Despite more than 50 years of intensive research on how migratory songbirds navigate between breeding and wintering grounds, the navigational map of birds remains unknown. This project attempts to resolve this question in a model system of migratory songbirds, the White-crowned sparrow, that breeds in Alaska and winters in California. Advanced radio-tracking technology will be employed to follow migratory birds for long distances in the wild. It is known from previous research that adult birds use map information when they migrate south from Alaska: Adults that were translocated during their migration from Washington State to New Jersey flew back towards California. Juveniles exposed to the same challenge continued to migrate south in New Jersey, indicating that juveniles navigate based only on an innate compass bearing. This difference between adults (possessing a map) and juveniles (possessing only a compass) provides an ideal system to manipulate sensory cues and test orientation success in wild migratory birds, navigating in the field, rather than in the laboratory.
This project will track 24 adult and 24 juvenile white-crowned sparrows during fall migration every year for 3 years. Researchers will expose 1/3 of the birds to olfactory deprivation (testing the olfactory map hypothesis), 1/3 of the birds to a magnetic pulse (testing the magnetic map hypothesis), and will use 1/3 of the birds as controls. From the orientation success of adult birds it will be possible to determine which cues are essential for the navigational map in migratory birds.
This project will be able to i) test and develop new tracking methodologies for small mobile organisms allowing for the monitoring of agricultural pest species such as locusts and disease vectors and ii) attract K-12 students to the study of songbird migration via the ?Science Buddies? network.
Every year, billions of birds migrate between continents. It is amazing how a small bird can find itâ€™s way from North to South America, for example, and even more amazing how it can find itâ€™s way back to the original breeding area in the North. The little bird needs to know where it is on the map and also needs to know how to get from one place on the map to another. This navigation and orientation task is even more challenging because once in a while the bird is blown off course by adverse winds, or needs to find out-of-place sites for foraging and stop-overs. Many theories exist to explain how birds navigate: they may use the sun, the stars, the magnetic compass information, may even be able to see magnetic field, or feel the Earthâ€™s gravitational field. Many tests for these theories were conducted in laboratory settings. We tested orientation and navigation of birds in the field by tracking individuals in various setups. We usually move birds outside of their known areas and see how they know where they were move to, and how they find back to their migration routes. We found that birds are orienting like boy scouts: they use the sun to calibrate their directions, and if necessary use their magnetic compass to find their direction. To know where they are, birds also use their sense of smell. This is an exciting and new finding for birds. During our investigations we also developed new tracking technologies for birds and other small animals, a system that will be flown as an experimental system on the International Space Station in 2015. We will continue our research towards understanding navigation in birds using this new tracking system and - once operational - have the chance to track birds during their entire lifetime, allowing us to finally understand how birds and other cross-continental migrants know and decide where to go.