Nothing known. Field and aviary observations detected no subsong in this species (156), although it may occur. The nature and development of Complex Whisper Song deserves attention simply because song and singing in this species appears to be almost exclusively intersexual in nature and little work has focused on development of this song type (see next).
Complex Whisper Song. Singing by male only; no known instances of female song. Complex Whisper Song is a muted, variable, continuous soliloquy or medley of phrases that may extend from a few seconds on a single perch (usual) to a minute or more as an on-going, unbroken sequence uttered on and between consecutive perches (49, 127; see Figure 8). Complex Whisper Song is sporadic and unpredictably timed (10). Most often the male does not sing while perched, and no evidence that a loud, stereotyped, ‘advertising’ or Primary Song occurs in species. As the male is nonterritorial, this song evidently functions in male–female interactions. See Repertoire and Delivery of Songs, below.
Flight Song. Appears not to have a stereotyped flight song as found in both Seaside Sparrow and Nelson’s Sparrow (introductory sequence a complex twittering followed by 1 or 2 primary songs given during towering display flight). Rather, Complex Whisper Song is typically uttered in flight between perches or as it approaches a new perch, where it continues without interruption. Some inter-perch singing may be performed in a shallow, looping flight (rarely parabolic flight course; JSG), but mostly aerial singing is performed in horizontal, stilted flight (rapid, shallow wingbeats) between 2 successive perches (JSG, unpublished data). No information on nature of flight singing in known hybrids between this species and Nelson’s Sparrow in Maine.
Male usually does not sing for several days after arrival on breeding grounds (JSG, unpublished data). Once females arrive, singing begins and persists into August at sites throughout the breeding range (JSG, CSE), although there is a gradual decline in song rates over the breeding season (157). Notably in this context, male singing rates in Maine were significantly correlated with time after high spring tides (117), but not in New York (JSG, unpublished data). In Maine, seasonal pattern of singing rate correlated with heavy failure of nests during high spring tides, followed by rapid renesting (117). Singing was not heard during molting period in New York where many juveniles and banded adults often remain in breeding habitat into October (adult 15%, immature 80%, n = 76) (JSG). In New England, breeding adults often linger into October, and at least a few immatures do, but relative numbers not known; no singing reported then (CSE). No reports of singing on overwintering grounds, and none heard in study populations in the Southeast during 2 multi-year studies (WP; A. Borowske, personal communication), including no response to playback during this season (A. Borowske). However, singing may occur rarely in early spring on overwintering grounds (this timing coincides with spring gonadal recrudescence in South Carolina in many males (WP).
Daily Pattern of Vocalizing
Appears to sing Complex Whisper Song most frequently in the morning during its roaming and apparent female-search activity (below, mating system). Males become quiet and more difficult to detect during midday, and resume some singing towards evening (10; JSG, unpublished data). Average song rates in Connecticut marshes were 2.5 ± 3.3 songs/15 min (40); song rates farther south in the range (e.g., Delaware and southern New Jersey) are notably lower than those in New England (G. Shriver, personal communication).
Places of Vocalizing
No spatial pattern known except apparently confined to an individual male’s home range. Male uses elevated, exposed places to perch and watch (and sometimes sing) opportunistically. Such perches include tops of tall forbs, bushes such as Iva (marsh elder), stems of Phragmites, on grid stakes, on wrack mats, or in clumps of persistent, old grass. Sometimes sings on the ground (10) or partly hidden in upper grass column (JSG).
Repertoire and Delivery of Songs
The variable song-like phrases and note-groups in Complex Whisper Song may be considered “song-types” (e.g., 158). No quantitative analysis of Complex Whisper Song is available; inter-phrase variability and song (phrase)-type sequencing within single episodes of singing has not been quantified. Phrase repertoire may be moderately high, but actual size needs to be addressed. The known characteristics of Complex Whisper Song appear to fit into 1 of the 2 song types of male oscines (159), that of “continuous singers,” which probably results from intersexual selection and features variable sequencing of elements (phrases) in an extended song complex.
