Towns and cities may provide suitable habitats for wildlife, including birds. In Africa, ecological studies on avian communities are, however, rare. Namibia is an exception to the rule, but even here, there is still an urgent need to conduct such studies in various urban habitats. This study has been conducted on breeding bird communities in Windhoek, the largest city in the country. Bird communities were quantified in five distinguished habitats by means of the line transect method. In total, 16 transects were designed, with a total length of 82.8 km. The studies were conducted in August 2020. The avian assemblage was composed of 32–45 resident (breeding) bird species in various habitats of the city, with 4–7 dominant species distinguished in each habitat. In all distinguished habitats, granivores comprised more than half of all birds recorded. Frugivores comprised 20.4–28.0% in most habitats. In most habitats, birds nesting on trees or shrubs comprised at least 50%, except for the city centre, where they comprised only 30.6%. On the other hand, only in the city center, species nesting on/in buildings comprised as much as 68.2%; in all other habitats their contribution ranged between 39.2% and 48.5%. The Shannon’s Diversity Index ranged slightly between 1.17 and 1.26. Also the Pielou’s Evenness Index was much the same (0.31–0.36) in all habitats investigated.
The grass ring phenomenon remains an interesting and enduring puzzle. Previous research has proposed various mechanisms, including Environmental stress and physical disturbance, Nutrient and water depletion, and the Self-Organization hypothesis, to explain ring formation. However, this process is highly complex and dynamic, hindering the development of a unified theory. This is primarily because grass rings of different origins, and even those at different developmental stages, are influenced by diverse factors. Furthermore, existing studies have often been limited to isolated cases, which highlights the need for more comprehensive, global-scale studies. Through a systematic analysis of publications, this review proposes three claims. First, they are classified based on genetic origin into single and multiple individual origins, which align with formation driven primarily by death-based and growth-based formation modes, respectively. Second, the grass ring is essentially a superorganism. Third, although grass rings are globally widespread, their formation mechanisms in regions above 4000 m remain elusive. Future research should prioritize key directions, including quantifying complete life cycles and elucidating mechanisms of high-altitude formation. This requires establishing international monitoring networks that integrate multi-omics with hyperspectral remote sensing to predict how grass rings develop under global climate change.
