Effect of a road on avian diversity in the Kalahari woodland

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.

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.

Most studies on edge effect are related to the forest-field edge, i.e. to the ecotone. However, there is a lack of studies attempting to investigate the effect of the distance from the forest/field edge on the avian communities in large continuous forests. The purpose of this study was to investigate this issue. The study area comprised a continuous coniferous forest, the so called Niemodlin Forest, situated in Opole Silesia, SW Poland. The line transect method has been employed in this study. In total, 54 breeding bird species were recorded. On particular 0.5 km section, the numbers varied from 34 to 48. Both the number of species and number of breeding pairs only slightly decreased with the distance from the forest/field edge. Overall, the differences between the mean densities of breeding species on 10 sections were not statistically significant. The Chaffinch Fringilla coelebs was by far the most numerous bird species, recorded as eudominant in 164 out of 165 sections. The Chiffchaff Phylloscopus collybita, Willow Warbler Phyloscopus trochilus and Blackap Sylvia atricapilla were dominants in all 10 sections, while the Blackbird Turdus merula dominated in nine (90%) and the Robin Erithacus rubecula in eight (80%) sections. The communal dominance slightly increased, but the number of dominant species and Pielou’s Evenness Index remained stable with the increase of the distance from the forest/field edge. While Shannon’s Diversity Index remained constant, Simpson’s Diversity Index decreased markedly with the increase in distance from the forest/field edge. The proportion of long-distance migrants slightly decreased, while that of short-distance migrants and residents remained constant with the increase in the distance from the forest/field edge. Strikingly, no such changes in the proportion of all feeding guilds were shown. More than half of all breeding bird species show a negative correlation between population density and the distance from the forest/field edge. The dominance of some species decreased with the increase of the distance from the forest/field edge: Hawfinch Coccothraustes coccothraustes, Starling Sturnus vulgaris, Blue Tit Parusa caeruleus, Raven Corvus corax, Wren Troglodytes troglodytes, Wood Pigeon Columba palumbus, and Wood Lark Lullula arborea. With the exception of the Yellowhammer Emberiza citrinella, the clearcuts in this study, not only failed to increase, but most probably caused a decrease in the number of both species and individuals. It is because clearing not only creates edges, but also causes loss of forest habitat and often results in forest fragmentation. Edge and area effect may in fact interact, in such way that the edge effect may drive out the area effect, causing the increase.

The mapping method was employed to study avian community structure in relation to rainfall in a town suburb in Highveld grassland in southern Africa. Studies were conducted in two breeding seasons: 1998, with dry spring; and 2001, with close to average spring rainfall. The total rainfall in 1998 was 1254 mm, while in 2001 it was 1445 mm, in both years much above the long-term annual average (866 mm). The avian community remained remarkably similar in both years, both in respect to the number of species (44 in 1998 and 53 in 2001), and dominance relationships. The Simpson’s Diversity Index was high and also very similar in 1998 and 2001 (D = 0.91; 0.93 respectively). In all years, dominant species included the Laughing Dove, Grey-headed Sparrow, Speckled Dove, Cape Turtle-Dove and Common Fiscal. The Southern Red Bishop in 2001 was also in the group of dominants. Significant differences were noted in the overall density of all birds, but contrary to expectation density was higher in 1998, with lower rainfall, than in 2001, with higher rainfall. The proportions of nesting and feeding guilds were similar in both years compared, except for the granivores, which were proportionally more common in 1998 than in 2001. This difference was mainly due to the Laughing Dove and Grey-headed Sparrow. Generally, it appears that the suburban avian community is more stable and more diverse than neighbouring communities in the natural habitats.

