Timed Species Counts Research Articles

Impacts of Artificial Lighting on Avian Biodiversity: A Case Study of Udaipur (Rajasthan), India

The pervasive presence of artificial light in urban environments significantly affects biodiversity. This study investigates the impact of light pollution on avian biodiversity in Udaipur, India. Excessive artificial lighting alters natural habitats, disrupts ecosystems, and affects the behaviour and abundance of various avian species. The study was conducted in Udaipur from December 2019 to March 2023, utilizing Visible Infrared Imaging Radiometer Suite (VIIRS) DNB Free Cloud Composite Imagery and field surveys. The research spanned rural and urban landscapes, employing methods such as timed species counts and point counts to assess avian fauna. The Shannon-Wiener Diversity Index was used to measure biodiversity, with ANOVA and Tukey’s post-hoc tests for statistical analysis. VIIRS data analysis revealed three light pollution clusters: dark, moderately dark, and bright areas. Avian diversity varied across these clusters, with significantly higher diversity observed in dark areas. Daytime and night time observations also showed variations, with higher biodiversity observed at night. Common species exhibited significantly higher abundance in brighter areas, while moderately dark and dark areas supported greater diversity. Artificial lighting has profound effects on avian biodiversity in Udaipur. Bright areas exhibit reduced biodiversity, while dark areas support richer ecosystems. This study underscores the importance of managing light pollution to preserve avian diversity and maintain ecological balance in urban environments.

Bird Community Composition and Functional Guilds Response to Vegetation Structure in Southwest Ethiopia

Shade coffee farms in southwest Ethiopia are known to host high levels of avian biodiversity. However, these farms vary in terms of forest management, which affects their understory, mid-story, crown cover, and canopy closure, and hence their structural complexity. Such differences in vegetation structure can potentially affect the survival of specialist bird species, and shade coffee farms may not equally contribute to avian biodiversity conservation. This study aimed to investigate how avian community composition, richness, and the relative abundance of different bird functional guilds relate to structural differences in vegetation shaped by forest management. Bird guild classification was based on bird species forest dependence, diet type, migration status, nest type, foraging, and nesting strata, and bird communities were surveyed using the Timed Species Counts (TSCs) method. Species turnover in bird communities was evaluated using detrended correspondence analysis and redundancy analysis, whereby multiple regression models were used to examine bird guild responses to vegetation structure. Total bird species richness and relative abundance did not respond to vegetation structure. However, the richness of forest specialists and understory foragers, and the relative abundance of mid-high foragers, all positively related to tree diameter at breast height (DBH) and crown cover, whereas the relative abundance of species with medium levels of forest dependency, mid-high/canopy foragers, and open-nesters were positively related to basal area and canopy cover. This study demonstrates that the relative value of shade coffee farms for avian biodiversity conservation depends on the type of forest management, and that bigger trees with larger crown cover provide a habitat of higher quality to habitat specialist birds.

Does Bird Diversity Affect Public Mental Health in Urban Mountain Parks?-A Case Study in Fuzhou City, China.

Intensified urbanization has caused a linear decline in the quality of urban biodiversity and indirectly harms our current human settlement environment. Urban mountain parks provide a refuge for the animals and plants and play a vital role in satisfying residents’ lives. At present, few studies are focusing on the impact of biodiversity on human mental health benefits of urban mountain parks in high-density construction areas along the coast of the Eastern Hemisphere. Here, we examined the relationship between bird abundance, Shannon diversity, Simpson diversity, and Richness and momentary mental health (positive, negative, and anxiety) in urban mountain parks. The timed species counts method was used to conduct three surveys of birds in urban mountain parks, and linear regression was performed on the relationship between bird diversity and mental health among sites. According to the regression model results, we found no significant correlation in any disturbance levels. As urban mountain parks are an essential part of the human settlement environment, how to improve the biodiversity and mental health of urban mountain parks is one of the focuses of research on biodiversity well-being in the future. Urban planning authorities and public mental health researchers should pay attention to the importance of biodiversity in urban development and consider how to realize the beautiful vision of the harmonious coexistence of humans, animals, plants, and the environment in which we live.

