Cave Guano Research Articles

A long record of environmental change from bat guano deposits in Makangit Cave, Palawan, Philippines

ABSTRACTWe present the first record of Holocene and Pleistocene environmental change derived from the chemical and stable-isotope composition of a tropical cave guano sequence from Makangit Cave in northern Palawan (Philippines). The 180 cm sequence of guano, derived predominantly from insectivorous bats and birds, consists of two distinct units. An upper section of reddish-brown oxidised guano to 110 cm was deposited since the mid-Holocene while a lower section of black, reduced guano was deposited through the Last Glacial Maximum (LGM) to >30 000 BP. Carbon-isotope (δ13C) values in guano deposited during the LGM are as high as −13·5‰ indicating that a C4-dominated grassland existed in the area around the cave at this time. Guano δ13C values of − 25‰ to − 28‰ suggest that this open vegetation was replaced by C3-dominated closed tropical forest, similar to that of the present, by the mid-Holocene. The results suggest that the climate of northern Palawan was substantially drier at the LGM than is currently the case.

Trophic structure and natural history of bat guano invertebrate communities, with special reference to Brazilian caves

The trophic structure and natural history of bat guano invertebrate communities in Brazilian caves was compared with information concerning bat guano communities in other caves throughout the world. The basis of Brazilian cave guano food webs are detritivorous organisms that directly consume guano, and microorganisms that live off deposits. These include mites, the most common organisms on guano, and others such as springtails (Acherontides eleonorae Palacios-Vargas & Gnaspini-Netto 1992), booklice (e.g. Psyllipsocidae), beetles (e.g. Dermestidae, Cholevidae), moths (e.g. Tineidae) and flies (e.g. Phoridae, Milichiidae). Facultative detritivores are also common, forming large populations when other organic substrata, such as vegetable debris, become scarce, as in the case of permanently dry caves. These are isopods (e.g. Trichorrhina sp.), diplopods (e.g. Pseudonannolene sp.), cockroaches, crickets (e.g. Endecous sp.), and silverfish (e.g. Coletinia brasiliensis Mendes & Ferreira in press). Other detritiv...