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Dodonaea viscosa

PTBG1000012107

055127

11225

K. R. Wood

April 14, 2005

PTBG

BISH, US

J. Polhemus

Hawaii

US

HAWAIIAN ISLANDS

Paokalani Islet

HI

Hawaii County

55

150 m offshore of Honokea Stream, 270 m long x 85 m wide

dicot

shrub, emergent in Lantana camara along eastern windward side, early flower, rare

dominated by invasive non-native Lantana camara and Pluchea carolinensis, natives include Chenopodium oahuense, Osteomeles anthyllidifolia, Schiedea globosa Chamaesyce celastroides var. amplectens, Cocculus orbiculatus, Eragrostis variabilis, Plectranthus parviflorus, Dodonaea viscosa, and Psydrax odorata.

Overview. Paokalani, Mokupuku, and Pa`alaea are three north coast offshore islets which lie just off the headland mouth of Honokea Stream in the Kohala Forest Reserve of the Big Island Hawai`i and are under the jurisdiction of the Department of Land and Natural Resources Division of Forestry and Wildlife (DOFAW) as State Wildlife Sanctuaries. Paokalani, which is the largest of the three, lies approximately 150 m offshore, is 73 m elev., and is 270 m long x 85 m wide. Adjacent and to the east is the middle sized islet of Mokupuku which is 21 m elev., and 150 m long x 45 m wide. Pa`alaea, the smallest of the three, lies at about 100 m offshore, reaches 13 m elev., and is 40 m long x 25 m wide. All three are running in a northeast to southwest direction and composed of weathered black basalt. Vegetation. On April 14, 2005, the author along with John Polhemus, Wildlife Biologist with the Department of Land and Natural Resources, Division of Forestry and Wildlife, visited Paokalani to conduct a biological inventory under the auspices of the Offshore Island Restoration Committee (OIRC). Having a high central ridge with very steep to vertical walls on all sides Paokalani can be very difficult to access and explore. On this occasion we were transported to the central ridge by Helicopter and utilized ropes to explore the vegetation along its steep slopes. This islet is dominated by the non-native Lantana camara (lantana) shrub which can thickly cover the islet in some sections, especially its central ridge and upper steeps slopes. Interspersed within the lantana shrubland is another non-native Pluchea carolinensis (sourbush) which can be occasional throughout the islet, yet reaching higher numbers on the steep western slopes. Several native Hawaiian plant species are still surviving on the island with some of them being somewhat common including Chenopodium oahuense (‘äweoweo) which can be observed most abundantly along the central ridge; Osteomeles anthyllidifolia (‘ülei) which is very common on the windward east side and around the southern end of the central ridge; Chamaesyce celastroides var. amplectens (‘akoko) a thickly branching shrub which was in early flower and fruit and found to be most abundant around the southern ridge line; Cocculus orbiculatus (huehue), a vine which was common along the southern ridge line; Eragrostis variabilis (käwelu), a common native grass along the ridge and upper slopes; Plectranthus parviflorus (‘ala‘ala wai nui), a common herb scattered throughout the islet’s ridge and steep slopes; Cyperus phleoides, a native sedge which was occasional throughout the islet; a few plants of Dodonaea viscosa (‘a‘ali‘i) were seen emergent out ot the lantana along the upper windward side of the islet; several healthy trees of Psydrax odorata (alahe‘e) are located just below the northwestern end of the islet; a single individual of Metrosideros polymorpha var. glaberrima (‘öhi‘a) was observed on the southeastern side of the islet and appeared to be dieing; approximatley seven patches of Schiedea globosa were observed in early flower around 10 m above the ocean on the northwestern side of the islet; the common shrub Scaevola sericea (naupaka kahakai), the prostrate herb Sesuvium portulacastrum (‘äkulikuli), and the sub-erect herb Portulaca lutea (‘ihi), were all observed around the lower slopes and within the salt water spray zone during rappels. It should be noted that the previously mentioned Schiedea globosa (Caryophyllaceae) was observed on both Paokalani and Mokupuku. The presence of S. globosa is very significant in that previous to a survey in 1995 this native species was unknown to occur on the Big Island. In 1995 a single sterile individual was observed on the seacliffs of Waipio and never observed again. Now there appears to be a viable population of this species on these islets. 