Altitudinal migration
Overview
Altitudinal migration is a type of animal migration involving movement up and down the slope of a mountain, typically on a seasonal basis. Unlike latitudinal migration, where animals move along the Earth's latitude lines to different climates, altitudinal migration sees animals moving up and down mountains, often in response to changes in food availability or temperature. This type of migration is common among a variety of animal species, including birds, mammals, reptiles, and insects.
Altitudinal Migration in Birds
Many bird species practice altitudinal migration, moving to higher altitudes during the warmer months and descending during the colder months. This migration pattern is often driven by food availability, with many birds moving to higher altitudes to take advantage of abundant insect populations during the summer months. For example, the White-throated Dipper in Europe migrates up and down the mountains following the abundance of their main food source, aquatic invertebrates.
Altitudinal Migration in Mammals
Mammals also exhibit altitudinal migration, with species such as the elk in North America moving to higher altitudes in the summer to forage on the lush vegetation, and descending to lower altitudes in the winter to avoid deep snow and harsh weather conditions. Other examples include the snow leopard and the Himalayan Tahr in the Himalayas, which move to lower altitudes during the winter months when their high-altitude habitats become inhospitable due to extreme cold and lack of food.
Altitudinal Migration in Reptiles and Insects
Reptiles and insects also engage in altitudinal migration, although this is less well-studied than in birds and mammals. Some species of butterflies and moths, for example, migrate to higher altitudes during the summer to breed, and then descend to lower altitudes in the winter. Similarly, some reptile species, such as the Black Rat Snake, migrate to higher altitudes during the summer to take advantage of warmer temperatures and abundant food resources, and then descend to lower altitudes in the winter to hibernate.
Factors Influencing Altitudinal Migration
Several factors can influence the timing and extent of altitudinal migration. These include changes in food availability, temperature, predation risk, and reproductive needs. For example, a decrease in food availability at higher altitudes during the winter may prompt animals to migrate to lower altitudes. Similarly, an increase in temperature at lower altitudes during the summer may drive animals to migrate to cooler, higher altitudes.
Impact of Climate Change on Altitudinal Migration
Climate change is having a significant impact on altitudinal migration patterns. As global temperatures rise, the zones of suitable climate for many species are shifting upwards in altitude. This can lead to changes in the timing and extent of altitudinal migration, with potential impacts on animal populations and ecosystems. For example, if animals migrate to higher altitudes earlier in the year due to warmer temperatures, they may arrive before their food sources are available, leading to potential food shortages.