Bird alpha, beta and functional diversities across three peri-urban woodland stands along an anthropogenic disturbance gradient: is formal protection a guarantee for ecological integrity?

Urban woodlands are significant as refugia for species of wild birds which contribute to provisioning a wide range of ecological services beneficial to nature and to humans. Due to the increasingly small and fragmental structure of these habitats, arising from constant expansion of city infrastructure, these birds are in increasing conservation peril with serious ramifications to the ecological and touristic values they represent. We assessed the alpha, beta and functional diversities of birds in three small woodland stands within the metropolis of Nairobi, Kenya and compared their variations along an anthropogenic disturbance gradient (Low, Moderate; High) based on relative openness, vegetation cover and rate of human visitation. Birds were surveyed using timed species counts during six sampling periods and grouped into three diet-guilds and three vertical foraging strata to assess compositional and assemblage turnover responses to disturbance. Functional overlaps in birds’ ecological roles were also evaluated, and potential candidate species for monitoring disturbance trends were identified. Alpha diversities were determined using Chao1 species estimator, and beta diversity evaluated through the PERMDISP function and main-test Permanova in PERMANOVA+ add-on of Primer-E, to assess species turnovers. Parameters were compared cross-site using general linear models while indicator species were identified using Indval function in R. Significant responses to impacts of anthropogenic disturbance were observed in abundance of birds overall, abundance of upper-stratum species, and in terms of alpha diversity of carnivores but not for other guilds. On the other hand, species turnovers occurred along the disturbance gradient for birds overall, in frugivores and also for both upper- and lower-stratum species. Species functional redundancies, depicting diminished habitat complexities, were detected in the most disturbed site for birds overall, amongst carnivores, all herbivores combined, and among the lower and middle-stratum species, but were not evident for birds overall in the low- or moderately-disturbed sites, nor among upper-stratum bird species. Only two species, both carnivorous, qualified as potential candidates for monitoring disturbance trends across the three woodland sites. These results demonstrate negative effects of anthropogenic disturbance on peri-urban woodland bird assemblage and composition, and greater resilience of taxonomic over functional diversity in response to such disturbance, but also that while formal protection may enhance bird’s community-level functional roles, not all guilds may benefit. Mitigating effects of disturbance requires measures for improving habitat structural heterogeneity to broaden birds’ assemblage composition, diversify their ecosystem roles at all levels and promote their site-based avi-tourism potential.

Effect of habitat disturbance on distribution and abundance of Papyrus endemic birds in Sio Port Swamp, Western Kenya

Wanyonyi SN, Mwangi EM, Gichuki N. 2018. Effect of habitat disturbance on distribution and abundance of Papyrus endemic birds in Sio Port Swamp, Western Kenya. Bonorowo Wetlands 2: 49-60. Papyrus (Cyperus papyrus) swamps are found patchily around the shores of Lake Victoria mainly along river inflows. The objective of this study was to investigate the distinct forms of habitat disturbance and their implications on the distribution and abundance of papyrus endemic birds. Data on bird counts, habitat quality, and types of disturbance were collected for six months, from October 2013 to March 2014. Total bird counts were established using Timed Species Count (TSC) and playback call technique at every fixed point. The researcher waited for 1 minute, calls of the study species were played to elicit a response of the secretive papyrus endemic birds. The number of each bird's species seen or heard within a radius of 25 meters was recorded for the next 9 minutes before transferring to the next point count. Habitat quality such as height, density, and level of maturity was determined in 1 m2 plots along transverse transects. Opportunistic observations were made to establish forms of disturbance present during vegetation and bird surveys. Papyrus endemic birds were highly distributed in sites with pure papyrus (55.58%) than in places with mixed plants (44.42%). The abundance of three endemic birds, White-winged Swamp-warbler, Papyrus Gonolek, and Northern Brown-throated Weaver, was significantly different in mixed and pure papyrus sites. However, the abundance of Greater Swamp-warbler was not significantly different in mixed and pure papyrus sites in Sio Port Swamp during the study period. Forms of habitat disturbance established were vegetation clearing and invasion by terrestrial and aquatic plants. As many as 76.47% of papyrus vegetation were young and regenerated (0-2 m high), 19.65% were immature papyruses (2-4 m) whereas 3.88% were tall mature papyruses (4-6 m high). The abundance of papyrus endemic birds was positively and significantly correlated with the density of vegetation in height ranging from 4-6 m. Thus, any change in papyrus density changed the abundance of papyrus endemic birds. Advance management of papyrus clearing is necessary for the long-term conservation of biodiversity.

