Publication Date:
2021-05-19
Description:
This study focused on bird surveys and habitat degradation which has been documented as the most immediate threat to the survival of bird populations globally (Recher and Lim, 1990; Robinson and Trial, 1996; Fanshawe & Bennum, 1999; Ford et al, 2001; Boere et al.2006). Research activities were conducted within the Tana Delta which is located along Kenya’s 600km coastline within latitude 02030′S and longitude 40020′E from October 2006 to August 2007. Six sites were chosen for ground truthing of remotely sensed data and for obtaining indicative estimates of bird species and population within the delta. Bird density estimates and species diversity were assessed using a combination of line transect and point counts (Bibby et al., 1992). Spatio-temporal data analyses were accomplished using Arcinfo GIS version 9.2.
The total area surveyed during this study was estimated at 367 Km2 spread across the six study sites within the Tana Delta and yielded 60, 054 birds for the entire survey period. The sighting registrations were dominated by shore birds (10 species) in Kipini and Shekiko which accounted for 73% of the total. Shakababo had the highest species diversity (30 species) while shorebirds had the least species counted (9 species). There was a significant increase (t=2.67, p〈0.001, 16df) in the number of birds observed during the South East Monsoons (SEM) compared to the registrations recorded during the North East Monsoons (NEM). The major habitat categories of the delta were found to comprise wetlands, perennial marshes, forested areas, mangroves, rangeland, barren and land tidal flats. The habitat total area in hectares for the study area was 291, 411 hectares but there were spatial variations for the land cover types between 1972 and 2004 mainly affecting forested areas and wetlands.
The change detection procedure and datasets used in the study resolved spatial changes in habitat cover within three categories i.e. wetlands (12.5%), forest areas (77.5%) and mangroves (10%). The three habitat categories have been identified as underlying the high diversity of birds within the lower Tana Delta area. Overall it was observed that the spatially degraded area comprised 1.68% of the total habitat area.
Colonization within degraded areas was observed as primary succession by species of lower value which were indicative of a declining bird habitat quality. Based on an ordinal score of 0-5 and frequency of observed birds, it was evident that forested areas had the highest diversity of birds, then forest areas, tidal flats and rangelands.
Description:
Published
Keywords:
Aquatic birds
;
GIS
;
Wetlands
Repository Name:
AquaDocs
Type:
Report
,
Not Known
Format:
24pp.
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