Birds and Climate Change

Siberian Jays

 

The Siberian jay is a small corvid with a wide distribution, reaching from Norway in the west all they way to eastern Siberia. It lives in the taiga, cold forests dominated by spruce and pine. It stays in the taiga all year round and does not migrate to warmer climates in the south as temperatures start to go down. It survives through the winter by storing bits of food around their territory, for example under the bark of trees, which they then eat throughout the cold seasons, together with any other pieces of food they can find. They are generalists, and eat everything from berries and seeds to bird eggs and small mammals. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Siberian jays live in social groups dominated by a breeding pair. Each group lives in its own territory, though the borders of these territories are relatively loose and not strongly defended. In addition to this breeding pair, the group also consists of a mixture of unrelated immigrants, retained offspring and, depending on the season and breeding success, current offspring. Retained offspring are offspring from previous breeding seasons that remain within their natal territory, for up to 3 years. However, not all offspring stay on with their parents, some leave their natal territory around 4-6 weeks after fledging. These early dispersers are usually kicked out by the offspring that stay on in the territory as retained offspring. The kicked-out siblings disperse and settle with other Siberian jay groups as "immigrants".

 

The retained offspring and the immigrants in a group are treated differently by the breeding pair. The retained offspring receive benefits in the form of increased access to food and better protection against predators, benefits that the immigrants have to live without. As a result, retained offspring have a higher chance of survival and also greater reproductive success as compared to their siblings that were forced to leave the natal territory. Even though the retained offspring do not help at the nest site, parents benefit from helping their offspring as it increases the chance of spreading their genes.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The major cause of mortality in Siberian jays, both of adults and of nests, is predation. The main predators of nests are other corvids, such as raven and Eurasian jays, while adults are targeted by goshawks. Siberian jays use calling to warn family members of impending danger, and even use different calls that convey information regarding the behaviour of the predator. Experiments have shown that calls provide information on whether hawks that are perching, searching or attacking.

 

Most of the predators of Siberian jays are visual hunters, and as such trying to remain inconspicuous is crucial in order to avoid being eating, or having your chicks being eaten. The jays achieve this mainly through trying to remain covered by the canopy. Considering this, a dense, complex forest structure is key for Siberian jays to remain hidden and avoid their predators. Several studies have shown that nest failure is larger in areas of an open forest structure as compared to a closed, dense structure. This finding translates into commercial forestry, which often leads to open forest structures dominated by pine, representing a big problem for the jays. Areas of commercial forestry consistently have a lower reproductive success than natural areas. The effect of forest structure on nest success is stronger in areas of higher predator densities, supporting the importance of trees in providing visual cover from predators. Further support is obtained from the finding that when exposed to playbacks of predator calls, breeders shifted their nesting site to denser forests (Eggers et al. 2006). Siberian jay parents further try to protect their nests by reducing the number of provisioning trips and lay smaller clutches when in the presence of high predator densities.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sources:

Eggers, S., Griesser, M., Andersson, T. and Ekman J., 2005. Nest predation and habitat change interact to influence Siberian jay numbers. Oikos 111: 150-158.

 

Ekman, J. and Griesser, M., n.d. Siberian jays: the life history of alternative dispersal pathways. Book chapter (not published).

 

Griesser, M., 2008. Referential Calls Signal Predator Behavior in a Group-Living Bird Species. Current Biology 18: 69-73.

 

Griesser, M., 2003. Nepotistic vigilance behavior in Siberian jay parents. Behavioral Ecology 14: 246-250.

 

Griesser, M. and Ekman, J., 2003. Nepotistic alarm calling in the Siberian jay, Perisoreus infaustus. Animal Behaviour 67: 933-939.

 

Griesser, M. and Lagerberg, S., 2012. Long-term effects of forest management on territory occupancy and breeding success of an open-nesting boreal bird species, the Siberian jay. Forest Ecology and Management 271: 58-64.

 

Griesser, M., Nystrand, M., Eggers, S. and Ekman, J., 2007. Impact of forestry practices on fitness correlates and population productivity in an open-nesting bird species. Conservation Biology 21: 767-774.