A comparative study of spring avifauna in natural biotopes and agricultural landscapes of the Tashkent Region, Uzbekistan

Аннотация

Between 2014 and 2022, a comprehensive analysis was conducted to compare the spring diversity of avifauna, including bird occurrence, density, similarity, and differences between natural biotopes and agrarian landscapes in the Tashkent region. This study assessed changes in avifauna composition resulting from the conversion of natural biotopes into cultivated areas and evaluated the influence of anthropogenic factors on bird behavior. During the spring months of March, April, and May, approximately 205 bird species were recorded. Of these, 186 species were observed in natural biotopes, while 162 species were identified in agrarian landscapes. Notably, 143 species were common to both biotopes, whereas 43 species were exclusive to natural biotopes, and 19 species were found only in agrarian landscapes. The spring avifauna was classified into six categories based on their occurrence: Resident (51 species), Breeding-Migratory (75 species), Migratory-Wintering (34 species), Migratory (25 species), Breeding-Migratory-Wintering (11 species), and Wintering (9 species). The study included a comparative evaluation of bird diversity in natural biotopes and agrocenoses.

Acta Biologica Sibirica 10: 1103–1120 (2024)

doi: 10.5281/zenodo.13920029

Corresponding author: Bunyod N. Ganiev (bunyodganiyev91@mail.ru)

Academic editor: R. Yakovlev | Received 5 June 2024 | Accepted 24 August 2024 | Published 27 September 2024

http://zoobank.org/F657BED6-A50D-481D-99B0-431EC31027B7

Citation: Ganiev BN, Azimov NN, Kholmatov BR (2024) A comparative study of spring avifauna in natural biotopes and agricultural landscapes of the Tashkent Region, Uzbekistan. Acta Biologica Sibirica 10: 1103–1120. https://doi.org/10.5281/zenodo.13920029

Keywords

Spring avifauna, natural biotopes, agricultural landscapes, diversity indices, occurrence characteristics

Introduction

Throughout human history, our dependence on natural phenomena has diminished as we began to alter our living environments to meet our needs. Consequently, natural biotopes have increasingly been replaced by agrarian landscapes, villages, megacities, artificial reservoirs, and various anthropogenic ecosystems. These alterations have compelled bird species, which have historically thrived in these areas, to either adapt to the changes, suffer due to their inability to do so, or migrate elsewhere (Azimov 2022; Chalikova 2023).

The rapid increase in global population, coupled with urbanization, climate change, and desertification – often triggered by the unsustainable use of natural resources – has significantly reduced the natural habitats available to many species, consequently affecting avifauna (McKinney 2002; Ali 2005; Akhrorov et al. 2022; Chalikova 2023). These anthropogenic alterations in bird habitats negatively impact species survival (Andren 1994; Recher 1999). Furthermore, Fischer and Lindenmayer (2007) emphasized that changes in landscapes can reduce species diversity, while birds serve as key indicators for assessing environmental health (Rajashekara and Venkatesha 2011; Colwell 2010; Ganiev et al. 2022).

The first studies focused on avifauna in the Tashkent region began in the second half of the 19^th century (Severtsov 1873; Russov 1878; Smirnov 1883; Loudon 1909, 1910; Severtsov et al. 1866). Existing research has primarily examined natural areas (Korelov 1956; Mitropolsky 2002, 2005, 2008; Kovshar 2002; Gritsyna et al. 2020; Ganiev 2022), the region's avifauna (Matyakubov 1970; Azimov 2020, 2022), or specific bird groups (Fundukchiev et al. 2004; Mitropolsky 2008). However, there is a notable lack of studies providing estimates of relative abundance or density of bird populations in the Tashkent region. The only available data regarding bird density in agrarian landscapes within Northeastern Uzbekistan was published by Azimov (2022). Moreover, there have been no comprehensive studies analyzing the similarities and differences in bird diversity between natural and agricultural landscapes in Uzbekistan.

This article aims to determine the species composition of the avifauna in the Tashkent region, analyze and compare its spring diversity, and assess the impact of anthropogenic factors on the behavior of bird species in both natural biotopes and agricultural landscapes.

Materials and methods

Study Area

The total area of the Tashkent region is 15,585 km², of which 40.56% are natural areas and 25.13% are agrarian landscape (Land Fund of the Republic of Uzbekistan 2015). The Qurama, Chatkal, Pskom, Maidontol, Ugom, and Karjantog ridges of western Tien-Shan, consisting of mountain and submountain regions, are located in the northeast and eastern parts of the region and occupy almost half of the territory. The southwest part consists of a plain descending to the Syrdarya River. The difference in height compared to sea level is more than 4 km. The coast of the Chirchik River starts at 250 meters, and the Adelunga peak of the Pskom ridge reaches 4300 meters.

