1. Sometimes obvious differences are unimportant and small differences are very important in distinguishing one

species from another, so read the text. The next time you are flipping through a field guide trying to identify some

plant or animal that you’ve found, keep in mind that there can be a lot of variation within a single species.

Whether you are using a field guide, or searching images on the internet, it is not always effective to simply look for

similarities and differences– you have to know which similarities and differences are important. This concept is often

misunderstood by novice naturalists. When trying to determine the identity of something, our instinct is to focus on

the most obvious similarities or differences, but those similarities and differences may not be meaningful characteris-

tics for identifying something. The truly meaningful characteristics that are used to identify wildlife are referred to as

diagnostic characteristics.

The overall look of the critter can help you narrow your search a little, but if you really want to ensure a correct identifi-

cation, you should also read the text. The text will point out the diagnostic characteristics. If you read the text about

the hognose snake you would learn that it comes in variety of colors, but that its upturned snout is different than any

other snake in most of its range. When you look at only a single specimen you have no way of knowing if that example

represents how they ALL look. The experts have studied the species and have seen many examples and have kept rec-

ords of which traits are the same among every individual of the species and which traits vary. They have done this work

so that you don’t have to. Good field guides will include this information. And as you study different kinds of field

guides you may notice that some classes and families of animals may have a great deal of variation within a single spe-

cies, and many others have species whose individuals are nearly identical. For example, you are more likely to find big

differences in the colors of two garter snakes than you are to find big differences in the colors of two blue jays.

Sometimes obvious differences are unimportant in wildlife identification, as shown by

these two eastern hognose snakes, or by these leaves and seed pods, all from common

milkweed.

Sometimes small differences are

very important such as the differ-

ences in the depth of the notches

that help distinguish the leaves of

invasive Chelidonium majus (left)

from the native Stylophorum di-

phyllum (right).

There are specialized field guides available for just about every kind of living thing, from trees and mushrooms, to

butterflies and snakes. Field guides are filled with detailed information for identifying wildlife, but there are some

general wildlife identification concepts that may not be obvious in the guides. Without an understanding of these

concepts, some people may struggle to correctly identify the plant or animal they are investigating.

Here are a few things to consider the next time you pick up a field guide.

Six Things to Know About Using Wildlife Field Guides

2. Insect field guides include only a fraction of the insects in your area.

A bird field guide might easily include every bird that nests in or visits your state. In most states that would be around

400-500 birds, but your state has tens of thousands of insects. A single field guide cannot include them all, so the

guides usually focus on the ones you are most likely to see. The less commonly seen insects are often not included in a

field guide, but the guide can still help you narrow your search. Once you find something similar in a field guide, you

can search for that similar insect with an online resources like BugGuide.net then look for images of its close relatives.

BugGuide.net is organized in a way that allows you to easily find closely related insects.

3. Field guides for groups with a lot of species, such as plants or insects, may use less specific naming standards.

When looking up insects in more than one source, you might occasionally see some confusing differences in the way

they are labeled. Sometimes a field guide shows an insect and uses it as an example of the larger group to which it be-

longs. This can be confusing if it is labeled with the general name of the large group. For example, a field guide may

have a picture of a harlequin bug, labeled “Harlequin Bug”, but another guide may show a picture of a Harlequin Bug,

labeled “Stink Bug” which is the common name for the subfamily Pentatomoidea, which includes harlequin bugs and

thousands of other similar species. Stink bug and harlequin bug are both accurate labels, but one is more specific. Per-

haps you might find yet another field guide that shows a different species of Pentatomoidea, still labeled “Stink Bug”

which could create further confusion. Scientists avoid this confusion by using scientific (Latin) names.

A harlequin bug’s scientific name is: Murgantia histrionica. A little review of classification and scientific names is some-

times helpful in clearing up confusion about wildlife names.

4. Be prepared for the ID challenges presented by age or life-cycle stages

Someone familiar with the appearance of an adult blue racer snake could easily

be stumped if they found a young blue racer, which is mottled with gray and

brown. A young bald eagle could be mistaken for a golden eagle before it devel-

ops its white head in its 4th or 5th year.

Insects have a lot of life cycle variation to complicate identification. Everyone is

familiar with a lady bug, but many people have never noticed a young lady bug

in its larval stage, and are quite surprised to find one and learn that it is a lady

bug. Caterpillars can be very tricky because they may molt multiple times before

they enter their pupal stage. In some species, the caterpillar changes considera-

bly with each molt. Other insects have nymph stages that look quite different.

Some species of tree-hoppers start life as a very spiky, sci-fi looking nymph that

looks nothing like an adult tree-hopper.

This not-so-familiar larva is the early

stage of the very familiar lady bug beetle.

With its long ovipositor this insect may inspire some curiosity, but

finding the exact name may be a bit of a challenge. It is a type of

ichneumon, a subfamily that has over 3000 species in North America,

many of which cannot be identified exactly without close examina-

tion of the vein patterns on their wings. Even the best field guides are

likely to only have a fraction of them. Specialized books are needed

for the rest.

5. Bird identification may be complicated by season, age and sex.

Males typically have bolder colors than the females. Some males will have bold coloration during the breeding season

(spring and summer) and drab colors in the fall and winter. Some species may also have distinct color differences be-

tween juveniles and adult. The best bird books will show all of these variations.

These variations are usually just related to color; their size, body shape and beak shape tend to stay the same, so make

note of these features when you spot an unfamiliar bird. Generally birds have pretty consistent coloration within sex

and age groups, (i.e. The juvenile males of a given species will all look alike; the adult females of a give species will all

look alike, etc.) so their differences are predictable and easy to identify with most good field guides, as long as you read

the descriptions carefully. In addition to these differences between sex and age groups, a few species regularly have

two or more different forms (sometimes referred to as phases), such as the screech owl, which has a gray phase and a

red, rusty phase, or a rough-legged hawk, which has light phases and dark phases. (The word ‘phase’ might seem to

imply that they grow out of it into a different phase, but that is not the case.)

6. Don’t forget to check the range maps.

Many field guides include range maps that show the regions where plants and animals might be found. After you have

looked at the pictures and read about the diagnostic features (see 1 above), it is a good idea to check the range of the

plant or animal. If you have found a snake in Ohio and its best match in the field guide seems to be a snake that only

lives in the Southwest you may have to re-evaluate. Check the text descriptions of Ohio species to see if there is a color

variation that is not pictured that might better match the one you found. Occasionally plants and animals, especially

birds, may show up outside of their range, but one should still diligently rule out the more likely, local birds before they

decide that a bird has flown out of its range.

Left: Juvenile chestnut-sided

warbler

Right: Mature chestnut-sided

warbler (spring)

For people who are trying to become more familiar with the wild things around them, field guides are a

great help. With these concepts in mind wildlife watchers can more easily interpret all of the valuable in-

formation that is available in field guides, and

6. Gestalt and wildlife-watching

When someone new to birdwatching starts hanging out with experienced birders, the new birdwatcher may notice a

peculiar and sometimes impressive attribute of the experienced folks. Experienced birders may catch a quick glimpse

of a bird, sometimes at a great distance where its diagnostic criteria are not easily seen, and declare with confidence

the identity of the bird. It sometimes comes as a shock when a birder glances at a distant speck in the sky and says,

without even looking through his binoculars, “Eagle.” What comes next is the peculiar part, when the novice says,

“How do you know it is not a vulture?” and the birder just shrugs.