In contrast to emphasis on continuous phrase delivery in a complex song here, descriptions in Saunders (160), Borror (161), and Sibley (3) are misleading (see also Greenlaw in 162), as they imply a stereotyped advertising song exists in the species and its basic pattern is very similar to that of Nelson’s Sparrow. Unlike Saltmarsh Sparrow, although nonterritorial (163, 127), Nelson’s Sparrow sings loud, stereotyped songs from elevated perches in distinct bouts, as do territorial emberizid sparrows generally (9). Other early, descriptive sources also mention song similarity in all sharp-tailed sparrows, providing a misleading view of the differences between songs of Saltmarsh and Nelson’s sparrows (55; Greenlaw in Salzman ). Woolfenden (10) correctly noted that the “song [CWS] usually lasts for nearly 20 s, or sometimes longer [JSG, unpublished data] and consists of a variable number of phrases like those described by Saunders .” However, Saunders implied that songs and singing behavior were similar among all male sharp-tailed sparrows.
Phrase variability in Complex Whisper Song does not resemble the pattern of stereotyped songs delivered in a bout of singing by individual Nelson’s Sparrow (see sonograms in 49, 127; this article). Notably, trill phrases are variable from one to the next. They may consist of a single trill, 2 different trills, or trills initiated or terminated by a note accent (see sonograms of Complex Whisper Song). They also are intermingled with groups of short, sharp notes that appear to be intercalated phrases among those containing 1 or 2 trills. In a limited sample, the intervals between phrases within Complex Whisper Song vary from 0.3 to 0.75 s, while intervals between elements within phrases are much shorter. Typical intervals between primary songs sung in bouts by other emberizids are measured in seconds. The phrase repertoire size of individual males is unknown. Apart from internal variability, the other feature of Complex Whisper Song is its quiet or muted quality. Even a close bird may seem to be distant if its position is not known to the observer.
Social Context and Presumed Functions of Songs
Complex Whisper Song flight singing occurs in 2 contexts: (1) during period of roaming in morning when male appears to seek contact with females and (2) following a pounce-and-scuffle interaction with a female during which the male may attempt to copulate (see Behavior: Mating System). In the latter case, the male sings Complex Whisper Song as it flies off after successfully mounting her. The report of several males singing while “fighting” probably refers to multi-male pounce interactions involving a female (10); we have not seen males fighting and singing among themselves in the field or in captivity (134). Ordinarily, during a pounce interaction, the male (usually only one male is involved) is silent, and will only sing after the female stops resisting and is mounted (see Behavior: Agonistic Behavior).
Complex Whisper Song apparently has a sexual (nonadvertising) function only (10; JSG). Similar continuous singing and song structure is known in other species in which song only serves in mate attraction (159). Informal playback of Complex Whisper Song in the field elicits limited response from nearby males. Complex Whisper Song appears to be a notice of dominance achievement during scuffling interactions with nonreceptive females when the male subdues her resistance. In cases where the female drives the male away, he leaves without singing (134). The quietness of song may be important in minimizing interspecific interference by a close relative in the vicinity (Greenlaw in 162).
Experimental broadcast of Complex Whisper Song and other vocalizations during prebreeding, breeding, and postbreeding periods neither increased settlement rates at sites with few birds, nor did it alter nest placement patterns within marshes with high densities of nesting birds, suggesting that song is not used for conspecific attraction during spring settlement (40).
Little published information available apart from that in Woolfenden (10) and Post and Greenlaw (156). Most of the following based on unpublished observations (JSG). Repertoire as now known consists of 7 calls. Calling is infrequent in both sexes, but females utter calls more often than males. Adult female call repertoire is apparently more varied (5 calls) than that of adult males (3 calls), but some may be used very rarely in one sex and easily missed. The known call repertoire of this promiscuous species is significantly smaller than that of the closely-related Seaside Sparrow (156), but perhaps not smaller than that of Acadian Nelson’s Sparrow (JSG, unpublished data).
