A geographical perspective on the relationship between Impatiens spur lengths and bill lengths of sunbirds in Afrotropical mountains

The critical role of coastal protected areas in buffering impacts of extreme climatic conditions on bird diversity and their ecosystem services' provisioning in the Eastern Cape Province, South Africa

In this study, we documented the diversity of bird species in the Eastern Cape coastal nature reserves (i.e., Hluleka, Dwesa, Silaka and Mkhambati nature reserves), and determined the potential role of each bird species in habitat maintenance using two functional traits (i.e., body mass and feeding mode) as the function's proxy. We applied the timed species count approach during bird observations, coupled with drive-by surveys to maximise spatial coverage of each nature reserve over four years. To evaluate functional diversity, bird species were classified based on functional traits such as the adult body, and their potential ecological role derived from their feeding mode and habitat associations. Over 864 h, we accumulated 818 bird records containing 178 different bird species that were classified into 58 families with 32 species occurring in all nature reserves. Shannon-Wiener Diversity Indices showed very high overall species diversity across the nature reserves (H > 3.5) with no differences detected across sites. Although no significant correlations between vegetation changes measured through Normalised Difference vegetation Index (NDVI) in each nature reserve and the number of bird records, forest bird species were dominant (42.1%; N = 178) throughout years of observation and diversity remained high (H > 3.5). Bird species abundance only increased significantly across all nature reserves during 2018-2019. All four nature reserves had a similar distribution of bird functional traits with both high functional richness (FRic = 1), and divergence (FDiv = 0.8) and moderate evenness (FEve = 0.4). Multiple Correspondence Analysis (MCA) demonstrated a positive correlation between bird sizes and functions with large birds mainly associated with predators and carrion. Small birds and medium birds had a similar composition of species in terms of functionality being seed dispersers across the nature reserves. A significant effect that insectivores and carrions displayed in MCA plots, suggest the availability of indirect pollination services. Despite extreme drought conditions across the country in 2019, NDVI levels remained largely consistent over time in these four reserves; and thus, they offer important refuge for birds during extreme climatic conditions such as drought.

Histo-morphological Characterization of the Tongue and Oropharyngeal Cavity of the Shining Sunbird (Cinnyris habessinicus)

Sunbirds, as specialized nectarivores, have developed multiple lingual and oropharyngeal peculiarities imposed by this dietary specialization that particularly extract floral nectar. We have described the functional morphology of the tongues and palates of the shining sunbird, Cinnyris habessinicus, using gross anatomical, histological, and scanning electron microscopic methods. The tongue was bifurcated with fringed lamella and extended posteriorly, forming a broad trough at the lingual body and terminating in two fleshy, alae linguae. The lingual apex and body are nonpapillate and nonglandular, and its root had a muscular pad followed by a conspicuous laryngeal mound bordered by three prominent rows of conical papillae. The lingual root had clusters of mucoid glands with rich acidic mucins, and the laryngeal region had complex papillary distribution at the back margins. Both the lingual body and root had well-developed skeletal elements, musculature, and connective tissues. Furthermore, the palate was membranous and made up of four main ridges with a central choanal slit guarded by choanal papillae. Overall, the presented results showed structural and anatomical features that are the results of the nectarivory dietary niche.

Morphological diversity and altitudinal differentiation of Aethopyga species

The morphological characteristics of birds are an important tool for studying their adaptation and evolution. The morphological evolution of a clade is not only constrained by the phylogenetic relationship, but also influenced by ecological factors and interspecific competition. Aethopyga is a group of small nectar-eating birds with obvious sexual dimorphism. They have slender and decurved beaks, which reflect their unique diet and foraging mode. Traditional and geometric morphometrics were combined to characterize the body morphology and beak shape of six species of Aethopyga distributed in China. We aim to assess the roles of phylogeny, altitude, and species interactions to morphological evolution. The main distinguishing characteristic among these six species were overall body size, the ratio of body weight, culmen and tarsal length to body length, tail length and wing length, and beak shape (slender/straight vs. thick/decurved). Although these dimensions cannot distinguish all species, they can show a clear distribution trend, and there is a significant Mahalanobis distance between each pair of species. There were no significant phylogenetic signals in morphological traits. The results of PGLS analysis show that altitude is significantly correlated with log-transformed tarsus length and beak-shaped PC1 (slender/straight vs thick/decurved dimensions) across the six species analyzed. Mantel test shows that the distance matrix of beak morphological characteristics showed a significant correlation with the altitudinal distance matrix. The results indicated no significant phylogenetic signal in the morphological characteristics of six species. In terms of beak shape, species with greater overlap in elevation distribution have more similar morphological characteristics, that is, less morphological differentiation.