Walia Special Edition on the Bale Mountains (2011) - Zoologische ...

Structuring of the Birds of the Bale Mountains National Park
Anteneh Shimelis 1 , Afework Bekele 1 , Addisu Asefa 2 , Stuart Williams 3 , Aaron Gove 4 and Simon
Thirgood 5
1 Addis Ababa University, Ethiopia
2 Bale Mountains National Park, Ethiopia
3 Ethiopian Wolf Conservation Programme, Ethiopia
4 University of Stockholm, Sweden
5 Macaulay Institute & Aberdeen University, UK
Abstract
Using bill morphology and species specific dietary requirements, we classified 117 resident
bird species of the Bale Mountains National Park. Five was the number of groups suggested by
preliminary cluster analysis. This was further confirmed by results of Principal Component
Analysis and Discreminant Function Analysis. A non-parametric statistical test showed the majority
of morphological and dietary attributes did have values that varied significantly across groups of
species. To determine the relevance of this species grouping in determining the structuring of the
National Park’s resident bird community, data on species distribution across habitat was evaluated.
This showed that, except in one instance, the distribution of species across habitats followed
significantly the determined group structure.
Introduction
As a community, a group of species collectively respond to environmental and ecological processes
as a result of their historical and ecological similarities (MacArthur 1971; Whittaker 1975; Diamond
1975; Holmes et al. 1979; Wiens 1989; Keddy 1992; Weihir & Kedy 2001; Wilson 2001; Krebs
2000; Simberloff and Dayan 1991). Understanding of the causes of such similarities and the
consequent group attributes is the central objective of both the theoretical and empirical aspects
of community ecology. Any study in the field, starts by asking “what is a community of living
organisms like when it is there?” Standard community definitions stress on features that emerge
consistently upon evaluation (Wiens 1989). The co-occurrence of individuals of several species in
time and space is one principal characteristics of the definition (MacArthur 1971; Whittaker 1975;
Diamond 1975; Holmes et al. 1979; Wiens 1989; Weihir and Kedy 2001; Wilson 2001; Krebs 2000).
This refers to partial or total distributional overlaps amongst species pairs as resident occupants
of a given area (Krebs 2000; Dunning et al. 1992). Another very important feature attributed to
communities is the interaction of species entities. Interaction in this sense refers to relationship of a
group of species at parallel planes of resource utilization (Holmes et al. 1979; Richard et al. 1986;
<strong>Walia</strong>-<strong>Special</strong> <strong>Edition</strong> on the Bale Mountains 15