New Data on Breeding Biology, Ecology, and Population Status of White-Tailed Eagle in Dagestan, Russia
Authors:   Kazan Federal University, Elabuga Institute, National Park “Nizhnyaya Kama”, Bekmansurov R.H. , Dzhamirzoev G.S. ,   Dagestansky State Nature Reserve, Ismailov H.N. ,   Dagestansky State Nature Reserve, Pkhitikov A.B. ,   Dagestansky State Nature Reserve
Published: October 2023

White-Tailed Eagle (Haliaeetus albicilla) in Dagestan is a nesting sedentary-nomadic, migratory, and wintering species of lowland areas (Pishvanov et al., 1991; Dzhamirzoev, Bukreev, 2009; Bukreev, Dzhamirzoev, 2013; 2020; Dzhamirzoev, Bukreev, 2020). Outside of plains, only one breeding territory is known in the floodplain of the Shura-Ozen River in the Buinaksky region. The main nesting areas are concentrated on the Terek-Sulak lowland and coasts of Kizlyar and Agrakhan bays. In the nonbreeding period, nomadic, migratory, and wintering eagles are regularly found in foothills and occasionally spread to highlands through river valleys. Three nestlings were tagged with GSM/GPS trackers in one nest in the Kizlyar Bay during the research program of the “Dagestansky” Nature Reserve (Bekmansurov et al., 2018). It was assumed that juvenile eagles could winter on the western coast of the Caspian Sea in Dagestan or not far from the republic in a southern direction. Tracking showed that juvenile eagles spend most of their time, including in winter, significantly north of the place they have left the nest. One eagle lost contact during the first autumn migration in the Volga delta. Tracking two other sibs for three years showed connections with the nearest areas north of Dagestan, from the mouth of the Don River in the west to the mouth of the Ural River in the east. In 2018 and 2022 we ringed White-Tailed Eagle nestlings with colored rings. The youngest in a brood of two nestlings that was ringed on May 26, 2018, in a nest built on an artificial platform in the lower reaches of the Kuma River, was found dead more than three and a half years later (December 27, 2021) on a medium voltage power line 10 kW in the Stavropol Territory. The straight-line distance between the nest in Dagestan and the death site is 146 km. We carried out additional research in 2022 and 2023 aimed at the inventory of nests and breeding territories and subsequent monitoring of eagles in breeding territories and studying nesting biology. This research was a part of projects for the study and conservation of large raptors in the republic of Dagestan, carried out with the support of the Non-governmental Environmental Central “Caucasus” and “Dagestansky” Nature Reserve. It has been determined that White-Tailed Eagle in Dagestan mainly nests on large poplars (Populus sp.) in forest belts along natural and artificial watercourses, rarely build nests on power lines supports. In Kizlyar Bay eagles continue to nest on abandoned ships. In addition, eagles have successfully nested on artificial platforms that were installed by the initiative of “Dagestan” Nature Reserve in the treeless area of the Caspian coast for a number of years already. The basis for artificial nests is steel welded structures for fastening and holding branches of the nest itself. Currently, scientists of the Reserve with support of the Non-governmental Environmental Central “Caucasus” have installed similar nesting platforms on the Agrakhan Bay coast, as well as at the Samur river mouth. Most eagles begin breeding in February, with first egg laying period between February 11–23 for different pairs. But some pairs lay eggs as early as the end of January. For example, on March 3, 2023, at least one week old nestling was found when examining a nest in the lower reaches of the Terek River, which corresponds to the egg laying in the third decade of January. Time of egg laying was calculated based on determining nestlings age by the wing length (Helander, 1981) and visual comparison of development using photo tables (Bekmansurov, 2018) and reverse recalculation based on the average incubation period of 37 days. Smallest distances between nests with nestlings in the densest breeding group on the coast of Agrakhan Bay in May 2022 were 0.49, 0.55, and 0.6 km. In March 2023 minimum distances between nests with brooding birds were 0.42, 0.43, and 0.6 km here. When monitoring 33 nests in the coastal areas of the Kizlyar and Agrakhan Bays in 2022, it was determined that the number of nests with nestlings in May (n=13) did not correspond to the number of occupied nests in February (n=23). In some nests, breeding was interrupted, probably after egg laying. In others, eagles did not reproduce for unknown reasons. The resulting ratio of nests with nestlings to occupied ones and to the total number of nests checked in the beginning of the season can be used to calculate the size of nesting White-Tailed Eagle population in the region. Breeding territories database has been formed based on the results of inventory in 2022–2023. It contains data on 84 territories, of which nests were found in 79, and in 5 territorial individuals were encountered. During monitoring in March 2023, out of 79 inspected nests 48 turned out to be occupied and 31 nests during remote inspection were classified as uninhabited and without signs renovation, some as deteriorating. Thus, the current population was estimated at no less than 50 nesting pairs. Taking into account territorial pairs that did not breed this season or that with interrupted breeding, the actual size of the nesting population may be slightly higher, which requires further clarification. The total number of White-Tailed Eagle in Dagestan outside of a breeding period may vary depending on the inflow and outflow of nomadic and wintering individuals. On December 8–17, 2022, 288 eagles were counted in Dagestan without coasts of the Kizlyar and Agrakhan Bays; in January 14–29, 2023, a total of 729 eagles were counted in the whole area. Currently White-Tailed Eagle is the most numerous raptor in the lowland area of Dagestan.