Результаты мониторинга гнездовых популяций солнечного орла в Дагестане (Россия) в 2022–2023 гг.

Abstract

Eastern Imperial Eagle (EIE; Aquila heliaca) breeding populations in Dagestan were monitored in 2021 and 2022 as part of the project “Study and Conservation of Eastern Imperial Eagle” implemented by the Non-governmental Environmental Central “Caucasus”, Russian Bird Conservation Union (RBCU), and Nature and Biodiversity Conservation Union NABU, with the support of the NABU International Foundation and VGP Foundation. EIE is sporadically encountered in the lowlands and foothills of Dagestan, from where it occasionally moves into mountainous areas where nests have not yet been found. It inhabits desert-steppe landscapes, along the edges of lowland and foothill deciduous forests bordering open arid spaces. EIE nests in trees, and in dry foothills and treeless plains builds nests on power line supports. It colonizes agricultural landscapes and, in the absence of direct harassment, successfully breeds near settlements, transhumance farm settlements (kutans), along roads and railways (Dzhamirzoev, Bukreev, 2020; our data). According to some data, EIE abundance in Dagestan was estimated from 30–40 breeding pairs in 2009 to 50–60 breeding pairs in 2020 (Dzhamirzoev, Bukreev, 2020), according to other – at least 130–180 pairs in 2009 (Belik et al., 2011) and the same amount in 2020 (Karyakin, 2020). Based on field research in 2022 and 2023, taking into account previously collected data, we entered 180 EIE nests and breeding territories into the database, of which 94 nests turned out to be occupied in 2023. Occupied EIE nests (n=94; 100%) in Dagestan are most often located on large Poplars (Populus) (n=47; 50%) and high-voltage power line poles (n=16; 17%). Less often they build nests on Elms (Ulmus) (n=6; 6.4%), Oaks (Quercus) (n=3; 3.2%), Willows (Salix) (n=2; 2.1%), Locusts (Robinia pseudoacacia) (n=2; 2.1%), and Pines (Pinus) (n=1; 1.1%). Trees on which the remaining 17 nests (20.2%) were located could not be identified up to species. In the northern part of Dagestan (Terek-Kuma Lowland – Nogai steppe and adjacent territories, from the lower riches of the Kuma River to the northern part of the Terek River delta) with the adjacent Stavropol Territory and Chechnya, 15 breeding territories were discovered, of which 24 were occupied nests, 25 – old nests, and 3 – breeding territories where territorial birds were observed, but no nests were found. Nest distribution here is allocated to artificialforest plantations in the southern part of the Nogai steppe, as well as poplar groves and tree groups along banks of rivers, canals, and artificial reservoirs. In the northern part of the Terek delta, colonies of Ground Squirrels (Spermophilus sp.) and other myomorphic rodents were found near most nests and breeding territories. We did not find Ground Squirrel colonies in the southern part of the Nogai steppe, and most likely the main EIE food source here are myomorphic rodents and Rooks (Corvus frugilegus). In the Terek-Sulak Lowland (from the northern part of the Terek delta to the lower reaches of Sulak), 59 EIE breeding territories were found, of them 32 – occupied nests, 25 – old nests, and 2 – breeding territories where no nests were found. Nests and breeding territories distribution here is allocated to forests along the lower reaches of Terek and Sulak Rivers, or groups and lone trees in fields and pastures, where Ground Squirrel colonies and other myomorphic rodents are also found in most cases. Colonies of rooks, which are found in large numbers throughout the area, as well as kutans where eagles can hunt poultry and pigeons (Columba sp.), are probably of secondary feeding importance. In central foothills and adjacent plains from the lower reaches of the Sulak to the lower reaches of the Khalagork River, 57 EIE breeding territories were recorded, of which 34 were occupied nests, 18 – old nests, and 3 – supposed breeding territories where no nests were found. It is also clear that EIE breeding territories here are allocated to pasture agrocenoses with ground squirrel and vole (Microtinae) colonies. EIE nests here are most often located on the high-voltage power line supports and in forest plantations along roads and railways, as well as among fields and pastures. In the Primorsky lowland and adjacent foothills of southern Dagestan, from the lower reaches of the Khalagork River to the lower reaches of the Samur, 14 breeding territories were discovered, of which 4 were occupied nests, 9 – old nests, and 1 – supposed breeding territory, where the nest was not found. Locations of EIE nests and breeding territories here has practically no relation to Ground Squirrel colonies. In the southern Dagestan, EIE mostly nests along the edges of small forests and lone poplars among fields and pastures, where a high number of voles is noted. In general, EIE breeding territories in plains and foothills of Dagestan are clearly associated with Ground Squirrel and Rook colonies, and to a lesser extent – with voles and other myomorphic rodents. The highest EIE nesting density was observed in the Terek-Sulak lowland and in the central foothills of Dagestan with adjacent areas of the Primorsky lowland, which is primarily due to the high number of Little Ground Squirrel (Spermophilus pygmaeus) colonies here, as well as, possibly, the abundance of rook colonies. Here there is a clear confinement of EIE breeding territories to fields bordered by forest belts and grazing areas with ground squirrel and vole colonies. We estimate the current EIE breeding population in Dagestan at 100–120 pairs. The condition of breeding populations is quite well, but they remain very vulnerable due to constant exposure to anthropogenic pressure. In particular, EIE nests on power line supports are often destroyed during repair and maintenance. Nests are destroyed as a result of demolition or logging, and nestlings subsequently die.