Weidensaul on “The New Migration Science”

Of all the cool things about birds (they fly! they sing! they have feathers! they are living dinosaurs!) one of the most profound is their astonishing seasonal migrations.

Scott Weidensaul writes for the Cornell Lab of Ornithology about technologies that are coming on line that enable scientists to gain unprecedented information about bird migrations.

[T]oday really is a truly exceptional time for migration science, with so many new avenues for documenting the journeys of birds.

First on the list are twenty first century leg bands, one gram geolocation recorders. Some larger birds can carry a satellite tag that tracks their travel and reports by radio. A cheaper and lighter option is a recording tag that logs the data, to be recovered when the bird is recaptured.

A third option are tiny radio transmitters that can be picked up by a network of collaborating receivers. With standardized signals and networked databases, a receiver can pick up and report any pings in its area, no matter who tagged the animal. The bird does not have to be recaptured, so there is much higher probability of encountering the tagged inividuals.

Weidensaul reports that both DNA and chemical isotope analyses can be made from a single feather or scrap of tissue. DNA can help sort out subpopulations, and isotope analysis can identify geographical history, e.g., of what the bird has eaten or drunk recently.

Recent improvements in data processing have enabled the routine use of NEXRAD weather radar to detect migrating flocks of birds each night. High resolution weather radar can also detect individual birds and reveal details of behavior. These studies, combined with remote sensing of vegetation and water, are enabling a detailed understanding of critical way stations where migratory birds rest for the day, and then continue.

With decades of archived NEXRAD, scientists are also studying trends over time. (The main trend is “down”, as we all might expect.)

Digital networks enable the combination of data from all these soruces, The internet also has automated the centuries-old traditions of collaboration among birders, creating massive crowdsourced datasets of observations.

Weidensaul reports current efforts to deploy cameras to automatically identify birds in cities. With today’s powerful visual analytics, it seems likely that inexpensive digital cameras will soon routinely identify and report individual birds.

Finally, inexpensive microphones on mobile devices or not can record high quality digital sound, which soon will enable a detailed picture of all the unseen birds in the area.


All of these digital technologies were developed for purposes other than ornithology. Almost no one develops complex and expensive technology just for observing birds. But birders will not be denied! These are some excellent examples of repurposing technology, and using powerful general purpose tools such as image and signal processing algorithms and machine learning.

And, of course, birders have been collaborating and crowd sourcing for centuries, long before computer scientists got into the game. Birders are some of the original citizen scientists, and, just as our feathered friends have persisted from dinosaur days, the global collaborative community of bird enthusiasts has survived centuries.  Now we have picked up digital technology and put it to good use.


  1. Bird Studies Canada. Motus Wildlife Tracking. 2017, http://motus.org/.
  2. Cornell Lab of Ornithology. eBird – Birding in the 21st Century. 2017, http://ebird.org/content/ebird/.
  3. Scott Weidensaul, The New Migration Science, in All About Birds. 2017, Cornel Lab of Ornithology: Ithaca. https://www.allaboutbirds.org/the-new-migration-science/

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