Cockatoos Invade Indonesia,

Twice!

By J. Richard Wakefield March 2004

Abstract

Cockatoos (Order Psittaciformes, family Cacatuidae) are distantly related to the rest of the parrots, having separated some 20-30 million years ago. They are very distinct in their appearance and habits. Australia is their expected place of origin. They remained isolated as that continent moved north due to plate tectonics. Once this plate collided in the north into a complex series of other plates it formed the Indonesian Archipelago. Cockatoos did not invade those islands until about 5 million years ago, when there was enough closure for them to make the flight across the sea. First into Papal New Guinea, and then into the other islands. This invasion would have been into well-established fauna and flora on these islands. Mitochondria DNA and allozyme data produces a phylogenetic tree showing that there were two separate invasions by the genus Cacatua. The order of invasion is not known. One sub-genus, C Cacatua went westward into the smaller islands and south to the Lesser Sunda Islands. They also invaded as far north as the Philippines and east ward into the Solomon and Bismarck islands. Some ambiguity persists on the actual order of the chain of speciation events.

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Introduction Cockatoos belong to the Order Psittaciformes (parrots) which evolved as a group independent of the rest of the Parrots. The Cockatoo family Cacatuidae is monophyletic (Christidis et al 1991). They are a distinct group compared to the rest of their order by having a number of differences. This includes the distinct head feather crest that can be raised and lowered, presence of a gall bladder, powder down, features of the carotid arteries and skull. They also do not have Dyck-texture in the feathers. In the other parrots this provides their feathers with the bright colourations such as greens and yellows (Adams et al. 1984). Christidis et al. (1991) noted that cockatoos have from 72 to 80 diploid number, where as the rest of the parrots have 60 to 72. Homberger (1996) also noted that the wood-ripping bill of cockatoos is distinctive compared to the rest of the parrots, most likely being one of the major contributors to their divergence. Today they are restricted to Australia and the eastern portion of the Indonesian islands ( Moluccaian Islands, Tinambar Island, Sulawesi Island and the Lesser Sundra Islands. ), Papal New Guinea, Bismarck Islands, Solomon Islands and the Philippines. Their origin is most likely Australia some time in on Gondwana some 20 to 30 million years ago (Homberger 1991), with invasion into Indonesia, as we will see, much later. Though the other parrots went on to colonize Africa and the New World, cockatoos were left stranded and isolated on Australia upon its isolation from Antarctica until the collision with Indonesia reduced the distance enough to cross into that region. Interestingly, compared to the rest of the Parrots, cockatoos comprise of only 6 genera and some 18 to 22 species. Cockatoos species range from abundant across the continent, to scarce in some smaller regions, to small populations of several hundred on some of the Indonesian islands. They inhabit a wide range of habitats, such as forest, grasslands and tropical forest. Their diet consists mostly of nuts, fruit, seeds and occasionally insect larva (which may have been their original diet, [Homberger 1996]). They are considered very intelligent, capable of quick learning, reasoning and have some problem solving abilities. Their beaks are well adapted for ripping apart wood or seed cobs to get at the most edible parts (Homberger 1996). This has lead to many of them to be considered crop pests (). Generally, they are monogamous, and in the case of the Major Mitchell’s Cockatoo, require a vary large range. Some, such as most of the Cacalua, are semi social living in flocks of 20 or more, while others, such as the Palm Cockatoo, are solitary. Though no studies have yet confirmed their longevity, in captivity they can live for up to 80 years. Breeding begins around 2 years, with successful clutches after 5 years.

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Figure 1: Distance Wagner tree for Parrots of Australia rooted by Cockatoos. Though only three cockatoos, their relationship different somewhat from Brown and Toft (1999), see below. From Christidis et al. 1991

All of this impacts an animal’s ability to colonize new areas as well as its ability to maintain a viable population when their habitat changes, both of which occurred in the island areas of Indonesia they invaded. New foods, competition from already entrenched species, and small population sizes would hamper any founding populations (MacArthus and Wilson, 2001). However, Cockatoo’s intelligence, curiosity and ability to exploit new foods certainly helped in any new territory. DNA phylogentic analysis has been used to determine the evolutionary history of the cockatoos (Brown and Toft 1999, see below). More often than not, phyogentic trees produce more than one cladogram. The island settings and the order of invasion should conform to the phylogentic tree, or conversely can also determine past geological settings. Thus, the

