Wednesday 15 May 2013

Hawaii

In April I co-led the Ornitholidays tour to Hawaii, visiting the four major islands in 13 days. We began in Oahu, flying into Honolulu from San Francisco. On the north coast we visited a golf-course that is well known as a wintering ground for wintering Bristle-thighed Curlews: the bristle-like feathers are visible if you click to enlarge the image. These rare waders are much easier to see here than on their breeding grounds in West Alaska. I remember going to find them from Nome in 1992 - we did see a pair, but not without a three and a half hour drive each way and an exhausting tundra-yomp of 7 hours, mostly on a carpet of dwarf willow!


Near Waikiki we walked up a wooded valley to see one of the forest endemics, the Oahu Elepaio. This is in the monarch flycatcher family, whose closest relatives are in the South Pacific. A simple squeaking noise attracted this recently-fledged juvenile to the branches above our heads. The local conservation authorities had been active here, spreading rat poison on the ground in the breeding territories. Almost all Hawaii's native forest birds are desperately endangered, and need some kind of helping hand. 


From Oahu we flew to Hawaii itself, always known as the Big Island. Here on the slopes of one of the most active volcanoes in the world we saw our first Ne-ne or Hawaiian Goose. The world population had dropped to about 30 individuals when the Wildfowl Trust at Slimbridge stepped in with a successful captive breeding programme. Now their future is assured, especially on the island of Kauai where the Small Indian Mongoose was never introduced. Unlike most wildfowl, this goose has only partially webbed feet, and the goslings don't need to be led to fresh water by their parents. Much of their food consists of berries, and they can be seen in dry, partially forested areas.  


Most of the Hawaiian forest birds are in one endemic family, the Drepanididae. Their ancestors were probably a pair of wind-blown honeycreepers from Central America. The remoteness of the islands has allowed plenty of adaptive radiation, such that at least 40 unique species evolved from the original colonists. Sadly most of these are now extinct, but on our tour we managed to see 12 drepanid species. (We would have seen far fewer without my Hawaiian co-leader David). Most are small green forest canopy feeders, but the two bright red ones, the Apapane and I'iwi, are the most successful. The one illustrated here, with ibis-shaped red bill, is the I'iwi. The most deadly threat to the survival of these native forest birds is avian malaria, which was introduced accidentally. The birds that evolved here have little or no resistance to it. 


Compare the I'iwi's bill with this one (right), belonging to the Palila. The Palila is also a drepanid, but has developed a crossbill-like beak, which it uses to prize open the pods of the mamane tree, (Sophora chrysophylla), in the bean family. This bird is critically endangered, and has suffered a two-thirds decline in numbers in the last 20 years. It only survives in one small area on the southern slopes of Mauna Kea, one of Hawaii's great volcanoes. The bird-songs most often heard here are of Eurasian Skylark, California Quail and even Wild Turkey (if you can call its gobbling noises 'song'): all were introduced, the latter two for hunting.  


Our next island was Maui. Here is one of the most massive volcanoes on earth, Haleakala. It rises to 10,023 ft above sea level, but it starts from great depths on the sea-floor. The endemics here are hard to find and still harder to photograph, but we found plenty of obliging waders such as this Wandering Tattler, another Arctic breeder on its northbound migration. Only in breeding plumage does it show these fine bars on its underparts. Some of us went out on a whale-watching boat too: Maui is famous as a breeding ground for Humpback Whales. Like the tattler, the whales were beginning their northbound migration. During their long sojourn in the warm waters the whales fast; only in the cold waters to the north do they gorge themselves on fish and krill - a feast that has to last them six months.   


Finally, we visited Kauai, the oldest of the main islands and the furthest to the north-west. Here, suburban gardens in Princeville have very distinguished breeding residents: the Laysan Albatross. They nested in this cliff-top location long before the plots were developed; and recent pairs have proved amazingly tolerant and site-faithful. Each year a successful pair raises a single chick: we saw one on a lawn, and another on a driveway, blocked off by parking cones for its own safety! The residents are proud of their annual visitors, and tolerant of folk like us snooping round their neighbourhood with long lenses.  


Kauai is a great island for seabirds. Here we watched a large breeding colony of Red-footed Boobies, with a few piratical Great Frigatebirds in attendance. Sometimes a frigatebird would chase a booby and force it to disgorge food. Here is a Red-tailed Tropicbird, which nests on cliff-ledges in the same area. Tropicbirds are always a delight to watch, and used to be popular with sailors, since they rarely fly more than a day's sailing from land. So, seeing the first tropicbird meant land ahoy. 


Also nesting on the same promontory were many pairs of Wedge-tailed Shearwaters. Their burrows were a common sight as we wandered along the tracks of the nature reserve. Many shearwaters only visit their nests at night; but the wedge-tail is happy to be seen by day, and at close range too. After the harrowing stories we heard about the relentless declines of the native forest species, it was a wonderful climax to the tour to be able to watch such a thriving mixed seabird colony. Hawaii is a brilliant place for a naturalist to visit - and Ornitholidays are likely to return in 2015. Many thanks to Peter Munro who has allowed me to use his excellent photos. 


No comments:

Post a Comment