The abundance of bird species in three sections of Kwale District's coastal forests in Kenya

Abstract. Musila SN, Manohar S, Mango N. 2017. The abundance of bird species in three sections of Kwale District's coastal forests in Kenya. Ocean Life 1: 69-83. Specifically, the diversity of bird species in the three coastal forests of Kaya Gandini Important Bird Area, Kaya Mtswakara, and Mwache Forest Reserve, Kenya, was studied between October 2007 and August 2008. To survey the understory birds of each forest, three ringing stations separated by 200-500 m and two net lines (60 m (18m x 2, 12m x 2)) and (54m (18m x 3)) separated by 60 m were utilized. Twenty-two Timed Species Counts (TSCs) were conducted in the treetops of each forest to determine the bird population. 10 m2 plots were established at 50-meter intervals around the ringing locations and TSCs survey routes, with the plot centers 10 meters perpendicular to the paths. One hundred forty-one different bird species were documented across all locations; 93 were found in Gandini, 88 in Mtswakara, and 91 in Mwache. Common to all three sections were 41 bird species types (29%), accounting for 44%, 47%, and 45% of all bird species documented in Gandini, Mwache, and Mtswakara, respectively. Overall, 38 species of forest birds were registered across all forests, including 34 in Gandini and 25 in both Mtswakara and Mwache. Four globally endangered bird species and 14 endemics to the East African Coastal Biome were discovered across all forest types. There were no migrating birds in any of the three areas, even though they were all a part of the same forest. Although Gandini and Mtswakara were the most similar, all three locations shared a similar habitat structure. Bird populations in Mwache were affected by human activities such as firewood collecting, extraction of building poles (5-10 cm DBH) for domestic and commercial use, and quarrying. Gandini stands out as the most crucial location for avifauna conservation due to its greater diversity of Forest Specialist (FF), Forest Generalist (F), understory, globally threatened birds and EACB species. Due to their close vicinity and the significant number of overlapping forest birds and internationally vulnerable bird species, all three forests should be conserved or maintained as a single forest block to ensure the survival of the greatest possible number of bird species.

Avian species diversity in different habitat types in and around North Nandi Forest, Kenya

AbstractForest fragmentation and degradation leads to formation of modified habitats whose ability to support existing avifaunal diversity is still largely unknown. Bird diversity in indigenous forest, disturbed forest, plantation forest and farmlands adjacent to North Nandi Forest reserve was studied between January 2015 and June 2015. The distribution of bird feeding guilds in these habitat patches was also evaluated. Birds were surveyed using point counts, timed species counts and line transects and classified into six feeding guilds. A total of 3,232 individual birds of 151 species were recorded in the four habitats. Significant difference on bird abundance across the four habitats (F = 15.141, P ≤ 0.05, df = 3, 1121) was noted. Shannon–Weiner diversity index H′ for bird community ranged from 3.06 for plantation forest to 4.05 for disturbed forest showing a relatively diverse bird community. Insectivores (F = 3.090, P ≤ 0.05, df = 3, 297) dominated the foraging species assemblage in all the habitats significantly. Linear regression analysis revealed a strong linear relationship on bird species richness and abundance with vegetation variables (P < 0.01 in all cases). The results indicate that disturbed forest and indigenous forest support high bird species richness than plantation forest and farmlands. However, high bird abundance was observed in farmlands and plantation forest as opposed to indigenous forest and disturbed forest as they provide dispersal routes over a short distance and are important for creating corridors between primary forests.

Diversity of Bird Species and Conservation of two Lacustrine Wetlands of the Upper Benue Basin, Adamawa-Nigeria.

