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 2021 under Action D1 of LIFE Prespa Waterbirds. 2021 was like 2020, 2019 and 2017, an extremely dry year. The maximum water level of Lesser Prespa lake during the period April-May 2020 was 853.84, i.e., almost the same as in 2020. As a result, shallow water areas on the outskirts of the lake were very few, below 5% of the total, exactly like in 2020, lower compared to 10-15 % in 2019, 25% in 2017 and much lower compared to 50-60% in 2018. The large reedbed in the area of KrinaAgios Achilleios, which in recent years has consistently hosted the largest percentage of pygmy cormorant and heron nests, was not used in 2021 for the third consecutive year, due to the low water level. As a result, these species sought suitable nesting sites in other places. In 2021, seven incidents of fire were recorded in the wetland, resulting in the burning of 70.9 ha of reedbeds. These fires did not affect the colonies of the target species of the project, due to the intensive vegetation management in the northern part of the lake, where the firebreak created in the region of Opaya prevented the spread of fire to a colony of great white egrets nearby. In the winter and spring of 2021, mass deaths of Dalmatian pelicans were recorded in several wetlands of Northern Greece caused by bird flu, according to laboratory analyzes. By the beginning of April, when the phenomenon subsided, a total of 183 dead Dalmatian pelicans were identified, with the largest number (73) being recorded in Lake Lesser Prespa. The first Dalmatian pelicans were observed in Prespa on 2/1/21 and a few days later the first eggs were laid, signifying the earliest start of breeding of Dalmatian pelicans at Prespa. A severe bad weather in late March had the most significant effects on nest abandonment and dead chicks. The number of breeding pairs was estimated at 1370, while the total breeding success of the Dalmatian pelican in 2021 was estimated at 0.79 young per breeding pair, which is a satisfactory rate compared to the previous years. The first arrivals of great white pelicans were observed on 5/3/2021. The number of great white pelican breeding pairs in 2021 was estimated at 841 and the breeding success was 1 young per breeding pair. Once again in 2021 we recorded a very large fragmentation of the mixed colony of herons and pygmy cormorants. The main feature of this fragmentation and indicative of the limited suitable nesting sites in the reedbed was the settlement of a 47% of pygmy cormorants and a 17% of little egrets on pelican nesting islets or on neighboring islets in the area of Krina-Agios Achilleios. In 2021, a total of twelve 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 2132 pygmy cormorant nests, 107 great white egret nests, 149 little egret nests, 222 nightheron nests and 74 squacco heron nests were counted, while no glossy ibis nest was detected. The great white egret breeding success was estimated in 2021 at 2.15 young per br. pair, a bit higher than 2020. During the pre-breeding and breeding season at least 14 individuals of ferruginous duck were present in the northern part of Lake Lesser Prespa and the estimated number of breeding pairs was 7 to 8. The results of the foraging sites monitoring showed that the areas suitable for feeding were extremely limited given the low water level in 2021. The total number of species observed in the sampling areas in 2021 was very low (12 species), like 2020 and 2019, while the total abundance of all bird species in 2021 was higher than in 2017, 2019 and 2020, but this is mainly due to the presence of large numbers of geese in dry meadows until midMay. 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 and 2020, in the areas of narrow reedbeds north and south of the hill of Kale. The sampling areas that accounted for the vast majority of birds had been managed during the current year or earlier, by cutting, grazing or fire or a combination, while the new sampling area added next to the mouth of the Lefkonas stream had an impressively high number of birds, mainly herons, which shows that the management carried out achieved its goal in terms of birds. Finally, a summary of the major conclusions for the current year is made, as well as a brief synthesis and evaluation of all the results of the project in regards to target waterbirds.
Action D1: Scientific monitoring of breeding populations habitat use and the phenology of waterbird target species for the year 2021 (in Greek with English summary)