SPECIES

Canada Warbler Cardellina canadensis

Len R. Reitsma, Michael T. Hallworth, Marissa McMahon, and Courtney J. Conway
Version: 2.0 — Published May 7, 2020

Sounds and Vocal Behavior

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Vocalizations

Development

Juvenile

Young observed chipping or squawking after being force-fledged (164; A. J. Erskine, unpublished data). Fledglings produce high-pitched chip calls when alone or accompanied by parents (A. Demko, personal observation). No data on early vocal learning.

First-year Breeders

Males believed to be closed-ended learners, where song learning is restricted to the first year of life. Upon arrival at first breeding territories in New Hampshire in late May, first-year breeders (second-year males) sang uncrystallized songs and subsequently modified song elements over the course of the season to match songs of neighboring older males by late June (165). Older (after-second-year) males, whether they were new or repeat territory holders, did not modify song elements in this way (165). Both second-year and after-second-year males added or dropped phrases (series of song elements) from their active repertoires between seasons depending on whether neighboring males used them (165).

No information on early song development; unknown whether phrase adding or dropping between seasons results from differential use of the repertoire learned in early life, or continued male learning of new elements after the first year.

Vocal Array

Songs

Broadcast Song. Clear, loud, distinctive broadcast song consists of 1 chip (rarely 2) followed by an abrupt, explosive series of elements that often ends with a 3-note phrase (94, 166, 97, 167). Described as "chip chupety swee-ditchety" or "chip, suey de swee-ditchety" (2), "chip, chippery, chippery, chippery, chee-the-chee" (168); always a distinctive pause after the initial chip(s).

Broadcast song is highly variable. Males do not have discrete song types; instead, they have repertoires of song variants (unique sequences of elements) composed of phrases (series of 1–7 song elements always sung in succession) used in multiple variants (167). Modal frequency of song was 4.66 kHz (range 2.58–7.93) for 16 birds in New Brunswick (166). Mean duration was 1.51 s in New Brunswick (range 1.25–2.6 s, n = 16 birds, 23 songs: 166) and 1.15 s in New Hampshire (range: 0.03-2.98 s, n = 59 males, 4,600 songs: 167).

Flight Song. Males reportedly have a flight song (variable warble containing elements of normal song, but more prolonged) given during rising flight on slowly flapping or quivering wings with direct and silent descent (14, 169). In New Hampshire, singing in flight occasionally observed during dawn chorus as males flew between perches while singing (A. Demko, personal observation).

Singing Modes

Males use two singing modes as in Setophaga, Vermivora, and Mniotilta species (170), but are unique among wood-warblers in that most phrases and song variants within a male’s repertoire occur in both singing modes. Mode I, used primarily during daytime singing by unpaired males or by paired males near females, consists of loud broadcast song. Mode II (Figure 4), used primarily during dawn singing by paired males or during daytime male-male interactions at territory boundaries, consists of loud broadcast songs which often contain low-frequency, low-amplitude phrases not used in Mode I songs. Each male in a New Hampshire population had 1–3 Mode II-only phrases in his repertoire of 7–16 phrases. The elements in Mode II-only phrases are structurally similar to other Canada Warbler broadcast song elements. In Mode II, males sing at a higher rate, use more different variants, and have more variable singing rhythm than in Mode I, and also produce chip calls continuously between songs (Figure 3; 167).

Calls

Both sexes give subdued chip (or tschip, tsik), and a loud, sharp check or chip alarm call (see Figure 5), and a high-pitched zzee in flight (11, 2, 16). Males have repertoires of 6–13 chip calls only produced between songs during Mode II singing, many of which are shared with neighboring males (167; A. Demko, unpublished data).

Comparison of Sexes. Only males sing, whereas both sexes produce calls. Male chip calls are often audibly louder and sharper than female calls (A. Demko and LRR, personal observation). One record of a female-plumaged bird singing on 9 June 2000 in Virginia (171).

Geographic Variation

No information on range-wide patterns such as song dialects, but some evidence of local song similarity among males. In a New Hampshire population with < 2 km between all territories, males clustered into song neighborhoods, where groups of males with adjacent territories shared many song and phrase types (165).

Phenology

Males sing frequently throughout the breeding season until mid-July (94, 86, 167). Unpaired males sing in Mode I throughout morning during early territory establishment. Paired males use Mode II during the dawn chorus, with sporadic daytime bouts of Mode I (during early pairing, incubation and when near the female) and Mode II (during offspring provisioning and male–male interactions; 167).

Daytime singing activity varies according to male’s breeding status: it is highest prior to mating and after nest failure, intermediate during incubation and post-fledging, and lowest during building, egg-laying, and offspring provisioning (167). During 10 min observation periods, males (n = 35) sang during 94% of visits while unpaired and 100% of visits after nest failure, but during only 71% of incubation visits, 64% of post-fledging visits, 44% of building and egg-laying visits, and 43% of offspring provisioning visits (167). During molting in mid-July, males sing infrequently (during < 50% of visits; 167), and song elements are less stereotyped (A. Demko, personal observation).

Males observed singing after molting, and during spring and fall migration (13, 95, 14, 60). Occasional singing observed on wintering grounds in Ecuador (L. Reitsma et al., unpublished data).

