This has been used with great success to investigate the nature of the magnetic compass sense in migrants (Wiltschko & Wiltschko, 1972; Wiltschko et al., 1993; Ritz et al., 2004; Zapka et al., 2009). Orientation cages provide Ferroptosis activation the potential for greater control as they can be performed indoors. Surprisingly, orientation cage studies have not been used as extensively to investigate the cues used in the navigational map as they have the compass, despite the fact that testing orientation after displacement has been shown to be possible (Thorup & Rabøl, 2007; Chernetsov

et al., 2008) as are simulated displacement experiments (Fransson et al., 2001; Henshaw et al., 2010; Deutchlander, Phillips & Munro, 2012). Second, recently, there have been calls for a return to field-based study of true navigation in migratory birds (Wikelski et al., 2007; Thorup et al., 2010; Guilford et al., 2011). This stems from concerns that migratory restlessness does not fully represent the behaviour of animals in the wild (Wikelski et al., 2007), and that we do not understand the full extent of the challenges that animals face during migration (Holland et al., 2007). Animal movements in the wild can now be tracked using remote monitoring devices, which provide the precision that

was lacking in mark recapture techniques. Torin 1 molecular weight In some cases global positioning system (GPS) precision is available and remote download from a satellite can be achieved [see Bridge et al. (2011) for a review of the technology currently available for tracking migratory birds]. However, tracking devices that can follow a migratory journey with sufficient precision to test

navigational decisions are still too large for the small songbirds that remain the focus of much of true navigation in migration. As tracking of migratory birds becomes more widespread, our understanding of the navigational challenges faced by both adults and juveniles will increase, which will undoubtedly aid in adapting the theories of true navigation (Guilford et al., 2011). However, field-based studies of wild birds face the same inherent weaknesses as field-based studies in the other model systems, in that control of access to cues is difficult. Field-based studies of migration face the added difficulty of predicting both the 上海皓元 timing of departure and goal of the animals. The former may cause problems in predicting the effect of treatments of sensory systems particularly when they are transitory, and the latter may increase the scatter in experimental groups, meaning an increase in the number of animals needed. Given that tracking technology remains relatively expensive and studies are often restricted by the number of devices available, this may lead to inconsistencies in results through lack of statistical power. Such studies are thus relatively rare, with no study of migratory true navigation using GPS telemetry having yet been published.