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geological setting of the Indonesian Islands would need to be explored to put any invasion into context. This paper will review the phylogentic relationships with that of the tectonic history of the invasion areas. There are copious papers written on this subject for other fauna (for example Ladiges et al 2003) where the special geological environment must be included in any study of biogeography in Indonesia. What can be shown is that, although the phylogeny may need some re-evalation or the renaming of genera and species, it does for the most part support the geological setting. It would appear that vicariant speciation and dispersal were the modes of speciation in the Cacatua genus, the only genus to invade the north. In fact, one can infer that there were at least two separate invasions from Australia by two different groups of cockatoos. Indonesian Geology There is only one small population cockatoos west of Wallace’s Line on a very small island, hence our discussion on the geological setting will focus east of that line (See Appendix III). The Indonesian archipelago is a mixture of island arc systems with raised and compressed sea floor emerging as other islands The tectonics of Indonesia is complex, with some 9 or more plates involved. None surpasses the complexity of this system in Indonesia. In fact, much of the literature on other similar systems often themselves reference pioneering work done in Indonesia (Charlton, 2000). Though other such systems exist (Japan, Philippines, and the Caribbean islands), none are thought to be more complex due to the plate interactions, or more tectonically active. The Indonesian area, where cockatoos are found, was formed due to the Australian Plate, considered independent of the Indian Plate (Sandiford et al, 2005), moving north colliding with the Eurasian, Philippine, Pacific and a number of smaller plates. The relative motion of Australia is approximately 7cm per year; one of the fastest plate motions measured anywhere (Hall, 2001). Papal New Guinea (PNG) is the logical stepping-stone for the movement of the cockatoos into the islands, this will be shown later from the phylogeny. Thus it is important to understand when and how it was formed to see if this confirms the phylogeny. PNG is the upper most island of the Australian Plate. It was formed during the collision of the Australian plate with a plate complex in the Pacific some 20 million years ago (Hall, 2001) This is much too old for initial invasion by cockatoos as at that time the Australian continent was too far south. Thus, the invasion of cockatoos in Indonesia must have happened long after most of the islands were well established.

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Figure 2: Basic Tectonics of the Indonesian and Australian area.

Figure 3: Tectonics of the eastern Indonesian area at 5 million years ago. Shaded land is current cockatoo ranges. From Hall, R. (2001).

The Philippine islands, the first to form 30 milliion years ago, were much closer to PNG five million years ago than they are today. The distance was an easy step for any cockatoo that lived in PNG. The islands subsequently moved north and rotated, carrying with it the ancestor of the species Cacatua haemaluropygia.

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The Solomon and Bismarck islands to the west of PNG were formed from the collision of the Pacific Plate with other smaller local plates. As these approached PNG, it became easier for any PGN Cacutua to found those islands. To the west, Ceram, Sulawesi and other smaller islands are the result of subduction induced volcanic activity. The islands of Flores, Sumbawa and Lombok also are of island arc volcanic origin. One of the strangest chunks of land in the archipelago is Sumba Island. This island is the southern most extension of the C. Sulphurea subspecies the Citron Cockatoo (C.s. citrinocristata). This island is not volcanic, but actually a remnant of possible Sundaland 40-50 ma consisting of continental crust that has been isolated for at least 30 million years (Abdullah et al 2000, Hall 2001). Timor island, east of Sumba Island, is also not an island arc origin, but from surfacing of compressed crust during deformation. Recent ice ages may have been a critical factor in the Cockatoo migrations. Though regardless they could have migrated across the channel that separates the Gulf of Carpentaria from the Gulf of Papau. Across this area the sea is very shallow, some 70 meters on average. During the last ice age, sea levels were from 70 to 150 meters lower, exposing this and much of the continental shelf as far west as Timor Island. Life Takes Hold Volcanic activity certainly played a major roll in the area. However, it is not likely that this would have had much influence on Cockatoo invasion. The only influence of volcanism was in the initial establishment of fauna and flora. In August 26, 1883 one of the islands of Indonesia exploded. That eruption cleared the slate, as it were, of all life on the local islands. Krakatau then became a scientist’s dream. It allowed the systematic documentation of how life colonizes new islands. This, then, can be used as model for how the islands in the whole archipelago became invaded by life. New inhabitants could only come from two directions, west on the Java side and east on the Sumatra side. The nearest undisturbed land was more than 40 kilometers away. Thus, the only possible way life could have gotten to the new land was either by floating on the currents, or airborne. Birds, it seemed, were very important in the dispersal of new plant life on the island. By Sept 1884, grass was noted for the first time on the remaining islands. By 1886 shore based plants were seen growing on the island. By 1897, the interior was being inhabited, but what was starting at that point was a clear division of fauna between the shoreline and the interior, which has persisted today (Whittaker et al 1989).

