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Hell yes: Komodo dragons!!! (again)

The views expressed are those of the author and are not necessarily those of Scientific American.


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What with all the monitor-themed goodness around these parts lately (see links below), it seems only fitting that I provide a re-vamped, substantially updated version of this Tet Zoo ver 2 classic (originally published in September 2007). Here we go…

Komodo dragon feeding scrum. Not sure what's in the middle, but I somehow doubt that it's alive.

Without doubt, one of the coolest living animals on the planet is the Komodo dragon Varanus komodoensis, a giant flesh-eating lizard that kills water buffalo, eats children, has venom glands, and is impervious to bullets (ok, I made that last bit up).

Unknown to western science until 1912 (when it was ‘discovered’ by J. K. H. van Steyn van Hensbroek, and described in the same year by Peter A. Ouwens), the dragon is the largest living lizard, big adult males exceeding 3 m in total length and 70 kg in weight. As usual with big animals, there are diverse views on exactly how big it can be. Some seemingly reputable sources provide maximum lengths of 3.5 m and weights of 250 kg or so (Steel 1996) whereas others have 70 kg (or slightly more) as the greatest weight attained in the wild (Ciofi 2004). Mark Carwardine’s Guinness Book of Animal Records gives the St Louis Zoological Gardens specimen (presented in 1928 by the Sultan of Bima) as the record-holder for the species, and in 1937 this was apparently 3.1 m long and 166 kg (Carwardine 1995). The big caveat here, of course, is that captive animals tend to be much fatter than wild ones. There are, of course, stories about people seeing (and even killing) Komodo dragons 4 m, 5 m and even 7 m long. [Image below by MattKingston.]

Captive Komodo dragon. This isn't an especially great photo, but I like it because it emphasises the long and low construction of these lizards - the tail being chunky and looking like a posterior continuation of the body. Image by MattKingston, licensed under Creative Commons Attribution 2.0 Generic license.

It’s said that the Komodo’s legs and tail become proportionally shorter and stockier as it gets larger (in other words, these parts of the body exhibit negative allometry). As a juvenile it’s an excellent climber and in fact is predominantly arboreal – indeed, juveniles live such different lives from adults they effectively function as separate ‘species’ (Imansyah et al. 2008). Parthenogenesis sometimes occurs (Watts et al. 2006), though as yet we have no idea how common it is in the wild. As an adult it can dig burrows, locate carcasses that are more than 3 km away, swim from island to island, and kill mammals as big as deer, wild pigs, and even water buffaloes and humans. Using teeth and claws, it disembowels, hamstrings and slashes its prey, and it may also shake prey to break the neck.

You can own your own toy Komodo dragons. Here are the four I own. Image by Darren Naish.

Stand-alone shot of the best Komodo dragon I own. If you like monitors, you really should own one. Smaller and cheaper than the real thing.

‘Infector killers’ or envenomators?

Until recently, it was thought that dragons infect prey animals with a toxic bite, this toxicity resulting from the transmission of bacteria that are ‘stored’ in the interdenticle slots on the margins of the posterior teeth*, septicaemia and death being the result. This became known as the ‘infector killer’ hypothesis, later applied by some people to theropod dinosaurs like Tyrannosaurus (Abler 1992, Horner & Lessem 1993).

* Anterior teeth are unserrated on both anterior and posterior carinae.

However, I’m not sure it was ever a good idea, since observations indicate that dragons ordinarily kill prey by injuring them with their teeth and claws (Auffenberg 1981), as mentioned above. That is, they don’t generally bite things, release them, and then track them down over days or weeks. Furthermore, the dragons have comparatively good oral hygiene and apparently don’t leave fragments of rotting meat stuck in their teeth, as was assumed by proponents of the ‘infector killer’ idea.

Magnetic resonance image of a Komodo dragon head, showing the complex mandibular venom gland (in B you can see the separate ducts leading to spaces between teeth). From Fry et al. (2009).

Today, it’s well known that the supposed effects of septicaemia reported as a consequence of dragon bite more likely reflect envenomation, the dragon actually possessing a complicated mandibular venom gland that allow it to inject toxins and anticoagulants into the wounds of prey (Fry et al. 2009). The gland is unusually complex compared to other reptile venom glands, with a large posterior compartment, and five small, anterior ones that send off ducts that emerge between successive teeth (Fry et al. 2009). Oral venom glands are now known to be reasonably widespread in lizards (Fry et al. 2005) and a case has been made for their importance in the predation style used by Komodo dragons and other big monitors (like the giant, extinct V. priscus). However, some varanid experts are sceptical about this proposal, arguing that the venom’s importance may have been grossly over-stated.

Friendly captive Komodo dragon. Image by Darren Naish.