Daily Pattern of Vocalizing

Dawn and Dusk Chorus

During the breeding season, males sing a dawn chorus beginning ~40 min before sunrise. The dawn chorus averages 40–70 min long with frequent chip notes between songs; males occasionally pause for < 5 min between singing bouts when changing perches, but typically sing continuously (A. Demko, unpublished data). Average dawn song rate for males in New Hampshire (n = 38) was 18.1 ± 0.8 songs/min (167). In New Hampshire, males began singing full dawn chorus on 22–24 May, 12–14 d after first males established territories, and 8–10 d after first females arrived. Dawn chorus abbreviated or absent after 1 July (A. Demko, unpublished data).

Dawn song is almost exclusively Mode II. In the New Hampshire population, two unpaired males and one paired male with a recently failed nest sang dawn chorus in Mode I (167). After the dawn chorus, unpaired males switch to Mode I immediately, whereas paired males are largely silent post-dawn with sporadic Mode I or II singing (A. Demko, unpublished data).

Males also sing a dusk chorus of Mode II songs interspersed with chips during the breeding season (167).

Daytime Singing

Singing activity peaks at dawn and dusk during the breeding season, but males also sing persistently throughout the early and mid-morning. During 10 min observation periods (n = 35 males), 100% of males sang before sunrise and 67–71% sang 0–4.5 h after sunrise, but only 44% sang 4.5 h or more after sunrise (167). Males are typically silent in late morning or afternoon, aside from infrequent Mode II song bouts during male-male interactions at territory boundaries (A. Demko, unpublished data).

Daytime singing of males varies according to their pairing status. Unpaired males sing continuously throughout morning in Mode I. Paired males sing intermittently in the morning, primarily in Mode I during nest-building, egg-laying, incubation, and after nest failure, and in Mode II during offspring provisioning and post-fledging (167).

Daytime singing also varies according to presence of conspecifics. Mode I is more often used by males near a female mate or when alone, whereas Mode II is more often used during male-male interactions with territorial neighbors or intruders (167). Some males observed perched < 1 m apart using soft (low-amplitude) songs in male-male interactions during early-season territory establishment (A. Demko, personal observation); not known if these soft songs communicate aggression as in other wood-warbler species (172).

Daytime song rate depends on the singing mode used; Mode I bouts average 5.7 ± 0.2 songs/min, whereas Mode II bouts average 13.8 ± 0.7 songs/min (167).

Places of Vocalizing

Males generally sing from low perches within territory (97, 155); 1–10 m above ground in New York, usually from exposed perches (173). Most frequently sing from exposed perch in tree emerging from subcanopy in New Hampshire, especially early in the breeding season and during the dawn chorus (A. Demko and LRR, personal observation). Relatively little flight during singing bouts compared to other warblers; based on observation of 30 flights of singing males, mean interval between flights during singing bouts was 20.4 s, and mean flight duration 0.6 s (28).

Females sometimes give several chip calls upon leaving nest during incubation. Parents give chip or alarm calls near nestlings and fledglings during actual or perceived threats (A. Demko and LRR, personal observation). One male did not sing while following incubating female during periods off nest but sang continuously while female was sitting on eggs (160).

Repertoire and Delivery of Songs

Song is variable among individuals and varies greatly within the same bird (94, 14). Least repetition and greatest number of elements/individual song (12.2) among 19 warblers examined (166). Males have complex repertoires of 70.5 ± 32.2 song variants, each composed of 3.8 ± 1.6 phrases. Most phrases are used in both Mode I and Mode II singing; however, each male uses 1–3 phrases, out of his total repertoire of 7–16 phrases, exclusively in Mode II singing (167).

Social Context and Presumed Functions of Vocalizations

Singing Modes

Males use both singing modes to advertise presence on the territory; however, Mode I and Mode II predominate in different contexts and likely have different functions. Mode I apparently serves in male-female communication: it is used by unpaired males throughout the day, and by paired males near a female. It is also the dominant mode used by paired males during daytime singing from early pairing through incubation, when most females in the population are fertile. Mode II likely functions in male-male communication: it is used by paired males during dawn chorus singing, and during interactions with neighboring males or intruders at territory boundaries (167). Experimental tests of male responses to each singing mode, and of male singing behavior near both male and female conspecifics, are necessary to compare the functions of the singing modes.

Song sharing may provide benefits for territory establishment, defense, and long-term tenure. Males who shared more song variants (i.e. whole songs) with other males held breeding territories at the site for more years than males with low song sharing. First-year breeders also modified song elements to more closely match songs of older neighboring males, suggesting a benefit to song matching. There was no association between song sharing and reproductive success within a season. However, both pairing success (91%) and fledging success (75%) are high in the study population, so factors other than song (e.g., availability of high-quality territories) may impact a male’s reproductive success (165). Experimental studies are necessary to examine how males use shared songs when interacting with other males, and whether use of shared songs during male–male interactions confers benefits for territory defense.

Call Notes

Agitated chips, frequently observed in response to human presence in territory or near nest (94; A. Demko and LRR, personal observation), may function to alert mate of potential danger. Chips of both sexes occasionally given during incubation when female is off nest probably communicate location to mate.

Nonvocal Sounds

Whirr of wings and loud snap of mandibles audible when pursuing flying insects during foraging (2, 160).

Recommended Citation

Reitsma, L. R., M. T. Hallworth, M. McMahon, and C. J. Conway (2020). Canada Warbler (Cardellina canadensis), version 2.0. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.canwar.02