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Once birds and bats started to arrive, looking for food, or driven off course, various tree species, such as figs, started to replace the grasses. The seeds being distributed by the droppings (Whittaker and Jones 1994, Shilton et al 1999). With not much to eat, bird mortality would have been high for the first arrivers. However, within 50 years, the islands were well inhabited, though not completely. In fact, this process is still occurring today, as new plants and animals arrive to take advantage of vacant niches. Now, more than 50 different species of birds have been seen on the islands, of which the vast majority are permanent residents. In geological terms this is nothing. Extremely rapid re-colonization. This must have been some of what would have happened as the whole chain of islands of Indonesia formed and were colonized. Hence, the likelihood that cockatoos would have encountered a newly cleared island is highly unlikely. Thus their invasion would have been on already well-established land. Extreme Biodiversity In 1860 Alfred Russell Wallace noted that Indonesia was one of the most distinctive, biologically, than any other place on the planet.

“The western and eastern islands of the archipelago belong to regions more distinct and contrasted than any other of the great zoolological divisions of the globe. (Quoted in Mayr, 1976)”

What was discovered is that the islands on the east side have fauna more closely related to Australian fauna, and the western islands’ fauna almost entirely from the Asian main land. The line where the two distinct ecosystems meet is now called the Wallace Line (see Appendix III). In fact, the number of bird species that have an Australian ancestry decrease in numbers as one moves westward across the archipelago. Cockatoos also seemed to have followed the same pattern of dispersal. Cockatoo Phylogeny Brown and Toft (1999) performed mDNA cladistic analysis on most of the Cockatoo species to get a phylogenic relationship. They utilized what Adams et al (1984) had already done with allozyme analysis on 10 species of cockatoos. The Brown and Toft’s group also excluded some of the species and subspecies (see Appendix I). They were only interested in the Generic level of relationships. Out Group species, which they included, were the Rock Dove, Common Canary and the Japanese Quail, noting the justifications for doing so. They also mapped into this the geographic location, giving each range a value of either present or not present in the ancestral range.

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Alloyme data came from Adams et al (1984), but Brown and Toft did all the mDNA extraction and analysis. Their results were processed using a number of methods, which produced a number of equally parsimonious trees. They then took the 12 resultant trees and created a majority-rule consensus tree (see Figure 4) For our purposes we need to see the Cacatua genre only. In fact, their Strict-Consensus tree of just their own mDNA analysis shows very nicely this phylogeny, and as we will see, fits well into the proposed invasion sequence.

Figure 5: Cacatua Phylogeny based on mDNA analysis. Two clear groups of sub-genera stand out, which fits well with their two distinct invasions of Indonesian islands. From Brown and Toft (1999)

Brown and Toft (1999) surmised from their data and trees that two distinct groups of cockatoos formed the Cacatua clade, which in fact has been suggested for some time from morphological data (Adams et al 1984). They also discovered that the Major Mitchel’s Cockatoo (C. leadbeateri) does not belong in the genus Cacatua even though some of the morphology is close (and hence shows as a sister group to the Cacatua). They also confirmed that cockatiels are part, though distantly, of the Cockatoo family.

Cockatoo Invasion Thus with all of the above understood, it is likely that a reconstruction of Cockatoo invasion sequence can be attempted. However, missing from above is any attempt of the age at which each speciation (node) in the Cacatua clade took place. Brown and Toft (1999) did not produce a Distance Wagner tree (though one can be done from the data they published, it is beyond the scope of this paper), and thus mapping to the tectonic events is problematic. What is clear is with the C. (Licmetis) clade some ancestor of C. Sanguinea invaded PNG from Australia, splitting then to the Solomons (C. Ducorpsii), Philippines ( C. haemaluropygia) and Tanimbar Island (C. goffini). Brown and Toft (1999) mDNA Strict Consensus tree (figure 5) shows those three species C. sanguinea, gofini and ducorpsii are triplets. Is it possible that these last two split simultaneously, one going off in each direction (see figure 6)

