Distribution and Abundance of the Glossy Ibis (Plegadis falcinellus) in Wintering and Breeding Grounds in Northeast Algeria

Atmospheric conditions play an important role in structuring avian communities in space and time. Here we assess the role of weather conditions on the distribution and abundance of the enigmatic glossy ibis (Plegadis falcinellus) in Northeast Algeria in both wintering grounds and in breeding areas in a survey spanning from 2011 to 2019. During the study period, cooler years were wetter and warmer years were drier. The wintering population size in the region could be estimated to 200-300 individuals. The number of individuals in wintering grounds increased in recent years in one site (Berrihane), but it did not show a strong association with weather conditions prior to wintering. Four breeding colonies were detected in highly-vegetated ponds with in-water trees where the number of breeding pairs was the highest. Extinction was recorded for two colonies (50% of colonies) where one permanently disappeared and one exhibited a series of extinctions and recolonizations across years. The estimated colony size was larger at El Dakhla (60–105 pairs) than El Chatt (0–42 pairs), Fezara Lake (25–41 pairs), and Tonga Lake (0–2 pairs). Climate conditions seemed to correlate with the number of pairs in one site (El Chatt) such that warm and dry years were associated with lower number of individuals. We discuss that disturbance and pollution might play a role in colony establishment but the number of pairs is positively related to the extinction of a nearby colony, suggesting that those refuge colonies are crucial for the persistence of the species in the area. This study presents historical data on the occurrence and abundance of a relatively unstudied species and gives new information on its climatic sensitivity which might be helpful for predicting future climate change impacts.