Bird species diversity long elevational gradients in different sites in the Sierra Madre Mountains in Isabela and Cagayan

Date

5-1992

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Andres Thomas L. Dans

Abstract

Bird species diversity was examined along elevational gradients in seven different sites in the Sierra Madre mountain range. Several assessment techniques were employed namely transect line counting, bioacoustics and general observations. The study sites were Palanan, Dikaclong, Diagopanay, Abuan, Dipalayag I and II and Los Dos Cuernos. A total of 116 resident species belonging to 42 families were identified in the transect counts. Of the 116 species, 43 are Philippine endemic while 20 are Luzon endemic. Eighteen species were classified further as threatened and near-threatened species. Using the Shannon-Weiner index, species diversity was examined. It was observed that there was a significant increase in species diversity index (H.) as elevation increased. Regression analysis showed that 85.25% of the total variation in H' was accounted for by elevation. A positive linear relationship was stablished. Species diversity was lowest in Palanan and highest in Los Dos Cuernos. This trend was attributed to the increase in the degree of habitat complexity, overlaps in environmental gradients, and degree of isolation from disturbance with elevation. Similarly, an increase in the proportion of frugivores and raptors while a corresponding decrease in insectivores was observed as elevation increases. This trend was attributed to the partitioning which may have occurred as a response to the changes in the availability of food resources along elevational gradients. Sorensen's similarity index revealed more than 60% similarity in species composition for all sites. Highest indices were observed in areas proximal to each other and areas that have the same vegetation type. The results showed a high degree of homogeneity along the mountain range. These trends confirmed the importance of Sierra Madre as a biological hotspot and a priority site for conservation.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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