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C. haemaluropygia was able to invade the Philippines because that set of islands was much closer to PNG some time around 5ma. This shows clearly in that this species is way at the bottom of the Licmetis sub-genera showing a very early split. But without some indication as to when this splitting (speciation) took place there is not much correlation as to when the islands west of PNG were invaded. However, the phylogeny of the subgenus C. (Cacatua) has a little ambiguous understanding of what happened due to the different cladograms produce by Brown and Toft (see figures 7A and 7B). The invasion, or what’s left of it, follows a set of islands to the west of PNG, with one heading to the east onto the Bismarck Archipelago (C. ophthamica). Brown and Toft’s tree, which includes both the allozyme and mDNA data, seems to imply that some ancestor to C. molucansis, C. alba, C. ophthamica and C. sulphurea invaded PNG. Remnants of that ancestor may have lived on in the Triton Cockatoo, a sub-species of C. galaria. From that ancestor the invasion apprears to have been westward twice, if the tree in figure 6 is a proper indication of the phylogeny. C. sulphurea is the

furthest west from PNG, but is the closest to this ancestor, with C. alba and C. moluccansis evolving later. This seems unlikely. However, if their mDNA only tree in Figure 5 is more correct, we have a better indication of what might have happened because we have a triplet between C sulphurea, C. ophthamica and the ancestor to C. alba and C. moluccansis. C. ophthamica went eastward around the same time as the ancestor to C sulphurea + C. alba + C. moluccansis went westward. Then this ancestor then went on to invade the Sulawesi Islands where C sulphurea evolved, but leaving

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behind a population on the series of Moluccian islands which then separated into C. alba and C. moluccansis (Figure 7B). Brown and Toft (1999), claim that the islands on which C. moluccansi is located (Moluccian) and the Bismarck islands (C. ophthamica) were once tectonically joined, hence, they argued, supports the closeness of the two species according to their cladogram in Figure 4. These two species then became separated geographically when PNG formed. This is somewhat hard to accept and no geological evidence was found to support their hypothesis. Unless more data is gathered and incorporated in this phylogeny, such questions remain a mystery. The subspecies of C. sulphurea then invaded the Lesser Sunda Islands south of Sulawesi Island (see figure 7). C.s. citrinocristata is found only on Sumba island while C.s. abbotti is found only on Solombo Besar Island, west of Wallace’s Line, which should make both of them the last in the phylogeny and the newest speciation. C.s. parvula on Timor and Samao Island, C. s. occidentalis is found on Lombok, Sumbawa and Flores, and Noesa Penida Island, and C. s. djampeana on the islands of Islands of Alor, Pantar, Djampea, Kalao, Kalao tua, Madu and Kaju adi, and Tukangbesi Islands

Figure 7. Map of invasion of the subspecies of the Cacatua Sulphurea into the Lesser Sunda Islands. Actual times of invasions and eventual permanent inhabitation are unknown.

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Cockatoo invasion would follow the equilibrium theory of island biogeography (MacArthur and Wilson 2001) which basically states:

The rate of species successful invasion decreases with the number of resident species on an island and the extinction rate increases with the number of resident species.

Since it appears cockatoos invaded already established areas, they would have been subject to this kind of pressure. Thus, it is very likely that some of these dispersal populations did not make it, and that skews the expected biogeographic reconstruction.

Conclusion

Not all of the phylogeny of cockatoos has been worked out completely. The uniqueness of the subspecies, and the specific dispersals onto islands of species not in the Brown and Toft study would miss specific details. However, their goal was not to go beyond the genera level. The relatedness of each of the species and subspecies could solve a number of remaining questions. Without the rest of the species and subspecies included, it is difficult to get a good understanding as to the chain of events that lead to the invasion of Indonesia. Working out phylogenetically the subspecies of C. sulphurea, for example, could tell us the order of invasion, and approximately when each split took place. Missing also from the current mDNA of Brown and Toft’s analysis was a Distance Wagner tree. This could provide a timeline as to when some of these speciation events took place. It could also answer the similarities between the Blue-Eyes and the Moluccan similarity other than the one proposed by Brown and Toft that does not fit well with the known tectonic events. It also may answer as to why the White Cockatoo lost its crest display colours with respect to the rest of the subgenus it belongs to (it also raises those crest feathers quite differently than the Moluccian or Sulphur Crested, personal observation). Generally, however, the basic understanding of how the invasion took place matches the tectonic chain of events. There were two distinct invasions, one of the Cacatua subgenus and the other of the Licmetis subgenus. A Distance Wagner tree may resolve which subgenus was first into Papal New Guinea, or if it was simultaneous invasion. It appears, though not confirmed, that cockatoos invaded the Indonesian Archipelago very late in their history, less than 5ma, thus at that time most of the islands were faunally well established. Cockatoos would have been a new invasion as far as the other species present were concerned. Cockatoos certainly have the tools (flying ability, their strong beak, wide food range, and a nimble zygodactyle feet) to take on any new environments. One of the more interesting questions still to be answered is why the Cacatua are all white? Very conspicuous indeed. What selection pressure changed them from black the prominent colour of the other cockatoos?

