Jeannette, Delmont, Will, Robin and Timothy.
We spent a few days in Aransas, Texas. In the mornings the folks and I would go birding. In the afternoon, we would all go to the beach.
What makes it a Grackle or a Grebe?
There are thousands of birds winging their way across the salt marshes of Aransas, yet my parents, without hesitation pick out a blackish bird with a long tail and pronounce it a "Boat-tailed Grackle"? This ability has always amazed me. I do understand that there is a method to recognizing which birds are a part of which species, but how do we do it? Even if every species has a unique set of "field marks" we still don't just sit down with the list of millions of types birds which are on our planet, and go down the list until we find a match. And even if you did, there are a lot of times when you don't see all the markings clearly, yet you can still identify the species.
When I think about the problem too much I realize that just as curious is that I can see two Least Terns and without thinking about it I know that they are the same species, even if I still need to thumb through my bird guide to put a name on them.
How about a simpler problem: how do we know that creature out there is even a bird? If I can figure that out I have a chance of later on figuring out that it is a Grackle and then maybe later a Boat-tailed, or maybe I'll confuse it with a starling or blackbird. I know it is a bird because it looks like a bird. It has wings. But let me qualify that a bit. Because it has wings unlike a bats or a dragon fly. It is covered with feather too - that seems important.
"When I see a bird that walks like a duck and swimsBut that really isn't the whole story. There are birds which due to misadventure have lost a wing, yet without hesitation we identify these still as birds. We do not try to classify them as a new species. There are also birds which don't fly, as Opus from Bloom County reminds us. We immediately identify penguins, ostriches emus and kiwis as birds. Is it their feathers? Their eggs? The fact that they are homeothermic (warm blooded)?
Actually we identify all of these merely as traits or features of birdness. I think the best modern definition of the Aves class is that they share a modern ancestor, and therefore a similar genetic makeup.
Which brings me back to the question "How do we know that this bird is a Boat-tail Grackle?" We didn't swab its inside cheek and do a DNA analysis, matching its DNA-fingerprint. Yet a bird watchers just know.
Well there are techniques.
If you tried to write out an algorithm for bird identification you might first try to classify our blackish bird as a grackle. Look at the size and the shape of the bird and that might be all you need. In fact, the inside cover of Peterson's Guide has silhouettes of birds to help you quickly identify what type of bird it is, and take a first step in finding the species. Is it a hawk or a thrush? That seems like an absurd question, but you need to start someplace.
One thing which I think is clear is that we don't really use the techniques which we might imagine. For example, our Boat-tailed Grackle (Quiscalus major) in in the order Passeriformes, which apparently is not very helpful since more then half of all birds fit into this order. It is also in the family Icterid, which is also quite large and includes meadow larks and cowbirds. Actually Grackles show up in a quintet of Genera; Quiscalus, Hypopyrrhus, Lampropsar, and Macroagelaius. And where was the help in this? Did this aid us in identifying the species? I do not think so. The catalog of taxonomy isn't really a field guide.
Sibley's Guide starts out by telling us that the first thing to look at is the beak. This will tell you what they eat and what family they are in. This may be good advice - but I am convinced that my parents know what species they are seeing even when they can not see the beak. Sibley and Peterson both advise looking for "field marks". This is a technique pioneered by Roger Tory Peterson. Compare what you see to a list of unique markers. Peterson also list voice, range and size - with a warning that size really is quite hard to estimate at a distance.
I think that there really is a more important technique unconsciously working in the brains of most birders. Look are the environment and think of the probabilities. I tell scouts that if you are in Hanover, or most of Vermont or New Hampshire, and you are asked to identify a tree that you can not see, call out "White Pine" with out hesitation and most of the time you will be right. Yes, there are a lot of hemlock, birches and maples, but the dominate species is 'Pinus strobus', the Eastern White Pine. It is a tree known to grow here, and it is very probable.
Birds follow the same rules, with the occasional 'exotic'. (For example, experienced birders have spotted the occasional Egyptian Vulture which were caught in freak storms and end up in Nottingham, England.) I have never seen a Laughing Gull in Hanover, and I noticed that the Common Loon did not show up on the Aransas' list. Part of this is the 'Range' factor which Peterson mentioned, but there is more to it then that. There is this factor of local environment and probability. When I am teaching scouts to avoid poison ivy I spend a lot of time on where to look for it. Poison Ivy is an 'edge plant', it likes to grow between fields and woods. It also likes to grow where the ground has recently been disturbed as one of the first steps of natural secession. So only look for it under those conditions. For birds, ducks rarely sit in trees (the Wood Duck - Aix sponsa - I think perches in trees just to confuses our preconceived notions), and Eagles hunt and fish near and in rivers, but do not paddle around on them. When you tip back your head to watch a winged creature high in the sky, that is a more likely place to find a hawk then a chickadee. In fact that Black-capped Chickadee is more likely found on the forest edge, fluttering above the poison ivy.
So, back to Aransas, how did my parents identify 49 species? I expect that experience really was the key to a quick identification. Yes there were lots of marks and clues such that when they saw that blackish birds they focused their attention on traits which they know to be unique. But then how do we explain the identification of the "Yellow-breasted Chat"? There was no experience to fall back upon. It was a new species to my parents, they had never seen it.
Last summer when my folks visited us in Stockholm there was a bird which we had often seen, but didn't recognize. It was a large waterfowl with a white face, like someone painted up to pantomime. In the spring its goslings, puffballs of fuzz, has inundated and entertained us as they waddled along the shores of Djurgårdens, Fjöderholmarna and even Brunnsviken, but I didn't know their name. My father immediately identified them as "Barnacle Geese". He made this identification with such ease that I assumed that he had often seen it. But like the Yellow-breasted Chat of Aransas, the Barnacle Goose of Stockholm was new to him. So how did that work? This was an identification without even a consultation with reference? True, later that day the identification was confirmed from a guide book. But how does the brain place the new species? It just fits. They were geese and chats as any experienced birdwatcher will know, but the identification of the particular species comes from studying the birds of a region ahead of time. And that speaks of a type of devotion to the field, a zeal for this ornithological pursuit.
The question of what something is and how to "pigeon hole" it is ancient. Aristotle wrote his "Categories" to try and help us out. We now can catalog all plant and animals by looking at their genetics and deriving their evolutionary history. We then can say that things are similar if they have similar ancestry. But,
There are more things in heaven and earth, Horatio,- or in the case, there are more things then what will fit into Linnea's System Natural. How do I know that Mars in a planet and Pluto is not? We have field traits to guide us and we require similar origins or evolution to know that it is a planet. Comets can glow, but they are not stars. The muon acts like an electron, except it is uncommon and it is 200 times heavier then the electron. These things are similar - but different.
I think that as we explore nature maybe we don't have a universal technique for cataloging items, for classifying objects. Appearance, history and how they act play into it, but they don't tell us everything. What we do in practice is watch, wait, watch some more, and then we eventually know what it is. Why we split up objects, or even birds into species and sub-species must just be because of the way we will use that information. Or maybe it is just how we need to organize it such that we can get our heads around what we see. We need to understand, in some sense, this barrage of information. We can not just view the world as a potpourri, a hodge-podge of unrelated individuals and objects. We need order to comprehend and understand. And in the end, if it walks like a duck ... or better yet, if it looks like a Chat and my folks say it is a Chat, it might just be a Chat.