Population Densities and Community Structure of Birds Breeding in a Suburban Wooded Grassland in the Highveld of Lesotho

The line transect method has been employed to assess species diversity, population densities and community structure of birds breeding in a mosaic of Kalahari Woodland and farmland, NE Namibia. The transect, 4.5 km long, was surveyed in 2014 and 2015. The total annual rainfall in 2014 was much higher than in 2015 (427 mm vs. 262 mm). In total, 40 breeding species in 2014, and 46 in 2015 were recorded. Six species were dominant in 2014 (Cape Turtle Dove, Laughing Dove, Emerald-spotted Dove, Blue Waxbill, and White-browed Scrub Robin) and only three species in 2015 (Cape Turtle Dove and Blue Waxbill and Yellow-fronted Canary). Although the cumulative dominance in 2014 almost doubled that in 2015, the Community Index in both years was almost identical. Also diversity indices and evenness index were very similar in both years compared. Granivorous birds were the most numerous feeding guild. Their contribution was similar in 2014 and 2015 (46.7 % vs. 43.4 %). Two other feeding guilds, insectivores and frugivores, comprised together more than 50 % in both years. The number of bird species and species diversity were not influenced by the differential rainfall. However, contrary to expectations, population densities of most bird species (at least the more numerous ones) were higher in the year with lower than in the year with higher rainfall. The number of species and species diversity was similar in the farmland and in neighbouring Kalahari Woodland in a pristine stage. However, population densities of most species were lower in the farmland than in the pristine woodland.

The species which make up the avian community are governed by a multitude of environmental and internal influences, and the crucial role of community ecology is to discern and explain the patterns arising from these influences. Some such influences are habitat structure and seasonality. This study aimed to investigate the structure of the avian community and population densities of birds in relation to habitat changes made by man, and in relation to differential rainfall. The study was set up in an urbanized riparian forest on the Zambezi River, NE Namibia. The forest close to the river bank has been slightly altered by human activities, while the one laying further afield has been highly modified by human settlements. The avian community was quantified using the mapping method. Counts were conducted in two wet seasons in 2013/14 and 2015/16. The rainfall was higher in the 2013/14 (428 mm) than the 2014/15 (262 mm) rainy season. In both seasons, 113 bird species were recorded. However, in particular, 91 species were recorded in 2013/14 and 101 in 2015/16. The Sorensen Index of Similarity between those two seasons was I = 0.89. Also, the proportion of dominant species was similar in both seasons, and the group was composed of the Dark-capped Bulbul, Red-eyed Dove, Laughing Dove, Blue Waxbill, and Grey-headed Sparrow. The Community Dominance was identical in both seasons when compared. Also, the diversity indices were very similar in both seasons. Also, all three diversity indices were almost identical in both seasons. The overall density was only slightly higher in 2015/16 than in 2013/14. The proportions of particular nesting, feeding, habitat, and residency guilds were very similar in both seasons when compared. The overall density was slightly higher in 2015/16 than in 2013/14, but the difference was not statistically significant. Also, for any particular bird species, the differences in population density between the two seasons were not statistically significant. Several bird species showed, however, statistically significant differences in their population densities between the natural and transformed portions of the riparian forest. The avian assemblage is probably stable over the years in regard to the number of breeding species and their densities, irrespective of year-to-year differences in rainfall, as water is not a limiting factor in this habitat. Bird species classified as forest specialists appear to be negatively affected by habitat transformation, while generalists (ecotone species) probably benefit from this transformation.

