Zugunruhe is a German

German language

German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 compound word consisting of Zug (move, migration) and Unruhe (anxiety, restlessness).

In ethology

Ethology

Ethology is the scientific study of animal behavior, and a sub-topic of zoology....

 it describes anxious behavior

Behavior

Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...

 in migratory animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s, especially in bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s. When these animals are enclosed, such as in an Emlen funnel

Emlen funnel

An Emlen funnel is a bird cage shaped like an inverted cone, used to study bird behaviour, in particular birds' migratory instincts. It is named after S T and J T Emlen who introduced the technique in 1966. An ink pad is placed on the bottom, so when the bird hops or flutters onto the sloping walls...

, zugunruhe serves to study the seasonal cycles of the migratory syndrome

Bird migration

Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

. Zugunruhe involves increased activity towards and after dusk with changes in the normal sleep pattern. Researchers have been able to study the endocrine controls and navigation

Navigation

Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...

al mechanisms associated with migration by studying zugunruhe.

Zugunruhe has been artificially induced in experiments by simulating long days. Some studies on White-crowned Sparrow

White-crowned Sparrow

The White-crowned Sparrow is a medium-sized sparrow native to North America.- Description :Adults are long and have black and white stripes on their head, a grey face, brown streaked upper parts and a long tail. The wings are brown with bars and the underparts are grey. Their bill is pink or yellow...

s have suggested that prolactin is involved in the pre-migratory hyperphagia (feeding), fattening and zugunruhe however others have found that prolactin may merely be associated with lipogenesis (fat accumulation).

The phenomenon of Zugunruhe was generally believed to be found only in migratory species, however study of resident species shows low-level Zugunruhe, including the oriented activity, suggesting that the endogenous mechanisms for migratory behaviour may be present even in resident species. Further suggestions for endogenous programs are provided by observations that the number of nights on which Zugunruhe is exhibited by caged migrants appears related to the distance of migration involved.