The line transect method was applied to assess the linear index of abundance and community structure of birds breeding in an area of Kalahari woodland used as range land for cattle. Four transects were designed along roads traversing the ranch. Each transect was 2.5 km long and was surveyed three times in 2014 and 2015. A total of 47 bird species were recorded but only 25-31 species were recorded on any particular transect. In the neighbouring pristine Kalahari woodland, the number of bird species on a12 km long transect was much higher (n = 88), and ranged in some sections (each 1.2 km in length) from 35 to 53. On any particular section, the number of dominant species ranged from 5 to 7, and their cumulative dominance on each section was similar, ranging from 53-56 %, while the community dominance index ranged from 0.23 to 0.35. The most numerous species were the Cape turtle dove and emerald-spotted wood dove, which were dominant on all sections. Together they comprised 28 % of all breeding birds. The avian community in the Kalahari woodland in Sachinga LDC did not differ from the neighbouring pristine woodland either in terms of species diversity or evenness. However, it differed significantly in terms of species richness, the proportion of main ecological guilds, and linear index of abundance of particular species. These differences could be mainly due to the structure of woody vegetation, which is much thicker in Sachinga than in the pristine woodland not used as pasture for cattle. The thickening of this vegetation on the ranch could have been caused by heavy grazing pressure by the cattle. Data published through GBIF (Doi: https://doi.org/10.15470/rova7r)

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)

In larger river valleys of southern Africa, riparian forests are among the main vegetation types. The forests are regarded as ones of the most diverse and distinct terrestrial habitats on earth. They also play a crucial role in wildlife conservation as corridors and refugia for wildlife. It is hypothesized that the closer to the river bank, the higher the species diversity, while population densities may increase with the increase of the distance from the river bank. In 2014, quantitative studies (by means of the mapping method) on avian community breeding in such forest on Zambezi River in Katima Mulilo were undertaken to measure this gradient. Four plots were designed along an increasing distance from the river bank in this forest. In terms of the number of species, there was a significant gradual decrease with the increasing distance from the bank (from 91 to 54 species). The number of breeding pairs per 100 ha increased with the moisture gradient (from 222 to 677). Shannon's (H') and Simpson's (D) indices were higher in the two plots closer to the bank river (H'= 3.44–3.85; D = 0.97–0.99), than in the two remaining plots (H' = 3.13–3.15; D = 0.92–0.93). Also the Pielou's Evenness Index was higher in two plots closer to the bank (J' = 0.84–0.85 vs. 0.77–0.78). The proportion of granivores in the avian community declined along the moisture gradient, while that of insectivores and frugivores – increased. These gradual changes can be linked to a parallel gradual changes of the amount of fruits and invertebrates.

Avian diversity is among the key components of the earth’s biodiversity that serve as unique barometers for environmental change. Bird diversity in unprotected habitats such as reservoirs in the Tigray region is less known. A study was conducted to assess the avian diversity in highland reservoirs of the Tigray region, particularly at Maygundi and Maysye reservoirs and their adjoining habitats from August 2022 to March 2023, covering both wet and dry seasons. A line transect and point count methods aided by binoculars were used to estimate avian species diversity and distribution. Biodiversity indices and Two-way ANOVA were used to analyze the data. A total of 1,813 individual birds belonging to 151 species, 17 orders and 51 families were recorded during the study period. Egyptian goose was the most abundant species (19.58 %), followed by Little Grebe (10. 86 %), Eurasian Coot (7.00 %), Ruff and Yellow Mantle Widowbird (3.31 % for each). A significant variation in the number of bird species between wet and dry seasons (F = 1225, df = 1, P = 0.02) and between reservoirs (F = 484, df = 1, P = 0.03) was observed. However, there was no significant difference in abundance of birds between wet and dry seasons in both reservoirs (P > 0.05). Maysye reservoir had high bird species diversity (H′ = 3.66), while Maygundi reservoir had the lowest (H′ = 3.24). The study shows that sedimentation and habitat destruction due to anthropogenic activities, including the expansion of settlements; agriculture and livestock grazing were the main threats to bird diversity. The highland reservoirs and their adjoining habitats support high avian species diversity including endemic and endangered species revealing the importance of the sites for bird conservation. Therefore, urgent conservation measures are recommended for long-term bird conservation.