Between January 2004 to December 2005, studies were carried out on the bird species diversity and relative abundance of two lakes, Kiri and Gyawana near Numan using the Timed Species Count (TSC) method. 163 species in 53 bird families and 160 species in 55 bird families were recorded at Kiri and Gyawana lakes respectively. There was no significant difference in species diversity within bird families between the two lakes (p>0.05). Whereas in Gyawana Lake, one of the sites qualifies for Ramsar site, none strongly qualifies as an Important Bird Area (IBA). The significance of these funding are discussed.

Bird and Plant Diversity in Tropical Landscape Mosaics in East Usambaras, Tanzania

The role of land uses outside protected areas in conserving tropical biodiversity remains poorly understood and contested. This paper summarizes the results of plant and bird surveys conducted in three rural landscapes in the East Usambara Mountains of Tanzania, covering a gradient from Village forest reserves to tree-based and other agricultural land uses. The species richness and occurrence of conservationally important species across the land uses were analyzed. Twelve plots of 0.2 ha, stratified among land use types, were established to survey the large trees, with sub-plots of 1 × 40 m for tree saplings, shrubs and non-woody plants, and 5 × 40 m plots for small trees. Avian richness was measured in the same sites as the plants through mist netting and timed species counts. The village forests had higher plant species richness and more conservationally important plant species compared to other land uses. Agroforest and fallows supported a relatively high number of plant species, but the species composition was largely different to the adjacent village forests. Bird species of conservation importance were recorded across all land uses. Village forest reserves and some of the tree-based agricultural land uses were found to contribute to biodiversity conservation goals in tropical landscape mosaics. There is a need to better integrate them, and address their multiple functions, in village land-use planning and conservation efforts at the landscape level.

A comparison of two survey methods for assessing bird species richness and abundance in tropical farmlands

Capsule Timed species counts could provide a more valuable bird survey tool in the humid tropics than previously suggested. Aims To compare the relative performance of two bird survey methods that differ in complexity – point counts with distance sampling; and timed species counts – for estimating the species richness and abundance of bird species in tropical farmlands. Methods Twenty-six sites were surveyed in banana–coffee farmland habitats north of Lake Victoria, central Uganda. Point counts and timed species counts, each lasting ten minutes, were conducted at ten stations in each site. Results The two methods provided similar estimates of species richness in farmland and a significant positive correlation between measures of frequency of occurrence of bird species from the two methods was found. There was also a significant positive correlation between density from point counts with distance sampling and frequency of occurrence of bird species from the ten-minute counts. Ten-minute counts tended to accumulate bird species faster than point counts but this difference was not significant. Conclusions In these relatively open farmland habitats species richness estimates from both methods were not significantly different. Although density can only be derived from point counts these densities were highly correlated with frequencies from the ten-minute counts. The frequency of occurrence method is much quicker and simpler, in terms of both field methods and analysis, because it does not involve distance estimation. The results presented here suggest that, at least in relatively open habitats, frequency of occurrence provides a valuable index of density of birds.

A SURVEY ON BIRDS OF THE YAYU FOREST IN SOUTHWEST ETHIOPIA

A survey of birds in the Yayu forest, southwest Ethiopia, was conducted between August and December 2009. Timed Species Count (TSC) method was used. The survey was conducted in seven selected sampling blocks, each with an area of 0.5 km 2 . The blocks were representative of vegetation types (afromontane forest, transitional rain forest and riverine forest) and conservation zones (core, buffer and transition). A total of 112 bird species were recorded. Species composition of birds showed significantly higher number during the wet season than the dry season. The number of bird species records of the seven blocks also showed significant difference. The study reinforces the designation of the Yayu forest as a biodiversity hotspot and it is recommended that ongoing conservation and biodiversity documentation efforts should continue.

