Tuesday, November 23, 2010

This Week in Nature: The 4th week in November: 'amakihi

What's Happening in Hawaii
during the 4th week in November:

Starting this week, 'amakihi are starting to nest in high, native forests on the island of Hawai'i. Although breeding at this time of year is unusual for Hawaiian birds, 'amakihi and nēnē have both developed this behavior. Perhaps there is a greater availability of food available during the rainy season.

The Hawai‘i ‘amakihi (Hemignathus virens) is a small generalist Hawaiian honeycreeper (Family: Fringillidae) that occurs on the islands of Hawai‘i, Maui, and Moloka‘i. Until 1995, the Hawai‘i ‘amakihi, and the O‘ahu 'amakihi (H. flavus) and Kaua‘i ‘amakihi (H. kauaiensis) were considered a single species: the common ‘amakihi (H. virens).

Plumage of all species is similar; males are yellow-green to olive in color, and females are generally similar, but duller. All have decurved bills.

Hawai‘i ‘amakihi are generalized foragers that most often glean arthropods from the leaves, blossoms, twigs, branches, and less frequently from tree trunks of a variety of trees, ferns, and shrubs. This species feeds on nectar predominately from the flowers of ‘ōhi‘a (Metrosideros polymorpha), māmane (Sophora chrysophylla), and native lobelias (Campanulaceae), but also forages on flowers of a number of other native and non-native plants. Hawai‘i ‘amakihi also eats fruit from native and non-native plants, but predominately from pilo (Coprosma spp.).

Hawai'i 'amakihi forages alone, in pairs, in family groups, or in mixed flocks. Courtship behavior is somewhat complex and includes courtship chases, advertising displays, and courtship feeding. Pairs will remain together for successive breeding seasons. The pair selects a nest site, the female builds an open-cup nest, then lays two or three eggs. Only females incubate eggs and brood nestlings. Males deliver food to females who then feed nestlings. Fledglings are dependent on parents for up to three months. The Hawai‘i ‘amakihi usually raise two broods in a season.

Drawn images taken from "Hawaii: A Calendar of Natural Events" 
published by Bishop Museum and Kamehameha Schools in 1989
For more info about 'amakihi, and to see photos, visit the Hawaii Comprehensive Conservation Strategy forest bird fact sheets.

Or click on the names below:

Tuesday, November 16, 2010

This Week in Nature: The 3rd week in November - Humpback Whales

What's Happening in Hawaii 
during the 3rd week in November:
Humpback whales are now beginning to arrive for their annual, five-month stay in island waters. Humpbacks come to calve, and preferring warm, sheltered water for this purpose, they can often be seen from shore. Arrivals can increase in December and January, with the peak population being reached in February, when much of the calving occurs. 

At least a few humpbacks winter near each of the main islands, but they can be found in greatest numbers in the enclosed waters off Maui's southern flank and over a shallow bank west of Moloka'i.

Of the several hundred adults present, perhaps 30 will bear calves, and some will also mate before setting out in April or May for their summer feeding grounds in the North Pacific. Humpbacks are known for underwater song, and their music evolves while they are here. New themes are started and old ones dropped, so that they leave with a different song than they brought. 

To see a video of singing whales, visit the Whale Trust.org Humpback Whale Song site. This site also answers many frequently asked questions about whale songs.

Visit the Discovery Channel webpage to hear Humpback whale songs as well as noises from other interesting creatures. (You may need Quicktime, RealPlayer or Windows Media player to access these audio files. DOFAW is not affiliated with Whale Trust or the Discovery Channel.)

Want to learn more about the Humpback's migration? Visit the NOAA Hawaiian Islands Humpback Whale National Marine Sanctuary site to play a fun migration game.

If you'd like to volunteer your time and join others to watch and count whales this winter, visit the NOAA Humpback Whale Sanctuary Ocean Count Volunteer page.

Natural history info and image taken from "Hawaii: A Calendar of Natural Events," 
published by the Bishop Museum and Kamehameha Schools in 1989.

Wednesday, November 10, 2010

This Week in Nature:The 2nd week in November - Nene

What's Happening in Hawaii 
during the 2nd week in November:

Nēnē, the Hawaiian goose (Branta sandvicensis), begins nesting on the upper slopes of Haleakalā, Hualālai, and Mauna Loa. Historically, at least five species of geese (family: Anatidae) occurred in Hawai‘i; today, only the nēnē, or Hawaiian goose, survives. Adult males and females are mostly dark brown or sepia with a black face and crown, cream-colored cheeks, and a buff neck with black streaks. Females are smaller than males. Compared to other geese, nēnē are more terrestrial and have longer legs and less webbing between their toes; these differences likely facilitate nēnē walking on lava flows.

