Animal distribution on Malay Peninsula and Sunda Islands mixed up

[Nikola Chavkoski]

I found it intriguing and even funny how certain animal are naturaly distributed in some islands/areas across Malaysia and Indonesia, while other are not, and vice versa, and the reasons behind that:

Elephant: Malay Peninsula, Sumatra, Borneo, but not Java (extinct);
Tiger: Malay Peninsula, Sumatra, but not Borneo; Java (extinct);
Leopard (Panthera): Malay Peninsula, Java, but not Sumatra (extinct long time ago, why?) nor Borneo;
Orangutan: Sumatra, Borneo (but not Malay Peninsula between the two islands);
Siamang: Malay Peninsula, Sumatra, but not Borneo;
Gibbon: Present on Malay Peninsula, Sumatra, Borneo, and on Java;
Tapir: Malay Peninsula, Sumatra, but not Borneo nor Java;
Rhinoceros: Sumatra, Java, Borneo, and not on Malay Peninsula (extinct not long ago);
Clouded leopard: Malay Peninsula, Sumatra, Borneo but not Java;
Sun bear: Malay Peninsula, Borneo, Sumatra, not on Java;
Banteng: Java, Borneo, extinct from Malay Peninsula, not present on Sumatra;
Gaur: Present on Malay Peninsula, but not on Sumatra, Borneo and Java.

 

[Swampy]

This is an interesting problem, and one much muddled by various expirations from islands, the extent to which these extirpations were human-mediated is still contested. Java is considerably drier and more seasonal that the other areas mentioned, particularly in the east, which would have driven local extinctions as it dried in the late Pleistocene. It is also the most densely populated and human-modified out of the regions that were attached to the Asian continental landmass in the Pleistocene, which has no doubt driven further extinctions. Some, such as tiger and elephant, are definitely human driven. Others, present in the pleistocene but not more recently, such as sun bears, siamangs, orangutan and sunda clouded leopard, are a lot more uncertain in their main drivers.