While adult dragons today mostly eat mammals that have been introduced to Komodo, Rinca, Flores and the adjacent islands, fossils show that dragons previously lived alongside dwarf elephants (both Elephas and Stegodon), and it has even been argued that the dragon might be a specialised macropredatory giant that evolved to kill these (now extinct) endemic mammals (Diamond 1987). However, there were plenty of other small and mid-sized mammals that inhabited the same islands at the same time so “their diet was possibly more varied than just pygmy elephant” (Mitchell 1987).

Island giant or island dwarf, smarts, and sociality

Furthermore, the Komodo dragon almost certainly isn’t an example of island giantism. Instead it apparently retains the large body size of a mainland ancestor (Gould & MacFadden 2004), and fossils reveal that its current range is very much relictual, since it previously occurred on Australia in the Pliocene and Pleistocene (Hocknull et al. 2012) (for more on that, see the 2012 article Goanna-eating goannas: an evolutionary story of intraguild predation, dwarfism, gigantism, copious walking and reckless thermoregulation). In fact, rather than being an island giant, the Komodo dragon might – in part – be an island dwarf, since some of the modern populations restricted to small islands seem to have average sizes lower than those on the bigger islands. Proper study is needed to demonstrate this.

Komodo dragon group, feeding on a big mammal carcass in a stream.

Dragons can be pugnacious beasts that might maim one another during combat (there’s a video where one dragon bites the entire tail off another individual); they also have cannibalistic tendencies. However, they also engage in appeasement behaviour, they show evidence in the wild of co-operative behaviour and have pretty clear dominance hierarchies, and they tame quickly and readily bond with humans. “It is the opinion of many keepers that dragons may be among or the most intelligent of reptiles” (Walsh et al. 2004, p. 12). As demonstrated by the awesome photos shown here, it is well documented (although poorly known) that they form ‘feeding scrums’ when attracted to a large carcass (Auffenberg 1981).

A group of (at least four) dragons feeding on a downed water buffalo. This scene may or may not be connected to the one above, I don't know.

The variable, widespread dragon

Finally, the wild population of several thousand individuals is generally regarded as relatively stable. Excepting Flores, the range of V. komodoensis was declared Komodo National Park in 1980. Some of the smaller populations (such as those of Gili Motang and Flores) are regarded as particularly vulnerable to habitat loss and other threats, such as slash and burn farming (Ciofi et al. 1999).

Historic, relictual distribution of the Komodo dragon: Komodo, Rinca, Gili Dasami and Gili Motang to the west, and Flores to the east. Image in public domain

Dragons are quite variable in genetic terms across their range, and the populations from the different islands can be recognised by eye once you know what to look for. Hien (2003) reported a new colour morph from Riung along the north-east coast of Flores. These dragons are greyish-yellow, with grey, white-speckled lower limbs. Are they just a local colour morph, or something more interesting? This population excepted, the two main populations on Flores (one in the northeast, the other in the far west) might or might not be closer to each other than the western population is to the one on Rinca. The Gili Motang and Komodo populations are apparently outside the clade formed by the Rinca and Flores animals, with the Komodo ones being the most distinct (Ciofi et al. 1999). This might show that these populations have been distinct for a long period of time (more than 10,000 years), or might indicate a complex colonisation history for the region. Anyway, no subspecies have been named… yet. Given that this modern range is very much relictual compared to the prehistoric one, we might wonder whether dragons were far more diverse genetically (and morphologically) in the past – in fact, they surely were.

Komodo dragon model at Grange Reptiles, Southampton. Image by Darren Naish.

The pictures used here of the group-feeding dragons were kindly supplied by Tim Isles (thanks Tim), but they’ve been used on the internet before: we lack data on who took the photographs and would be interested to get any news on this. Thanks to Hanneke Meijer for reminding me about Hien (2003).

For previous articles on varanids and other platynotan lizards, see…

Refs – -

Abler, W. L. 1992. The serrated teeth of tyrannosaurid dinosaurs and biting structures in other animals. Paleobiology 18, 161-183.

Auffenberg, W. 1981. The Behavioral Ecology of the Komodo Dragon. University of Florida Press, Gainesville.

Carwardine, M. 1995. The Guinness Book of Animal Records. Guinness Publishing, Enfield, Middlesex.

Ciofi, C. 2004. Varanus komodoensis. In Pianka, E. R., King, D. & R. A. King (eds) Varanoid Lizards of the World. Indiana University Press, Bloomington, pp. 197-204.

- ., Beaumont, M. A., Swingland, I. R. & Bruford, M. W. 1999. Genetic divergence and units for conservation in the Komodo dragon Varanus komodoensis. Proceedings of the Royal Society of London B 266, 2269-2274.

Diamond, J. 1987. Did Komodo dragons evolve to eat pygmy elephants? Nature 326, 832.

Fry, B. G., Vidal, N., Norman, J. A., Vonk, F. J., Scheib, H., Ramjan, S. F. R., Kuruppu, S., Fung, K., Hedges, S. B., Richardson, M. K., Hodgson, W. C., Ignjatovic, V., Summerhayes, R. & Kochva, E. 2005. Early evolution of the venom system in lizards and snakes. Nature 439, 584-588.

