide van Tets)

[cryptodude100]

Does anyone know the length of the skull? Thank You!

[dysmorodrepanis]

The 1988 paper should be online at www.notornis.org.nz/contents.php?volume_issue=n35_1 sometime soon. Then we can resolve this issue.

[dysmorodrepanis]

Ah, it is already here: www.notornis.org.nz/free_issues/Notornis_35-1988/Notornis_35_1.pdf

[dysmorodrepanis]

Although one cannot compare directly (the Marine Ornithology paper measures whole wings, the Notornis paper only single bones). it seems that the tasmani specimens extend the size range of the Masked Booby from LHI to the variation seen in Kermadec birds (which were not compared to the original tasmani specimens. Since there seem to be some minor differences, mainly in the sternum, I am not completely convinced that tasmani is extant and only became smaller due to hunting pressure. The LHI population seems to have had a differing annual rhythm, which in some seabirds has caused subspecies and even species to separate (like the Oceanodroma on Guadalupe Island). But altogether, that would still mean that the birds are best regarded as a subspecies of dactylatra, because they were apparently not very distinct except in size (bearing in mind that the comparisons - Kermadec bones and the original tasmani bones - necessary to settle this have not been done it seems).

So we have either:

Sula dactylatra tasmani - extant, all over the Tasman Sea (LHI, Norfolk, Kermadec), large LHI birds selectively hunted, which led to local size reduction, or

S. d. fullagari - extant, all over Tasman Sea, breeds (Southern Hemisphere) late winter - spring, and
S. (d.) tasmani - extinct, LHI and NI., bred (Southern Hemisphere) autumn - early winter; extinct on LHI c.1800(?), on NI in the 12th century AD.

Is a "broader carinal apex, anterior carinal margin and separation between the dorsal lips of the coracoidal sulci" compared with similar-sized sternums of dactylatra a diagnostic charccter when one compares the largest LHI specimens with the largest Kermadec specimens? If so, the latter approach is true. If not, the former. The question is, how pronounced are the differences? In absolute length, the original tasmani specimens are clinal with the modern dactylatra bones.

[dysmorodrepanis]

Apparently (Notornis 28(3):210), the present population of S. dactylatra breeds in the S Hemisphere spring/summer:

"MASKED BOOBY Sula dactylatra
Two hundred pairs breed on Nepean and 100 pairs on Philip. Breeding was more advanced on Philip, where fledglings were common and eggs few. On Nepean more eggs and young chicks than fledglings were present. The last adults at the remnant of the 100-acres colony on Norfolk were killed during the 1977-78 season."

But they are S. d. fullagari without doubt. Still, it shows that there may be considerable variation in breeding season even now.

(about visits in December 1978 and 1979, www.notornis.org.nz/free_issues/Notornis_28-1981/Notornis_28_3.pdf)

[another specialist]

dysmorodrepanis said:

Ah, it is already here: www.notornis.org.nz/free_issues/Notornis_35-1988/Notornis_35_1.pdf

OSTEOLOGICAL DIFFERENCES BETWEEN
SULA AND MORUS, AND A DESCRIPTION OF
AN EXTINCT NEW SPECIES OF SULA FROM
LORD HOWE AND NORFOLK ISLANDS,
TASMAN SEA
By G. F. VAN TETS, C. W. MEREDITH, P. J. FULLAGAR
and P. M. DAVIDSON
ABSTRACT
Osteological differences between boobies, Sula, and gannets, Morus, were
found for every major element examined. These differences confirm that
Sula and Morus are generically distinct.
Sula rasmani n.sp. is described from bones found in aeolian coral sand
dunes at Lord Howe and Norfolk Islands, Tasman Sea. Sula tasmani is
larger than extant and known fossil species of Sula, the upper part of
its massive bill being more concave laterally.
INTRODUCTION AND METHODS
At Lord Howe and Norfolk Islands, Tasman Sea, bones were found in
situ and as float of two species of booby (Sula). The bones were determined
as being of the Masked Booby (S. dactylatra), which still breeds there,
and of a similar but larger booby, which we shall call the Tasman Booby.
The Tasman Booby is described in this paper as a new extinct species.
The bones were collected from aeolian coral sand, at Lord Howe Island
from a storm-eroded cliff at Middle Beach and from sand used for airport
construction and at Norfolk Island from storm-eroded beaches and a sand
quarry at Emily and Cemetery Bays (van Tets et al. 1981, 1984; Rich
& van Tets 1982, 1984; and Rich et al. 1983).
The bones of the Tasman Booby were compared with those of all
extant species of Sulidae and with descriptions of those of fossil Sulidae.
Comparative material came from the collections of the Australian Museum,
Sydney (AM); the Australian National Wildlife Collection, CSIRO Division
of Wildlife and Rangelands Research, Canberra (ANWC); the British
Museum (Natural History), Tring (BM); the Monash University
Department of Earth Sciences (MU); the Museum of Victoria, Melbourne
(MV); the National Museum of New Zealand, Wellington (NMNZ); and
the University of Michigan Museum of Zoology, Ann Arbor (UMMZ).
Bones that lack the hard, smooth texture and the detailed sculpturing
of fully formed bones are called juvenile and are considered to be of young
birds close to fledging, but not chicks or fully grown birds.

