It began with an osprey named Julie, who in 2015 migrated from the Detroit River in Michigan all the way to Maracaibo, Venezuela, stopping at wetlands and wildlife refuges along the way. Julie wore a GPS tracker. John Nelson took Julie’s data and created a series of maps of her journey that represent a brilliant use of negative space: aerial and satellite imagery is shown only along the paths she took; everything else is blanked out. It’s a linear map of a bird’s entire world. The Story Map goes into more detail; the accompanying text is frankly beautifully written. John explains how he made the maps here.
Eurasian reed warblers don’t need no stinkin’ marine chronometers. A new study suggests that the migratory birds make use of magnetic declination to determine longitude, “at least under some circumstances under clear skies. Experienced migrants tested during autumn migration in Rybachy, Russia, were exposed to an 8.5° change in declination while all other cues remained unchanged. This corresponds to a virtual magnetic displacement to Scotland if and only if magnetic declination is a part of their map. The adult migrants responded by changing their heading by 151° from WSW to ESE, consistent with compensation for the virtual magnetic displacement.”
Not, it would seem, accurate enough for the species to earn a chunk of the Longitude Prize, and it’s not like John Harrison should have been messing about with birds instead of clocks, but interesting all the same. [GeoLounge]