Date: 5/21/19 8:05 am From: Butch Tetzlaff <butchchq8...> Subject: Re: Question for the empid experts
One of the biggest questions with identification of any organism is how do we know we're right?
Though I do have a banding permit, I am hardly an "expert" on bird ID. But it seems the problem stems from three basic issues.
First, as birders, we have no control group. The only way to definitively know what it is that we are looking at is to do a DNA test on it. And that's assuming we have a standardized DNA fingerprint of every species. Even then, it assumes that species are immutable (they aren't) and that they don't hybridize (they do).
Second, just looking at a bird in the field (or in a field guide) ignores all the subtle variation in the population that exists. Birds can vary visually because of diet, health, ectoparasite load, and any number of other reasons. There is also regional morphological variation within all species, and those gradations typically don't play by the rules of boundaries.
Which leads us to the third issue...as a birder, we have no idea where the bird we are looking at came from, which means we have no idea from which metapopulation it originated or what it's genetic history is. Is it passing through? Did it get blown off course? Did it engage in long-distance juvenile dispersal (which is common) and now call Arkansas home even though it was hatched Pennsylvania from a parent that came from New Jersey?
All this means that even if one went into museums and looked at (and measured) all the study skins of a species like Peter Pyle did back in the 80's and 90's to create his definite work on bird ID (Identification Guide to North American Birds Parts 1 & 2), we still couldn't be sure we are looking at what we think we are looking at, because now we have introduced the variable of time. That study skin that was collected back in 1867, how has it been stored? How many times was it handled before gloves were required? How has time degraded the feather pigments? From what location did that bird originate even though it was collected in Nebraska? We'll never know.
You can see the complexity here, and all we want to do is pin a name to a bird. Now I am not suggesting that it can't be done; new ways to identify, age, and sex birds are always being discovered. But at the same time, I do hope it helps us realize that it's not as easy as we often think it should be. But it is more fascinating, because of it!
Butch Tetzlaff Bentonville
On Tue, May 21, 2019 at 8:37 AM Daniel Mason <millipede1977...> wrote:
> So I visit a bird ID forum semi-frequently... I use it to get ID's from > time to time as well as help others with ID or simply watch a few > conversations and TRY to pick up better skills. I learn better in the > field still but, it's interesting and I try to remember what I learn. > > I was "taught" something today that surprised me a bit... that empids > aren't really that difficult once you get used to them... more > importantly that you don't need to HEAR a willow or alder to tell them > apart. I've always read and heard that you shouldn't bother trying and > have seen many very well experienced birders leave their sightings as > empidonax sp if the bird doesn't vocalize. This is what I believed to be > absolute truth so, I never bothered looking at them carefully. (One of > these days I'll try and study the newer field guides better...) > > So on this forum, someone asked for flycatcher IDs and, one of the > pics... someone just said it was a willow flycatcher. Someone agreed > just as quickly so, I asked about that. How did they know? I looked in > the field guides and I can see some subtle differences but, they're > subtle. One was the eye-ring, the bird in the picture really had none > that I could see in the photo at all. Anyway, this is the response I got. > > "Yes, a lot of experts and banders will tell you that they are > completely unidentifiable but that's not fully true. Older birders tend > to be stuck in the mindset that they are inseparable from the time they > were one species. > > Typical Alder and Willow have fairly distinctive looks. Classic Willow > here has a more crested head, more dull colored back with some brownish > gray tones, wingbars tend to be less strong and less white, and a weak > to no eyering. > > Alder typically has a flat head unlike typical Willow, more olive > greenish overall with little to no brownish gray, stronger white > wingbars, and a stronger, often complete eyering. > > GISS (general impression of shape and size) tends to be very useful with > empids. With empid experience, you'll get a strong Willow or Alder > impression on a bird." > > If this is true... if you can get such an "impression" and have it be > reliable, well even then it will take some time for that to help me in > the field. I mean, those things don't stay still very often. Up, down, > left, right... where did you go? HA. But if this information is > fairly accurate, it may help me learn to ID some from photos better, > provided I get better photos. > For now, of course, I'll stick to hoping they make a sound I can use. > But I wanted to get some other opinions on this information. Looking at > a field guide the other night I can say that there did appear to be some > visual differences between the two. I'm just kind of questioning how > reliable that is. So... anyone that might be "stuck in their mindset" > or a newer learned birder(that might know this info) have any thoughts? > I always err on the side of caution and, that's not going to change... > but if I can learn new things, well I'll sure try. > > Daniel Mason > > > --- > This email has been checked for viruses by Avast antivirus software. > https://www.avast.com/antivirus >