Biologists use the Eiffel Tower to track bird migration because its height and lights serve as a major nighttime landmark.

The Eiffel Tower is strategically located along the East Atlantic Flyway, a primary migration route used by millions of birds annually. Since its completion in 1889, the structure has served as a unique platform for meteorological and biological research. Biologists from institutions like the National Museum of Natural History in Paris utilize the tower's height to study nocturnal migration patterns that are otherwise difficult to observe from the ground.Modern research involves the use of high-definition thermal cameras and acoustic sensors to record the calls of passing birds. Studies have shown that over 100 different species, including songbirds and raptors, pass over Paris during the spring and autumn months. The tower's elevation allows scientists to collect data on flight altitude and speed, providing insights into how urban environments affect migratory behavior.Light pollution is a significant concern for avian safety, as artificial light can lead to fatal collisions. To mitigate this, the Société d'Exploitation de la Tour Eiffel collaborates with environmental groups to manage the tower's 20,000 light bulbs during peak migration nights. By dimming or altering the beam patterns, they reduce the 'phototactic' effect that draws birds off course. This ongoing study helps conservationists develop better urban planning strategies to protect biodiversity across Europe.