The use of bird species richness and abundance indices to assess the conservation value of exotic Eucalyptus plantations

The East Usambaras are within the Eastern Afromontane hotspot, which is known for its exceptionally rich biodiversity. The original forest of the East Usambaras has been reduced by human activities, including establishment of Eucalyptus plantations, but little is known about the value of these plantations for biodiversity. Therefore, from July 2003 to June 2004, we studied avifauna in natural forests and plantations using the timed species count (TSC) method, based on which we provide an assessment of the conservation value of Eucalyptus plantations to the local avifauna. From 240 TSCs, 100 species in 79 genera, 32 families and seven orders were recorded. A total of 63 forest species were recorded in forest and 41 forest species in the Eucalyptus plantations with four forest species exclusively in the plantations. The two habitats shared a greater percent of non-forest bird species (85%) than forest bird species (64%). There was some degree of seasonal variation in species richness and relative abundance between habitats. The study shows that ‘responsibly managed’ plantations could benefit some local avifauna. We recommend proper management of the Eucalyptus plantations, including the retention of some undergrowth and of surviving isolated forest trees, in order to provide hospitable habitats for birds.

The abundance of birds in Uganda’s inhabited areas and the importance of pastoral areas

AbstractThe Uganda bird‐monitoring programme has so far generated more than 18,600 observations from the 37 sites where land birds are monitored annually. Ten of the sites are in farmed area (agroecosystems), thirteen in semi‐natural pastoral ecosystems and fourteen in natural ecosystems (mainly national parks). The farms are almost entirely small‐scale and very diverse in their land use systems. Monitoring is by Timed Species Counts from which the frequency of recording of each species at each site can be generated (with over 460 species recorded so far, the overall spread sheet contains many zero values). The species numbers overall were the highest at natural sites (375 species), which also had the highest numbers of birds that often use trees, and those which are specialist grassland or aerial species or Palearctic visitors; but numbers of Red Data species are the highest in semi‐natural sites. As one would expect, formerly forested areas and moist savannas support most tree birds, whilst Red Data species were most frequently recorded in areas of impeded drainage – typically, these are periodically flooded. Grassland specialists are more common in dry than in moist savannas. Palearctic migrants are nowhere common. Uganda’s pastoral areas, on which domestic livestock graze and browse on predominant natural vegetation, are rich in birds and deserve a much more detailed study.

On the use of Timed Species Counts to estimate avian abundance indices in species‐rich communities

AbstractTimed Species Counts (TSCs) have been found to provide useful data for assessing the relative abundances of birds in conservation studies, particularly in species‐rich areas, such as many tropical habitats. An index is conventionally based upon the mean TSC from a number of counts. In this paper, we develop a new statistic, λ, which is based upon the assumption that the number of encounters with a species in unit time has a Poisson distribution. Using the same assumptions on detectability that underlie earlier analyses of TSC data, values of λ, unlike the simple mean TSC, are directly proportional to abundance. However, TSC data are affected by detectability, so that comparisons of relative abundance for the same species between similar sites have greater validity than those between different species. Explicit formulae for calculating an estimate of λ and its SE from sample data are described. Although λ can be estimated from either TSC data or the simple proportion of counts in which the species was encountered, for the commonest species a simulation study shows that only data in full TSC form provide accurate estimates. The difference becomes negligible for scarcer species. The use of λ in preference to mean TSC scores is recommended where it is important to compare values of relative abundance.

Avifauna of two upland evergreen forest reserves, the Atewa range and Tano Offin, in Ghana

