How to identify specimens (by Brian O'Shea)
On your lab final you will be asked to identify specimens of about 25 of the ~230
species that we have covered in lab thus far. Some of these may be familiar from
field trips, but most will not. The purpose of this guide is to attempt to facilitate
your acquisition of techniques to help you separate the various families and
species from one another in a systematic fashion. Remember that not all field
marks depicted in guides will be visible or useful for identifying stuffed
specimens. This guide focuses on features that you can assess easily on a study
skin.
Imagine this situation. You are presented with a specimen and asked to identify
it. Your first impression is that the bird is kind of small, with an insectivore-type
beak. It is greenish, with some yellowish, and no markings on the underside, but
it has a thingy near the eye. You start to panic and ultimately scribble something,
hoping that I can't read it but will somehow give you the benefit of the doubt. That
will not happen. You need to have a systematic way to narrow the possibilities,
because there are many greenish-yellowish birds with some kinds of markings
and thingies in various places.
When ornithologists view a specimen, they immediately evaluate the bird's
"general impression". This is a subconscious, reflexive action that usually results
in the bird being placed to family or species almost instantly (after a brief
confirmation of diagnostic features). You will need to duplicate this process (at a
slower rate, perhaps) for the specimens on the lab final. This is how it's done.
Step 1. Predictive morphology
First, look at the bill, wings, tail, and feet to determine if they fall into any of the
predictive categories that we have covered in lab. Keep in mind that these
categories often complement one another: for example, a bird with a
climbing/bracing tail is more likely to have "tree-climber" feet than webbed feet. If
you can place at least one feature of the bird into a predictive category, and you
know roughly which families/species do the behavior indicated by that category,
you have already eliminated a large portion of the possibilities.
In many cases, however, the bird's morphology will not give you much if any
predictive information (which is the case with many of the Passeriformes), or you
will have several options within a predictive category. You must then move on to
examine some of the bird's finer features.
Step 2. Unusual field marks
The second step is to evaluate whether the bird has some unusual color or
pattern. This is a pitfall for many people, because they tend to dwell on one
specific color and try to categorize birds by their dominant color(s). This doesn't
work for the most common colors in birds namely, green, yellow, brown, black,
and white. The plumage of many birds is a combination of two or more of various
shades of those colors. Calling something a "brown bird" isn't going to get you
very far if you don't know how to tell which "brown bird" it could be. In such a
case, stand back and move on to the next step. Fortunately, unusual plumage
colors do exist, and it should be fairly easy to distinguish the species that sport
such colors. For example, if a bird is black, white and orange, it is one of three
species: American Redstart, Baltimore Oriole, or Blackburnian Warbler. The lists
of species with lots of red or blue plumage are similarly short. These species
should be "no-brainers"; learn them and get them out of the way. If you can't
identify a Roseate Spoonbill, you can't graduate.
A similar approach can be taken with pattern. For example, few species are
entirely one color learn those species. The triangular red patch on the breast of
a male Rose-breasted Grosbeak is unique among Louisiana birds. So is the
yellow tail-tip on a Cedar Waxwing. Most ducks have a diagnostic facial pattern.
Other features, such as streaking or wing bars, are common to many birds, so
learn to ignore those at first. Focus (briefly) on anything that stands out as
somehow unusual, color- or pattern-wise.
Step 3. Determine family
You're still stuck with your greenish-yellowish eye-thingyed thing. By this point
you have determined that it has an insectivore bill, but that doesn't help you
much. You're fairly confident that it belongs to one of the families in the
Passeriformes, so the next step is to determine which one. This is the third step
get it to family. You should know how to tell a warbler from a vireo, and both of
these families from a thrush. Half of your points on the identifications will come
from your placement of a specimen into the correct family or order. See the
Appendix for some common cross-family mistakes.