- ., Wroe, S., Teeuwisse, W., van Osch, M. J. P., Moreno, K., Ingle, J., McHenry, C., Ferrara, T., Clausen, P., Scheib, H., Winter, K. L., Greisman, L., Roelants, K., van der Weerd, L. Clemente, C. J., Giannakis, E., Hodgson, W. C., Luz, S., Martelli, P., Krishnasamy, K., Kochva, E., Hang Fai Kwok, Scanlon, D., Karas, J., Citron, D. M., Goldstein, E. J. C., Mcnaughtan, J. E. & Norman, J. A. 2009. A central role for venom in predation by Varanus komodoensis (Komodo Dragon) and the extinct giant Varanus (Megalania) priscus. Proceedings of the National Academy of Sciences 106, 8969-8974.

Gould, G. C. & MacFadden, B. J. 2004. Gigantism, dwarfism, and Cope’s rule: “nothing in evolution makes sense without a phylogeny”. Bulletin of the American Museum of Natural History 285, 219-237.

Hien, P. 2003. Erster photographischer Nachweis von ungewöhnlich gefärbten Varanus komodoensis (OUWENS 1912) bei Riung, Flores, Indonesien. Sauria 25 (1), 3-9.

Hocknull, S. A., Piper, P. J., van den Bergh, G. D., Due, R. A., Morwood, M. J., et al. 2009. Dragon’s paradise lost: palaeobiogeography, evolution and extinction of the largest-ever terrestrial lizards (Varanidae). PLoS ONE 4(9): e7241. doi:10.1371/journal.pone.0007241

Horner, J. R. & Lessem, D. 1993. The Complete T. Rex. Souvenir Press, London.

Imansyah, M. J., Jessop, T. S., Ciofi, C. & Akbar, Z. 2007. Ontogenetic differences in the spatial ecology of immature Komodo dragons. Journal of Zoology 274, 107-115.

Mitchell, P. B. 1987. Here be Komodo dragons. Nature 329, 111.

Steel, R. 1996. Living Dragons. Blandford, London.

Walsh, T., Visser, G. & Lewis, R. 2004. Komodo Dragon Husbandry Manual of the AZA/SSP & EAZA/EEP: accessed online, 2005, at http://www.varanusweb.com/species_content/Kd-HDL-2004.pdf.

Watts, P. C., Buley, K. R., Sanderson, S., Boardman, W., Ciofi, C. & Gibson, R. 2006. Parthenogenesis in Komodo dragons. Nature 444, 1021-1022.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at darrennaish.wordpress.com. He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at tetzoo.com! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. vdinets 1:28 pm 03/5/2014

    Darren: is there a published source for cooperative behavior?
    I wonder if anybody has studied the predator/prey population dynamics on those islands. When you walk around Rinca, it seems like there are many more dragons than ungulates. The only scientific explanation I could come up with was that there’s a secret government cover-up program, with tourists being regularly fed to the dragons and their spouses later sharing life insurance payouts with corrupt local officials.

    Link to this
  2. 2. Heteromeles 1:30 pm 03/5/2014

    Great to see one of my favorite articles updated.

    I’d wondered about the “insular gigantism” idea. So far as I could remember, the dividing line between insular dwarfism and insular gigantism was somewhere around cat sized. Animals smaller than cats got bigger, animals bigger than cats got smaller. The Komodo Dragon was always a weird exception to this pattern, and I’m not surprised that it’s more likely to be an insular dwarf.

    Question for the herpetologists: is there any literature on how lizard behavior changes when it bonds with a human, or is this not studied?

    Link to this
  3. 3. MichaelGG 1:36 pm 03/5/2014

    Interesting, concise and reasonably thorough. I feel like I have learned some things today.

    I would like to not see apostrophes around “discover”. If you don’t want to use that word, then don’t use that word. But of course, there is no other word that conveys the meaning:

    “when it was ‘discovered’ by J. K. H. van Steyn van Hensbroek”

    I discovered Alaska. Very likely so did you. That someone else discovered before me is certain. That many people will discover it again is certain. My entire life has been a life of discovery. It’s fun.

    Scientific American is about discovery; revealing to its readers things that the reader did not know until that very moment.

    That other people already know this stuff is irrelevant.

    Link to this
  4. 4. vdinets 2:48 pm 03/5/2014

    Heteromeles: the two smallest hummingbirds are island endemics, and there are lots of island dwarfs among Caribbean geckos. I wonder what was the size of ancestral moas and elephant birds.

    Link to this
  5. 5. SciaticPain 2:49 pm 03/5/2014

    Australia has the biggest feral camel population in the world. Given that dragons lived on Australia in the Pleistocene and that the continent has what some consider an overpopulation of camels (in all actuality an overpopulation of cattle but different story) this begs the question of reintroduction of dragons to help quell the numbers.

    Too much mucking around with nature? Potential unintended consequences? Have komodo/monitor lizard reintroductions happened elsewhere?