During the years 1996-2001, the line transect method has been employed to assess the species composition, dominance structure and relative abundance of birds resident in traditional farmlands, in the lowlands (10 transects with the total length of 43.9 km) and foothills (10 transects with the total length of transects 46.5 km) of Lesotho, southern Africa. This has been done to show the role of this farming in biodiversity conservation. A total of 76 resident species have been recorded in farmlands of Lesotho, 62 species in the lowlands and 53 species in the foothills. In the lowland farmlands the dominant group was composed of 6 species, namely the Prinia, Cape Bunting, Cinnamon-breasted Bunting, Cape Canary, Neddicky and Common Quail (35.8 %); in the foothills the group was composed 5 species: Karoo Prinia, Cape-turtle Dove, Laughing Dove, Cape Bunting and Cape Canary (35.9 %). Eighteen species bred in significantly different densities in lowlands and foothills. While insectivorous birds were more numerous in the lowland than foothill, the reverse was true with granivorous birds. Those two guilds comprised together 78% and 83% in the lowland and foothill respectively. The proportion of species in each guild was similar. In the lowland farmland the following eight species were more common that in the foothill farmlands, while in foothill farmland 10 species were more numerous than in lowland farmland. Species diversity and evenness were strikingly high and similar in lowlands and foothills, although Sorensen Similarity Index between these two areas was low (I = 0.44). Both species diversity and structure of dominance in avian communities in Lesotho farmlands indicate that the traditional farming play a positive role in biodiversity conservation.

Roads may have negative or positive effects on wildlife. I surveyed birds along a c. 21 km transect alongside a road from Katima Mulilo to Ngoma bridge in the Zambezi Region, north-eastern Namibia, and on a second transect (control) parallel to the first one and 200–400 m away from the road. The habitat is Kalahari Woodland, partly transformed to cultivated fields. The number of bird species was similar on both transects (56 vs. 48 species; x2 = 0.62, p > 0.05), but the number of breeding pairs (overall population density) was much higher away from the road than close to it (409 vs. 283 pairs; x2 = 22.9, p < 0.01). The Shannon’s Diversity Index was very similar, while Pielou’s Evenness Index was identical in both transects compared. Five species (Blue Waxbill, Burchell’s Starling, Cape Turtle Dove, Fork-tailed Drongo and Grey-headed Sparrow) were dominant on both transects, while the African Grey Hornbill was dominant only on the transect away from the road, whereas the Red-billed Hornbill and Grey Go-away-bird were dominant only close to the road. Four species (African Grey Hornbill, Cape Turtle Dove, Meyer’s Parrot and White-browed Scrub Robin) had population densities significantly higher on the transect away from the road than close to it. However, population densities of nine other species did not differ significantly between the two transects. In general, the avian communities along and away from the road were similar, probably because traffic volume was rather low and the land cover on both transects was similar in terms of natural vegetation and degree of transformation.

In April 2013, a transect c. 1100 km long with 100 points arranged in 5 sections was designed in northern Namibia between Ruacana Watefall (W) and Kongola (E) to study avian diversity in relation to gradual changes in precipitation (c. 350 mm in W to c.600 mm in E). In total, 81 bird species were recorded in all 100 points, but in particular section, the numbers were low, ranging from 22 to 38 species. In overall, the most frequent and most numerous (dominant) were the following species: Cape Turtle Dove, Blue Waxbill, Grey-headed Sparrow, Laughing Dove and Fork-tailed Drongo. Together they comprised 42.2 % of all individuals recorded. All of them, except for the Fork-tailed Drongo, were granivores. Only nine species were recorded in ten or more points. Besides the above-mentioned dominant species, the following other were in this group: Black-chested Prinia, Black-throated Canary, Pied Crow and White-browed Scrub Robin. In particular section the number of dominant species ranged from 5 to 7, without a gradient. Two species, the Cape Turtle Dove and Blue Waxbill, remained dominant in all fi ve sections. Th e Laughing Dove and Fork-tailed Drongo — in four sections, and the Grey-headed Sparrow — in three sections. Although, no gradient in species diversity, evenness, and dominance structure was recorded, signifi cant diff erences between two most western and two most eastern sections were apparent. Two species were more frequent and numerous in the eastern than in the western sections: White-browed Scrub Robin and Cape Turtle Dove; while the following species were more frequent and numerous in the western than the eastern sections: African Palm Swift , Black-chested Prinia, Black-throated Canary, Blue Waxbill, Grey-headed Sparrow and Pied Crow.

