At around 1250 hours on the 23rd July 2008, there was a loud call in my garden that I traced to a pair of Oriental Pied Hornbill (Anthracoceros albirostris). The birds were perching on the TV aerial on the roof of my neighbour’s house.

The male hornbill was calling on and off loudly with the female by his side (top left). The latter then preened the head of the former (top right) before joining in with a call of her own (below left).

The male then began preening himself, starting with his tail feathers and going on to his breast and then his wing feathers.

The female then joined in preening herself, starting with waxing her tail feathers with oil from the preen gland (top right).

After about five minutes, the female suddenly flew off followed by the male a few seconds later.

Ingo Waschkies was in Belum-Temenggor, Malaysia recently and documented the annual gathering of the Plain-pouched Hornbill (Rhyticeros subruficollis) (above). The fig trees around Tasek Temenggor, an artificial lake created by the damming of the Perak River were in fruits.

Large flocks of the hornbill arrived via a few flight corridors to feast on the figs. Ingo reported that there were around two to three thousand birds flying over the lake: “…Some spectacular groups had more than 50 birds with the max being just over 80! This must surely count among the most spectacular bird sights in Malaysia.”

The Plain-pouched Hornbill occurs in Peninsular Malaysia, west and south Thailand and south Myanmar. The male has a bright orange-yellow pouch (left top) while the female is smaller, has an all-black head and neck and a sky-blue pouch (left bottom). Apparently these hornbills arrive annually to coincide with the figging of the trees.

There are many, including experienced birders, who mistakenly refer to these arrivals as annual migration. This is actually a local “migration” and definitely not a migration in the true sense of the word. After all, the majority of the hornbills are basically sedentary and the Plain-pouched definitely do not migrate to winter elsewhere.

Generally, hornbills congregate in large flocks to forage. Such foraging flocks are relatively stable and move in a unit. There is also feeding flocks where birds gather in large numbers for part of a day, a full day or even many days. These are temporary flocks where the birds arrive and leave in an uncoordinated manner. A third type of flocking is the communal roost, formed as foraging flocks gather in the evening.

The arrival of the Plain-pouch Hornbills to Malaysia from Thailand most probably, is a forging flock. Once arrived, the daily morning gathering in Temenggor as seen by Ingo is probably feeding flocks. In the evenings they fly off en masse as a roosting flock.

All images by Ingo Waschkies.

References:
1. Kemp, A. C. (2001). Family Bucerotidae (Hornbills). Pp. 436-523 in: del Hoyo, J., Elliott, A. & Sargatal, J. eds. (2001). Handbook of the birds of the world. Vol. 6. Mousebirds to Hornbills. Barcelona: Lynx Editions.
2. Kinnaird, M. F. & O’Brien, T. G. (2007). The ecology and conservation of Asian hornbills: Farmers of the forest. University of Chicago Press.

This post is a cooperative effort between www.naturepixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.

Most birders know that the female hornbill seals herself inside a tree cavity when she is ready to lay her eggs. But how many have actually witnessed the hornbill breaking out of its cavity when the chicks inside are ready to leave the nest?

Let alone document the stages?

It has to be left to a photographer to undertake the assignment. Dr Eric Tan, an avid nature (bird) photographer, was at Pulau Ubin at the right time when the female Oriental Pied Hornbill (Anthracoceros albirostris) was breaking out of her nest. He meticulously documented the various stages and is here sharing them with everyone.

When the female is ready to lay her eggs, she enters the nest cavity, usually in a tree trunk. The male then brings her mud that she mixes with her faeces and mashed fruits to seal the entrance until only a narrow opening is left (above).

The female then begins to pull out her wing and tail feathers and then lays her eggs. The male will, in the meantime, delivers food for her and her chicks (above).

Once the chicks are ready to fledge, she will start breaking out of the cavity. This seal is then brick-hard and generally impenetrable from the outside. She needs to use her bill like a pickaxe to slowly break down the seal. As the seal slowly breaks down and the entrance enlarges, she needs to squeeze herself out. First her large bill and casque appear, then her head pops out (above, top row). Next, one of her shoulders pushes out, followed by the wing. Once one of her wings is free, she emerges partially before becoming totally free to immediately fly off (above, bottom row).

