Behavior

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

Not observed to come to ground. Hops on branches. Flight direct. Male has more rapid, silent, whirring wing beats while singing in flight. During prebreeding competition, groups of males have Aerial Displays ranging to 100 m above ground with dogfights involving ≥2 individuals in twisting or circular chase flights (Lepson and Freed 1995 ).

Preening, Head-Scratching, Stretching, Bathing, Anting, Etc

Scratches head by bringing foot up over wing. Characteristic drepanidine odor may be distributed by preening, since it seems strongest around uropygial gland (Pratt 1992 , JKL). Not observed to ant (no ants native to Hawai'i; Howarth and Mull 1992 ) or bathe, possibly because of abundant rainfall in habitat.

Sleeping, Roosting, Sunbathing

Poorly known. Active until nearly dark. 'Akepa in one large mixed-species flock stopped foraging and settled on subcanopy branches at dusk (S. Fretz and P. Hart pers. comm.). Sunbathing not observed, but likely occurs, since it has been observed in 'Akiapo¯la¯'au (Hemignathus munroi ) at Hakalau Forest NWR (JKL).

Daily Time Budget

Not quantified. Appears to feed nearly constantly when not involved in agonistic displays. Rarely still during day, except when incubating and brooding.

Physical Interactions

Generally tolerant of conspecifics. Most agonistic interactions occur in context of prebreeding competition from Oct through Mar. Male aggressiveness peaks during Feb, just before start of nesting season (Lepson and Freed 1995 ). Few overt signs of dominance or aggression aside from prebreeding competition. Adult males seen to displace subadults, but not vice versa (Lepson and Freed 1995 ).

Prebreeding competition consists of countersinging and lengthy Song Bouts, chases (often involving several individuals), Grappling Fights, and Arboreal and Aerial displays by groups of males (Lepson and Freed 1995 ). Grappling Fights take place in tree canopies: males scratch and bite each other while giving loud, rapid sweet or chweet calls, occasionally falling to the ground. Arboreal Display consists of several males rapidly singing and making fast, short, bouncing hops in canopy of a tree, usually with a female visible nearby. Aerial Display consists of up to 8 or more males singing and chasing each other in twisting dogfights in groups as high as 100 m above ground (Lepson and Freed 1995 ). Possible similar display involving 2 males seen once on Maui (Perkins 1903 ).

Possible Threat Display observed once between 2 males, who slowly hopped back and forth in front of each other, similar to Arboreal Display or Courtship Display (see Sexual behavior, below), but much slower and entirely silent. This display continued for >30 min in late afternoon, until observer had to leave; display observed again the next morning. Shortly after this interaction, one of the males disappeared, and his mate then paired with the other male (Lepson and Freed 1995 ).

Communicative Interactions

During competitive season, Oct–Mar, males frequently countersing and engage in Song Bouts, characterized by >2 males simultaneously singing vigorously in close proximity (Lepson and Freed 1995 ).

Territoriality

Male does not defend all-purpose territories or nest sites in order to attract female, but appears to practice roving mate defense (Lepson and Freed 1995 ). Breeding pairs frequently reuse nest cavities from year to year. One pair at Hakalau Forest NWR used the same cavity 5 yr in a row, until the tree fell. Some cavities have been used by ≥2 pairs in 6-yr period (JKL).

Individual Distance

Individuals frequently forage near each other without apparent interaction, particularly when in flocks (see Social and interspecific behavior, below). More than 40 individuals may feed in same tree, often within 25 cm of each other, but distances not quantified. Outside of flocks, typically found alone, ≥10 m apart; pairs typically forage within 1–2 m of each other (JKL).

Mating System And Sex Ratio

Socially monogamous with long-term pair bonds (Ralph and Fancy 1994b , Lepson and Freed 1995 ). Pairs very rarely have ≥1 nesting attempt per year; the few pairs observed remained together for both attempts.

Strongly male-biased sex ratio of approximately 2:1 has been suggested by museum collections (Amadon 1950 , Hatch 1985 ), but field studies at Hakalau Forest NWR indicate a much more even sex ratio. Museum collections probably biased because bright males more likely to have been noticed and collected. Sex ratio more even when calculated either from net captures or from local population estimates provided by demographic computer program JOLLY (Brownie et al. 1986 , Pollock et al. 1990 ), which utilizes recaptures and resightings of banded birds to provide unbiased population and survival estimates. Sex ratio (male: female) over 6 yr averaged 1.14:1 (range 0.88–1.39; Lepson and Freed 1995 ) by the JOLLY method. Birds banded as juveniles and later sighted or captured as adults yielded 12 males and 10 females (1.2:1 sex ratio; Lepson and Freed 1995 ). Sex ratio based on total net captures was also 1.2:1 (n = 106; JKL).