Grasslands occupy 24% of the Earth’s surface. In most areas of the world these are either destroyed, fragmented or converted into cultivated fields. In Africa, their biodiversity is still insufficiently known. This study reports on the avian assemblages associated with grasslands in South African Highveld and Lesotho Drakensberg. Special attention was paid to the species richness, diversity, and population densities and dominance of particular species. Birds were counted by means of the Line Transect Method in three distinguished grassland types: Dry Cymbopogon-Themeda Grassland (transect length: 28 km), Wet Cymbopogo-Themeda Grassland (27 km) km, and Mountain Themeda-Festuca Grassland (31 km). In total, 86 bird species were recorded. While cumulative dominance was similar between the Dry and Wet Grassland (61–65%), these two were much different from that in the Mountain Grassland (46%). However the dominance index was similar in all three grassland types compared (0.25–0.33). Only one species, the long-tailed widow Euplectes orix was a common dominant species for all three grassland types. African stonechat, wing-snapping cisticola Cisticola ayresii, Levaillant’s cisticola Cisticola tinniens and yellow bishop Euplectes capensis were dominant only in the Mountain Grassland; northern black korhaan Afrotis afroides and the eastern clapper lark Mirafra fasciolata—only in the Dry and Wet Grassland; ostrich Struthio camelus, cloud cisticola Cisticola textrix, African quailfinch Ortygozpiza atricollis and pied starling Spreo bicolor—only in the Dry Grassland, while the helmeted guineafowl Numida meleagris, zitting cisticola Cisticola juncidis and African pipit Anthus cinnamomeus—only in the Wet Grassland. Despite these obvious differences in dominance and population densities of species, Diversity and evenness indices were similar in all three grassland types. Shannon’s Diversity Index (H’) varied between 1.22 and 1.35; Simpson Diversity Index between 0.91 and 0.94, while Pielou’s Evenness Index (J’) varied between 0.33 and 0.36. However, Sørensen Similarity Index between the three grassland types was low, ranging between 0.07 and 0.26. Proportions of ecological guilds were similar in the Dry and Wet Grassland but differed from mountain Grassland. In comparison with other tropical grassland, avian communities in southern Africa are characterized by higher species richness and higher its variance between particular grassland types.

Forest fires are a threat to biodiversity, lives, and livelihoods in many parts of the world. In Namibia, there is growing concern over the increasing frequency and severity of forest fires. The aim of this research was to map out fire-vulnerable zones in Zambezi Region in north-eastern Namibia using remote sensing and geographic information system (GIS) techniques. A forest fire risk zone map was developed from a combination of several forest fire-promoting variables. To assess vegetation condition, Normalised Difference Vegetation Index (NDVI) was calculated from Landsat TM images resulting in six classes. A toposheet map was used to classify land cover and land use into six density categories. Using SRTM imagery elevation data and topographic map, the slope, aspect, drainage density, and other coverages were determined. Geomorphologic and meteorological data were also used in the determination of forest fire risk zones. Forest fire vulnerable zones were defined by assigning subjective weights to each layer's classes based on the perceived sensitivity to fire or ability to cause fire. The final product categorized the Zambezi Region into four fire vulnerable categories: extremely high risk, high risk, moderate risk, and low risk. An area of 137000 ha (9.6%) was at very high risk, 665400 ha (46.5%) was at high risk, and 64600 ha (4.5%) was at low risk. Vegetation structure, geomorphology, land cover, and precipitation were major determinants of fire vulnerability. High elevation and low vegetation moisture status increased fire vulnerability. Lower fire risk (than expected) was recorded at low elevations due to the vegetation type being a limiting factor. Mid-elevated areas were at very high fire risk due to interactive effects of elevation, high temperature, and low humidity. Slope, aspect, and drainage density did not significantly influence fire risk due to low occurrence of pronounced slopes and aspects.

