Sounds and Vocal Behavior

The below pertains to the Hawai'i 'Akepa, unless otherwise noted. Presumably, the Maui 'Akepa is similar.

Development

Poorly known. Young Hawai‘i males in the spring of their second year, even before acquiring any adult plumage, have been observed to give songs that are not distinguishable by ear from those of adult males.

Fledgling has faint, nasal gnee or nee call for a few days after leaving nest. Juvenile has a distinctive, down-slurred mewing zeer or djeer call (see Figure 5A) during dependent period, particularly when soliciting food from parents. This call differs from intense buzzing calls that juveniles give when actively begging for food and being fed. Juvenile calls are the most conspicuous and characteristic sounds of postbreeding flocks. Juvenile begins to give typical adultlike calls while still dependent on parents; adultlike calls more frequent toward end of dependent period. After independence, 2–3 mo after fledging, gives adultlike calls. Juvenile call of ‘Akepa differs dramatically from that of juvenile Hawai‘i Creeper, which is a stuttering de-de, de-de-de.

Vocal Array

Song. Song of Maui 'Akepa is described as resembling that of Hawai‘i birds (Engilis 1990). Male song on Hawai‘i I. is a high, descending trill, lasting 2–3 s; each repeated element rises and falls, giving a lilting effect (see Figure 5B). Descending quality of song distinctive in field, but not pronounced on sonograms, and probably caused by decreasing volume:

TEEEDLEleeedle, le^ee dle; le^ee dle, _{le^ee dle}

Closest to song of Hawai‘i Creeper, which has a dry, monotonically descending trill without the ups and downs of Hawai'i ‘Akepa song. ‘Amakihi species have loud, ringing, even-pitched trills that also lack ups and downs. Maui ‘Alauahio has very different song, a jumbled warble longer than Hawai'i ‘Akepa song and rarely repeated in sequence. Song may resemble that of Maui ‘Alauahio, as does its call (Shallenberger and Pratt 1978). Some variation among and within individual males. Only male gives primary song, but one female gave a softer version of song while incubating in nest; this sounded like a distant singing male (JKL). Songs described in more detail and additional sonograms presented in Scott et al. (1979) and Pratt (1989); recordings available in Pratt (1996).

Whisper Song. Like many Hawaiian honeycreepers, Hawai'i ‘Akepa has extended, soft vocalizations that are widely referred to as “whisper songs” (see medialink) and do not appear to be typical subsongs. Whisper Song characterized by short repeated notes and mimicry of other species' calls, but usually includes only Hawai'i ‘Akepa songs. Given by adult males and females, usually while perched motionless, but occasionally while foraging (JKL). May continue for several minutes without pause. Function and social context poorly understood, but has been reported in association with bathing, courtship, and copulation in ‘Anianiau (Eddinger 1970). First reported in ‘Hawai'i Akepa by Perkins (1903), who believed it to be given only by females.

Calls. Adult calls consist of short, frequency-modulated whistles that sound as if they have 1–3 notes (Pratt 1989), similar to a rising sweet, keewee, or teedle-lee (see Figure 5D). Perkins (1903) reported only 2-note calls for all islands, and mentioned that O‘ahu and Maui ‘Akepa calls were identical. Gives all 3 call types frequently while foraging (JKL). Female gives rapidly repeated pairs of 2-note and 3-note calls (e.g., keewee-keewee) during incubation when soliciting food from her mate (JKL); these calls usually are in response to typical calls from male. Female may give rapid peeping calls when soliciting copulations, and rapid hissing calls during copulation (see Behavior: sexual behavior, below). Rapid seet calls given as alarms in response to aerial predators; alarm calls similar to those of other Hawaiian honeycreepers (JKL). Single-note call sometimes indistinguishable from that given by Hawai‘i Creeper, but is usually “sweeter”; 2-note and 3-note calls distinctive. Hawai‘i Creeper call typically a “drier,” harsher cheek or sweek. ‘Amakihi call typically a buzzy zee or jee-yee. Call of Maui and O‘ahu ‘Alauahio a loud, dry chip or chick. See also the discussion of vocalization development, above.

Phenology

Male sings throughout year and during all weather except heavy rain. Overall singing rates peak Feb–May (Ralph and Fancy 1994a). Frequency of Song Bouts with other males (see Behavior: Agonistic Behavior) peaks in Oct–Feb during lengthy prebreeding competition (Lepson and Freed 1995). Whisper Song most frequent Sep–Oct as prebreeding competition begins, and absent or nearly so May–Jul as nesting ends and flocking begins (JKL). Calling rate does not vary through the year (C. J. Ralph unpubl. data).

Daily Pattern Of Vocalizing

Male sings throughout day. Songs are more frequent just after sunrise and before sunset, but there is no pronounced “dawn chorus” as in many continental species. Both sexes call throughout day, with no obvious temporal pattern. No song or calls at night.

Places Of Vocalizing

Male sings most frequently while perched, usually in upper canopy. Also sings while in flight. Songs frequently given as part of hopping Arboreal Display and during Aerial Display. The only female known to sing did so while on nest.

Repertoire And Delivery Of Songs

Repertoire poorly known. All songs similar, but variation occurs between and within individuals. Variation appears to be due primarily to frequency modulation, occasionally changing tempo within songs.

Social Context And Presumed Functions Of Vocalizations

Song given in variety of situations. Paired and unpaired males sing alone, in pairs, and in flocks. Function of song imperfectly known. Male may sing near other males without any apparent reaction, particularly while foraging in mixed-species flocks. Male sings both from perches and in distinctive fluttering or “whirring” flight with rapid, silent wing beats; songs do not sound different in these 2 contexts (JKL). Hawai‘i ‘Akepa is not territorial, but often countersings with other males, particularly during competitive season (Oct–Mar). Song Bouts consist of several males simultaneously singing during competitive season (Lepson and Freed 1995). In addition, songs are frequently and vigorously given in premating competitive Arboreal and Aerial displays by groups of males. Only one female observed to sing during a 6-yr study; function of song in female unknown.

Juvenile call presumably functions to get attention of and maintain contact with parents. May also be given as a sign of subordinance: One older hatch-year bird gave adultlike calls, but switched to juvenile calls after an aggressive interaction with the larger and behaviorally dominant ‘I‘iwi (Drepanis coccinea ; JKL).

None known.