When a Bird Becomes an Individual: the One-legged Great Egret

Andy McGannBanding, Bird Websites, eBird, Nemesis Bird Podcast, ScienceLeave a Comment

Books can be (and are) written about the ornithological knowledge gained through studies that involve the practice known as “bird banding” (or “ringing” overseas).

To put it simply, banding involves the capture and marking of a wild bird with a unique serial number.  In the USA and Canada, those numbers are generated by the US Geological Survey’s Bird Banding Laboratory. They are stamped onto a lightweight metal alloy band, which is then placed around the leg of a bird.  The practice is nearly harmless, when conducted properly, and the oversight of such research is quite rigorous!

The real magic of banding is that it transforms birds from just another anonymous member of a species into an individual.  It allows a bird to be recognized, with certainty.  Yet the biggest drawback of the serial-number-stamped-onto-a-band system is that it requires the bird to be handled again in order for the tiny number to be read by human eyes.  So the bird has to be recaptured, or the band otherwise recovered, for example if a banded bird is found dead.  This is obviously a huge limitation!  However, there are other methods that allow for the remote visual identification of individual birds.  The most common method is a unique combination of colored plastic leg bands, in addition to the metal serial number band.  Even in today’s age of gadgets and technology, this simple approach is still the foundation for almost all studies of bird demography.

But a careful amateur observer will occasionally get lucky, and spot an animal with a unique injury or mutation.  Suddenly, one of the local birds becomes special.  It becomes a recognizable individual.  One such example occurring right now is a Great Egret that has been hanging out on the Conejohela Flats of the Susquehanna River in Lancaster County, PA.  This bird has been in the vicinity for the last couple of weeks.  Apparently it is doing fairly well at catching food and avoiding (more) predators.
This egret’s presence on The Flats coincides with the time of year when Great Egrets are found in the greatest abundance there (see eBird chart below).  This is almost certainly due to an annual pattern among many species of birds called Post-breeding Dispersal (or Post-Natal Dispersal for those birds that hatched this summer).  This phenomenon occurs after the breeding cycle activities wrap up for the year, and birds become less tied to the specific geographic area where they nested.  For many species, they have little left on their “To Do List” besides feeding themselves in preparation for molt and migration, and perhaps they do some “prospecting” for more promising areas for nesting next year.

Average Count - Great Egret on the Conejohela Flats

eBird data showing the Average Counts of Great Egrets on the Conejohela Flats

As this particular Great Egret shows us, careful observation of individual birds allows us to gain insights into the more generalized lives of a species.  This sub-discipline is often referred to as Life History study. One of the best and earliest compilations of life histories was written in the early 1900s by Arthur Cleveland Bent, and it has more recently been transcribed into a free website.  However, the modern scientific source for avian life histories is the Birds of North America (BNA) Online.

For easier-to-read accounts of the lives and livelihoods of our birds, I would recommend Kenn Kaufman’s book, Lives of North American Birds  and  Pete Dunne’s book, Pete Dunne’s Essential Field Guide Companion.  Observant birding goes way beyond merely identifying the species you encounter in the field.  Reading and learning more about the avian life histories will not only make you better at species identification, but it will prepare you for those rare occasions when you encounter your own window into the lives of individual birds — if you can recognize them!