26.03.2013 Views

June 1 - 3 , 1978 - University of Hawaii at Manoa

June 1 - 3 , 1978 - University of Hawaii at Manoa

June 1 - 3 , 1978 - University of Hawaii at Manoa

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

ROOF RAT DEPREDATIONS<br />

ON HIBISCADELPHUS (MALVACEAE) TREES<br />

James K. Baker and Melinda S. Allen<br />

Mauna Loa Field St<strong>at</strong>ion<br />

<strong>Hawaii</strong> Volcanoes N<strong>at</strong>ional Park<br />

<strong>Hawaii</strong> 96718<br />

INTRODUCTION<br />

The genus Hibiscadelphus Rock (Malvaceae) is endemic to the<br />

<strong>Hawaii</strong>an Islands. It is one <strong>of</strong> the world's rarest (genera)<br />

groups <strong>of</strong> trees. Of six described taxa, H. bombycinus Forbes<br />

(1920), from the island <strong>of</strong> Hawai'i, azd H. wilderianus Rock<br />

(lgll), from the island <strong>of</strong> Maui, are believea to be extinct.<br />

- H. hualalaiensis Rock (1911), from the island <strong>of</strong> Hawai'i, and<br />

H. - distans Bishop and Herbst (1973), from the island <strong>of</strong> Kaua'i,<br />

still survive in the wild but both species are few in numbers.<br />

H. giffardianus Rock (lgll), from the island <strong>of</strong> Hawai'i, the<br />

type species for the genus, is extinct in the wild but four trees<br />

are growing under cultiv<strong>at</strong>ion in arboreta, and seven others are<br />

growing in the type locality in Kipuka Puaulu (Bird Park) in<br />

<strong>Hawaii</strong> Volcanoes N<strong>at</strong>ional Park.<br />

A hybrid, H. X puakuahiwi Baker and Allen (1976, 1977)<br />

origin<strong>at</strong>ed in Kipuka Puaulu where its parent species,<br />

- H. giffardianus and H. hualalaiensis, grow in close proximity.<br />

The hybrid has been-cultiv<strong>at</strong>ed widely in arboreta and in priv<strong>at</strong>e<br />

gardens around Hawai' i.<br />

It was during observ<strong>at</strong>ions on the damage to a number <strong>of</strong><br />

Hibiscadelphus trees by ro<strong>of</strong> r<strong>at</strong>s, R<strong>at</strong>tus r<strong>at</strong>tus L., th<strong>at</strong> the<br />

hybrid trees were discovered in 1973. This series <strong>of</strong> observa-<br />

tions on r<strong>at</strong> utiliz<strong>at</strong>ion <strong>of</strong> bark, buds, flowers, nectar, and seed<br />

pods followed th<strong>at</strong> initial study.<br />

Feeding on bark<br />

Ro<strong>of</strong> r<strong>at</strong>s were sporadically observed feeding on bark on<br />

three trees in close proximity to one another in Kipuka Puaulu.<br />

Two <strong>of</strong> these trees are H. giffardianus and the third a hybrid.<br />

Bark feeding on trees was first noticed in the l<strong>at</strong>e 1960's when a<br />

number <strong>of</strong> major limbs were girdled and killed on the oldest <strong>of</strong><br />

the living Hibiscadelphus trees. Efforts were made <strong>at</strong> th<strong>at</strong> time<br />

to control the problem by placing r<strong>at</strong> guards around some <strong>of</strong> the<br />

limbs; by poisoning the r<strong>at</strong>s with warfarin; and by c<strong>at</strong>ching them<br />

in snap traps. Warfarin was the most successful control<br />

technique.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!