    Link to this
  6. 6. Jurassosaurus 3:17 pm 03/5/2014

    I’ve heard talk about reintroduction of Komodo dragons to Australia for years now. I’m thinking this is one of those biological control plans that works better in theory than in practice.

    Link to this
  7. 7. Heteromeles 4:29 pm 03/5/2014

    Unless Komodo Dragons can eat cane toads and survive…

    On second thought, yes, this might be one of those extraordinarily bad ideas. How does a Komodo Dragon kill a camel again?

    More to the point, I’m not sure that a dwarf Megalania could survive in the modern outback.

    Then again, sea level rise might move the Komodo dragons to other islands all on their own. That would be…interesting.

    Link to this
  8. 8. SciaticPain 5:13 pm 03/5/2014

    Feral camel distribution is concentrated largely in the arid interior. Cane toad distribution largely in the more mesic north. Although cane toads are spreading I wonder if they can spread to arid regions being native to central/south America.

    Regarding how a komodo dragon would kill a camel- the same way it kills 500+kg water buffalo on Komodo Island today- an initial, superficial bite to a lower extremity with envenomation, followed by a lingering death watch for 1 or more days, poor camel succumbs to venom, other dragons join in for a nice ‘feeding scrum’.
    The other alternative I guess for camels is the quarter million animals killed through drought/government culling:http://www.treehugger.com/natural-sciences/australia-feral-camel-population-drops-one-quarter-drought-culling.html

    But yeah dragon introduction will probably never happen, although with a history of reptilian predators on Australia, I would still argue if you had to pick a predator to introduce dragons would make the most sense. And at least 10,000 years without dragons is still a long time without them.

    Back to cane toads. I have read about dragons being quite tolerant of venemous snake bites, I wonder if they could handle bufotoxins?
    On the same topic is that a program to train northern quolls to avoid
    cane toads has met with some success:
    http://www.australiangeographic.com.au/news/2010/04/taste-training-for-northern-quolls/
    but I hear freshwater crocs are not doing too well with the toads although salties can eat them from what I gather… but yeah invasives are a bummer. Could you train hatchling freshies to avoid cane toads? Maybe you could, I mean crocs use tools after all.

    Duane Nash

    Link to this
  9. 9. naishd 7:14 pm 03/5/2014

    Great comments – lots here to respond to, but no time right now. Cane toads: I recall an article showing that Lace goannas were dying after eating roadkill toad… no reason to think that Komodo dragons would be any different. More later.

    Link to this
  10. 10. BilBy 8:26 pm 03/5/2014

    The fact that quolls can learn to avoid cane toads through taste aversion is great; though there is a role for generational transfer of this CTA. There is no reason that brite and brany lizards could not do the same, but there won’t be scope for a generational transfer.

    Link to this
  11. 11. voyager 9:38 pm 03/5/2014

    English major and dedicated NPR listener here: I don’t know how you people call yourselves scientists. An article about Komodo Dragons and nowhere in the source material is there mention of Bob Elliot and Ray Goulding? The shame, the shame.

    Link to this
  12. 12. SciaticPain 9:42 pm 03/5/2014

    @Bilby true that about generational transfer. Hopefully freshies find some adaptive strategy to deal with cane toads. Would be a shame to lose them.

    Link to this
  13. 13. vdinets 9:54 pm 03/5/2014

    Duane Nash: hatchling crocs eat mostly insects and small fish. By the time they are likely to catch a cane toad, they are most likely out there by themselves, and their mother can’t teach them to avoid toads even if she has been trained to do so. Besides, no one has ever documented any parental teaching in crocs, although feeding of the offspring does happen.

    Link to this
  14. 14. vdinets 9:58 pm 03/5/2014

    BTW, if someone would consider a private dragon introduction to Australia, I know one recently elected official whose office would make a perfect introduction site…

    Link to this
  15. 15. SciaticPain 11:10 pm 03/5/2014

    @vdinets insects, small fish, and, what do Aussies call crayfish? Yabbies- I always loved that name.

    Now if training freshies not to eat cane toads can’t work I wonder if gene insertion from salties or crocs native to Central/South America that may have tolerance to the bufotoxin could work. But then you have the whole messing with nature dilemma again…

    Politician from Australia? Could it be the one who says: Too much forest is ‘locked up’ in national parks?

    Link to this
  16. 16. Mahay 11:34 pm 03/5/2014

    I should probably point out the distribution map used in this article is one I made for Wikipedia seven years ago, as a 19-year-old A-level student. The original map is here:
    http://online.sfsu.edu/bholzman/courses/Spring99Projects/komodo.htm
    I’m not sure why I completely filled Flores for the historic range, I guess I just assumed it must have been distributed there at some point.

    It’s a little embarrasing, I just tried googling ‘lion distribution’, ‘wolf distribution’, ‘tiger distribution’, ‘jaguar distribution’, ‘leopard distribution’ and ‘hippo distribution’, and maps that I made as a teenager are the first to come up for all of them. All highly inaccurate of course – especially the wolf map! But I think I did that one when I was only 15.