Tuc (Chic) call. See Figure 9. Earlier transliterated as “Chic” (127), but simple “Tuc” seems more apt. Short, single, soft, toneless vocalization, given only by female so far as known. The only syntactical distinction of the call is an opening plosive element that is rendered here as “t” or “ch.” Woolfenden (10) thought males might give it rarely, but not yet documented. Females employ call in social context associated with defense of young (“mobbing”) and in agonistic encounters with males (rarely with females, WP). Call repeated in series of single notes on ground or in flight. Used most routinely when female leaves or approaches (less commonly) nest when brooding or feeding young (see also W. DeRagon in 164). Nest departure calling is widespread in female songbirds, but it is rare for the behavior to be primarily used or restricted to late nest cycle (164). The female is most conspicuous when provisioning nestlings as she flies on long commutes to feeding sites. Any time a female is exposed, males that spot her converge and interact with her (see Sexual Behavior). JSG and WP witnessed some males breaking off aerial chases and swerving away when female initiated the call during flights. The departure call in this species during late stage nesting may be recognized as a sex-specific signal by an unreceptive female that is likely to be very defensive. This call variously rendered in other sources as “chip” (140, “tsick” or “tsuck” (10), “cup” (113), or “chuck” (156).
Tic call. See Figure 9. A single, moderately high-pitched, sibilant note, usually repeated in a series after distinct pauses. Most often associated with Tuc call in “mobbing” contexts near nests, or uttered once or twice when surprised before suddenly fleeing. Given from perches by female only, so far as presently known. Similar call in same contexts given by Seaside Sparrow (156) and many other emberizids (JSG, unpublished data).
Tic-twitter. A short series of tic notes (to which it may be related as a high intensity version of single tic calls) uttered as a moderately high-pitched chitter. Given by both sexes. Usually associated with strong ‘fear’ situations when hiding or sudden escape is necessary, as in the approach of an aerial predator (e.g., appearance of Northern Harrier, Circus hudsonius) flying towards sparrow, or sudden appearance of low-flying Red-winged Blackbird (Agelaius phoeniceus) that evidently startles an exposed bird. Perhaps functions as predator or danger alert in prefleeing and fleeing contexts. Similar to “Si twitter” of Seaside Sparrow (156).
Cee-lisp. See Figure 9. A single, weak, high-pitched call containing a double band of frequencies (fundamental and overtone), penetrating and ventriloquial in quality, carrying short to moderate distance. Used by both sexes during annual cycle on breeding and post-breeding (autumnal) grounds. Often employed by local birds gathering in late summer and fall in loose feeding groups, and by migrants during fall stopover (156), but not yet confirmed on overwintering grounds (WP), although likely to occur. Evidently serves a social contact function. In breeding season, sometimes uttered by female during sexual chases by male, and by solitary males shortly after spring arrival on breeding grounds. In all contexts, call also may carry message of subordinance.
Chic call. See Figure 10. An abrupt sneeze-like vocalization, given only by female. Woolfenden (10) thought males might give this call rarely, but no instance of male use has been documented. Females employ the call in social contexts associated with defense of young and during food provisioning when disturbed and in agonistic encounters with males (rarely with other females [WP]). Call given singly or repeated in a spaced sequence on ground or perch, or in flight (10). This call variously transliterated as tsick or tsuck (10), chuck (156), chip (140), cup (113), or chup (A. Spencer, personal communication).
Scream. See Figure 9. A short, single or doubled call, harsh and low-pitched, transliterated as zhree (zhree-zhree) or zhraa, usually 1 s or less (single call) in duration. Somewhat variable in frequency structure. Uttered by both sexes, but usually by female, in agonistic and sexual encounters, and when handled. Perhaps strong defensive threat function in adults. “Squealing distress call” reported by Woolfenden (10) in 7-d-old nestlings during handling may be this call.
Nestling call. Very weak and high-pitched lisps uttered by young nestlings (first several days of age) as they stretch neck upward and gape when female at nest with food. Often barely audible to human ear at nest, and inaudible more than 1 m from nest. Transliterated as peep (10) or seep (JSG). At age 0–1 d, given frequently as single note, but a doubled version appears on day 2 (10). Call evidently functions in sibling competition for food in soliciting context.
“Reedy” call. A quiet note reported by Woolfenden (10) in nestlings 7 d and older. This call evidently replaces the weak seep call of younger nestlings and may serve a similar function.