Understorey forest bird diversity in relation to habitat structures along elevational gradients of Mt. Makiling, Luzon Philippines
2010
Pagaduan, D. C., Philippines Univ. Los Baños, College,Laguna (Philippines)
Understorey bird diversity differs along elevation gradient of the Northeastern slope of Mt. Makiling [Philippines]. Habitat types were characterized as forest edge at the 40 masl (meters above sea level), secondary lowland forests at 200 and 400 masl, grassland at 600 masl, mid-motane forest at 800 masl and mossy forest at 1000 masl. Twenty mist-nets were employed on each elevation and left open for five consecutive days. Captured birds were immediately released after measurement and recording. The mid-montane showed the greatest species diversity index (2.45) and mossy forest with the least (1.67). Evenness index was highest at 200 masl (0.89). Most of the frugivores inhabit the undisturbed and abundant vegetation at 800 masl. Insectivores are widely distributed on the different elevation but with varying specific feeding behavior. Semi-raptorial invasive species increases in number on forest edge with abundant plant forms at 40 masl. Redundancy Analysis (RDA) indicates great association of habitat structure with the feeding guilds of birds (P=0.0260). Aside from disruption of ecological processes through imbalance of feeding guilds, human disturbances such as conversion of land area for agricultural practices, habitat fragmentation and community development are factors that could contribute to the decline of understorey birds on the lower elevation of this forest reserve.
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