COMPARISON OF THE OSTEOLOGY OF
SULA AND MORUS
At least from the time Linnaeus (1758) placed the boobies in Pelecanus
piscator and the gannets in I? bassanus, there has been debate about the
taxonomic distinctions between boobies and gannets. The New Zealand
checklist (Kinsky 1970,1980), the World checklist 2nd Ed. (Dorst & Mougin
1979), as well as Voous (1973), Cramp & Simmons (1977), Nelson (1978)
and Harrison (19831, considered boobies and gannets to be congeneric,
while the Australian checklist (Condon 1975), the World checklist 1st Ed.
(Peters 1931), as well as Serventy er al. (1971) and Olson (1985), restricted
the boobies to the genus Sula Brisson 1760 and placed the gannets in
the genus Morus Vieillot 1816.

[another specialist]

The differences between Sula and Morus were based on external
features (Ogilvie-Grant 1898, Mathews 1913, Mathews & Iredale 1921,
Wetmore 1926, Berlioz 1950, von Boetticher 1957, Palmer 1962, Serventy
et al. 1971) and can also be made from comparisons of signal patterns
(van Tets 1965) and from skeletal morphology as described below.
Skull
In Sula the surface of the maxilla is rough all over the portions covered
by horny plates. In Morus it is also rough except for an area directly
in front of the naso-frontal hinge (Figures 1 and 2) where the top of
the bill at its base is covered by skin and feathers. Shufeldt (1888, 1902)
noted this difference when comparing the maxilla of Morus bassanus with
those of Sula sula (=piscator) and other species of Sulidae, presumably
S. nebouxii (=gossz) and S. leucogaster (=brewsterz), as shown on his Plate
XXIII, figures 10 and 11 (1902).
From a lateral view, the dorsal profile of the skull shows a dip in
front of the naso-frontal hinge, where the surface is smooth, and a bulge
behind the naso-frontal hinge (Figure 2) in Morus, whereas in Sula the



profile has a slight convex bulge in front of the naso-frontal hinge and
a relatively straight slope behind the hinge and above the orbits.
Pectoral girdle
At the cranial end of the sternum there is a prominent ventral manubrial
spine in Moms, but not in Sula, as was noted by Shufeldt (1902). The
furcular facet on the carinal apex is from a lateral view deeply concave
(Figure 3) in Moms and varies in Sula from slightly concave to slightly
convex. The ventral edge of the carina is relatively narrower in Morus
than in Sula (Figure 4).

[another specialist]

The sternal facet at the symphysis of the furcula is relatively narrower
and deeper in Morus than in Sula. The clavicular shafts are relatively
thicker in Moms than in Sula. There are usually one or more pneumatic
foraminae between the coracoidal facet and the scapular tuberosity in Morus,
but not in Sula.