The Tashkent region is located on the border of a harsh continental climate. Annual precipitation is up to 440 mm. The average annual air humidity is 56%, the wind speed is 1.4 m/s, and the temperature is +14.8 ℃. In winter, the temperature can drop as low as -34 ℃, while in summer it can rise as high as +43 ℃ (National Encyclopedia of Uzbekistan 2002). The study of the avifauna of the region was carried out during the years 2014–2022. Field research was carried out at 15 observation stations selected from standard biotopes in plain, sub-mountain, mid-mountain and high mountain zones of the region. Observation stations include areas with a radius of 2.5-10 km. The avifauna of the agricultural landscape was studied in wheat fields, cotton fields, and orchards, which comprised a large part of it. 20 wheat fields, 14 cotton fields, and 13 orchards were designated as observation stations. They consist of an area of 0.6-2.7 km² (Fig. 1).

Figure 1.The map of the research observation stations in the Tashkent region.

In this study, we classified natural biotopes as areas unaffected by human activity and agricultural landscapes as the various agrocenoses formed by anthropogenic influences. To examine the avifauna, we employed the route method as outlined by Bibby et al. (1998). In natural biotopes, the survey routes spanned 2.5 to 10 kilometers in length, with a width of 100 meters in flat terrains and up to 30 meters in mountainous regions, particularly in forested areas. In contrast, the routes in agricultural landscapes varied from 300 meters to 2 kilometers in length, with widths of 20 meters in orchards and up to 100 meters in cotton and wheat fields.

During the research, we utilized several observation tools, including Viking (10x50) and Swarovski SLS (15x56) binoculars, as well as Viking (20x60) and Swarovski ATX (30-70x95) spotting scopes. We employed a mechanical counter to tally bird sightings, a Garmin GPS navigator to record the coordinates of observation sites, and a Canon camera with a 400 mm lens for capturing images of the birds. For bird identification, we referred to the field guide "Birds of Central Asia" by Raffael Aye et al. (2012).

Statistical analysis

Following the methodology outlined by Bibby et al. (1992), encounter rate values were categorized into five abundance categories: <0.1, 0.1-2.0, 2.1-10.0, 10.1-40.0, and >40. Each category was assigned an abundance score: 1 for rare, 2 for uncommon, 3 for frequent, 4 for common, and 5 for abundant. Although data collection was conducted across all biotopes during the spring season, variations in the length of observation routes made direct comparisons challenging. To ensure accuracy, bird counts were standardized as averages per 10-hectare area.

Additionally, previous studies were referenced to determine the characteristics of bird occurrence in the Tashkent region (Korelov 1956; Sagitov et al. 1987; Mitropolsky et al. 1990; Kashkarov et al. 1995; Mitropolsky 2005; Kovshar 2019a, 2019b). The species list generated from our research utilized Koblik and Arkhipov's taxonomy (2014) and followed the systematic rankings and nomenclature standards set by the International Ornithological Congress World Bird List v 9.2 (Gill and Donsker 2019). We used MS Excel 2013 for statistical data processing.

Results and discussion

Diversity, richness, and density

We found that 387 species occur on the territory of the Tashkent region. In the process of our research, in the spring season, a total of 205 species belonging to 16 orders and 39 families were recorded in the natural biotopes and agrarian landscapes of the Tashkent region. Of these, 186 species were found in natural biotopes and 162 species were found in the agrarian landscape. 43 species of birds were found only in natural biotopes, 19 species were found only in fields, and 143 species were found in both areas (Table 1).

Note: B – breeding, M – migration, W – wintering, R – resident.

Natural biotopes include broad-leaved mountain forests, a middle stream valley, juniper mountain forest, mountain steppe, rocks and scree, plain water reservoirs, tugai forests, and sand dunes in the desert zone. In these biotopes, the average number of birds per 10 hectares is 841.74. It is equal to H' = 4.32 according to the Shannon Wiener index, SR= 27.47 according to the Margalef diversity index, D=0.98 according to the Simpsons index, and J = 0.83 according to the Pielou index (Table 2).

