Long-tailed Jaeger (Stercorarius longicaudus)
The long-tailed jaeger relies heavily on the lemming as a source of food. In years of low lemming numbers, long-tailed jaegers may not breed at all!
The pigeon-sized long-tailed jaeger is the smallest of the jaegers, recognizable by its long central tail feathers, which project 10-25 cm beyond the rest of the tail.
The long-tailed jaeger has a circumpolar range, and is most common in the High Arctic, only occurring in the Low Arctic in Siberia. It winters in tropical waters, with large colonies frequenting Chile.
While in the Arctic, the food of long-tailed jaegers consists primarily of lemmings, but they also prey on small birds, particularly in years when lemmings are scarce. They also eat insects, which are the main food given to the young.
The number of eggs laid by long-tailed jaegers is directly proportional to the lemming population; in bad years they may lay one egg, or none at all, but in good years they lay up to three eggs. The survival rate of the young is also dependent on the size of the local lemming population. The long-tailed jaeger’s small body size, relative to that of other jaegers, is an adaptation to the High Arctic; smaller bodies require less food to reach maturity. This is important because of the short summer, which limits the time available for the offspring to grow. The incubation period of these jaegers is also somewhat shorter than those of the two other species, allowing the birds to delay breeding if the early part of summer is especially cold.