Action D1: Scientific monitoring of breeding populations habitat use and the phenology of waterbird target species for the year 2020

We report herein on the results of the scientific monitoring of breeding populations, habitat use and the phenology of waterbird target species for the year 2020 under Action D1 of LIFE Prespa Waterbirds. 2020 was, like 2019 and 2017, an extremely dry year and in fact significantly drier than the previous ones. The maximum water level of Lesser Prespa lake during the period April-May 2020 was 853.78, i.e. even lower than that of 2019. As a result, shallow water areas on the outskirts of the lake were very few, below 5% of the total, much lower compared to 10-15 % in 2019, 25% in 2017 and 50-60% in 2018. A late snowfall on April 2 with 21.5 cm was the most significant snowfall of winter 2020. The large reedbed in the area of Krina-Agios Achilleios, which in recent years has consistently hosted the largest percentage of pygmy cormorant and heron nests, was not used in 2020 for the second consecutive year, due to the low water level. As a result, these species sought suitable nesting sites in other places. In 2020, three incidents of fire were recorded in the wetland, resulting in the burning of 53.9 ha of reedbeds. Compared to 2019, when 300 ha of reedbed were burned, the impact of the fires of 2020 was small, however, in one of them, in the reedbed of Lefkonas, five nests of great white egret were destroyed. It is worth mentioning that the firebreak of Agia Anna, 6 which was created in the framework of the management interventions of the project, helped to stop the spread of fire in larger parts of the reedbed. The first Dalmatian pelicans were observed in Prespa on 20/1/20. A significant late snowfall in early April and while more than 70% of the nests had formed, forced a large percentage of breeding pairs to abandon their nests. The number of nests was estimated at 1585. The total breeding success of the Dalmatian pelican in 2020 was estimated at 0.44 young per breeding pair, which is the lowest breeding success ever recorded since 1987. The first mass arrivals of great white pelicans were observed on 10/4/2020. The number of great white pelican breeding pairs in 2020 was estimated at 721-779 which is the highest number ever recorded in Prespa since 1987 and the breeding success was at 1.03-1.11 young per breeding pair. As a consequence of the severe drought, an unprecedented fragmentation of the mixed pygmy cormorant-heron colony was observed. The main feature of this fragmentation and indicative of the limited suitable nesting sites in the reedbed was the settlement of the largest numbers of pygmy cormorants and a significant proportion of little egrets and night herons on pelican nesting islets or on neighboring islets in the area of Krina-Agios Achilleios. In 2020, a total of ten discrete nesting sites of pygmy cormorant and herons were identified, two of which consisted of many smaller ones. In all breeding units, a total of 1730 pygmy cormorant nests, 102 great white egret nests, 149 little egret nests, 162 night-heron nests and 43 squacco heron nests were counted. No glossy ibis nest was detected. The great white egret breeding success was estimated in 2019 at 2 young per br. pair, well below the one in 2018 and closer to that of 2017 and 2019, both very dry years. During the pre-breeding and breeding season at least 17 individuals of ferruginous duck were present in the northern part of Lake Lesser Prespa and the estimated number of breeding pairs was 3 to 6. The results of the foraging sites monitoring showed that the areas suitable for feeding were extremely limited given the low waterlevel in 2020. The total number of species observed in the sampling areas in 2020 was very low, similar to 2019, while the total abundance of all bird species in 2020 was even lower than in 2017, three times less than in 2018 and almost equal to that of 2019. Most species and the highest abundance were observed not in the areas of the northern part of the lake as in 2018, when there was sufficient flooding but, as in 2019, in the areas of narrow reedbeds north and south of the hill of Kale. In these places, asthe reedbed is narrow, vegetation management, grazing and in some cases fire, kept the reedbed open enough to reveal areas with shallow water. Yet, in other areas of the lake in the northern part, the withdrawal of the waters was so great that the depth of the managed areas was not enough to reveal shallow water areas which remained covered under dense reeds. It is worth noting that significant numbers of birds were observed in the two estuaries of Mikrolimni and Lefkona streams, where vegetation management in the riverbed had taken place. This demonstrated clearly that the lower the waterlevel of the lake, the more vital becomes the increase of managed areas of reedbeds for the target waterbird species

Action D1: Scientific monitoring of breeding populations habitat use and the phenology of waterbird target species for the year 2020 (in Greek with English summary)