We present the first record of a new breeding colony of Whiskered Tern Chlidonias hybrida in Algeria, located at Lake Mékhada. Ecological data were collected during the first week of July 2025 to evaluate the colony’s structure and breeding parameters, which were then compared with those of the long-established colony at Lake Tonga. The spatial distribution of the 68 recorded nests (37 active nests) revealed the presence of two distinct sub-colonies, clearly separated by a running watercourse. Nest placement within both sub-colonies was influenced by proximity to the colony centre, as indicated by significant positive and negative correlations of nearest neighbour distance and nest density, respectively, with the distance to the colony edge, based on PCA and Wilcoxon tests. Nest composition at the newly established site in 2025 consisted exclusively of fixed aquatic vegetation Typha angustifolia, Glyceria fluitans and Scirpus lacustris compared to the original site, which was historically dominated by the floating Nymphaea alba. Reproductive data also confirmed notable shifts: the clutch size in 2025 was similar to that recorded in 2024 at Lake Tonga, showing a general trend for a reduction in clutch size, from three-egg clutches (1996–1997) towards two-egg clutches. Our study highlights a potentially significant shift in the breeding ecology of the Whiskered Tern, underscoring the need to initiate a dedicated monitoring scheme to better understand these emerging ecological dynamics and their consequences for population viability.
Elafri et al. (Fri,) studied this question.