According to the Shannon Wiener index, the composition of the broad-leafed mountain forest is equal to H= 3.7, middle stream river valley avifauna is H'= 3.39, the juniper mountain forest avifauna is H'= 3.43, the mountain steppe avifauna is H = 3.26, rocks and scree avifauna is H'= 2.73, the desert avifauna is equal to H'= 3.3. The biotope sequences are SR= 16.32, SR= 12.17, SR= 11.34, SR= 7.7, SR= 7, and SR= 18 according to the Margalef diversity index, respectively. In Simpsons index, D=0.96, D= 0.94, D= 0.96, D= 0.94, D= 0.92, and D= 0.93. Under Pielou’s index, J = 0.79, J = 0.77, J = 0.79, and J = 0.69 (Table 3).

In the agriculture fields, the average number of birds per 10 hectares is 290.66. It is equal to H = 3.98 according to the Shannon Wiener index, SR = 28.38 according to the Margalef index, D = 0.97 according to the Simpsons index, and J = 0.78 according to the Pielous index (Table 2). According to the Shannon Wiener index, the composition of the avifauna of the wheat fields in the agrarian landscape is H'= 3.41, the avifauna of the cotton fields is H'= 3.63, and the avifauna of the orchards is H'= 3.59. According to Margalef's diversity index, it is equal to SR= 25.3, SR = 14.85, and SR = 18.58 according to the sequence of fields. According to the Simpsons index, D= 0.932, D= 0.964, and D= 0.947. According to the Pielou index, it is equal to J = 0.71, J = 0.83, and J = 0.76 (Table 3).

In addition to natural biotopes, the average number of species found in the agrarian landscape per 10 ha is not the same. For example, the number of 34 species in natural biotopes is higher than in the agrarian landscape: On the contrary, in the agricultural landscape, compared to natural biotopes, there are 12 species with greater abundance. Additionally, 10 species (Glossy Ibis, Eurasian Hobby, Jack Snipe, Solitary Snipe, etc.) were found in similar numbers in both areas (Table 4).

Abundant status of avian fauna in Tashkent region

The occurrence rates of birds in natural biotopes and agrarian landscapes were categorized based on the classification system developed by Bibby et al. (1992). In natural biotopes, two species – Black-throated Thrush and Common Chaffinch – were classified as abundant. In contrast, no species in the abundant category were recorded in agrarian landscapes.

In the common category, 23 bird species were identified in natural biotopes, while only 5 species were found in agrarian landscapes. For the frequent category, 52 species were present in natural biotopes compared to 27 in the agrarian land-scape. The uncommon category included 99 species in natural biotopes and 110 species in agrarian habitats. Additionally, 10 rare species were observed in natural biotopes, with 20 identified in agrarian landscapes.

These findings highlight the significance of natural biotopes as crucial habitats for a majority of avifauna species. The absence of abundant species in agrarian land-scapes, alongside a marked increase in species classified as common and rare, suggests that agrarian environments serve as secondary habitats for many birds.

Spring is a particularly notable season for bird observation and study, not just in the Tashkent region but across the Republic. This season allows for the observation of wintering, migratory, nesting, and vertically migrating species. Within the study area, of the recorded species, 75 (37%) were classified as breeding migrants (BM), 51 (25%) as residents (R), 34 (17%) as migratory and wintering (MW), 25 (12%) as migrants (M), 11 (5%) as breeding-migratory-wintering (BMW), and 9 (4%) as wintering (W) species, as summarized in Table 1.

Notably, 14 species from the BM group – including Black Stork, Egyptian Vulture, Short-toed Snake-eagle, Eurasian Oystercatcher, Common Tern, Alpine Swift, Eurasian Crag Martin, Rufous-tailed Rock-thrush, Blue-headed Redstart, Northern Wheatear, Sulphur-bellied Warbler, Hume’s Whitethroat, Eastern Rock-nuthatch, and Grey-necked Bunting – were found exclusively in natural biotopes. Conversely, species such as Little Bittern, European Turtle-dove, and Pied Bush Chat were uniquely identified in agrarian landscapes, while 58 species were recorded in both environments (see Table 4).

Note: *- species that include in the red data book of the Republic of Uzbekistan, ** - species that include in the World Red List (IUCN), *** species that include in the red data book of the Republic of Uzbekistan and in the World Red List (IUCN).

In comparing the diversity of nesting species between natural biotopes and agricultural landscapes, we found that 29 species are exclusive to natural biotopes, while 8 species are unique to agricultural areas. Additionally, 100 species are present in both environments. Overall, a total of 52 nesting species were recorded in the agricultural landscape (Salikhbaev 1952, 1959; Matyakubov 1968, 1969, 1970; Azimov 2022). Among the 51 resident bird species, 15 were found only in natural biotopes, whereas 3 species – House Sparrow, Mongolian Finch, and Desert Finch – were exclusive to the agricultural landscape. The remaining 33 resident species were observed in both habitats.