A simplified mapping method has been employed to quantify avian assemblages in a plot with a mosaic of built-up areas (129 ha) and semi-natural or open areas (85 ha; grass, trees, shrubs) in the Katima Mulilo town, Namibia. Overall, 65 breeding bird species were recorded in the study plots (51 in the built-up areas, and 50 in the ‘open’ areas). Five of them, Rock Dove Columba livia, Grey-headed Sparrow (Passer diffuses), Dark-capped Bulbul (Pycnonotus tricolor), Laughing Dove (Streptopelia senegalensis) and Blue Waxbill (Uraeginthus angolensis) were classified as dominants. The cumulative dominance was 69.9% in the built-up area and 55.6 % in the ‘open’ area. The structure of the avian community in the built-up area was unexpectedly similar to that in the ‘open’ area. Almost the same number of breeding species was recorded, and almost identical diversity and evenness indices were calculated. However, the Sorensen Similarity Index was rather low (I = 0.69). Also, the overall density of all breeding birds was much lower in ‘open’ than in the built-up area. Granivorous birds were by far the most numerous feeding guild comprising in the built-up area 68.1% and in ‘open’ area 62.2 % of all breeding birds. Also, similar between the two areas compared was the proportion of granivores (17.7% vs. 19.7%) and insectivores (11.5% vs. 13.2%). These were also similar to the proportions of the main nesting guilds. Only the guild nesting in/on buildings was much higher in built-up than in the ‘open’ area. Although species richness was not high, population densities of some species were very high in the urbanised habitat. It is recommended to protect the larger specimens of marulas and other tree species in this habitat, as they play a vital role in maintaining the high population densities.

In austral summer 2016/17, a provisional bird atlas project was conducted in the town of Walvis Bay (~260 ha), Namibia. In total, 18 breeding bird species were recorded. Four eudominant species (Cape Sparrow, Rock Dove, Laughing Dove, and Common Waxbill) comprised together 65.2% of all breeding birds. Three dominant species – House Sparrow, Southern Masked Weaver, and Speckled Pigeon – comprised additional 23.0%. The community dominance index (DI) was = 0.40, Shannon’s Diversity Index H’ = 2.21, Simpson’s Diversity Index D = 0.87, and Pielou’s Evenness Index J’ = 0.76. By far the most numerous feeding guild were granivores (88.0% of all birds recorded) followed by insectivores (6.0%) and frugivores (5.3%). Tree and/or shrub nesting birds comprised 59.5%, while birds nesting in/on buildings the remaining 40.5%. There were neither ground-nesting nor holenesting birds. Structure-wise, the avian community in the town resembles avian communities in other parts of the world (strong dominance of granivores, such as sparrows and doves). In austral summer 2018/19, a total of 25 marine species were recorded in the lagoon, of which nine (36%) were Palearctic migrant and 16 (64%) African residents. In terms of the number of individuals, Palearctic migrants constituted 17% and African residents 83%. More than half of all marine birds were Greater Flamingos, while the most numerous Palearctic species was the Curlew Sandpiper.

Among the different biomes in southern Africa, tropical riparian forests appear to be especially rich in terms of biodiversity, but little is known about avian communities occupying these forests. In this paper, bird counts were conducted in May, July–August, and October–November in 2013 and 2014. The line transect method was used. A transect 16.6 km long was designed along the Zambezi River between S 17.4975 E 24.3478 and S 17.4874 E 24.447. In total, 146 bird species were recorded. The number of species detected each season varied from 95 to 100. The number of dominant species was consistently low, varying between 2 and 3 depending on the month. However, the cumulative dominance and the dominance index were much higher in the dry season (May–August) than in the wet season (October–November). Two species were dominant each month: Euplectes axillaris and Pycnonotus tricolor. Vidua macroura and Estrilda astrild were dominant only in October, while Streptopelia capicola was dominant only in May. The group of subdominants was much more diverse than dominants and included 13 species. The Shannon diversity index increased between July and November from 3.45 to 4.05 but Simpson's diversity index did not show any seasonal trend. Pielou's evenness index was higher in the wet season (0.82–0.88) than in the dry season (0.76–0.79). The proportions of the main feeding guilds were much the same throughout the year, except for November, when the proportion of insectivores markedly increased, while that of granivores decreased. Riparian forest corridors in urbanized environments may be viewed as main instruments for offsetting the negative effects of habitat loss and fragmentation. Dataset published through GBIF (DOI: 10.15470/0ssr1v)

