By Thomas C. Grubb, Jr. , Department of Zoology, Ohio State University
The Boxwood Press; Pacific Grove; 1986
(Used with Permission)
Suppose we have come to a great marsh or swamp to spend a day watching water birds. after scanning the habitat and, perhaps, taking notes on the kinds and numbers of the birds present, we sit in the sun on an old log eating our sandwiches, and get to wondering why so many wading birds have white feathers. Great Egrets, Snowy Egrets, and immature Little Blue Herons are all covered in white plumage. Someone ventures that perhaps white feathers help the birds catch fish because they reflect the blue of the sky down into the water, making the white bird match its background. Somebody else suggests that is white feathers have evolved only because they fool fish, then all white birds should feed on fish. We al begin to leaf through our field guides, calling out white-feathered species and what they eat. White-tailed Tropicbird, White Pelican, and Gannet all eat fish. Then we come to the swans, which are white, but eat vegetation. We try another idea, that white feathers are only possessed by birds that eat any aquatic food. This would take care of the swan problem. Off we go again through our field guides, but not too far. Snow Geese are white, yet they graze on land. As our lunch ends, we conclude that we do not have any firm idea why birds are white, but we are sure it is not solely because they eat aquatic food. Whooping Cranes and Ivory Gulls are also white and eat aquatic food, but Snow Geese disobey the rule, so the rule, as it stands, must be wrong.
Over our lunch, we have just engaged in analytical ornithology. We have used the scientific method to investigate a property of nature. The scientific method is a system which creates a general statement about some natural phenomenon, then assesses it systematically. The general statement is called a hypothesis. It is created by combining previously unrelated bits of knowledge in a new way. We then evaluate the hypothesis by making a prediction that we can test. The test will tell us if the prediction is true or false. If the prediction is false, the hypothesis must also be false. If the prediction turns out to be true, we do not know whether the hypothesis is true or false; only that we could not disprove it.
Analytical ornithology uses the scientific method to test hypotheses about the lives of birds. In order to gain a better appreciation of how this method works, let's translate our lunch-time thinking into components of the scientific method. We saw white birds in the swamp, and we knew from our reading or from first-hand observation that they ate fish. From these two pieces of information, one of us answered our question about white feathers by creating the hypothesis that all white birds eat fish. We then predicted that if all white birds eat fish, all the white birds in our field guides must eat fish. We tested the prediction by paging through while noting what each white-feathered species ate. The swans proved the prediction false, so the hypothesis had to be false. This outcome was not unusual; a large proportion of hypotheses in science are proven false. We had only to create a new hypothesis accounting for the swans. We stated that all white birds eat aquatic food, animal and/or vegetable. We disproved this second hypothesis, with the Snow Geese, but let's for a moment pretend we didn't. Let's pretend we failed to find the Snow Goose, ptarmigan and Snowy Owl. We would have gone through the entire field guide noting that every other white bird we found ate aquatic prey. We would then have proven true the prediction that every white bird in our field guides ate aquatic food. Would we have proven true the hypothesis that all white birds on earth eat aquatic food? No; we would only have failed to prove it false. Somewhere in the highlands of Sumatra or in the vast expanse of Siberia, there could be a white-feathered species that does not eat aquatic food. Until we noticed Snow Geese, ptarmigan, and Snowy Owls, we could only say that we had not been able to show the hypothesis was false, but that we never could prove that it was absolutely true. This conclusion indicates a very important attribute held in common by all branches of science. In a real sense, nothing in all of science is true; there are only some things we have failed to disprove. Figure 1.1 illustrates how the scientific method is used to test hypothesis., and Figure 1.2 depicts the relationships of descriptive and analytical ornithology to the components of the scientific method.
Components and processes of
the scientific method.
Observations, including the results of previous testing, are
combined inductively into a hypothesis of cause and effect.
From this hypothesis, one or more particular predictions are
deduced. The validity of each prediction is evaluated by
empirical testing. If the testing proves the prediction
false, then the parent hypothesis must also be false. If the
test proves the prediction true, then the test has also
failed to disprove the parent hypothesis, and our belief is
strengthened that the parent hypothesis might be true. In
science, a hypothesis cannot be proven to be true, they can
then be used in formulating new hypotheses, thus continuing
the circuitous nature of the scientific method.
Components and processes of the scientific method. Observations, including the results of previous testing, are combined inductively into a hypothesis of cause and effect. From this hypothesis, one or more particular predictions are deduced. The validity of each prediction is evaluated by empirical testing. If the testing proves the prediction false, then the parent hypothesis must also be false. If the test proves the prediction true, then the test has also failed to disprove the parent hypothesis, and our belief is strengthened that the parent hypothesis might be true. In science, a hypothesis cannot be proven to be true, they can then be used in formulating new hypotheses, thus continuing the circuitous nature of the scientific method.
Incidentally, on snowy winter evenings, it can be quite enjoyable to play the game of making hypotheses and testing them with field guides. For example, females are always less colorful than males. Within a taxonomic family, forest birds are always brighter than open-country birds. Juveniles always resemble females in color, never males. Birds of coniferous woods are always brighter than those of deciduous forest. The higher the latitude, the more seabird species and the fewer land bird species are found. More species reach a limit to their range in Kansas than anywhere else in North America.
Used properly, the scientific method is a very powerful tool for the ornithologists because it tells him or her when a mistake has been made. In the succeeding chapters on field ornithology, I will advance a number of hypothesis and suggest methods for determining whether they are wrong.