For the 9 wintering species, 3 species – Merlin, Short-eared Owl, and European Goldfinch – were found exclusively in agricultural landscapes, while the other 6 species – Goldcrest, Hooded Crow, Common Chaffinch, Brambling, Yellowhammer, and Reed Bunting – were present in both environments.

Discussion

The following bird species are naturally absent from agrarian landscapes as they are specifically adapted to mountain ecosystems: Chukar, Black Stork, Himalayan Vulture, Griffon Vulture, Cinereous Vulture, Bearded Vulture, Egyptian Vulture, Tawny Owl, Eurasian Crag Martin, White-throated Dipper, Altai Accentor, Blue Whistling Thrush, Rufous-tailed Rock-thrush, Blue-headed Redstart, Greenish Warbler, Yellow-browed Warbler, Hume's Whitethroat, Rufous-naped Tit, Eastern Rock-nuthatch, Red-mantled Rosefinch, White-winged Grosbeak, and Gray-necked Bunting. Additionally, water-dependent species such as Common Teal, Gray Heron, Purple Heron, Common Coot, Eurasian Oystercatcher, and Common Tern were not recorded in agrarian landscapes during the spring season due to the lack of suitable aquatic habitats.

The absence of raptor species like Saker Falcon, Barbary Falcon, Northern Goshawk, Common Buzzard, Greater Spotted Eagle, Steppe Eagle, Golden Eagle, Alpine Swift, Eurasian Penduline-tit, and Asian Gray Shrike in agricultural fields can be attributed to the limited conditions necessary for their survival, primarily caused by human activities.

Rare species in the Tashkent region include Merlin, Western Osprey, European Honey-buzzard, Pallid Harrier, European Turtle-dove, Short-eared Owl, Red-throated Thrush, Fieldfare, Redwing, Pied Bush Chat, Black-headed Penduline-tit, House Sparrow, European Goldfinch, Desert Finch, and Rustic Bunting. Although Little Bittern is generally considered a common species, it was not observed in our study of natural biotopes due to its secretive behavior. Similarly, the Northern Long-eared Owl, which is a winter visitor and rarely nests, was not recorded during daytime surveys.

Our research revealed the occurrence of 186 species in natural biotopes compared to 162 species in agrarian landscapes, indicating a significant drop in species diversity in agricultural areas. It seems that certain species, such as Steppe Eagle, Eurasian Oystercatcher, and Asian Gray Shrike, which have been previously documented in the region, may have been displaced due to the expansion of agrarian land. Additionally, the population of Desert Finch has sharply declined and may even be facing extinction. Conversely, the expansion of habitats for synanthropic species, including Rock Dove, Eurasian Collared Dove, Laughing Dove, Long-tailed Shrike, Common Myna, and Eurasian Tree Sparrow, has facilitated their population growth.

In total, 54 species listed for regional and global protection were identified in the Tashkent region (Sagitov et al. 1987; Mitropolsky et al. 1990; Shernazarov et al. 2019; https://www.iucnredlist.org). During the spring season, 23 of these species were observed at the study sites (Table 4). Specifically, 13 rare and endangered birds were found exclusively in natural biotopes, while 4 species were limited to agrarian landscapes and 6 species were recorded in both areas. Overall, bird diversity is greater, and populations are more abundant in natural biotopes compared to agrarian landscapes. Even in areas where species overlap, natural biotopes consistently exhibited higher bird densities. Nonetheless, the presence of 4 species unique to agrarian landscapes highlights their unique and important ecological roles in these environments.

Conclusions

This study marks the first assessment of bird fauna in the Republic of Uzbekistan using the aforementioned indices and the analysis of bird diversity across different biotopes. During the spring season, the variety and abundance of bird species in the Tashkent region are notably higher in natural biotopes compared to agrarian land-scapes. Any alteration to a natural biotope impacts its components and disrupts the ecological balance. The expansion of agrarian landscapes promotes the proliferation of habitats, resulting in an increase in synanthropic species.

Acknowledgement

We are deeply grateful to the Ugom-Chotkal State National Nature Park Administration and the Chotkal State Biosphere Reserve for their unwavering support and for creating conditions for us to conduct research in their territory. We also express our sincere gratitude to Umarov Sanjarbek for his close assistance in preparing the GIS map for the article. The authors also express their sincere gratitude to the anonymous reviewer for suggestions and comments, which were invaluable and significantly improved the quality of the material.

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