Некоторая информация о биологии сизого голубя

UDC 598.265.1:574/577(575.146) SOME INFORMATION ABOUT THE BIOLOGY OF THE ROCK PIGEON

B.N. Doniyorov

Bukhara State University, M. Iqbol Street, House 11, Bukhara, Uzbekistan email: b.n.doniyorov13.05.1984@mail.ru

Annotation. This study presents observations on the biology of Columba livia conducted in the Bukhara oasis between 2007 and 2020. Climate change and the transformation of natural habitats— particularly deserts converted into agricultural lands, orchards, vineyards, and urban infrastructure— have intensified the spread of C. livia into cultural landscapes. In anthropogenic environments, this species is frequently encountered around buildings, warehouses, and agricultural fields. While its numbers are increasing in agrocenoses, they are declining in natural habitats, mainly due to changes in food sources, water availability, and human activity.

The earliest migrations were recorded in February, influenced by temperature, precipitation, and feeding conditions. Nesting behavior shifted from natural sites—such as cliffs—to cultural structures, including courtyards, power transmission lines, historical monuments, and old nests of Pica pica. Competition for nesting sites was observed with species such as Acridotheres tristis and Otus brucei, prompting C. livia to reuse old nests as a strategy to conserve energy and enhance reproductive success. Colonial nesting—up to 11 pairs in one location—facilitated information exchange and protection against predators.

In total, 60 nests, 26 eggs, and 44 chicks were documented. Each nest consistently contained two eggs, ensuring efficient energy allocation in brood care. These findings confirm the species’ ethological and ecological adaptation to anthropogenic environments.

Keywords: Columba livia, Pica pica, Acridotheres tristis, Otus brucei, Bukhara oasis, biology.

Introduction. Climate change and anthropogenic activity have significantly altered the natural habitats of Columba livia, shifting its presence from natural landscapes to agrocenoses. These changes have affected its distribution, population dynamics, biological adaptations, and ecological roles. Although general studies on ornithofauna exist within Uzbek ornithology, the specific adaptation of C. livia to agroecosystems in desert zones remains insufficiently studied. Most previous research has focused on natural habitats.

For example, Bogdanov (1983) studied the distribution and reproduction of birds in the natural zones of Uzbekistan; Harrison and Grinsmith (1993) examined bioecology in Europe, North Africa, and India; Gibbs, Barnes, and Cox (2001) considered the global ecology of pigeons; Hume (2002) analyzed morphology and distribution in Europe and the United Kingdom; Korovin (2004) investigated nesting in the Southern Urals; Lever and Gilmore (2005) documented global cases; Robson (2007) focused on Southeast Asia; Brazil (2010) covered East Asia; Fuller (2015) presented historical data on the passenger pigeon; and Thomas (2019) studied vocal behavior in Northwestern Europe.

In the agrocenoses of the Bukhara oasis, new habitats for birds have emerged. However, the bioecological behavior of C. livia under these conditions has not been specifically examined. Therefore, it is necessary to investigate its geographical and ecological distribution, population size, occurrence patterns, adaptability, ecological significance, and potential negative consequences.

Materials and Methods. The biology of Columba livia in the agrocenoses of the Bukhara oasis was studied using stationary observation methods developed by Novikov (1949) and Malchevsky (1981). Observations were carried out in different seasons in the city of Bukhara as well as in the districts of Jondor, Bukhara, and Vabkent. Field studies employed a 20×50 binocular, Canon PowerShot A580 camera, SHS-1-150 caliper, SL-5868p sound level meter, CHQ/PS500 electronic scales, ruler, black pencil, marker, and colored threads. The duration of observations at fixed points ranged from 5 to 60 minutes.

Results. Columba livia is a widely distributed, resident species in the Bukhara oasis. It is noticeably larger than other pigeons in the region and exhibits complex ethological behavior. The species occurs year-round in rural and urban areas, shelterbelts, and agrocenoses. Population density varies significantly between urban zones and agrobiogeocenoses. Based on extrapolated counts per 10 hectares, the average seasonal values in the green zones of Bukhara city were: spring – 28.8; summer – 9.7; autumn – 49.1; winter – 103.1. In cemeteries: spring – 4.5; summer – 3.4; autumn – 4.9; winter – 6.7. In orchards: spring – 10.7; summer – 7.2; autumn – 9.3; winter – 9.8. In cereal fields: spring – 10.1; summer – 8.7; autumn – 14.7; winter – 18.1. In vegetable fields: spring – 3.5; summer – 4.2; autumn – 4.9; winter – 7.3. In cotton fields: spring – 3.3; summer – 3.6; autumn – 2.7; winter – 3.9.

The vocalization of C. livia consists of two to three syllables, usually heard as “gu-guu” or “guguu-guuv.” These sounds are important for intraspecific communication, territorial marking, and mate selection. Peak vocal activity occurs from March to October, coinciding with breeding and feeding periods. In winter (November–February), vocalization decreases due to reduced population density. In 2008, severe frosts completely halted vocal activity. Between 2007 and 2020, the first vocalizations were recorded between February 4 and March 3, confirming the species’ sensitivity to climatic conditions.