The number-one clue for family ID is the bill. Know your bills. This alone will give
you a big advantage in placing a bird in the proper family. True, the "standard
insectivore" phenotype is rather plastic, but variation within families is quite small,
and hopefully you'll move on to other diagnostic/confirmatory features without
really noticing that you checked the bill at all. In any case, you will probably cue
in on the bill relatively early in the identification process, not only because it is
part of Step 1, but because people tend to focus on facial patterns; this is a good
thing, as described in the next step.
Step 4. Facial recognition
Assess the bird's facial pattern. Learning birds is a lot like learning to recognize
people's faces. It is absolutely essential that you be familiar with the various
topographic regions, especially those of the head. This applies to birds in general
and Passeriformes species in particular. Know the difference, for example,
between an eye line and an eye ring -- and, within a family, which species have
them and which don't. Know where the lores are relative to the forehead. Note
any contrasting pattern (many warblers have diagnostic head patterns). If the bird
appears "plain-faced" (i.e. does not have any obvious markings), this too can be
a useful clue to identification.
Going over some of the "challenging" species pairs given in the Appendix, and
learning to quickly distinguish one species from the other, will help clarify your
understanding of topographic regions and their use in identification.
After suppressing your fifth panic attack of the day, you have taken another look
at that confounded yellowish thingy. Its standard insectivore bill is on the skinny
side, the bird itself is rather small, and the facial pattern is prominent; on the
basis of these features you decide it's a warbler (Parulidae). You remember that
many warblers are some combination of green and yellow, so your confidence
rises a bit. Looking at the face, you note that what was once a "black thingy near
the eye" can more accurately be described as a patch of black that extends
across the forehead, totally encompassing the eye and extending onto the
auriculars. You now have a pretty good idea of what this bird is, but before you
write anything down, you need a final confirmatory clue. Which brings you to step
5.
Step 5. The underside
Look at the bird's ventral surface. Is it spotted? Streaked? Barred? Does it have
any unusual pattern or features (e.g., pink hearts? Orange stars? Purple
horseshoes?) Again, it is imperative that you know the topographic regions for
example, sides vs. flanks, etc. Where are the markings? this is probably most
important. Are they confined to the breast? Extending from the sides onto the
flanks? Is the underside completely unmarked? Is there contrast in color between
the throat and breast, or breast and belly? Are there patches of color anywhere?
Almost as soon as you saw your quiz bird, you casually registered something
that fits each of the steps above (except Step 3) generally small, with an
insectivore beak but no other good predictive info, hence the panic (Step 1),
greenish-yellow coloration that didn't strike you as particularly unusual, let alone
diagnostic, hence continuing panic (Step 2), eye-thingy (Step 4), unmarked
ventral surface (Step 5). Gathering yourself a bit, and remembering some of the
tips we'd given you for identifying various families, you correctly guessed
(perhaps) that it belongs to the Parulidae. Step 3 accomplished retroactively.
This is very likely how you will approach most of the specimens during the lab
final whether you know it or not, you will look at the face (because everyone
does) and the ventral surface (because it will be facing up). The key is to
recognize how you're processing the information that is presented to you in the
form of a dead bird, and to eliminate panic by systematically reducing the
possibilities of what that bird could be.
At long last, you have taken a good look at your quiz bird's underside, and noted
the complete absence of markings on a yellow breast contrasting with a white
belly. This could mean only one thing Common Yellowthroat. You jump up on
the table and roar in triumph. Years later, reflecting upon that jubilant day, you
suddenly realize that you actually made things far too hard on yourself . . . No
other small, greenish-yellow bird in Louisiana has the "mask" of the male
Common Yellowthroat. Unusual pattern. Step 2. You vow to re-read your Sibley
Guide cover to cover.
Hopefully this guide will help you make sense of the many families and species
of Louisiana birds that you have to know for your lab final. More importantly, we
hope that learning to identify these species will foster an appreciation for the
avian diversity of Louisiana (remember that there are ~150 species occurring
here that we didn't cover in lab) and encourage you to spend more time outside
enjoying birds.
