Observers track migration of birds of prey through Java

Observers track migration of birds of prey through Java

By Paul Jepson

BOGOR, West Java (JP): A network of observers is tracking the
southward migration of birds-of-prey into Java and East
Indonesia. For many years ornithologists have known about the
October passages of buzzards and hawks across the straits between
East Java and Bali. But it was only in 1995 that staff of
BirdLife International discovered that these birds were funneling
over the Puncak Pass on their way through Java. This finding has
inspired a desire to know more about migratory routes and the
numbers and species involved.

BirdLife's Iwan Setiawan, who is coordinating an initiative
called Raptor Migration in Haze Condition, points out that there
is a more serious purpose to these surveys.

"We are worried that fires in Sumatra and Kalimantan may
disrupt bird migration. Our surveys aim to assess whether
migratory fly-ways cross fire risk zones and if birds become
disorientated when they meet smoke or haze. An e-mail group of
observers in Japan, Taiwan, Malaysia, Singapore and Indonesia is
sharing information to answer these important questions."

Iwan has mobilized local bird clubs to conduct watches
throughout October at 12 sites from Sumatra, east across Java to
Bali. One of the most active of these clubs is the Cibodas Bird-
watching Association (CIBA).

"We started counts at the Puncak Pass on Oct. 6, but the large
movements did not start until around the 16th," says the club's
director, Adam A. Supriatna.

"We are now counting about 500 birds a day and expect this
peak to continue for about three weeks until early November".

Last month, I joined Richard Grimmett, head of BirdLife Asia
and a leading expert on bird-of-prey identification at the Puncak
observation point, just above the Rindu Alam restaurant.

At about 9 a.m. we watched a flock of 80 or more raptors
spiral up on a rising thermal from their night-time roost in a
forest patch in the tea plantation. After pointing out the five
large birds as Honey Buzzards, he explained the difficulty of
identifying smaller sparrowhawks that made up the bulk of the
flock.

"About 80 percent of the birds we identify are Chinese
Goshawks but most go over too high to be certain. The other
species is Japanese Sparrowhawk. This is identified by blunter
wings and barred under-wing, but a good view is required to be
sure of identification."

He went on to say: "These are birds moving down from their
breeding grounds in East Russia, Northeast China and the Korean
Peninsula. We think they migrate down the Bukit Barisan range of
Sumatra taking advantage of up-drafts off the mountains but their
final destination beyond Bali is not clear."

Estimating numbers is difficult. Vincent Nijman, who has made
a special study of bird-of-prey in central Java notes: "We
counted 2,800 passing through the Dieng Mountains of central Java
last week, but they are clearly moving over a broad front and we
are only seeing a proportion of the birds moving."

The Sumatra-Java-Bali fly-way is not the only migration route
into Indonesia.

Jim Wardill of the conservation project Action Sampiri, which
is based on the remote Sangihe island in North Sulawesi, says:
"We have long suspected that birds of prey island-hop south
through the Philippines and the Sangihe-Talaud archipelago into
North Sulawesi. Last year we confirmed this by counting 2000
migratory hawks passing through Sangihe."

According to these experts there is some evidence that the
fires and El Nino droughts of the last two years may have
disrupted the migration, but there is no evidence of any decline
in numbers. Importantly, these surveys highlight the need for
careful siting of power lines in migratory bottle-neck areas and
protection of forest at critical points along the flyway.

"Large numbers of birds-of-prey roost and hunt for food in a
small patch of forest just below the Puncak Pass in the Telaga
Warna tea plantation. It is a critical stop-over site on their
migration. We are working with plantation worker communities to
ensure protection and restoration of this forest," said Adam
Supriatna.

CIBA's work will help ensure that migrating birds-of-prey find
a safe haven to rest on their long journey east and that bird-
watchers can continue to enjoy the wonderful spectacle of flocks
of these magnificent birds spiraling upwards and over the pass.

The writer is a consultant in several institutions, including
the BirdLife International.