Urban stormwater ponds with large semi-aquatic zones are important resting and wintering habitats for snipes

Wetlands have suffered severe losses due to land-use and climate change, strongly contributing to the recent biodiversity crisis. This is especially true for urban areas. However, urban stormwater ponds, which have recently been constructed with increasing frequency, can represent valuable habitats for both flora and fauna. While previous studies have highlighted the importance of stormwater ponds as habitats for various plant and animal taxa, their role as resting and wintering habitats for birds has received little attention so far. In this study, we aimed to identify the importance of such stormwater ponds as resting and wintering habitats for the declining jack snipe ( Lymnocryptes minimus ) and common snipe ( Gallinago gallinago ). Our study in the oceanic north-west of Germany revealed that relatively small urban stormwater ponds with large semi-aquatic zones were important habitats for both species. In the study year, spring migration ended earlier and autumn migration started later than usual in both species. Climatic conditions during the migration/wintering period had a clear impact on the phenology of the snipes. In the climate models, higher amounts of precipitation prior to the survey fostered their densities. In the habitat models, the key drivers of snipe density were (i) the distance to woodland and (ii) the cover of sparse low-growing vegetation in the semi-aquatic zone. Both had a positive effect. Overall, a high habitat quality was the key for high snipe densities in the stormwater ponds. More precisely, food availability, shelter against predators and absence of anthropogenic disturbance (only jack snipe) drove snipe densities in the stormwater ponds. Based on our findings, newly created stormwater ponds should exhibit low slope angles (1: 15–20), large semi-aquatic zones and regularly be managed. • Small urban stormwater ponds with large semi-aquatic zones were important habitats. • Spring migration ended earlier and autumn migration started later than usual. • Higher amounts of precipitation prior to the survey fostered snipe densities. • High habitat quality was identified as the key driver of snipe densities. • Low slope angles, large semi-aquatic zones and regular management are required.