Action A2. Summary-Waterbird Monitoring 2018

We assessed the population sizes of the nine target-species of waterbirds for 2018, i.e. the two species of pelican, pygmy cormorant, four herons, glossy ibis and ferruginous duck. Methods used included counts from vantage points between end-January to May, “arrival-departure” counts at the colonies, visits to pelican colonies after the end of the breeding season (July and September) to count nests and dead individuals and counts of nests on photos taken by drone. The use of feeding sites by the target species was assessed through counts at a number of sampling sites from pre-selected observation points. The winter of 2017-18 had been of medium harshness in all northern Greece, so the first Dalmatian pelicans arrived at Lake Mikri Prespa on 19/1/2018 and incubation started on 26/1/2018.  The breeding population size was estimated at 1266 pairs and breeding success at 0.73 young per nest, a low value for the species in the area. The first great white pelicans were observed on 24/1/2018 but most arrived in April and a few in May. The species’ breeding population was estimated at 588 pairs and the breeding success at 1.2 young per nest, a record high for the species at least in Greece. We also counted 2051 pygmy cormorant nests, 135 n. of great white egret, 100 n. of little egret, 89 n. of night heron, 31 n. of  squacco heron and 1 n. of glossy ibis. The populations of the four latter species were lower in 2018 than in 2017. The breeding success of great white egret in 2018 was between 2.2-2.5 young per nest, much higher than that of 2017 (1 young/nest). The breeding population of the ferruginous duck was estimated at 4-8 pairs.  The species was present in Prespa all year round except in February. As regards the frequency of use of the foraging sites, our results showed that the overall species richness in 2018 (24 species) was almost three times higher than in 2017 (9 species), while the mean abundance in 2018 (106 individuals per sampling) was more than twice higher that of 2017 (46 individuals per sampling).  Most species and higher densities were observed at sampling sites of the northern part of the lake, between Slatina Laimou and Koula. This can likely be attributed to the proximity of these sites to the nesting colonies of the target-species, but also to the fact that during the late summer-autumn 2017 the low water level facilitated access and permitted mowing of aquatic vegetation in large areas which next year flooded and created foraging sites. During May-June the majority of pygmy cormorants (61.1%), little egrets (86.6%) and squacco herons (76%) used feeding sites at the shores of Lake Greater Prespa, while practically 100% of night herons fed at Lake Lesser Prespa. Our overall results confirm that priority for management must be given to the same areas that were pointed out in the Management Guidelines for 2017 (Malakou et al. 2018).  A small area with ferruginous ducks nesting should be added to the areas which should be left unmanaged.