On the scapula, at the anterior base of the acromion, is a pneumatic
foramen on the dorsal side in Morus and on the ventral side in Sula.
The distal end of the blade is less angular with respect to the shaft in
Morus than in Sula.
Above the anterior sternal face of the coracoid, as noted by Wetmore
(1926) and Brodkorb (1955), is a bulge in Sula and not in Morus (Figure
5). On the bulge is the anterior intermuscular line of Fisher (1945). Where
the line terminates at the sternal facet is a prominent tubercle in Sula
and not in Morus. The line ends at the sternal facet also more laterally
in Morus than in Sula. Howard (1936) reported that the anterior sternal
facet is relatively longer and narrower in Morus than in Sula, that the
dorsal end is relatively broader in Morus than in Sula, and that the bicipital
attachment is small and faintly marked in Morus but is a large and prominent
pit in Sula. From a dorsal view, the furrow between the bicipital attachment
and the glenoid facet is relatively broader in Morus than in Sula. The
sterno-coracoidal process is pointed in Morus and truncated in Sula (Figure
5).



Wing
The humerus is longer than the ulna in Morus and shorter than the
ulna in Sula, including S. abbotti, where the humerus is almost as long
as the ulna (Figure 6, Shufeldt 1902, Miller 1935, Howard 1958, Bourne
1976). The median crest of the humerus extends further distally in Morus
than in Sula (Figure 7) and on the anconal or ulnar side, as indicated
by Howard (1958), the central ridge is rounded and indistinct in Morus
but is angular in Sula. At the distal end, Morus has a shallower impression
for M. brachialis anticus than Sula. On the internal side of the olecranal
fossa, Morus lacks the overhang with a few foramina under it (Wetmore
1930) that is indistinct in Sula abborri and prominent in other Sula. The
shapes of the external (= radial) condyle and the attachment for M. pronator
brevis are too variable for us to confirm any of the differences between
Morus and Sula that were suggested by Wetmore (1926, 1930, 1938).
There is a foramen in the proximal radial depression of the ulna in
Sula but not in Morus (Figure 8). The impression of M. brachialis anticus
is relatively longer in Morus than in Sula. The shaft of the ulna is relatively
thicker in Moms than in Sula. Relative to the internal and external condyles
at the distal end of the ulna, the tip of the carpal tuberosity is more distal
in Sula than in Morus.
S tasmanl
t
A t A
A$ %S abbott~
S nebouxll o
A
- A A
A A S dactylatra M capens,- . ' % Mbassanus
A . 9 -
0 t . 8
0 . 1 1 1 s sula o . ;#om
l ff '0 M serrator
0 . 0
S varlegata
S leucogaster 0
oO
1 6 0 140 150 160 170 180 193 200 210 220 230 mm
At the distal end of the radius on the palmar side, relative to the
scapho-lunar facet, a prominent foramen is more proximally located in
Morus than one or more smaller foramina in Sula.
At the proximal end of the carpometacarpus, the pneumatic foramen
in the internal ligamental fossa is much larger in Morus than in Sula,
and the anterior carpal fossa has a prominent foramen in Sula and not
in Morus. In Sula a ridge extends from the external ligamental attachment
almost to the proximal end of metacarpal 111. Morus does not have this
ridge. In Sula the groove of the carpal trochlea extends farther on to
the proximal end of metacarpal I11 than in Morus. We did not find any
significant differences in the shapes of the pollical facet between Moms
and Sula, as was suggested by Brodkorb (1963b).

Pelvic girdle
On the synsacrum, the anterior articular facet of the centrum is in Morus
as deep as or deeper than it is wide, and in Sula it is as wide as or wider
than it is deep.



The caudal part of the ilium is relatively broader above and behind
the ilio-ischiatic fenestra in Sula than in Morus. The ilial process on the
caudal edge of the pelvis is small and knoblike in Moms and in Sula abbotti,
and it is large and pointed in other Sula.

Leg
The femur of Moms is longer with a relatively thinner shaft than
that of Sula. At the proximal end, the junction of the trochanter and
the trochanteric ridge is more angular in Sula than in Moms. The distal
end is relatively broader in Sula than in Moms.
The tibiotarsus of Moms is longer, with a relatively thinner shaft,
than that of Sula. The proximal and distal ends are relatively wider in
Sula than in Moms. At the proximal end, the inner cnemial crest in Moms



is hooked at the distal end and in Sula not hooked. At the distal end,
the anterior intercondylar fossa and the posterior intercondylar sulcus are
relatively wider in Sula than in Morus.