    I’m now a Zoology graduate and working on my first publication, so this is probably something I should clear up at some point…

    Link to this
  17. 17. Tayo Bethel 12:47 am 03/6/2014

    Would Komodo dragons be able to survive underthe arid conditions of the Australian Outback? At least at large sizes?
    It occurs to me that if Komodo dragons were pygmy elephant specialists they would have gone extinct when the elephants did. The fact that they did not indicates a versatile large predator, not a specialist.

    Link to this
  18. 18. Dartian 1:50 am 03/6/2014

    Darren:
    fossils reveal that its current range is very much relictual, since it previously occurred on Australia in the Pliocene and Pleistocene

    Are there other non-aquatic reptiles on Flores that are of Australian/Papuan origin? Both the extant and the extinct endemic terrestrial mammals of that island are/were of Asian origin*, as was the extinct Flores giant tortoise Geochelone (Meijer et al., 2010). (Apart from komodoensis there was also another, medium-sized monitor lizard species on Flores – Varanus hooijeri – but I don’t know if anything at all is known about its affinities within Varanidae.)

    * A possible exception of one of the extinct rodents, Spelaeomys, which might have been of Papuan origin (Musser, 1981).

    References:

    Musser, G.G. 1981. The giant rat of Flores and its relatives east of Borneo and Bali. Bulletin of the American Museum of Natural History 169, 67-176.

    Meijer, H.J.M., van den Hoek Ostende, L.W., van den Bergh, G.D. & de Vos, J. 2010. The fellowship of the hobbit: the fauna surrounding Homo floresiensis. Journal of Biogeography 37, 995-1006.

    Link to this
  19. 19. SciaticPain 2:21 am 03/6/2014

    Ironically enough Smithsonian channel aired the documentary Venom Islands in the states showcasing dragons, among other venomous critters, of these islands. Unfortunately the show was not up to date on former geography of dragons.

    #16 I was a little perplexed at this map… why would dragons be so restricted on Flores?

    #17 The islands that the dragon live on now are semiarid. Goannas, quite big, do fine in the outback. Dragons can dig burrows to escape extreme temperatures.

    #18 The islands have spitting cobras/vipers. Asian origin for those but there may be more stuff with Australasian origin if you look further.

    Link to this
  20. 20. Dartian 3:11 am 03/6/2014

    SciaticPain:
    The islands that the dragon live on now are semiarid.

    That’s a bit of an exaggeration. Flores is relatively dry (especially its northern coast), but the island is, or at least used to be, to a large extent covered by forests. Climate-wise, the Lesser Sunda Islands cannot really be compared with the genuinely arid centre of Australia, where those feral camels live.

    The islands have spitting cobras/vipers. Asian origin for those

    Well I knew that already. What I was asking was if there are any extant species of Australo-Papuan origin there.

    there may be more stuff with Australasian origin if you look further.

    I have looked for Flores/Komodo reptile species checklists but found nothing useful yet (although admittedly I haven’t made a hugest of efforts). I therefore asked this question here, as I know that this blog is read by people more knowledgeable about reptile distribution than I am. And IMO, this is a question that is also of more general biogeographical interest.

    Link to this
  21. 21. Mahay 3:22 am 03/6/2014

    #19 By original map, I meant that’s a link to the map I used as a source. So I can’t speak for the accuracy of the ‘present’ (1997, apparently) distribution, which I more-or-less copied, but I can tell you that the ‘extirpated’ distribution in the map Naish has used was purely an assumption by my 19-year-old self.

    Link to this
  22. 22. naishd 3:35 am 03/6/2014

    Voyager (comment # 11): go to the original version of this article here and look at the comments. Ha :)

    Link to this
  23. 23. naishd 4:44 am 03/6/2014

    Some responses to comments and questions…

    vdinets (comment # 1) asked if there’s a published source on the mention of co-operative behaviour. I was sure that there was – I’ve certainly heard informal suggestions that they will gang up to perform what looks like co-operative group-hunting. I also just found this, here, at Reptipage…

    “There have been reported occasions of one or more V. komodoensis banding together in order to take down a large prey animal (e.g. A water buffalo). Each monitor would apparently take a different side and alternate attacks. While this would increase efficiency by allowing the monitors to take a break in between attacks (King & Zahn,98), studies by Walter Auffenberg et al, seem to indicate that this is a rare event if it happens at all.”

    On body size variation in Komodo dragon populations, I had missed this paper…

    Laver, R. J., Purwandana, D., Ariefiandy, A., Imansyah, J., Forsyth, D., Ciofi, C & Jessop, T. S. 2012. Life-history and spatial determinants of somatic growth dynamics in Komodo dragon populations. PLoS ONE 7(9): e45398. doi:10.1371/journal.pone.0045398

    The authors show that growth patterns in dragon populations differ not only between the sexes, but also due to density, prey density and perhaps island size, “with the presence of dwarf and giant forms in part suggesting spatial variation in growth”. So, study of the sort required to test the dwarfism hypothesis has actually already been done.

