8 
THE CONDOR 
Vol. XV 
birds. The latter gave attention indeed, but would not heed the repeated warn- 
ings. My advances had the effect of bringing all the flock together, whereas 
otherwise they would have scattered over the entire ledge of, say, a hundred feet 
length. Now and again the flock shifted, but always they came back, alighting 
at the extreme tip of the reef where the waves frequently bandied them. For the 
most part they fed silently, ])ut as often as I made some unusual demonstration 
or as often as the wave swept about them, a murmur of complaint arose. The 
flock came to attention, or a few shifted position, if the water was actually too 
tleep. But the moment danger was over, work was resumed upon the barnacles. 
• My last exposure, tlie last of twenty-one plates, was made at a distance of 
eighteen feet, and at that range only half of the flock would go on the plate. The 
exposure ( f. i6, 1-140) was perfectly timed, and it marked, I am proud to con- 
fess, the most thrilling moment of a ten-year experience in bird photography. 
Fig-. 6. Surf-birds: the parting shot 
From a photograph, copyright, 1913, by W. E. Da'vv.son 
CONCEALING AND REVEALING COLORATION OF ANIMALS* 
By JUNIUS HENDERSON 
C oncealment is only one factor of safety and not always the most im- 
portant factor. There are numerous others, such as the sharp hearing, keen 
scent and speed of deer and antelopes, the weapons and strength of ele- 
phants and tigers, the protective armor of turtles and armadillos, the shells of 
clams and oysters, the spines of sea urchins and porcupines, the offensive or ir- 
ritative secretions or stench of certain invertebrates, which render concealment 
comparatively unimportant in many cases. 
Natural selection means the suiwival, not of those forms wdiich have a single 
advantageous character, but of those whose combined characters as a whole best 
fit them for existence in their natural environment, surrounded by their natural 
enemies. Hence the very popular supposition that under the doctrine of natural 
selection all animals must be concealingly colored, is unwarranted in theory and 
unsupported by the facts. If a given species be varying in the direction of con- 
cealing coloration and in no other direction, naturally those forms, or mutants, or 
whatever we wish to call them, whose colors are in closest harmony, would be 
* Abstract of an address before the University of Colorado Scientific Society. 
