Comments thread for "The Bornean Tiger: Fact or Fiction?"

[BorneanTiger]

The Palawan tiger
 
I have noticed something about the fossils discovered in the Philippine island of Palawan, which might affect the issue of whether or not the tiger was there, even if to a minor degree. Firstly, let's start with a description of Palawan, before talking about what I noticed about the fossils.
 
Palawan is that narrow yet noticeably sized island in the southwest of the Philippines, near the Greater Sunda Island of Borneo: https://www.flickr.com/photos/tamaratiu/5854493319, https://commons.wikimedia.org/wiki/File:Greater_sunda_islands.png

*This image is copyright of its original author

*This image is copyright of its original author

Image of Palawan by Lonely Planet: https://www.lonelyplanet.com/philippines/palawan

*This image is copyright of its original author

Puerto-Princesa Subterranean River National Park, a UNESCO World Heritage Site: https://whc.unesco.org/en/list/652/ 

*This image is copyright of its original author

 
Not only is Palawan close to Borneo, they are thought to have been connected in prehistoric times, judging from the molecular phylogeny of rodents of the family Muridae (including house mice and Old World rats), though there is no geographical evidence to support this, so it could be that their masses were greater in those times, which meant that the Balabac Strait between them was narrow enough for tigers to swim from Borneo to Palawan: https://books.google.com/books?id=JmSsNuwMAxgC&pg=PT219&sa=X&redir_esc=y#v=onepage&q=palawan&f=false, http://macrocosm-magbook.blogspot.com/2008/07/more-evidence-of-ancient-tigers-in.html, https://www.sciencedirect.com/science/article/pii/S0031018208002113?via%3Dihub

*This image is copyright of its original author

 
The fossils are two articulated phalanx bones, possibly from the same toe, besides a distal segment of a basal phalanx (ICWM-2376) of the 4th or 5th digit of the manus or pes, which were excavated amidst an assemblage of other animal bones and stone tools in Ille Cave near the village of New Ibajay in the province of El Nido, in the northern part of Palawan. One bone (IV-1998-P-38239) was a full basal phalanx of the second digit of the left manus, and the other (IV-1998-P-38238) was the distal portion of a subterminal phalanx of the same digit and manus. With the former bone having a greatest length of 46.44 mm (1.828 inches), and the latter having a medio-lateral width of the distal end of 16.04 mm (0.631 inches), for example, their measurements were similar to those of Malayan and Indian tigers. The other fossils were identified as being of long-tailed macaques, deer, bearded pigs, small mammals, lizards, snakes and turtles: https://www.sciencedirect.com/science/article/pii/S0031018208002113?via%3Dihub
   
 
Ille Cave, north Palawan: https://pia-journal.co.uk/articles/10.5334/pia.308/

*This image is copyright of its original author

*This image is copyright of its original author

A potential prey of the tiger, the Palawan bearded pig (Sus ahoenobarbus), a different species to the Bornean bearded pig (Sus barbatus): https://www.zoochat.com/community/media/...us.177240/

*This image is copyright of its original author

Scenario 1: The tiger subfossils were imported from elsewhere
 
From the stone tools, besides the evidence for cuts on the bones, and the use of fire, it would appear that early humans had accumulated the bones. Additionally, the condition of the tiger subfossils, dated to approximately 12,000 to 9,000 years ago, differed from other fossils in the assemblage, dated to the Upper Paleolithic. The tiger subfossils showed longitudinal fracture of the cortical bone due to weathering, which suggests that they had post-mortem been exposed to light and air. Tiger parts were commonly used as amulets in South and Southeast Asia, so it may be that the tiger parts were imported from elsewhere, as is the case with tiger canine teeth which were found in Ambangan sites dating to the 10th to 12th centuries in Butuan, Mindanao: https://books.google.com/books?id=JmSsNuwMAxgC&pg=PT219&sa=X&redir_esc=y#v=onepage&q=tiger&f=false, https://books.google.com/books?id=e-hyDgAAQBAJ&pg=PA80&sa=X&redir_esc=y#v=onepage&q=tiger&f=false
 
