In Situ Clock Shift Reveals that the Sun Compass Contributes to Orientation in a Pelagic Seabird.

Compass orientation is central to the control of animal movement from the scale of local food-caching movements around a familiar area in parids [1] and corvids [2, 3] to the first autumn vector navigation of songbirds embarking on long-distance migration [4-6]. In the study of diurnal birds, where the homing pigeon, Columba livia, has been the main model, a time-compensated sun compass [7] is central to the two-step map-and-compass process of navigation from unfamiliar places, as well as guiding movement via a representation of familiar area landmarks [8-12]. However, its use by an actively navigating wild bird is yet to be shown. By phase shifting an animal's endogenous clock, known as clock-shifting [13-15], sun-compass use can be demonstrated when the animal incorrectly consults the sun's azimuthal position while homing after experimental displacement [15-17]. By applying clock-shift techniques at the nest of a wild bird during natural incubation, we show here that an oceanic navigator-the Manx shearwater, Puffinus puffinus-incorporates information from a time-compensated sun compass during homeward guidance to the breeding colony after displacement. Consistently with homing pigeons navigating within their familiar area [8, 9, 11, 18], we find that the effect of clock shift, while statistically robust, is partial in nature, possibly indicating the incorporation of guidance from landmarks into movement decisions.

Simultaneous registration and landmark detection.

We are developing a system for patient management in colorectal cancer, in which a difficult case of non-rigid registration, namely of pre- and post-therapy images, arises. Numerous non-rigid registration algorithms have been proposed in medical image analysis, and we have applied several leading algorithms to our non-rigid registration problem; but with unpromising results. The fundamental reason appears to be that they lack with knowledge of the particular application. We propose a graphical representation of anatomical knowledge relevant for colorectal cancer, and of the ways in which this anatomy may be predicted to change as a result of chemo and radiotherapy. We show how we interleave this representation with an adaptive registration algorithm to make the non-rigid registration result both robust and accurate.