Five decades of breeding populations census for 12 species of colonial waterbirds in northwestern Italy

Abstract

Colonial waterbirds, a major biodiversity element occurring in the core of ultra-anthropized Europe, are ideal indicators of the wellness of inland wetlands. Nonetheless, there is a critical knowledge gap in their trend and population status. We present an uninterrupted 47 years-long dataset of the breeding populations of 12 species of colonial waterbirds (Ardeidae, Phalacrocoracidae, Plataleidae, Threskiornitidae) throughout a 58,000 km2 agricultural region in the higher Po basin (NW Italy). A trained team of collaborators censused with standardized field techniques the number of nests of each species at 419 colonies in the 1972–2018 period, summing up a total of 236,316 records. Data cleaning and standardization were performed for each census year, ensuring robust and consistent data. This dataset is among the largest ever collected for a guild of European vertebrates. It has already been used to describe the factors influencing population trends, and still offers opportunities to explore a wide range of key ecological processes such as biological invasions, global change consequences and biodiversity impact of agricultural practices.

Population Trend of Colonially Nesting Heron Species in Greece

“…The nesting populations of colonially nesting herons have fluctuated widely over the years both in Europe and worldwide. Factors such as climate/weather and land cover changes, water management, agricultural intensification, and changes in cultivation practices (especially for rice) are major drivers of these population fluctuations [3,4,[6][7][8]31,32].…”

“…The importance of the long-term monitoring of heron colonies for the successful management of breeding species and their wetland habitats is recognized, which is why many western European countries have adopted such monitoring schemes. In the UK, for instance, monitoring-especially for the Grey Heron-has been carried out since 1928, while in France, Spain, and Italy heron populations are systematically monitored since the 1960s or the 1970s [3][4][5][6][7][8].…”