Diversity patterns of small mammals in the Zambales Mts., Luzon, Philippines

Abstract

In 2004 and 2005, we conducted a survey of the small mammals on Mt. Tapulao ( ¼ Mt. High Peak, 2037 m) in the Zambales Mountains, Luzon Island, Philippines in order to obtain the first information on the mammals of this newly discovered center of endemism. We also tested two hypotheses regarding the relationship of species richness with elevation and the impact of alien species on native mammals. The survey covered five localities representing habitats from regenerating lowland rain forest at 860 m to mossy rain forest near the peak at 2024 m. We recorded 11 species, including 1 native shrew, 1 alien shrew, 8 native rodents, and 1 alien rodent. Two species of Apomys and one species of Rhynchomys are endemic to Zambales; this establishes the Zambales Mountains as a significant center of mammalian endemism. Species richness of native small mammals increased with elevation, from five species in the lowlands at 925 m to seven species in mossy forest at 2024 m; total relative abundance of native small mammals increased from 925 to 1690 m, then declined at 2024 m. Alien small mammals were restricted to highly disturbed areas. Our results support the prediction that maximum species richness of small mammals would occur in lower mossy forest near the peak, not near the center of the gradient. Our results also support the hypothesis that when a diverse community of native Philippine small mammals is present in either old-growth or disturbed forest habitat, ''invasive'' alien species are unable to penetrate and maintain significant populations in forest.

Archboldomys(Muridae: Murinae) Reconsidered: A New Genus and Three New Species of Shrew Mice from Luzon Island, Philippines

“…8). It is readily distinguishable from S. musseri by the following combination of dental features: (1) longer maxillary molar tooth row (shorter in S. musseri); (2) broader M1 (narrower); and (3) narrower incisors at their tips (broader), and from S. kalinga and S. montanus through targeted surveys of isolated mountains and mountain chains, using multiple sampling procedures to ensure detection of species that have varied food and foraging habits in different habitats along the elevational gradient (e.g., Balete et al, 2009;Heaney et al, 2011;Rickart et al, , 2011b. In the case of Archboldomys and Soricomys, the use of live earthworms as bait, the targeting of montane and mossy forest at high elevations, and surveys of even small mountain chains, have been crucial in detecting the animals.…”

Invasive aliens on tropical East Asian islands

“…Several species of human-commensal rodents and shrews have also been dispersed throughout the region. Their ability to invade native forests is largely unknown, but studies in the Philippines suggest that alien species are unable to penetrate undisturbed or regenerating forests with a rich native small mammal fauna (Balete et al 2009). …”

Chapter 2: Mammalian Diversity Patterns on Mount Palali, Caraballo Mountains, Luzon

“…Most of the islands are volcanic in origin and have had no dry-land connection to the Asian continent throughout their geological lifespan (Heaney, 1986;Hall, 1998). Previous surveys have shown that each major island (or set of closely adjacent islands that were connected to each other during the last glacial maximum) is a unique center of mammalian diversity, with levels of endemism ranging from 40% to nearly 90% (Heaney, 1986;Heaney & Regalado, 1998;Catibog-Sinha & Heaney, 2006;Balete et al, 2009). Additionally, each major island has a unique history of geologic processes that resulted in isolated mountain ranges and peaks of differing elevation.…”

“…Each of these areas has been shown to harbor a distinct set of mammals and each is recognized as a subcenter of mammalian endemism Heaney et al, 1999;Ong et al, 2002;Duya et al, 2007;Balete et al, 2009, this volume). Additional mountain ranges and isolated peaks on Luzon are part of our ongoing effort to locate and document all of the subcenters of endemism (e.g., Balete et al, 2009;. This paper constitutes the first documentation of the ecology and diversity patterns of mammals on another mountain range on Luzon, the Caraballo Mountains.…”

“…This hypothesis is based on a pattern documented on six mountains of the Philippines: Mount Isarog (Heaney et al, 1999), Mount Tapulao (Balete et al, 2009), and Mt. Bali-it, Balbalasang , on Luzon; Mount Guinsayawan on Negros Island (Heideman et al, 1987;Heaney et al, 1991); Mount Timpoong on Camiguin Island (Heaney et al, 2006a); and Mount Pangasugan on Leyte Island (Rickart et al, 1993).…”