Birds play an important role as bioindicators of climate change. For this reason, it is important to know the species richness, diversity and evenness of birds found on small islands. The location of the study was in Haruku Island Maluku. Bird data collected included all bird species, taking into account certain bird species that are sensitive to environmental changes. Bird data collected by the Line Transect method is to use work lines on rectangular data plots in the specified location. This method was chosen because it can trace the plot area of data in a short time and allow repetition of data collection in one day according to the desired time. This method of analysis is to determine the level of diversity in the form of diversity indices, then to scale up the species abundance and then to calculate the estimated population density. The results of the study found 23 species of birds. There were 2 large families recorded, namely: Family Columbidae of 4 types, and Family Psittacidae as many as 5 types, while the other Family groups only had 2 or 1 types.The overall value of the bird species wealth index in 5 data transects is MEDIUM with the value of the Type Wealth Index 3.975863. Then the five Diversity Index of data transects is Medium with the Diversity Index value 2.710911452. Furthermore, the evenness index on five data transects has a fairly good value, which is included in the High Equity Index category with the Evenness Index value of 0.864588 which approaches the number one. From the analysis simulation results, it was found that the temperature aspect, in this case the temperature range at the study location when the data collection did not affect the number of bird species at all, while the estimated altitude aspect has the potential to influence the bird species encounter rate. This condition is quite reasonable because if we look at the data on the number of bird species collected on different transects of data placed in different segment elevations, there seems to be a tendency to increase altitude, so the number of species recorded tends to decrease.

Habitat loss, pollution, and climate change have a global impact on bird diversity, particularly in central Mexico, where human disturbances and unplanned urbanization can lead to the decline of this faunal group. In this study, the effects of season (rainy, warm–dry, or cool–dry) and environmental variables (size, perimeter, vegetation cover, built cover, distance to nearby greenspaces and distance to the closet natural vegetation patch) on the avian diversity at different sites located in a peri-urban landscape in the Metropolitan Area of Mexico City were determined. The study was conducted using the linear transect method to assess the diversity and composition of bird communities from November 2019 to March 2022, recording 290 total bird species. Zumpango Lagoon was the study site with the highest diversity (N = 209, H′ = 3.22) and evenness index (J′ = 0.76). Linear mixed models were used to determine the effects of season and environmental variables of the study sites on the avian diversity. The effect of distance to the nearest greenspace was significantly more positive during the rainy season than the two dry seasons. An ANOSIM test also showed that the avian community associated with water bodies differed significantly from the other communities (R = 0.16, p < 0.001). Despite some anthropogenic activities and human intrusion, sites with water bodies retain a high diversity of birds. This finding indicates the need for immediate conservation efforts to protect many resident breeding species and wintering migratory birds in the study area.

Land-use change driven by human population growth and economic activity will continue to impact both natural habitats and land currently being used for food, fiber, and fuel production. The effects of this conversion on economically important ecological services will in large part depend on how native biodiversity responds to these changes. We investigated how agriculture-related land use change influences the avian community in northeastern Argentina by examining common agricultural land uses (pasture/annual crops, young and mature large-scale eucalyptus plantations, mixed-use farms with citrus, blueberry and small stands of eucalyptus) and remnant native espinal savannas. In this region, afforested eucalyptus plantations represent a new land-use change from the land cover of pasture with intermixed annual crops that has dominated the region. In this mosaic, we used point counts to assess how avian diversity and community structure differed between land uses. Bird species richness was lowest in older plantations and highest in the espinal savanna, with the other land uses having intermediate richness. Abundance trends followed the same pattern, with low overall abundance in the plantations, intermediate levels for pasture/annual crops, and highest abundance in the espinal. Distinct bird community assemblages were strongly associated with each land use, and between young and mature eucalyptus stands. Birds can be useful indicators for biodiversity as a whole, and the depopulated and depauperate avian community within the eucalyptus plantations will likely lead to reduced provision of many ecosystem services in this region if the spatial extent of plantations continues to expand.

