Compass orientation in migratory birds
In further studies, we will investigate the effect of cue-conflict situations to birds’ orientation, and include measurements of the polarized light conditions during exposure. A rather sensitive sensory system is required to detect the low (< 10%) degrees of polarisation transmitted, and we do not yet know if birds possess such a sensitive system. We will also perform simulated magnetic and real displacements to study the use of a map vs. clock-and-compass model for orientation during first and later migrations, but also to investigate how the expression of the birds endogenous migration program are affected by external magnetic information. Adult (experienced) and young (migratory naïve) songbirds will be compared.
The Emlen funnel
Jannika Boström is preparing orientation cages, so called Emlen funnels, for studies of orientation in Northern Wheatears on Arctic Ocean sea ice. The bottom of the cage is lined with Tipp-ex paper, on which the bird leaves scratchmarks when trying to fly off. These marks give us an indication of what direction the bird is heading at.
Ongoing orientation experiment
The scratches on the soft Tipp-ex paper shows the bird´s migration direction. These papers can be analysed by circular statistic. Here, a dunnock (Prunella modularis) is studied within an orientation cage.