Luxembourg’s Naturmusée (MNHN - National Museum of Natural History) has released the results of the seventh edition of the City Nature Challenge (CNC) that took place from 25 to 28 April 2025.
In a press release, MNHN explained that the City Nature Challenge is an annual global event. CNC 2025 saw more than 600 regions across six continents come together to observe and document local biodiversity. 102,945 people took part in 62 countries and more than 3.3 million observations were recorded. La Paz, Bolivia, was the champion with 148,000 observations, closely followed by the San Antonio metropolitan region in the United States with more than 133,000 observations. The highest number of species was recorded in Cochabamba, Bolivia, with 7,134 different taxa.
In Luxembourg, 251 participants made 10,635 observations of 1,784 different species using the iNaturalist application. Experts validated more than half of these observations, confirming the presence of 927 different species in Luxembourg. The CNC revealed an incredibly rich fauna and flora in Luxembourg. MNHN stated that among the most remarkable observations were:
- a pair of sand lizards (Lacerta agilis) sunbathing;
- a narrow-bordered bee hawk-moth (Hemaris tityus) rarely seen in the south of the country;
- a common tern (Sterna hirundo) visiting the "Baggerweier" in Remerschen;
- the first iNaturalist record in Luxembourg of the very rare hoverfly Xanthogramma Laetum;
- the occurrence of the invasive American skunk cabbage (Lysichiton americanus) in Rindschleiden;
- a detailed photo of a lady orchid (Orchis purpurea);
- an image of hart's-tongue fern (Asplenium scolopendrium) unfurling its young fronds;
- a Eurasian eagle-owl (Bubo bubo) resting well hidden in its nest, nestled in a cliff.
The most observed species during CNC 2025 in Luxembourg were:
Plants:
- garlic mustard (Alliaria petiolata) – 116 observations;
- ground ivy (Glechoma hederacea) – 98 observations;
- herb Robert (Geranium robertianum) – 95 observations.
Animals:
- feral pigeon (Columba livia var. domestica) – 59 observations;
- common carder bee (Bombus pascuorum) – 57 observations;
- mallard (Anas platyrhynchos) – 46 observations;
- common blackbird (Turdus merula) – 44 observations;
- European honey bee (Apis mellifera) – 40 observations.
MNHN added that the success of CNC 2025 in Luxembourg would not have been possible without the commitment of the many participants. For the first time, two participants in CNC Luxembourg contributed more than 1,000 observations each.
The three most active observers were Sylvie393 (1,096 observations and 401 species), claudekolwelter (Claude Kolwelter) (1,071 observations and 582 species) and Tobinatur (Tobias Polzer) (962 observations and 542 species). The three best identifiers were philipp_the_magnanimous (1,491 identifications), thierryh (Thierry Helminger) (507 identifications) and fregje (452 identifications).