Comparing the numbers of four bird species, House Sparrow, Cape Glossy Starling, Laughing Doves and Cape Turtle Dove in Gauteng and Limpopo Three of the species showed significant declines in one or both province. The Cape Glossy Starlings was the only specie to show an increase in both provinces.

Abstract. There is increasing concern in southern Africa about the possible decline of rainfall as a result of global warming. Some studies concluded that average rainfall in Zimbabwe had declined by 10% or 100 mm during the last 100 years. This paper investigates the validity of the assumption that rainfall is declining in Zimbabwe. Time series of annual rainfall, and total rainfall for (a) the early part of the rainy season, October-November-December (OND), and (b) the mid to end of the rainy season, January-February-March (JFM) are analysed for the presence of trends using the Mann-Kendall test, and for the decline or increase during years with either high or low rainfall using quantile regression analysis. The Pettitt test has also been utilized to examine the possible existence of change or break-points in the rainfall time series. The analysis has been done for 40 rainfall stations with records starting during the 1892–1940 period and ending in 2000, and representative of all the rainfall regions. The Mann-Kendal test did not identify a significant trend at all the 40 stations, and therefore there is no proof that the average rainfall at each of these stations has changed. Quantile regression analysis revealed a decline in annual rainfall less than the tenth percentile at only one station, and increasing of rainfall greater than the ninetieth percentile at another station. All the other stations had no changes over time in both the low and high rainfall at the annual interval. Climate change effects are therefore not yet statistically significant within time series of total seasonal and annual rainfall in Zimbabwe. The general perception about declining rainfall is likely due to the presence of multidecadal variability characterized by bunching of years with above (e.g. 1951–1958, 1973–1980) and below (e.g. 1959–1972, 1982–1994 ) average rainfall.