Scenario 2: The tiger migrated to Palawan from elsewhere
 
On the other hand, the proximity of Borneo and Palawan also makes it likely that the tiger had colonized Palawan from Borneo in the Middle Pleistocene, about 420,000 – 620,000 years ago, during periods in which relative sea levels decreased to their lowest, at circa −130 m (−430 ft), by the expansion of ice sheets. Considering the ability of tigers to swim, it is possible that the tiger crossed the Balabac Strait when the distance between the islands of Borneo and Palawan was much less than today, during the Middle and Late Pleistocene, before the Last Glacial Maximum circa 18,000 years ago: https://www.sciencedirect.com/science/article/pii/S0031018208002113?via%3Dihub, https://www.researchgate.net/publication/223800396_Palaeoenvironments_of_insular_Southeast_Asia_during_the_Last_Glacial_Period_A_savanna_corridor_in_Sundaland, https://www.sciencedirect.com/science/article/abs/pii/S0277379101001019?via%3Dihub, https://www.nature.com/articles/nature03975

Piper et al.: https://www.sciencedirect.com/science/article/pii/S0031018208002113?via%3Dihub
     

12 non-volant mammals in Palawan have close relatives in other islands of the Sunda Shelf, including Borneo. Thus the Palawan is considered to be the northeastern part of the biogeographic region of the Sunda Islands. It is believed that Palawan had a landmass of approximately 100,000 km² (39,000 miles²), when the sea was 120 metres (390 feet) lower than at current levels during the Last Glacial Maximum, and that the climate was dry and cool compared to now, with open woodland mostly constituting the vegetation, except perhaps for a few savannahs. Palawan was inhabited by a number of arboreal and terrestrial animals, such as pigs and deer, as indicated by an archaeozoological study of Ille Cave: https://www.sciencedirect.com/science/article/pii/S0031018208002113?via%3Dihub, https://www.researchgate.net/publication/255591467_The_mammals_of_Palawan_Island_Philippines, https://link.springer.com/article/10.1007%2FBF00142213
 
At the end of the Pleistocene, the Balabac Strait widened due to the amelioration of the climate and subsequent rise of the sea level. The widening of the strait would have isolated the Palawan tigers and narrowed their available territory. The rise in sea level was such that almost 90% of Palawan got inundated, and its total landmass reduced to less than 12,000 km² (4,600 miles²), by around 5,000 years ago. Moreover, in the early Holocene, closed canopy rainforest would have replaced the open seasonal woodland and savannah. As indicated by the Terminal Pleistocene archaeozoological record from Ille Cave, climatic and environmental change, besides predation by humans, put pressure populations of deer, which were likely important resources for the tiger. The number of deer thus declined after 5,000 years ago, and before the start of historical records. To put it simply, a significant decrease in habitat and food resources, isolation from other populations by increasing sea levels, and possibly hunting by humans likely caused the extinction of the Palawan tiger population, just as these or similar factors threaten existing populations of tigers. To date, no evidence exists for the tiger surviving in Palawan beyond 12,000 years ago: https://www.sciencedirect.com/science/article/pii/S0031018208002113?via%3Dihub, https://www.sciencedirect.com/science/article/abs/pii/S0277379105001617?via%3Dihub, https://link.springer.com/article/10.1007%2FBF00142213
 
As mentioned by The Philippine Business and News, if the tiger wasn't native to Borneo or Palawan, then why would natives there use foreign animals for their rituals? https://thephilbiznews.com/2019/07/05/environment-feature-sumatra-tigers-in-palawan/
 
As it is, the case of the 2 Palawanese tiger toe-bones being found in Ille Cave amongst the fossils of other animals, which were likely collected by humans, somewhat resembles the case of 9 claws or toe bones of Upper Pleistocene Eurasian cave lions (Panthera spelaea or Panthera leo spelaea) from roughly the same period (the Upper Paleolithic or Pleistocene, around 16,000 years ago), which were found in La Garma Cave in Spain, amongst the fossils of other animals, including horses and goats, and were likely to have been used by early humans for rituals, and it is not like cave lions did not occur in the Iberian Peninsula: https://www.nytimes.com/2016/10/27/science/cave-lion-pelts-caverns.html 

The area within the La Garma cave system where the cave lion claws were found, credit: Pedro Saura

*This image is copyright of its original author

 
8 of the 9 cave lion toe bones found in the Upper Paleolithic cave site, credit: Marian Cueto

*This image is copyright of its original author

Reply