Ancient Greek Heroes VS. Modern Day Heroes

Animated Migration Maps: How to Track Birds 

Countless species of animals migrate: take for example, whales, butterflies, wildebeest...but most
recognizably, birds. Over 4,000 of avian species migrate every year, which is over 40% of the total
known bird populations globally; those migratory birds including cranes, vireos, flycatchers,
[ruby-throated] hummingbirds, ducks, geese, and swans, tanagers, swallows, orioles…the list goes on.
Yet even with this immense index of species, ornithologists (those who study birds) take on the hefty task
of tracking these species and their north-south adventures. 

Tracking migration has come in many forms over time, but overall, it’s a fledgling science. The
earliest migration tracking is dated is 1804, when naturalist John James Audubon, namesake of the
National Audubon Society(geared towards researching and educating the intricacies of ornithology)
noticed that the same birds return to the same places on a fairly regular schedule. He realized that these
migratory birds disappear over the winter and reappear almost magically over the spring through fall
while some, called resident birds, stayed put. 

Audubon’s discovery eventually prompted scientists to use metal bands and tags to identify

starting and ending points of migration routes. Sometimes, a distinct plastic tag or a dye on the bird’s

neck would be used, as it was lighter and easier to spot from a distance- the observers wouldn’t want to

spook the likes of a sandhill crane. 

However, despite many millions of birds having been tagged in this way, the recovery rate is quite

low for the vast majority of bird species examined. Also, for small birds like the red-eyed vireo, which

weighs a mere 0.6g, tags are far too heavy for them to carry thousands of miles south. An alternative to

tagging is to use miniature transmitting devices – radio transmitters, radar and satellite tracking – that

serve as active markers and are small enough (<0.5 g) to be attached to even small birds or mammals.

The location of the marked animal can be inferred by tracing the individual using a receiver, or by

triangulation using several receivers. Either way, miniature transmitters, alongside another method

called stable isotope analysis, were a breakthrough and are still widely utilized. 

A stark issue with all of the technology mentioned above is this: they involve tracking migration by
tagging a single organism and receiving it, which was too vague as a single datum point to speak for the
movements of entire populations. So we know how a single Canada Warbler travelled, but how does
the entire population move? What stops do they take along the way, if any? In regard to bird conservation,
which areas must we preserve to ensure safe migration paths? A single bird can’t tell us that. But
birdwatchers, it turns out, can help answer those questions. eBird, a program at the Cornell Lab of
Ornithology, is the largest citizen science project in the world, and it has been collecting observations
of birds reported by bird watchers around the world for more than fifteen years, adding up to more than
750 million observations of birds. Using this data, Cornell can make stunningly accurate migration
maps, animated to illustrate the movement of a species over time.

Barn swallow abundance: April

Barn swallow abundance: August

These are three screenshots of an animation following the migration of the barn swallow. The maps provide comprehensive analysis or frequency by the swallows in accordance to the time of year, which is a great step in migratory tracking. This system being fairly new (which is why it's a current event), I personally can't wait to see what it can provide for us bird nerds. 

Barn swallow abundance: February