Pair Bond

Duration and Maintenance of Pair Bond. Pairs apparently begin to form in mixed-species flocks during summer months. Males and females seen together in flocks often remain paired and mate in the following nesting season. Most pairs maintain long-term bonds, frequently over several years (7 pairs at Hakalau Forest NWR nested together for at least 3 yr in sample of 12–16 nests/yr). Some pairs remain together throughout year, but others have been seen to join separate postbreeding flocks and resume their association after the flocks break up (JKL). Most individuals nest together for several breeding seasons and acquire a new mate only after the old one disappears, but 1 pair seen to break up and change mates (JKL, contra Ralph and Fancy 1994b ).

Courtship Displays and Copulation. Courtship Display similar to that of other Hawaiian honeycreepers (e.g., Hawai'i 'Amakihi; van Riper 1987 ). Most frequently, male gives rapid 1-note calls while quickly hopping back and forth in front of female in tree. Occasionally male will hop to and from female or turn 180^o to left or right while hopping in place. Copulations infrequently seen and rarely observed well. Soliciting female gives high-pitched peeping calls unlike any other 'Akepa calls. In one well-observed copulation, female held piece of nesting material in her bill during copulation, and male quickly mounted her 3 times, the last time the longest. After copulation, female dropped the nesting material, then preened male's face for 10 s, and shortly thereafter entered nest 25 m away (JKL). A different pair was observed to give a hissing vocalization during copulation (JKL), and the female of a third pair briefly mounted the male after copulation at nest entrance during nestling stage (E. A. VanderWerf pers. comm.). Groups of males have been seen in vicinity of nests during presumed fertile period of female (JKL, LAF).

Extra-Pair Copulations

None observed. One possible attempt observed: An extra-pair male performed Courtship Display in front of a female constructing a nest. He then appeared to attempt to mount her, and both fell out of the tree in a Grappling Fight (see Agonistic behavior, above), grasping each other with their talons and falling halfway to the ground before separating (JKL).

Degree Of Sociality

Gregarious during postbreeding flocking season Jun–Oct, when >40 individuals may be found in a single flock. Flocks form around family groups with dependent offspring, but nonbreeders and unsuccessful breeders also join (Lepson and Freed 1995 ). Remainder of year, typically in pairs or alone, except for group displays by up to a dozen males during prebreeding competition (see also Agonistic behavior, above).

Play

No information.

Nonpredatory Interspecific Interactions

Observations by JKL, unless otherwise noted. Usually the most common species in interspecific flocks with endangered Hawai'i Creeper and smaller numbers of Hawai'i 'Amakihi and endangered 'Akiapo¯la¯'au. Most flocks contain 20–30 individuals and occasionally up to 80 individuals; once at Hakalau Forest NWR in summer of 1994 a "superflock" with >100 birds was observed (P. Hart pers. comm.). Typically little interaction between species, but call notes very similar, which may assist in flock cohesion. Responds strongly to aerial predator alarm calls of 'Elepaio (Chasiempis sandwichensis ), which appears to serve as a sentinel species.

Regularly chased or displaced by aggressively dominant and variably territorial 'I'iwi, even though foraging niches and dietary items overlap little or none. Also chased by occasionally territorial 'Apapane and territorial Hawai'i 'Amakihi. One adult female observed making unsuccessful attempt to solicit food from male Hawai'i 'Amakihi, which was feeding fledglings. Juvenile 'Apapane sometimes approach 'Akepa while latter are feeding fledglings; occasionally solicit as well. 'I'iwi and 'Apapane have been observed to enter cavities of active 'Akepa nests, but have not been observed to steal from 'Akepa nests; however, they are known to steal nesting material from nests of other species (Eddinger 1970 , JKL).

No specific information on effects of predation on 'Akepa, but predation by rats (Rattus spp.), cats (Felis catus ), and Barn Owls (Tyto alba ) has been inferred or documented to have serious effects on many native Hawaiian forest birds (Munro 1944a , Atkinson 1977 , Snetsinger et al. 1994 ). See also Demography and Populations: Causes of Mortality.