    Mahay (comments # 16 and 21): ok, so you were young when you did those maps. Well, they still look nice and show what I wanted them to show. You’re right that showing a prehistoric distribution encompassing the whole of Flores might well be over-enthusiastic, but, on the other hand, it might not be that wrong.. we do know from historic accounts and fossils that dragons were far more widespread on the island. Theoretically, they might therefore have occurred from east to west and north to south on Flores.

    Link to this
  24. 24. Jerzy v. 3.0. 5:05 am 03/6/2014

    I wonder if any ancient DNA was done on those Komodo dragons from Australia. Or Megalania for that matter? I think chance is that giant Australian dragons were be separate convergent species. Not many truly land animals have ranges spanning all the way from Australia to Lesser Sundas.

    About Australian reintroductions, I always wondered why nobody reintroduced Tasmanian devils to the mainland Australia. Especially to areas where wild dingos are not present. Devils don’t bite people and are endangered themselves.

    Link to this
  25. 25. naishd 5:15 am 03/6/2014

    Jerzy (comment # 24) says: “Not many truly land animals have ranges spanning all the way from Australia to Lesser Sundas”. As covered recently in other Tet Zoo articles, note that Timor monitors were originally thought to occur on Australia and then all the way west to the Lesser Sundas. Knowledge of integumentary characters (and, theoretically, genetics too) then allowed people to argue that these populations were actually not conspecific. It’s conceivable that this is the case with these dragons too: that is, that what looks like one species in osteological terms would actually turn out to be more than one if we had data on integument, genetics and so on.

    In other words, it’s conceivable that what we currently term the Komodo dragon might actually be a species complex. Or — is it just an exceptionally good disperser? It’s not exactly a typical monitor, after all.

    Link to this
  26. 26. naishd 5:20 am 03/6/2014

    Oh – Tasmanian devils on Australia… did you know that devils have been found on Australia? There are one or two roadkilled specimens and also one or two reliable reports of trackways. One of the roadkilled specimens (it’s figured in one of the Australian cryptozoology books, maybe Healy & Cropper’s Out of the Shadows) was stored in a freezer – I asked the late Peter Chapple a few times about doing DNA work on it but nothing ever happened. It’s assumed that these animals were escapees or the result of some sort of introduction attempt.

    Link to this
  27. 27. Dartian 5:49 am 03/6/2014

    Darren:
    Tasmanian devils on Australia… did you know that devils have been found on Australia?

    Here is an entire webpage devoted to that subject, with details about individual cases.

    Of course, it’s hard to say what to make of these occasional discoveries of Sarcophilus on mainland Australia. Escapees from captivity and/or deliberate introduction attempts do indeed seem to be the most likely explanations. A surviving relict population sounds a bit far-fetched, but then again, if long-beaked echidnas Zaglossus apparently still survived on mainland Australia almost within living memory (Helgen et al., 2012)… Who knows?

    Reference:
    Helgen, K.M., Miguez, R.P., Kohen, J.L. & Helgen, L.E. 2012. Twentieth century occurrence of the long-beaked echidna Zaglossus bruijnii in the Kimberley region of Australia. Zookeys 255, 103-132.

    Link to this
  28. 28. DavidMarjanovic 11:14 am 03/6/2014

    I wonder what was the size of ancestral moas and elephant birds.

    Uh, they’re descended from flying birds… so…

    Potential unintended consequences?

    Not for humans. Australia is already the land where you might accidentally get killed.

    long-beaked echidnas Zaglossus apparently still survived on mainland Australia almost within living memory

    AAAAAAARRRRRRRGH

    Link to this
  29. 29. Yodelling Cyclist 11:26 am 03/6/2014

    Why AAAARRRGH?

    Link to this
  30. 30. Heteromeles 12:01 pm 03/6/2014

    AAAAAAARRRRRRRGH has an online version, too:

    http://www.pensoft.net/journals/zookeys/article/3774/twentieth-century-occurrence-of-the-long-beaked-echidna-zaglossus-bruijnii-in-the-kimberley-region-of-australia

    Link to this
  31. 31. Yodelling Cyclist 12:08 pm 03/6/2014

    AAAAAAAAAAARRRRRGGGGGGGGGGGGGGHHHHHHHHHHHG!!!!!!!!!!!!

    Link to this
  32. 32. vdinets 9:35 pm 03/6/2014

    Darren: thanks! I guess if there’s nothing more recent, it means that there’s no cooperative hunting :-(

    Link to this
  33. 33. Jurassosaurus 9:57 pm 03/6/2014

    That or there’s just not enough wild observations to catch it (cf. parental feeding in reptiles, or fruit eating in crocs).

