1925] 
Storer: A Synopsis of the Amphibia of California 
221 
The voice of Hyla regilla is probably the best known of all 
amphibian voices in the Pacific states, as it is to be heard in many 
places and through a long season each year. In the spawning season, 
or more properly, as long as there is any likelihood of spawning, the 
‘ chorus note, ’ the note which serves to bring the scattered individuals 
together for breeding purposes, is uttered. This, to human ears, 
sounds like kreck-ek and is uttered over and over again in rapid 
sequence. The note is uttered only by the males, and ordinarily only 
when in, or over, water which is suitable for spawning purposes. I 
have never heard it given by a female or by a male when out on dry 
land, although captive individuals in bottles or aquaria will often 
give it, especially if several are confined together. Normally when 
‘singing’ a male hyla spreads himself out on the surface of the water 
with all four legs widely extended and this extent of bodily area in 
combination with the distended vocal sac makes it possible for the 
animal to float on top of the water with but a minimum of support. 
Sometimes a croaking hyla will perch on some dead weed or grass 
stalk close to the surface of the water. When this chorus note is 
being uttered the single rounded thin-walled vocal sac located on the 
chin is swelled out to the utmost and serves as a resonator. The sac 
remains partially distended between notes, reaching its greatest 
volume at the end of a note, when it is so large as to protrude some 
distance beyond the end of the snout. When fully relaxed the folded 
skin on the sac is blackish, but when fully distended all of the black 
disappears and the surface takes on a slight iridescence. 
Individual males watched and timed in the vicinity of Berkeley 
have been found to utter their notes at about one-second intervals 
(11, 12, and 15 notes in 15-second intervals, 28 in 30 seconds, another 
at the rate of 80 a minute and exceptionally even faster) . The inter- 
vals between notes are very short, just long enough for the air, which 
has been forced out into the vocal sac, to be returned to the lungs 
again. An individual hyla may continue in voice for a minute or 
more without a pause, but usually the ‘songs’ are shorter. 
When several hylas are ‘singing’ together their individual ‘songs’ 
overlap, so that the chorus is continuous. There is a tendency for the 
notes to be uttered in unison so that at times, when strict synchronism 
occurs, each alternate note (the main syllable) is stressed. But where 
there are many hylas together it is difficult to pick out the efforts of 
the individuals. At times a chorus will continue for many minutes 
but more often it goes on for a time, then dies out, soon begins again, 
