Habitat loss / degradation
Most macaques are naturally forest dwellers. Some urban macaques survive largely on human handouts and human waste, but as the Covid pandemic has shown, this survival is tentative and when the handouts stop, survival can be extremely challenging.
Deforestation is a serious problem across Asia. Southeast Asia’s deforestation rate is amongst the highest in the world, and it has already lost a huge amount of biodiversity. As habitats disappear, so do those macaque species that cannot adapt to life in human-dominated environments. Those that can adapt (the "synanthropes") become increasingly visible as they raid crops, rummage through human refuse, receive handouts, and/or become more comfortable in the presence of humans. This can create the impression that their numbers are booming, when in fact, the opposite may be true. In 2008, the late Ardith Eudey made this point about long-tailed macaques (Macaca fascicularis), which as a result have just been reclassified by the IUCN as Vulnerable.
Habitat degradation is also linked to increased prevalence of zoonotic diseases, putting both humans and macaques at extra risk.