The South West of Western Australia (SWWA) has been of interest to research due to the decrease in rainfall over this region since the 1950s with a significant shift since the 1970s. SWWA depends on the winter rainfall for meeting its agricultural water requirements and town water supply. A decrease in rainfall has adverse impacts on these sectors. The decreasing trend has been attributed to the decrease in the magnitude and frequency of the westerlies which bring rainfall to this region and the major changes in the large-scale atmospheric phenomenon such as the Southern Annular Mode. The observed decline in water levels in the dams of this region indicates a decrease in runoff which is mostly a result of decrease in heavy rainfall. This suggests to the need to characterize the rainfall changes in SWWA both temporally and spatially. Total rainfall can be decomposed into light, medium and heavy rainfalls, and the land responds differently to these rainfall classes. The light and medium rainfall is crucial in replenishing the soil moisture which is beneficial to vegetation. While heavy rainfall contributes mostly to runoff flowing into dams, it also poses a higher risk of soil erosion compared to light and medium rainfall. This study aims to quantify contributions from these rainfall classes to the decrease and interannual variations in rainfall, and to relate the decrease to station characteristics, i.e., latitude, elevation and the mean annual rainfall, and to the largescale circulation pattern known as the Southern Annular Mode (SAM). The Southern Annular Mode (SAM) is the north south movement of the westerlies which are winds from west to east and occur in the midlatitudes between the 30˚ and 60˚ in the northern and southern hemispheres. Long-term data for 30 stations were used, and daily rainfall was divided into three classes in such a way that they contributed equally (one third of the total) to the total rainfall of each station. It was observed that the decrease in heavy rainfall was mainly responsible for the decrease in total rainfall, followed by the medium and light rainfalls. Stations with a higher rainfall along the coast were more likely to experience a decrease in rainfall than those in the drier inland areas. Stations, where rainfall was strongly correlated with SAM, were mostly concentrated along the west coast of SWWA and the SAM index explained 9% of the variation in heavy rainfall and 11% in total rainfall for the region. Rainfall volume is a crucial aspect because the precipitation over an area such as a catchment largely determines water resources availability for that area. Changes in the rainfall volume have considerable implications for regional water resources planning and management. As the rainfall volume is the product of the wet area, which is the area receiving rainfall and the rainfall depth, the change in rainfall volume is the result of change in rainfall depth or that in wet area or both. No study has yet been undertaken to examine the change in rainfall volume in SWWA. This study also aims to examine the spatial and temporal changes in rainfall volume and to attribute this change to that in the wet area and that in the average rainfall depth in SWWA. Gridded daily rainfall data at 0.05° resolution for the period from 1911 to 2018 were used for an area of 265,952 km2 in SWWA. The results showed that regions near the coast with mean annual rainfall ≥ 600 mm showed significant decreasing trends in rainfall volume, and 84% of which could be attributed to a decrease in the wet area, while the decrease in rainfall depth only played a minor role. The regions farther inland showed an increasing trend in rainfall volume although the trend was not statistically significant. The regions near the coast also showed a decreasing trend in wet area with a higher number of rain days while the regions farther inland showed an increasing trend in wet area with a lower number of rain days. In the coast, the rate of decrease in rainfall has been reduced, and heavy rainfall, in fact, has increased over past 30 years, although, there was no concurrent change in SAM. The runoff in SWWA has been steadily decreasing which has led to reduction in the water available for water supply and agriculture. The study aimed to understand the role of rainfall changes in the decrease of runoff in the study area. Daily rainfall, potential evapotranspiration and runoff data for 10 catchments in SWWA were used. It was observed that all catchments exhibited a decreasing trend in runoff while the rainfall showed an increasing trend in some catchments. Further, the rate of change in runoff was found to be 2.6 times the rate of change in rainfall. The AWBM model overpredicted the runoff suggesting the presence of factors besides the decreasing rainfall in the observed decrease in runoff. The results indicated that the decrease in rainfall has led to a persistent decrease in groundwater table, which accelerated the decrease in streamflow in the region. This study focused on the trend in rainfall of different intensities and their contribution to the total rainfall trend. It was found that the decreasing trend was mainly concentrated along the coastal region (high mean annual rainfall) while the inland region (low mean annual rainfall) experienced an increasing trend in rainfall. In other words, the wet regions were becoming drier and the dry regions were becoming wetter. The trend and variability in heavy rainfall was observed to be the major contributor to the variations in total rainfall. Rainfall volume along the coast also showed a significant decrease and this was mainly due to the decrease in wet area while the decrease in average daily rainfall depth only played a minor role. Although, in the long term, the rainfall shows a decreasing trend, in the recent period, the rate of decrease in the total rainfall has reduced and the heavy rainfall, in fact, has increased with no concurrent change in SAM. The decrease in runoff was not solely caused by the changes in rainfall, but the steady decline of groundwater levels in the region could also be contributing to the decreasing runoff. Although, in the recent years, the rate of decrease in rainfall has reduced, the groundwater in this region needs to first recover before we can observe any positive change in streamflow in this region.

In terms of biodiversity, riparian forests are among the richest habitats in the world, but in the tropical regions of the world, these forests are understudied. In the present study, the avian community was quantified in the Zambezi rural riparian forest in NE Namibia for two years, with a similar rainfall (423 mm in 2013 vs. 428 mm in 2014). In total, 135 breeding bird species were recorded in the study area. Sörensen Similarity Index was I=0.79. There were two dominant species: Quelea quelea and Euplectes orix. The group of subdominants were represented by 11 species. The species composition and population densities only slightly differed between the years 2013 and 2014. The proportions of three main feeding guilds, insectivores, granivores, and frugivores were similar in the riparian forests. This feature distinguishes this community from others studied so far in southern Africa, where either granivores or insectivores are the dominant guilds.

