Apapane are small at when fully grown. There is distinct sexual dimorphism in size: male apapane have a mass of, while females average. Adult apapane are bright crimson and have distinct white undertail-coverts and lower abdomen. 'Apapane are often seen with a tail-up posture, showing off their white feathers.
Song
'Apapane are active singers. There is a lot of variation in calls and songs, but phrases are often repeated. They are known to sing at a perch for 10-30 second intervals, and their song may include repeated squeaks, whistles, rasps, melodic trills, and clicking sounds.
Diet
Apapane are often found in the outer canopy of ōhia trees feeding on nectar. They also glean insects and spiders from leaves and small twigs in the canopy; they do not forage on the ground. In 1953, a study of 63 'apapane found that 87% of them had butterflies and moths in their stomachs; 75% had eaten hoppers ; 60% ate lacewing larvae ; and 43% had recently consumed spiders. Other native trees 'apapane use for foraging are māmane, koa, naio , kōlea '', alani, kanawao, koki'o ke'oke'o, and 'ōlapa.
Breeding
The breeding season starts in Oct/Nov and peaks February through June. Apapane nests are often on the terminal branch of ōhia ; nests have been found in tree cavities and lava tubes as well as in the top of koa, kāwau and hapuu. The female lays 1-4 eggs and incubates for 13 days. Interestingly, during incubation the male does not visit the nest but will feed the female when she is away from the nest. While the female does not sing or call from the nest, she locates her singing male and begs for food. Once the eggs hatch, nestlings are fed by both parents. Young 'apapane are dependent on their parents for less than 4 months.
Habitat and Distribution
Apapane are found in high-elevation native mesic and wet forests dominated by ōhia and koa trees. Their range is extensive and their densities change as they move around in search of flowering ōhia. They are detected at low elevations on most islands, however, most apapane are found at elevations above, where there are fewer mosquitoes. 'Apapane live on the islands of Hawaii, Maui, Kauai, Molokai, Oahu, and Lānai. Their populations are stable and are considered a species of least concern by IUCN.
Threats and Conservation
The main threats for 'apapane are habitat loss, disease and the introduction of alien species. ‘Apapane can be found on all of the main Hawaiian Islands except, Niihau and Kaho’olawe, where it is primarily found at high elevations where rates of avian malaria are comparatively low. The species is also threatened by non-native mammalian predators like Small Indian Mongooses, Rats, and . ‘Apapane are the most abundant honeycreeper species with the largest range. The total population has been estimated at more than 1.5 million individuals with the largest populations on Hawaii and Maui Islands. The species has the highest reported prevalence of avian malaria but mortality is lower than most other honeycreeper species. This may be in part because seasonal migrations to lower elevation forest put it in contact with mosquitoes, which are less common at higher elevation. Malaria is a bloodparasite, and death is usually cause by anemia, the loss of red blood cells. Like other honeycreepers, fowlpox may also be lethal to ʻapapane, which, like avian malaria, is transmitted by mosquitoes. Fowlpox causes wart-like lesions to form around the bird's eyes, beak, legs, or feet, inhibiting feeding, seeing, or perching. It is believed that at least a small portion of the population is becoming resistant to malaria, as some pairs have been seen breeding in mid-elevation forests, ~300m, where the rate of malaria transmission is high. Today there are no direct actions being taken concerning this species, however anything that is being done to help rarer species of birds throughout Hawaii will also help the apapane. Organizations throughout the islands have established nature reserves to protect native habitat. Fencing off sections of land to keep out feral ungulates, especially pigs, goats and axis deer enables native plants to recover from overgrazing and ungulate damage and helps restore native bird habitat. In recent years another threat has put native bird habitat at risk. Conservation groups are diligently working to reduce the risk of spreading a disease called Rapid ʻŌhiʻa Death. This disease along with ōhia dieback and ōhia rust could lead to a rapid decline in ōhia forests, an important nectar source for apapane.
