Application of birds as ecological Bioindicators for monitoring habitat change: A case study from Abijata-Shalla lakes national park, Ethiopia

Ecological bioindicators are a species or group of species whose ecological attributes (e.g. presence/absence, abundance, etc) readily reflect the abiotic or biotic state of an ecosystem. Although the interest in using of bioindicators as a simple and cost-effective tool in ecological monitoring has been increasing worldwide, their inappropriate selection and application have put under question their utility as a conservation tool. In this study, using a priori defined suitability criteria, we explored whether reliable ecological bioindicators can be identified within the avifauna associated with savannah woodland and gallery forests habitats in the Abijata-Shalla Lakes National Park (ASLNP), Ethiopia, and tested the reliability of using them for effective monitoring of future changes in tree structure within the national park. We counted birds along 10 transects established in each of the disturbed and undisturbed sites of two vegetation types (savanna woodland and gallery forest), and recorded data on tree abundance and cover. For the undisturbed sites of the two vegetation types, we identified two types of bioindicators: characteristic (i.e. species with strong habitat specificity) and detector (species that span a range of ecological states). Of the total 86 species recorded across the study sites, one characteristic and three detector species for the savanna woodland, and three characteristic species and one detector species for the gallery forest were identified. However, only the characteristic bioindicator species showed significant difference in abundance between the two land use types in each vegetation type; thus were regarded as reliable potential bioindicators. Further, the abundance of these characteristic bioindicator species showed strong and significant positive correlations with both tree abundance and cover in each vegetation type. We conclude that bird species selected as characteristic bioindicators can potentially be used for effectively monitoring of future changes in tree abundance and cover in the undisturbed sites of the ASLNP. We also suggest that ecological bioindicators selected following the procedures we used will have valuable potential application in the monitoring of habitat integrity.