RECENT DATA REGARDING COLONIAL WATERBIRDS IN DANUBE DELTA BIOSPHERE RESERVE (ROMANIA)

摘要

The study presents the results of the monitoring of all identified colonies of waterbirds in the Danube Delta Biosphere Reserve, without the pelican species, in the period between 2015 and 2018. We compared our results with those from a previous study in 2001. The largest number of total breeding pairs for all colonial waterbird was recorded in 2016 (51 457 bp). Most of the species showed a relatively high variation in breeding population size over the years. The most stable population across the 4 years study, according to the Coefficient of variation (CV) was that of Eurasian Spoonbill (Platalea leucorodia, CV = 0.13). Compared with previous studies from 2001, this species population remains largely constant (CV= 0.01). However stern and gulls populations (Sternidae) shows a high degree of variability both during our study and compared with previous one. Sternula albifrons decrease their population since 2001 by 96.15%, Thalaseus sandvichensis by 89.4% and Larus melanocephalus by 78.75%, while Chlidonias niger and Chlidonias hybrida have increased.