These limited observations on chorus structure in Smilisca show the presence of behavioral organization. The methods of establishing the organization and the significance of the call-order in breeding have yet to be discovered.
Calling males of S. baudini are often close together; some individuals have been observed almost touching one another, but no indication of territoriality or aggressive behavior has been witnessed. The more distant spacing of the stream-breeding species S. sila and S. sordida may be a function of calling-territories, but no direct evidence is available to substantiate this supposition.
Sex recognition and amplexus.—Observations on Smilisca baudini indicate that the calls of males attract females. At Tehuantepec, Oaxaca, México, a female was first observed about two meters away from a male calling at the edge of a rain pool; in a series of short hops she progressed directly towards the male, although vegetation obscured him until she was less than a meter away. When she approached to within about 20 centimeters of the male, he took notice of her, moved to her, and clasped her. At Chinajá, Alta Verapaz, Guatemala, a female swam directly across a pool about three meters wide to a calling male. Her line of movement took her within a few centimeters of a silent male, to whom she paid no attention. She stopped just in front of the calling male, which immediately clasped her. At a large muddy pond 4 kilometers west-northwest of Esparta, Puntarenas, Costa Rica, a female was observed swimming toward a small submerged tree; a male was calling from a branch about one meter above the water. The female climbed to a branch about 20 centimeters below the male, which upon seeing her there immediately jumped down and clasped her. These few observations of S. baudini show that in this species females are capable of locating calling males by means of phono-orientation; visual reception on the part of females seems to be secondary. Contrariwise, males apparently become aware of the proximity of females by seeing them; once a male sees a female he usually tries to clasp her. Possibly the males receive stimuli by means of chemo-reception, but in each observed instance the male obviously looked at the female.
Amplexus is axillary in all members of the genus. Normally amplexing males hunch their backs and press their chins to the females' backs. Clasping pairs are usually found at the edge of the water, but sometimes amplexus takes place in trees or bushes.
Egg deposition.—Oviposition has been observed only in Smilisca baudini. On the night of June 28, 1961, at Chinajá, Alta Verapaz, Guatemala, a clasping pair was observed at the edge of a shallow rain pool. After sitting for several minutes in shallow water, the female (with male on her back) swam part way across the pool and grasped an emergent stick with one hand. The female's body was nearly level with the surface of the water, and her hind legs were outstretched as deposition commenced; eggs were extruded rapidly. After a few seconds the female moved slowly to another twig a few centimeters away and deposited more eggs. This process was repeated until the female was spent. The spawn resulted in a surface film covering roughly one square meter. It is doubtful if this type of egg deposition occurs in any other species in the genus, especially those that lay their eggs in streams.
The breeding calls of the six species of Smilisca are alike in their explosive nature. Calls are emitted quickly with a short burst of air filling the vocal sac, which immediately deflates. Phonetically the calls can be described as a single "wonk" or series of such notes in S. baudini and S. cyanosticta, a low growl in S. phaeota, a relatively high pitched rattle in S. sordida, and a low squawk usually followed by one or more rattling secondary notes in S. puma and S. sila. Quantitatively, the calls of the six species differ in number of notes, duration of notes, and in pitch (Table 8, Pls. 10 and 11). Although no measurements were taken on the intensity of the calls, we observed in the field that each of the species has a loud voice. The call of S. baudini seems to carry farther than any of the others.
| Table 8.—Comparison of Breeding Calls in Smilisca. (Observed Range Given in Parentheses Below Mean. In Species Having Primary and Secondary Notes, Only the Primary Notes Are Analyzed Here.) | |||||||
| Species | N | Notes per call group | Duration of note (seconds) | Pulses per second | Fundamental frequency (cps) | Major frequencies (cps) | |
| Lower | Upper | ||||||
| S. baudini | 20 | 8.0 | 0.11 | 174.7 | 166.2 | 351 | 2507 |
| (2-15) | (0.09-0.13) | (140-195) | (135-190) | (175-495) | (2400-2725) | ||
| S. cyanosticta | 10 | 1.2 | 0.38 | 147.0 | 145.1 | 841 | 1894 |
| (1-2) | (0.25-0.45) | (110-180) | (135-160) | (480-975) | (1600-2100) | ||
| S. phaeota | 10 | 1.6 | 0.31 | 116.0 | 143.0 | 372 | — |
| (1-2) | (0.10-0.45) | (100-130) | (110-165) | (330-495) | |||
| S. puma | 28 | 3.7 | 0.13 | 208.2 | 145.6 | 743 | 1868 |
| (2-10) | (0.06-0.35) | (187-240) | (125-200) | (495-980) | (1456-2240) | ||
| S. sila | 15 | 2.4 | 0.16 | 108.5 | 103.0 | 899 | 2218 |
| (1-6) | (0.06-0.28) | (97-120) | (90-115) | (665-1180) | (1980-2700) | ||
| S. sordida | 19 | 1.7 | 0.29 | 104.7 | 123.1 | 1216 | 2694 |
| (1-6) | (0.18-0.45) | (78-135) | (90-140) | (1150-1540) | (2340-2990) | ||
Call rate.—The rate at which call-groups are produced varies from one every few seconds to one in several minutes. In S. baudini, cyanosticta, phaeota, and sordida, call-groups are produced as frequently as every 12 seconds, but usually more time elapses between call groups. In S. sordida, five or more minutes sometimes elapse between call-groups. The interval is somewhat less in S. phaeota. Calls are repeated at much shorter intervals in S. puma (5-55 seconds) and S. sila (4-20 seconds).
Notes per call-group.—Except for S. puma and S. sila, the series of notes produced in any given call of a species of Smilisca is essentially the same; there is no differentiation into primary and secondary notes. Smilisca cyanosticta and S. phaeota emit only one or two relatively long notes per call-group, whereas S. baudini and S. sordida produce as many as 15 and 6 notes, respectively. Males of S. puma and S. sila often produce only the primary note; sometimes this is done several times before the secondary notes are produced. For example, one S. puma (KU 91711; tape No. 379) produced the following number of notes in consecutive call-groups: 1, 1, 1, 1, 2, 2, 3, 1, 4; secondary notes are present in only four of the nine call-groups. A typical series of consecutive call-groups in S. sila (KU 91852; Tape No. 385) has 1, 1, 1, 2, 4, 2 notes per call-group; secondary notes are present in only half of the call-groups. Smilisca puma apparently always produces at least two primary notes before emitting secondary notes; sometimes only primary notes are produced in one series of calls. The number of secondary notes following a given primary varies from one to nine; the modal number is one, and the mean is three in 27 call-groups. Smilisca sila frequently begins a series of calls with two or more primary notes, but sometimes the first primary note is followed immediately by two or more secondary notes. The number of secondary notes following a given primary varies from one to five; the modal number is one, and the average is two in 13 call-groups.