The study of avian species diversity and abundance at the Taunsa Barrage Ramsar site was carried out from September 2019 to March 2020. Taunsa Barrage is an important wetland for international and local migratory birds, including waterfowls, waders, and long-distance migrant avifauna. Data were collected by direct counts made on four-point transects representing a disturbance gradient due to humans and different habitats. Species diversity indices, analysis of variance (ANOVA), and other statistical methods were used to analyze data. A total of 150 avian species of 19 orders and 53 families were recorded. These included 66 migrant species and 84 resident species. The spotting of ten globally threatened species also highlights the importance of wetland for avian species. On average, 1511 ± 373 ( mean ± SD ) species of birds were recorded every month. Shannon’s diversity index indicated that Transect Point 2 had higher species diversity ( H ′ = 3.779 ), followed by Transect Points 3, 4, and 1 ( H ′ = 3.769 , H ′ = 3.491 , and H ′ = 3.457 , respectively). Evenness index showed that birds evenly distributed in September ( E = 0.5584 ) than November ( E = 0.310 9). ANOVA showed a significant difference ( F = 4.800 , df = 3 , P = 0.002 ) of avian diversity and abundance among the transect points. But there was no statistically significant interaction between months ( F = 1.23 , df = 6 , P = 0.233 ). The results showed that the Taunsa Barrage Ramsar site harbors plenty of resident migratory and threatened bird species. Hence, it is important to protect its habitat and need to protect avian diversity by overcoming major threats.

In order to understand the diatom community structure and reveal the pollution status and water quality in Nanchong section of Jialing River,15 diatom samples and water quality samples in five cites or counties of Nanchong city,were collected according to normal methods,in dry season,level season and rainy season,respectively.Chemical indices including COD,TN and TP were measured.The diatom community structure including diatom species composition,cell densities,Shannon-Weaver diversity index and Lloyd-Ghelardi evenness index were analysed,and the water quality was evaluated combined with chemical index.The results showed that:(1) 136 taxa,which belonged to 2 class,10 family and 26 genera were observed(including variety and form).Pennatae diatom species numbers were richer than that of centriate diatom.The percentage of Pennatae diatoms and centriate diatoms were 94.52% and 5.48% to the total diatoms,respectively.Langzhong section had the highest species numbers with 86 and Nanchong section had the lowest species numbers with the number of 48;The cell densities of diatom was in the range of 4500—39000 ind/L with the mean value of 18213 ind/L.Langzhong section had the lowest cell densities of diatom with the value of 12600 ind/L and Nanchong section had the highest cell densities of diatom with the value of 23700 ind/L.The diversity index was in the range of 1.05—3.30,with the mean value of 2.44.Langzhong section had the highest diversity index with the value of 2.85 and Nanchong section had the lowest diversity index with the value of 1.80;the evenness index was in the range of 0.22—0.66 with the mean value of 0.47.Langzhong section had the highest evenness index with the value of 0.55 and Nanchong section had the lowest evenness index with the value of 0.35.(2) The diatom species numbers,cell densities,diversity and evenness index took on noticeable seasonal and horizontal distribution distinction.To seasonal change,the diatom community structure had similarities in level season and dry season,with more species numbers,higher cell densities,diversity and indices evenness indices than those in rainy season.To horizontal distribution change,from upstream to downstream,the diatom species numbers decreased and diversity index and evenness index declined gradually,however,cell densities of diatom increased gradually.The sampling sites at upstream of the city had more species numbers,lower cell densities and higher diversity indices and evenness indices than those at downstream.(3) Species diversity index and evenness index as well as chemical items were used to evaluate the water quality in Nanchong section of Jialing River.The results consistently indicated that the water quality in Nanchong section of Jialing River belonged to β-mesosaprobic Zone all in all and the water body possessed certain self-purification ability.The water quality of Langzhong section was the best of all,which belonged to Oligosaprobid Zone;those of Nanbu,Xinzheng and Peng'an sections were between β-mesosaprobic Zone and Oligosaprobid Zone,which of Nanchong section was the worst of all,belonging to α-mesosaprobic Zone.To improve and protect the water quality of Jialing River,some prevention and cure measures and suggestions were given in the paper.