Birds living in mountain forests are adjusting to the effects of climate change and habitat loss in various ways, including moving to higher altitudes to find cooler temperatures. These adaptations vary among species, depending on their geographic location and the type of habitat they rely on. Over the past thirty years, the National Museum of Natural History has documented a 30% decline in bird species found in agricultural areas and a 10% decline in forest-dwelling birds, largely due to climate change and habitat degradation. Mountain ecosystems have been especially impacted, with temperatures rising by +2 °C—twice the global average—according to the European program LIFE PastorAlp. Changes in land use, such as the abandonment of pasturelands, have further altered these environments. Human activities have significantly influenced mountain bird populations, prompting them to adopt different survival strategies. Some species undergo physical and physiological changes, while others adjust their breeding or migration patterns. Many birds move along latitudinal or altitudinal gradients to track more favorable climates. In mountainous regions, altitude plays a key role in temperature regulation, with a decrease of -0.6 °C for every 100 meters gained in elevation. This makes altitudinal shifts a measurable way to study how birds respond to warming temperatures. To track these movements, researchers compared bird distributions across different time periods in the Northern Alps at Sixt-Fer-à-Cheval and in the Vaucluse at Mount Ventoux, covering altitudes from 350 meters to 1,800 meters. Surveys conducted between 1970 and 1980 were repeated in the 2000s and 2020s, using listening points during breeding seasons to record species presence at various altitudes. These observations, made under optimal weather conditions, help scientists estimate the number and distribution of bird species in these regions. The results showed that different bird species respond to climate change in varied ways. Some move higher up the mountain to escape rising temperatures, while others move downward or stay in place. The same species may react differently depending on the region, with those in colder environments often being more sensitive to warming. The availability of suitable habitats is crucial for forest birds, influencing where they can live and how they are distributed. Researchers are collecting additional habitat data to better understand how changes in bird distribution relate to habitat loss, with the goal of guiding forest management practices that support bird populations.