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On a side note, invasions into new territories mean higher selection pressures, coupled with smaller less stable populations, means they are more prone to extinction. Though the pet trade of this birds has had its toll, certainly now the biggest threat to the Cacatua species is loss of habitat due to over logging. Efforts are underway to help save these birds from extinction, though some populations may have already gone.

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Appendix I Cocaktoo Common and Species names. Bolded use in study by Brown and Toft (1999)

Genera Species Common Range Cacatua alba White (Umbrella) Cockatoo Aru Islands ducorpsii Ducorps Cockatoo Solomon Islands galarira galerita Sulphur Crested Cockatoo North-east coast Australia galarira triton Triton Cockatoo Papua New Guinea goffini Goffins Cockatoo Tanimbar Is. Kai Is. haemaluropygia Philippine Cockatoo Philippines leadbeateri Major Mitchells Cockatoo Central and Southern Australia moluccansis Moluccan Cockatoo Southern Moluccas: Seram, Saparua,

Haruku ophthamica Blue-eyed cockatoo New Britain, New Ireland (Bismarck) pastinator Western Corella sanguinea Little Corella Throughout Australia sulphurea abbotti Medium Sulphur Crested

Cockatoo Solombo Besar Island

sulphurea citrinocristata Citron Crested Cockatoo Sumba Is. sulphurea djampeana Islands of Alor, Pantar, Djampea, Kalao,

Kalao tua, Madu and Kaju adi, and in the Tukangbesi Islands

sulphurea occidentalis Lombok, Sumbawa and Flores, Noesa Penida Island

sulphurea parvula Timor and Samao Island sulphurea sulphurea Lesser Sulphur (Yellow)

Crested Cockatoo Celebes and adjacent Buton Island, introduced to Singapore

tenuirostis Slender Billed Corella Eolophus rosaicapittus Galah Cockatoo Callocephaion fimbriatum Gang-gang cockatoo Extreme south-west Australia Calyptorhynchus lathami Glossy Cockatoo South-Eastern Australia baudinii Long-billed Black-Cockatoo Australia magnificus Red-Tailed black cockatoo Australia funereus funereus Yellow-tailed black cockatoo Australia funereus baudinii White-tailed black cockatoo Australia latirostris Slender-billed Black-Cockatoo Australia banksii Red-tailed Black-Cockatoo Australia Nymphlous hollandicus Australia Proboscigar aferrimus aterrimus Palm Cockatoo Cape of York Peninsula in Northern

Australia aferrimus goliath Goliath Palm Cockatoo New Guinea aferrimus stenolophus Very North-west tip of New Guinea

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Appendix II, Identification

Licmetis clade Philippine Cockatoo

Goffins Cockatoo

Little Corella

Ducorps Cockatoo

Western Corella

Slender Billed Corella

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Cacatua Clade

Sulphur Crested Cockatoo

Triton Cockatoo

Moluccan Cockatoo White (Umbrella) Cockatoo

Blue-eyed cockatoo

Lesser Sulphur (Yellow) Crested Cockatoo

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Citron Crested Cockatoo

Medium Sulphur Crested Cockatoo

Non-Cacatua Clades Major Mitchells Cockatoo

Galah Cockatoo

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Gang-gang cockatoo

Glossy Cockatoo

Long-billed Black-Cockatoo

Red-Tailed black cockatoo

Yellow-tailed black cockatoo

White-tailed black cockatoo

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Palm Cockatoo

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Appendix III Geography of Indonesian Archipelago

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