29 species of vascular plants were observed. 16 (55%) were native and 13 (45%) were alien. 19 numbered vouchered specimens were made and will be housed at the PTBG & BISH herbaria. Threats. Non-native invasive plant species pose the most serious threat to Paokalani at this time. As previously mentioned Lantana camara (lantana) and Pluchea carolinensis (sourbush) are currently the most dominant weedy species. Pennisetum setaceum (fountain grass) poses a very serious threat because of its ability to completely dominate ecosystems. This is the first time the author has observed this invasive grass on any of Hawaii’s offshore islets. Another prolific invasive is Schinus terebinthifolius (Christmas berry), which like all the previously mentioned non-natives can cover large areas and displace native species. Additional note-worthy non-native plant species observed include: Conyza bonariensis (hairy horseweed); Digitaria ciliaris (Henry's crabgrass); Emilia fosbergii (pualele); and Melinis repens (Natal redtop). Mokupuku & Pa`alaea. While on Paokalani we were able to observe vegetation of the adjacent islets of Mokupuku and Pa`alaea with the use of binoculars. This including 12 plant species on Mokupuku and four species on Pa`alaea. Species observed on Mokupuku include the following natives: Argemone glauca (pua kala); Chamaesyce celastroides var. amplectens (‘akoko); Chenopodium oahuense (‘äweoweo); Eragrostis variabilis (käwelu); Osteomeles anthyllidifolia (‘ülei); Portulaca lutea (‘ihi); and Sesuvium portulacastrum (‘äkulikuli). In addition the following non-native species were observed on Mokupuku: Digitaria ciliaris (Henry's crabgrass); Lantana camara (lantana); Morinda citrifolia (noni); Portulaca oleracea (pigweed); and Schinus terebinthifolius (Christmas berry). Species observed on the small Pa`alaea islet include the following natives: Chamaesyce celastroides var. amplectens (‘akoko); and Sesuvium portulacastrum (‘äkulikuli). Non-native species include: Digitaria ciliaris (Henry's crabgrass); and Lantana camara (lantana). Seabirds. During our research we observed Black noddies (Anous minutus ~ noio) foraging around the islets and most-likely nesting and roosting in the sea-cave observed on the medium sized islet of Mokupuku. White-tailed tropicbirds (Phaethon lepturus dorotheae ~ koa`e kea) were foraging and engaging in courtship displays off all three of the islets. At least one Red-tailed tropicbird (Phaethon rubricauda rothschildi ~ koa`e`ula) was seen, and while it was difficult to tell the numbers of each variety, not more than eight were observed during the visit. It is uncertain whether any of the tropicbirds were nesting or roosting on the islets, yet there is ample room on the ridges, and several "pit stops" were observed by birds on the lower slope of the south side of Paokalani. Wedge-tailed shearwater (Puffinus pacificus ~ 'Ua 'u kani) were present on Paokalani and likely on the medium sized islet of Mokupuku, and possibly on Pa`alaea. A total of 49 apparently occupied burrows (AOB) were counted on the ridge and northern tip of Paokalani. AOB are defined as burrows with one or more indicators of recent use by birds, including fresh digging at the mouth of the burrow, in addition to guano and/or an actual bird/egg in the hole. It appears that the wedge-tails are most common along the ridgelines, but could possibly utilize cracks and crevices in the leeward side of the lower bench. Thirty-two of the 49 burrows were clustered on the northern tip of Paokalani. It could also be noted here that a pair of Japanese white-eye (Zosterops japonicus) were observed foraging in Pluchea bushes on the northern slope of Paokalani, and a single Hawaiian Hawk (Buteo solitarius) was observed circling overhead.

October 4, 2011

August 6, 2023