I’m not nearly clever enough for such use of alliteration in a post title…this is straight from the source! But it’s such a great name and title for the material, I had to use it. Using eBird data that provides millions of bird sightings submitted by everyday citizens, Cornell University put together animated maps that depict bird migrations in the Western Hemisphere (click to see the animated maps). 118 species are represented, showing typical migration routes over the course of a year.
It’s fascinating to view. The animation starts at the start of a year, and there’s not much movement at first, as birds are settled into their winter range. A few oddballs start migrating quite early, but by March there’s widespread movement which crescendos in April and May before most birds are in their summer ranges. Some species already start moving back south during the month of June, and by September there’s a mass south-bound flux of birds.
The long established monitoring programs of the Breeding Bird Survey and Christmas Bird Count are great, providing relatively consistent observations of birds for well established routes and locations over several decades. This animated map, however, helps to show the power of eBird. As someone who has used eBird both as a birder for the recording of my sightings, and as a scientist for the use of the data in bird species distribution modeling, I’m well aware of some of the difficulties with the data. Given that anyone can enter sightings, there’s no systematic sampling design, there’s definite bias in sightings towards both heavily populated areas and for more “charismatic” species, and there are issues with reliability of sightings with bird ID skills ranging from novice to expert. But given that eBird data aren’t limited to a specific season or geography, they offer an opportunity that BBS and CBC cannot…the ability to track bird movement, and also track how those movements change in the face of climate change or other stress factors.
Very cool map…it’s very interesting to try and follow one dot over the course of the year! Only thing I wish it had were some kind of label (or clickable dots) so you knew what species each dot represents.