The chicks will then be enticed to leave the nest by the adults not bringing them food. As the chicks are not of uniform age when the female breaks out, the questions that need to be answered are: 1. Does the female re-seals the nest? 2. Do the chicks take over the job? 3. Is the entrance left unsealed? 4. Who returns to feed the remaining chick/s, the male or the female? There is obviously a need for further observations.

The sealing of the female inside the cavity provides security from predators, prevents the nesting cavity from being flooded and keeps off competitors – other hornbills that may otherwise try to evict the occupants for their own use. However, Kinnarid & O’Brien (2007), “…believe that nest-sealing evolved as a female strategy to ensure male fidelity.” With the male kept busy foraging for himself as well as for his mate and later the chicks, he would have no time to indulge in extra-pair copulations or maintain another female sealed in another cavity.

Reference:
Kinnarid, M. F. & O’Brien, T. G. (2007). The ecology and conservation of Asian hornbills: Farmers of the forest. University of Chicago Press.

This post is a cooperative effort between www.naturepixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.

In a talk to update the public on the Singapore Hornbill Project on 22nd May 2008, Marc Cremades, who initiated the project together with Prof Ng Soon Chye, announced that the population of the Oriental Pied Hornbill (Anthracoceros albirostris) in Singapore has seen a sudden explosion.

These large and impressive birds have been slowly increasing in number over the last decade or so. When the project was initiated in 2006, the hornbill population was below 30 birds, with about 20 in Pulau Ubin.

The use of nesting boxes in the offshore island of Pulau Ubin has contributed to this sudden increase in population. The birds have been accepting these nesting boxes and using them to breed, and to raise a number of chicks successfully (top).

According to Marc, there are at least seven breeding pairs in Ubin and about 19 juveniles around. He estimates that the total population for Singapore is around 50.

Soon, these artificial nesting boxes will be tried on mainland Singapore. And hopefully, more Singaporeans will get a see these large and impressive birds.

The Bird Ecology Study Group is proud to be associated with the Singapore Hornbill Project.

The above image is courtesy of the National Parks Board, Singapore.

Ben drew my attention to the 2004 special issue of the journal, Bird Conservation International. This special issue, dedicated to the conservation of hornbills, carries some of the many papers read at the Third International Hornbill Workshop held in Phuket, Thailand in 2001.

Ben e-mailed me, “I just came across a bit of interesting trivia from an introduction page of a special supplement of Bird Conservation International dedicated to the conservation of hornbills… Dec 2004. Vol 14 Supplement S1:S3. The excerpt that caught my attention was this:

“’This volume is dedicated to the memory of Elizabeth Glassco Hudson (1956– 2002). One of Lis’ most powerful and exhilarating experiences was in Singapore, in 1994, when a Great Indian Hornbill (Buceros bicornis) flew just over her head, making that sound that only hornbill wings can make. She stood in that bird’s wake, mesmerized.’

“Interesting, isn’t it? Considering that it is one of our non-native birds that had a mesmerizing effect on a visitor. The Great Indian Hornbill is a synonym for the Great Hornbill.”

The Great Hornbill, also known as the Great Indian Hornbill, is native to Sumatra, Peninsular Malaysia and northwards to the southern Himalayas.

Great Hornbills are escapees in Singapore. It was the fashion to keep such birds once and there were probably a number of smuggled birds in Singapore then. A few escaped, or were they released, for one reason or another? Anyway, from the above account, at least one bird was around as far back as 1994.

A pair of Great died in the island of Sentosa many years ago, when poison was commonly used to control the rat population there. A bird was also sighted in the Singapore Botanic Gardens, checking out a nesting hole

Currently, only a single Great Hornbill remains, causing much excitement among the urban population when it visits their homes - see here: 1, 2 and 3.

In 2006 a Great and a Rhinoceros (B. rhinoceros), both female, were seen in Eng Neo prospecting a nesting hole in an old tree - see here: 1, 2, 3 and 4.

Image of Great Hornbill at Eng Neo by YC.