Bat
Microbats make use of magnetoreception, in that they have a high sensitivity to the Earth's magnetic field, as birds do. Microbats use a polarity-based compass, meaning that they differentiate north from south, unlike birds, which use the strength of the magnetic field to differentiate latitudes, which may be used in long-distance travel. The mechanism is unknown but may involve magnetite particles.
Nihoa millerbird
Using mist nets, 85 Nihoa millerbirds (60 males and 25 females) were captured and banded. Banding permits identification of previously captured birds and reduces stress that can be caused by multiple captures. Most importantly, however, banding allows individual birds to be identified in the field and enables biologists to identify pairs, map their territories, and track individual survival from year to year through repeat sightings. Photographs and measurements of wing and tail feathers were taken from each individual, as well as small feather samples for genetic analysis. Growth bars visible on the tail feathers can help scientists determine the age of the bird, and comparison of photographs and measurements with results of lab analyses will aid in finding a way to sex Nihoa millerbirds in the field. Development of these methods will ensure that the right numbers of male and female birds are moved to Laysan.
Several Nihoa millerbirds were placed in a temporary enclosure and presented with a selection of island insects. The purpose was to identify millerbird dietary preferences and see if the birds would eat in captivity. Preliminary results showed that the birds fed readily from a plastic container of prey items. Of the choices offered, they left behind only lady bugs, sow-bugs, and ants. One bird was quick to chase down fast-moving cockroaches before taking smaller, slower insects such as spiders and beetles. Another test with a male and female showed that, after a brief adjustment period, the pair fed together without hesitation.
Using an iPod and a speaker, the team played millerbird songs within the territories of all 60 banded males and recorded the responses with a microphone. These recordings were used to determine the territories of 20 males and will also be analyzed to determine if differences exist in millerbird songs across Nihoa. Preliminary spectrograph analysis of the recordings shows variety among the songs of male millerbirds, but more research is needed to determine if these differences are significant. Identifying millerbird dialects on such a small spatial scale would be a novel finding and a major accomplishment of the expedition.