    Link to this
  34. 34. Tayo Bethel 2:33 am 03/7/2014

    I have a question.
    why would Komodo dragons engage in cooperative hunting? I dont mean something that just looks like cooperative hunting, but actual cooperation between individual animals. I’m not saying it cant happen, mind you–hatchling iguanas displaying what in human males might be called chivalrous behavior long ago disabused me of the notion that altruistic behavior was restricted to archosaurs and mammals. But why would Komodo dragons, who are so aggressive toward each other, have a reason to cooperate with each other?

    Link to this
  35. 35. naishd 8:42 am 03/7/2014

    Why engage in co-operative hunting? Well, couldn’t the same be asked of co-operative behaviour in any animal? Possible answers: it’s selfish, proving beneficial to individuals, and arises occasionally and opportunistically purely because it can (that is, the animals involved are ‘smart enough’, or behaviourally flexible enough, to permit such behaviour); it provides a genetic advantage (animals that help others – like mates or relatives or offspring – pass on more DNA); its occurrence is random, but no more damaging to survival than is hunting alone. And dragons aren’t aggressive to one another all the time, nor are they equally aggressive to all individuals all the time.

    Note, by the way, that I’m not defending or supporting the idea of social hunting in these animals, just providing theoretical reasons why it might occur, or persist.

    Link to this
  36. 36. Heteromeles 9:29 am 03/7/2014

    My general response to the “Why cooperate” question is to reference Robert Axelrod’s Evolution of Cooperation, which is about the iterated Prisoner’s Dilemma game and the tit for tat strategy. It’s worth reading, especially when he notes that even bacteria has demonstrably figured out the tit for tat strategy.

    Since I worked with symbiosis for my thesis (mycorrhizae in my case), I feel entitled to get a little snarky any time someone feels the need to wildly speculate about why two organisms cooperate, as if this is surprising and unusual. You’d be dead if it weren’t for the pounds of bacteria in your gut, to pick one intimate example. This doesn’t mean that symbiotes are always nice to each other. Many mycorrhizal relationships actually look like a Mexican standoff on the cellular level, and the tit for tat strategy works only when each side can “retaliate” (read injure or kill) the other. Your gut bacteria can kill you if you’re stupid enough to let them escape your intestines and cause peritonitis.

    My simple explanation for cooperative hunting is that the Komodo dragons know each other. Since even bacteria can figure out the odds of cooperating with each other or attacking each other, presumably something like a Komodo dragon can figure out that simultaneously attacking a big hunk of meat with a couple of other dragons results in some meat and relatively little risk of injury, while chasing off the other dragons and attacking the water buffalo by itself results in a greater chance of combat injuries from the other dragons, followed by a greater risk of being hurt attacking the buffalo, followed by the need to fight off other dragons once the buffalo is actually dead, all to get more meat. Since the dragons have a pretty good idea of what the other dragons can do to them and to the buffalo, it’s rather simpler for them all to jump the buffalo together. As I noted, bacteria, mycorrhizal fungi, and plants make equivalent calculations all the time, so it doesn’t take a huge brain to figure this out. The preconditions for cooperation are long-term relationships, a reward for cooperating, and the ability to hurt each other badly if they don’t cooperate. All three apply to the dragons.

    I’d strongly recommend reading Axelrod’s book if you haven’t already. It’s very straightforward, and it really needs to be known better in the biology world. If you want something rather more stuffy and far more deeply disturbing, I’d suggest reading Jan Sapp’s Evolution by Association. It’s a history of the science of symbioses, and it points out that the reason so many scientists find cooperation weird is entirely political, and it dates back to the fight between capitalism and communism. Capitalists embraced competition in the natural world as proof that their political system was the only correct one, communists embraced mutualisms as demonstrating that capitalism was evil and species normally cooperate with each other, and this so polarized and poisoned the study of species relationships that, to this day, English ecology texts still have five pages on symbiosis and a long chapter on competition, and many papers on each subject have never been translated out of Russian (for symbiosis) or English (for competition). In this case, the science has been so politicized that most biologists don’t realize how one-sided their educations are in regard to the study of interactions.

    Link to this
  37. 37. Tayo Bethel 2:03 pm 03/7/2014

    Thanks for the replies. Note that I’m not questioning the intelligence of Komodo dragons or their ability to cooperate, justreasons why a solitary predator might wish to do so. Take leopards, for example. Like most cats (or most carnivorans)? leopards are solitary but not asocial, and rare instances of what might be called cooperative hunting have been reported between mating leopards. Whether many of these seeming cooperative efforts were coincidental or not is a matter of speculation, but i tend to think that in a few cases cooperation might have been intentional rather than a happy accident. So I’mnot atall opposed to the idea of cooperative varanids.
    Comment 36: I had no idea capitalism and communism influenced evolutionary science to suchan extent. Sounds scary.

    Link to this
  38. 38. DavidMarjanovic 2:13 pm 03/7/2014

    Why AAAARRRGH?