Finally, a disclaimer: not all birds will be safely identifiable by strict adherence to
my 5-step program. Some degree of familiarity with every species covered in lab
is essential for a perfect score.
Reading material
The following references should be in the library and may be useful:
Dunn, J.L., and K.L. Garrett. 1997. Warblers (Peterson Field Guide Series). More
warbler illustrations than you will ever want to see, but gives you a good feel for
variation within species.
Peterson, R.T. A Field Guide to the Birds (Eastern). I learned birds as a young
kid with the Peterson guide, and I still think that it is the best one out there for
beginners. The plates are straightforward, with minimal clutter, and arrows point
straight to the key field marks.
Rising, J.D. 1996. A Guide to the Identification and Natural History of the
Sparrows of the United States and Canada. In-depth sparrow coverage.
There are a multitude of similar guides and reference books for individual
families; check the library, they should all be in the same section.
Appendix
"Challenging" species
This list is intended to give you a "heads up" so you are prepared to confidently
resolve common identification dilemmas, should they face you in the near future.
I am only listing easily confused species pairs or groups; it's up to you to
remember how to separate them.
** Note: Selection of bird species for the lab final is a computerized, random
process. These species are no more or less likely to appear on the exam than
any others. **
Ring-necked Duck vs. Lesser Scaup
Snow Goose vs. Ross' Goose
Redhead vs. Canvasback
Bufflehead vs. Hooded Merganser
Black vs. Turkey Vulture
Sharp-shinned vs. Cooper's hawk
King vs. Clapper Rail
American Coot vs. Common Moorhen
Semipalmated vs. Piping vs. Snowy Plover
Black-bellied vs. American Golden Plover
Greater vs. Lesser Yellowlegs
Spotted Sandpiper vs. Sanderling vs. Dunlin
Western vs. Least vs. Pectoral Sandpiper
Long-billed Dowitcher vs. Wilson's Snipe
Herring vs. Ring-billed Gull
Royal vs. Caspian Tern
Mourning vs. White-winged Dove
Inca Dove vs. Common Ground-Dove
Chuck-wills-widow vs. Whip-poor-will
Common Nighthawk vs. Eastern Screech-Owl
Downy vs. Hairy vs. Red-cockaded Woodpecker
Pileated vs. Ivory-billed Woodpecker
Eastern Kingbird vs. Black-billed Cuckoo
Eastern Wood-Pewee vs. Acadian Flycatcher vs. Eastern Phoebe
Northern Rough-winged Swallow vs. female Purple Martin
American vs. Fish Crow
Vireonidae vs. Parulidae
Yellow-throated Vireo vs. Pine Warbler
Winter vs. House Wren
Loggerhead Shrike vs. Northern Mockingbird
Brown Thrasher vs. Wood Thrush
Hermit vs. Swainson's Thrush
Regulidae vs. Parulidae
American Pipit vs. other streaked, brown birds
Tennessee vs. Orange-crowned Warbler
Blue-winged vs. Pine Warbler
Blackpoll vs. Black-and-white Warbler
Yellow-throated vs. Blackburnian Warbler
Northern vs. Louisiana Waterthrush, and waterthrushes vs. Ovenbird, and all three vs. thrushes
Common Yellowthroat vs. Kentucky Warbler
Swainson's vs. Worm-eating Warbler
Prothonotary vs. Blue-winged Warbler
Orchard Oriole (female) vs. female Summer Tanager
Rusty Blackbird from grackles, and all 3 from crows
Common vs. Boat-tailed Grackle
Blue Grosbeak vs. Indigo Bunting
Indigo Bunting (female) vs. sparrows, female House Finch, and female House Sparrow
House Sparrow (female) vs. sparrows, female House Finch, and female Indigo Bunting
Savannah vs. Song Sparrow
Field vs. Chipping Sparrow
Swamp vs. White-throated Sparrow
House vs. Purple Finch