Birds show phylogenetic variation in the relative importance of respiratory versus cutaneous evaporation, but the consequences for heat tolerance and evaporative cooling capacity remain unclear. We measured evaporative water loss (EWL), resting metabolic rate (RMR) and body temperature (Tb) in four arid-zone columbids from southern Africa [Namaqua dove (Oena capensis, ∼37 g), laughing dove (Spilopelia senegalensis, ∼89 g) and Cape turtle dove (Streptopelia capicola, ∼148 g)] and Australia [crested pigeon (Ocyphaps lophotes), ∼186 g] at air temperatures (Ta) of up to 62°C. There was no clear relationship between body mass and maximum Ta tolerated during acute heat exposure. Maximum Tb at very high Ta was 43.1±1.0, 43.7±0.8, 44.7±0.3 and 44.3±0.8°C in Namaqua doves, laughing doves, Cape turtle doves and crested pigeons, respectively. In all four species, RMR increased significantly at Ta above thermoneutrality, but the increases were relatively modest with RMR at Ta=56°C being 32, 60, 99 and 11% higher, respectively, than at Ta=35°C. At the highest Ta values reached, evaporative heat loss was equivalent to 466, 227, 230 and 275% of metabolic heat production. The maximum ratio of evaporative heat loss to metabolic production observed in Namaqua doves, 4.66, exceeds by a substantial margin previous values reported for birds. Our results support the notion that cutaneous evaporation provides a highly efficient mechanism of heat dissipation and an enhanced ability to tolerate extremely high Ta.

Sustainable production of moth bean through genotype management under arid environments

A compilation of the known distribution of Boophilus ticks in Africa and Latin America is presented, together with details on climate preferences. B. annulatus is recorded mainly in the western part of a strip from the equator to parallel 20 degrees N. It associates with woodlands and forests (lowland rain forest and secondary grassland). This species is also present in the Mediterranean region, associated to woodland and open areas. B. decoloratus extends southern to parallel 20 degrees N, in woodland with montane vegetation and Zambezian miombo; some records have been collected in the highveld grassland. B. geigyi is mainly collected in the western range of a stripe extending between parallels 5 degrees N and 18 degrees N, associated with Sudanian woodland, lowland rain forest with secondary grassland and woodland. Confirmed records of microplus in Africa are restricted to Malagasy region and south and eastern Africa, being predominant in the Zambezian miombo, deciduous forest with secondary grassland, and woodland. In Latin America, microplus is abundant in the Mesoamerican corridor to Venezuela and Colombia, and southern in Brazil and Argentina. The tick is mainly associated to the biomes of Chaco and Pampas in Argentina, the North-central moist Andes, the Atlantic forest (southern range) and the moist Meso-American vegetation (northern range). Most collections of B. annulatus and B. geigyi came from areas where winter minimum temperature is above 15 degrees C, maximum temperatures remain between 33 and 36 degrees C and maximum rainfall is recorded between June and September. B. decoloratus and African B. microplus are recorded in sites with low temperatures in May-September. Minimum temperature requirements are similar for both B. decoloratus and African B. microplus, and both are around 4 degrees C less than the value recorded for collections of Latin-American B. microplus. The rainfall pattern observed for decoloratus shows a minimum in May and June. The requirements of total rainfall are highest for B. microplus in Latin America, while records of African B. microplus are concentrated in areas of low rainfall between May and October, and high rainfall between November and March (low rainfall in the same period for B. decoloratus). Statistical analysis revealed the existence of populations (demes) with ecologically different requirements within each tick species. Both B. annulatus and B. decoloratus showed many different demes clearly associated to defined areas. The collections of Latin American B. microplus are very homogeneous according climate preferences and well separated from the African counterpart.