    Too many emotions. :-) Happy that it survived so long (yay, more monotremes in the world). Upset that it likely did die out after all. Excited about the possibility that it might still occur…

    Thanks for the link to the paper!

    Link to this
  39. 39. Vpanoptes 10:41 pm 03/7/2014

    Just a few comments re: “reintroduction” of Komodos to Australia and the cane toad situation. The point has been made that (re?)introducing Komodos to Australia may present a significant risk because of cane toads. Yup, could well be. Also, given the disastrous history of introducing exotics (of any stripe) to Oz is likely to meet some very stiff and well-informed resistance. Other things and issues are probably more deserving of our time, money and effort.
    The point has also been made that it might be possible to negatively condition freshwater crocs and possibly native goannas not to eat cane toads (a la the quoll situation), there are huge problems with this. As above, time, effort and money required to achieve anything significant is probably beyond any realistic effort that could be made. I worked on the effect of cane toads on a couple of the larger goanna species (Varanus panoptes and V. gouldii) several years ago. Had some significant pre- and post-toad invasion data on mortality rates, results were pretty depressing. 1.4% of the animals tracked pre-toad was a mort (cause unknown), over 70% of 50+ animals tracked (10 months) post-toad were morts. Some very obviously (established by necropsy) caused by cane toads. Having observed several small and large V. panoptes die from cane toad poisoning, it wasn’t pretty and was significantly depressing. Having observed, captured and monitored well over 100 of these two species over a course of two years, I have great respect for their “intelligence” – they are smart – probably smarter than some mammals (possums come to mind, but that isn’t saying much). One of the discouraging things I heard in Oz was otherwise informed folks (among them some biologists) engage in some quasi-Lamarckian speculation that eventually the cane toad situation would work itself out since the goannas that ate or tasted toads would survive and this trait would be passed on to their offspring. Are goannas “smart enough” to learn (or be taught) not to eat cane toads? A big maybe. In the big picture, it may not make a hell of a lot of difference. One more object lesson in why 28 g of prevention is worth 0.454 kg of cure….

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  40. 40. Heteromeles 10:52 am 03/8/2014

    Vpanoptes: Almost makes you want to breed up a chytrid to go after cane toads. No wait, that would be a bad idea too most likely.

    Horribly frustrating, really. Too bad we can’t convince the virologists to go after cane toads or something.

    Link to this
  41. 41. John Scanlon FCD 11:03 am 03/8/2014

    I keep spending more and more time in the Pilbara (seen a few Perenties and some other new-to-me varanids lately; lots of Gould’s but no panoptes, with relevance to the goanna-eating-goanna post), but yet to get any work in the Kimberley. When that happens, Zaglossus is definitely on my list of things to look out for… (the W.A. Department of Parks and Wildlife has listed it as part of the state’s fauna, but ‘presumed extinct’).

    Based on the situation in North-west Queensland, freshwater crocs suffer major mortality when toads arrive and some adults continue to die with toads in their mouths and guts, but the population persists and seems to be stable a couple of decades later. You may have seen pictures of a ~70 cm freshy being eaten by an Olive Python the other day, at Lake Moondarra where there are plenty of toads (not Water Python as reported, which don’t occur there).

    Varanids are hit harder, but shortly before I left Mount Isa someone reported seeing a V. mertensi close to town, which had apparently completely disappeared in the first year or so of toad presence (late ’80s). Gould’s and Perenties were also around but pretty scarce, while acanthurus, big enough to eat small toads, were quite abundant and turned up in houses sometimes. Regular Mulga Snakes (Pseudechis australis) were no longer found close to town, but in my last week there I caught a Pygmy Mulga (P. pailsi*) just outside my front gate, and they’re certainly frog-eaters.

    I don’t think it takes Lamarckian thinking to hope that these species will survive the toadslaut. Things won’t be the same, but they’ll stay interesting.

    (*I use this name because it was published before 2000)

    Link to this
  42. 42. DavidMarjanovic 5:51 am 03/9/2014

    (*I use this name because it was published before 2000)

    What do you mean?

    Link to this
  43. 43. John Scanlon FCD 8:22 am 03/9/2014

    I apply the principles of Kaiser et al to names proposed in non-reviewed samizdat ‘journals’, as discussed previously at Tet Zoo. :)

    Link to this
  44. 44. Christopher Taylor 7:45 pm 03/9/2014

    About Australian reintroductions, I always wondered why nobody reintroduced Tasmanian devils to the mainland Australia.

    There is the Devil Ark project in the Hunter region of New South Wales. This is a free-range but enclosed reserve where a population of devils has been established. The ppopulation is there primarily as a facial tumour-free pool from which devils may be re-introduced to Tasmania; I don’t know whether it is intended to be a permanent population.

    Link to this
  45. 45. Heteromeles 8:00 pm 03/9/2014

    Just to add to the annals of highly questionable introduction ideas, how about introducing Komodo Dragons to the lower Fly River region of PNG? I mean, just because we don’t own the land or have much idea what’s there, what could go wrong?

    Link to this

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