Before nest construction, C. livia undergoes a pair formation phase involving complex social and sexual signals: aerial chases, bill touching, vocalizations, wing displays, circular flights, feather ruffling, and brief copulatory postures. These behaviors strengthen pair bonds and increase reproductive success.

Nests are built on roofs, cornices, and historical monuments, and are sometimes reused from other species. In 2009–2010, egg-laying was observed in nests of Pica pica. Nest height (n=10) ranged from 2.7 to 27.0 m (mean – 16.2 m), associated with multi-story buildings. Competition for nesting sites was noted with Pica pica, Otus brucei, Acridotheres tristis, and Streptopelia decaocto. Nest construction is carried out by both sexes and may take up to 100 hours. Typically, one pair occupies a single structure.

Nest materials are collected within a 90 m radius and include plant parts (Malus domestica, Prunus spp., Populus, Salix, Triticum, Phragmites australis) and synthetic items. Nests are small (3.5 cm), flat, and porous. Morphometric data: depth – 48.9 mm, width – 208.9 × 208.5 mm, base – 110.3 mm, height – 80.0 mm, wall thickness – 65.8 mm, mass – 58.6 g. Eggs are white, oval, and laid one per day (sometimes with a gap). Dimensions: length – 36.8 mm, width – 28.1 mm, apical part – 18.5 mm, basal part – 22.5 mm, mass – 15.9 g.

Incubation lasts 18 days, mainly by the female. The male guards from a distance of 8.3 m. Shell cracks appear on days 13–15. Chicks hatch weak, covered with yellow down, and gradually develop feathers. By days 7–8, contour feathers form; by days 14–15, chicks attempt to leave the nest. They remain under parental care for another 3–4 days.

Columba livia is granivorous. In spring and summer, it feeds on wheat, maize, weed seeds, and insects; in autumn and winter, on waste and seeds of Juniperus virginiana and Carpinus orientalis. It is found in fields, markets, cemeteries, warehouses, dumps, and nurseries. To aid digestion, it ingests stones and metallic fragments. It coexists with species such as Acridotheres tristis, Streptopelia senegalensis, Pica pica, Passer montanus, Corvus cornix, and others.

The species roosts and breeds on cultural monuments, contributing to their deterioration. It carries parasites and competes with domestic poultry and livestock. By feeding on waste, it performs a sanitary function. Its droppings enrich soil with phosphorus. Nest materials include weeds, limiting their spread. However, in recent years, stray cats, predatory birds, and human activity have reduced population numbers.

Discussion. Columba livia is widely distributed across the natural landscapes of Southern Europe, North Africa, and Asia. Classic studies, such as Darwin’s On the Origin of Species (1859), used pigeons to illustrate artificial selection, while Goodwin’s Pigeons and Doves of the World (1967) provided extensive information on their biology and ecology. These foundational works confirm the ecological versatility of the species.

Field observations in the Bukhara oasis demonstrate that C. livia thrives in agrocenoses, including urban zones, agricultural fields, and anthropogenic environments. Its presence in these habitats exceeds that in natural biotopes, indicating a shift in distribution. The abundance of food resources and nesting sites has contributed to population growth, although climate change and the use of avicides have caused declines in certain regions.

The species reproduces rapidly and maintains extended breeding seasons, often producing several broods per year. It contributes to ecosystem services such as seed dispersal, biomass cycling, and pest control. However, it also poses challenges, including sanitary concerns, competition with native species, and potential biological invasions.

Columba livia has bluish-gray plumage with iridescent neck feathers that play a role in mate selection. Its strong orientation ability has been widely studied in avian navigation research. Reproductive behavior includes the formation of monogamous pairs and cooperative parental care. Nests are typically built in urban structures, clutches consist of two eggs, and incubation is shared.

The species has a flexible diet, feeding on grains, seeds, and insects, supported by a digestive system adapted for efficient nutrient absorption. A high metabolic rate enables long flights and rapid responses to threats. Its cardiovascular and respiratory systems are specialized for flight, featuring a strong heart and an efficient system of air sacs.

The morphological, behavioral, and physiological traits of Columba livia reflect its evolutionary success and ecological adaptability. These characteristics ensure the resilience of the species under diverse conditions. Future research should focus on genetic variation within populations and its implications for conservation and urban wildlife management.

Conclusion. Columba livia has proven its success as a resident species in the Bukhara oasis, demonstrating a high degree of adaptability to anthropogenic environments. Its morphological, ethological, and physiological traits are closely linked to the expansion of its range, the seasonal and spatial dynamics of its population, and flexible reproductive strategies. Complex behaviors associated with nest building, pair formation, incubation, and chick rearing significantly contribute to the biological success of the species.

•  Vocal activity and phenological rhythms are sensitive to climatic conditions, making the species a valuable indicator in bioacoustic monitoring. Dietary flexibility, the ability to inhabit diverse agrocenoses, and its sanitary role define it as an integral component of the ecosystem. However, increasing population density may lead to competition with native species, sanitary issues, and damage to cultural monuments.

•  Future research should focus on the genetic structure of Columba livia populations, their ecological role in urban environments, and their impact as potential biological invaders. Reference

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