Recognizing Birds at a Glance: General Impressions, Shape and Size

When I first started getting into birdwatching, it was a little overwhelming.  Even just focussing on local birds, there were huge numbers to learn to identify. I got hung up on memorizing patterns of plumage. The colour of a bird’s feathers can be very important in positively identifying a species, but I was getting discouraged when I could only catch a short or partial glimpse of a bird, or when the bird was backlit, making the colours difficult to discern. I was focussing too much on the details, and less on the overall picture.


Little brown birds, seen from behind and partially blocked by plants: the bane of my existence. 

Then I read the introduction to a book called Better Birding, in which authors George Armistead and Brian Sullivan talked about GISS: General Impressions, Shape and Size. They explained that identifying birds was not necessarily about spotting one particular tell-tale clue, but overall impressions. The author used the analogy of being able to spot your best friend in a crowded room from behind. How do you know it was her? Well, it’s her favourite café, in her favourite booth, with her favourite drink in front of her, but even if there was someone else sitting there with the same beverage wearing a similar coat to one of hers, you’d still know that it wasn’t her. It was also in how she holds herself, what her voice sounds like, and so on. It’s to do with behaviour as well as looks.

I found this idea to be extremely helpful. This is how I can know a Canada Goose at a glance, even in flight and silhouetted against the sun. I’m not necessarily looking for anything specific about them. They just look, sound, and act like Canada Geese. The trick is then to get in enough observation time to build up a vocabulary of bird behaviour for more species than the handful I grew up knowing.

Once you start to know the GISS of a species, the identification of a drab female can get a lot easier. The female Red Winged Blackbird is a small-ish brown-ish bird, but has the exact same GISS as the male, just a different colour.

Drab Female Red Winged Blackbird perched on a cattail.

If she acts like a blackbird and hangs out with blackbirds and looks like a blackbird in every way except, well, being black… She’s probably a female Red Winged Blackbird.

But even really knowing only a limited number of birds really well right now, GISS is still useful for identifying species that are new to me. In May, I was walking in the Lois Hole Provincial Park in St. Albert, Alberta, with my mother and a pair of binoculars. I am very familiar with Red Winged Blackbirds: what they sound like, how they fly and how they move about the cattails. Then a bird that caught my eye. It wouldn’t have last year, when I had spent less time observing Red Winged Blackbirds closely. In that lighting (it was a cloudy day), it seemed dark in colour, and held itself like a blackbird… but something about it seemed off to me. I looked at it more closely through my binoculars, and found that the shape of its tail looked odd, not like what I would expect from a Red Winged Blackbird. Though it was dark in colour, it didn’t have the expected red epaulettes, and definitely didn’t look like a female of the species.

Small dark bird viewed from a distance, partially blocked by tree branches.

This is the bird I saw. Let’s enhance!

However, with a few small differences, the overall GISS led me to think that this bird may in the blackbird family. So pulled up my handy-dandy Sibley bird book app and went to the section with the Red Winged Blackbirds to look at its relations… and there I had my answer: a Common Grackle. It was a little bit bigger than a Red Winged Blackbird, its tail was a different shape, and looking at some photos I took of it later, I could more clearly see the different beak length and of course the plumage differences that were not as obvious to me in the field. (They are ever so slightly iridescent and have blue heads!)

A Common Grackle hops along wet ground at the edge of a pond.

Half an hour later, I spotted another grackle in better lighting and was able to admire its pretty blue plumage!

I never would have looked more closely at this bird if I hadn’t known Red Winged Blackbirds so well. Grackles were just similar enough to make the differences jump out at me. It was the similarities in the general impressions, shape and size of this bird that helped me narrow it down to a definitive identification.

Further Resources

  • Armistead, George L. and Brian L. Sullivan. Better Birding: Tips, Tools & Concepts for the Field. Princeton, New Jersey: Princeton University Press, 2016.
  • The Sibley eGuide to Birds App.


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