Nēnē, Haleakalā National Park, Maui.
Photo by Forest & Kim Starr

Nēnē pairs mate for life. Nēnē have an extended breeding season and eggs can be found all year except May-July, although the majority of birds nest between October and March, and most clutches are laid between October and December. Nēnē nests consist of a shallow scrape, moderately lined with plant materials and down. Pairs typically return to previous years’ nests sites, typically in dense vegetation; when available, kīpuka may be preferred. Females lay between two and five eggs which hatch after 30 days. Young are not fed by their parents; however, young remain with their parents for up to one year.

Nēnē, Haleakalā National Park, Maui.  
Photo by Forest & Kim Starr 

In 1951, the wild nēnē population was estimated at 30 individuals. Current population is estimated at between 1,300 and 1,500 individuals with 378 birds on the island of Hawai‘i, 295 to 325 birds on Maui, 720 birds on Kaua‘i, and 74 birds on Moloka‘i. All populations have been or are currently being supplemented by captive-bred birds.

Historical threats included habitat loss and degradation, hunting, and predation by rats (Rattus spp.), cats (Felis silvestris), dogs (Canis domesticus), and the small Indian mongoose (Herpestes auropunctatus). Current threats include predation by the non-native mammals listed above, exposure in high-elevation habitats, nutritional deficiency due to habitat degradation which may result in low productivity, a lack of lowland habitat, human-caused disturbance and mortality (e.g., road mortality, disturbance by hikers), behavioral problems related to captive propagation, and inbreeding depression.

Nēnē at Namana o ke Akua Haleakala National Park, Maui 
 Photo by Forest & Kim Starr

The goals of conservation actions are not only to protect current populations and key breeding habitats, but also to establish additional populations, thereby reducing the risk of extinction. Past and current actions include captive propagation and release of captive-bred individuals into the wild, predator control, habitat enhancement, research and monitoring, private conservation efforts, formation of the Nēnē Recovery Action Group, and public education.

For more details about the nēnē life cycle, and how DOFAW is working to protect the nēnē, visit the Hawaii Comprehensive Wildlife Conservation Strategy nēnē fact sheet.

Also, visit the HEAR.org nēnē page.

Check out Forest and Kim Starr's gallery for more beautiful images of nēnē and other native Hawaiian species. 

Drawn image from "Hawaii: A Calendar of Natural Events"
published by the Bishop Museum and Kamehameha Schools in 1989.

Text: Hawaii Comprehensive Wildlife Conservation Strategy, October 2005. 

Tuesday, November 2, 2010

This Week in Nature:The 1st week in November - Hawaiian pepperwort

What's Happening in Hawaii 
during the 1st week in November (Welehu):

A Welehu ka malama, noho i Makali'i.
Li 'ili 'i ka hana.

The month of Welehu is ruled by the Pleiades.
Work is done a little at a time.

Hawaiians reckoned the beginning of Welehu and of the rainy season from the date when the Pleiades, or Makali'i, rise at sunset - as they will this week. Work is limited by the storms and by kapu related to Makahiki. Another proverb says, "Rest the head on the pillow; Welehu is the month."

On O'ahu, at Koko Head and Lualualei Valley, winter rains cause sprouting of 'ihi'ihi-lau-ākea, the Hawaiian pepperwort (Marsilea villosa). Superbly adapted for life in normally arid areas, this aquatic native fern goes dormant in dry weather, dying back into fuzzy, rust colored runners and spore capsules that lie waiting to germinate. With rain, the runners put up shoots that resemble four-leaf clover, carpeting the ground in emerald green. If the rain is heavy enough to form a pool, spore capsules will awaken from their decades of slumber and release spores within half an hour. 

For more about this plant species, visit the Hawaii Ecosystems At Risk (HEAR.org) info page. View photos of Marsilea villosa at Forest and Kim Starr's searchable photo gallery.

To see additional photos of the Hawaiian pepperwort, visit the University of Hawaii botany webpage.

Taken from "Hawaii: A Calendar of Natural Events"
published by the Bishop Museum and Kamehameha Schools in 1989