Ntiamoa-Baidu, Y., Asamoah, S.A., Owusu, E.H. & Owusu-Boateng, K. 2000. Avifauna of two upland evergreen forest reserves, the Atewa Range and Tan0 Offin, in Ghana. Ostrich 71 (1 & 2): 277–281. Data are presented on the avifauna of two Upland Evergreen forest reserves in Ghana: Atewa Range Forest Reserve and the Tano Offin Forest Reserve. The data obtained for the two reserves using three survey techniques: transect counts, timed species counts and mist-netting are compared. A total of 105 species were recorded for the Atewa Range Forest Reserve while the Tano-Offin Forest Reserve yielded 110 species. Mean species encounter rate in the transect counts at Atewa was 24.2 per km while individual bird encounter rate was 52.6 per km; encounter rates at Tano Offin were 31.2 per km. and 98.2 per km for species and individual birds respectively. The most common species encountered in Atewa was the Yellow-whiskered Greenbul Andropadus latimstris (7.1% of observations in transect counts and 6.7% in spot counts), while the Green-crested Touraco (6.6% of transect counts) and Green Hylia (5.7% of spot counts) were the most abundant at Tan0 Offin. The records for Atewa included four globally threatened species while Tano yielded three threatened species. Two species of birds, the Equatorial Akalat Sheppardia aequatorialis and the yellow-bellied Greenbul Phyllastrepus flavostn'atus were recorded for the first time in Ghana from the two reserves. The bird community at Tan0 Ofin was significantly more diverse than that at Atewa. In both reserves, spot counts yielded more species (67.6% and 74.5% of total recorded at Atewa and Tan0 respectively), than transect counts and mist nets. 31 species recorded in both spot counts and transect counts at Atewa were not captured in mist nets, while nine species caught in mist nets were not recorded by the two methods. The figures for the Tano Offin reserve were 43 and six respectively. We conclude that of the three survey techniques, the timed species counts offer the most comprehensive results for rapid assessment of forest avifauna, but a combination of all three methods is necessary for complete coverage. The need for management of the two reserves to maintain their unique biodiversity in the face-of threats from mining and logging is discussed.

Implications of forest utilisation on bird conservation

Waiyaki, E. & Bennun, L.A. 2000. The avifauna of coastal forests in southern Kenya: status and conservation. Ostrich 71 (1 & 2): 247–256. The biological importance and uniqueness of East African coastal forests is widely recognised; they form an Endemic Bird Area. Important remnants of this fragmented habitat OCCUT on the southern Kenyan coast, but their avifauna has been little studied. In October 1992, September 1993 and May-August 1994, we systematically assessed the avifauna of fifteen South Coast forest fragments (and the threats facing them) using mist-netting, timed species counts and direct observations. Sixty forest-dependent bird species were recorded, amongst them three that are globally threatened (Sokoke Pipit Anthus sokolcensis, Spotted Ground Thrush Turdus fischeri, East Coast Akalat Sheppardia gunningi) three that are near-threatened (Southern Banded Snake Eagle Circaetus fasciolatus, Fischer's Turaco Tauraco fischeri, Plain-backed Sunbird Anthrepres reichenowi) and four that are ‘restricted-range’ (Fischer's Turaco, Sokoke Pipit, Mombasa Woodpecker Campethera mombassica, Uluguru Violet-backed Sunbird Anthreptes neglectus). Globally or regionally threatened and near-threatened species were relatively rare and were patchily distributed across forests. In contrast, most other forest species were widely distributed, being present in most or all fragments. The breakdown of traditional conservation systems, selective logging, encroachment by cultivation and fire-maintained grassland, fragmentation, allocation of land for urban development, pole cutting, charcoal burning, hunting and trapping, prospective mining, bark stripping and elephant damage are the major threats to the continued survival of these forests. Shimba Hills (Mkongani & Longomagandi), Gandini, Mrima, Marenji, Dzombo, Waa, Buda and Gongoni forests met the criteria for Globally Important Bird Areas set by Birdlife International. A number of urgent steps are needed for improved forest management if these important sites are to survive and retain their biological diversity.

Methods of studying the distribution, diversity and abundance of birds in East Africa—some quantitative approaches

In this paper we compare the use of transect counts with a simpler method of investigating bird diversity and numbers, particularly in terrestrial habitats, both natural and non‐natural. Transect Counts (TCs) have long been widely used, whereas Timed Species Counts (TSCs), which estimate relative abundance, are comparatively untried. We find that TSCs give results which are comparable to those from TCs in most respects, except that they can only be used indirectly for estimating population densities, and they give different measures of diversity. However, TSCs generate data on many more species much faster than do TCs and are therefore more cost‐effective in most situations. In particular, TSCs are useful for community studies. We show, for example, that in natural habitats bird populations are positively correlated with the amount of woody vegetation, but not with rainfall. Diversity too increases with woody vegetation. Because TSCs are simple, more of them can be made for a given input of time, and hence more distributional data are obtained as an additional benefit.