Hornbills
Hornbills are fruit-eating birds with eight species found in Sarawak. They include the Helmeted Hornbird,(critically endangered) Rhinocerous Hornbird, Black Hornbill, White-Crowned Hornbill, Wrinkled Hornbill, (threatened) the Oriental Pied Hornbill, the Bushy Crested Hornbill and Wreathed Hornbill.(least concern species). The Malay peninsula supports ten Hornbills.
The “horn” on the bird is called a casque. Its primary function is to release body heat to the surrounding air. Another thought is the casque makes the sound louder along with a certain frequency, much like if we turn up the radio on our favourite station.
Horn Bill’s nest in the cavity of trees with the entrance sealed with mud except for a small slit to receive food. These cavities protect the eggs from predators and provide for a stable temperature. The hornbills rely on woodpeckers to create a hole or for branches to break off and the resulting scar to decay because of fungal infections, thus making a hole. The process usually occurs in large old-growth trees.
The Hornbill needs two factors to survive. The first is a place to nest, and the second is fruit trees. Scientists have tried several different nesting boxes to replace the cavities found in old-growth forests which have been cut down.
In the first experiment, a section of the tree was cut out. The cut was 18 cm high, 8 cm wide and 25 cm deep. The distance from the ground to the cavity entrance was 2.6 m. I have sent the author an e-mail to see if any further experiments were carried out. There was no reply.
In the second experiment, an artificial nest box was compared to a natural site. In September 2013, five artificial boxes composed of plastic were erected along the Kinabatangan River. Four of the artificial nests were cylindrical, while the last one was square. Two of the nesting boxes were not used because placement in the canopy was among rotting trees and bees nests. The humidity and temperature were recorded for five months. The man-made boxes had wildly fluctuating temperatures and humidity, while the natural site had a 1-2 degree C temperature change. Materials used to construct the man-made boxes must be adjusted. However, the Hornbills seemed interested in plastic homes.
The third experiment took place in Brunei. The targeted Hornbill was the Oriental Pied Hornbills which resides with humans in the Panagia region, which is between the two towns of Kuala Belait and Seria. The boxes were made of wood. The average height was 70-90 cm, the width and depth were 38-48 cm, while the square or triangular shaped entrance was 10 cm above the floor. They were placed high in the trees in a human-populated area. Some of the results include the birds did not use the nesting boxes until the second year after erection. The hornbills returned year after year to their nesting sites, although it is not certain if they were the same pair. The nests attracted monkeys, natural flooding because of rain, children playing too close to the feeding site and poaching. The boxes required constant repair because of termites and humidity. The experimenters recommend the boxes be placed high and out of sight so the chicks have a place to alight and also to prevent poaching.
Native Uses of the Hornbill
Trophies of Helmeted and rhinoceros hornbills were widely used among the Iban for personal decoration and dancing. Hornbills were constantly collected as part of the warrior costume among the Iban. Both Iban and other tribes used feathers for head decoration. The feathers decorated their clouded leopard skin capes and machetes. Orang Ulu women used a brace of hornbill feathers for their traditional dancing. A study revealed a single orang ulu dancer used 40 feathers, twenty for each hand for her displays. Researchers confirmed that four birds must have been killed since the Hornbill has only ten tail feathers. Given that the Rhinoceros Hornbills occupies an area of 1.5 km, those four birds would have been wiped out all the birds in 2.5 km of forest.
Wood carvings of hornbills are the centrepiece of many different Ulu races. The Gawai Kenyalang is an Iban ritual that celebrates victorious raiding and headhunting. It also boosts the courage and fighting spirit of the warriors who were actively engaged in headhunting. The forces of the supernatural were also enhanced.
The ceremony begins with a carved hornbill atop a huge pole with its beak facing the direction of the enemies longhouse. Prayers and offerings are laid before it. The Hornbill’s spirit is then launched. It flies to the enemies longhouse, where it puts all the other spirits out of commission. The spirit of the Rhinoceros Hornbill will tear off the longhouse foundations, plunder the property and weaken the warriors.
Notes from other countries
Bhutan
In Bhutan, a study of the Rufous Necked Hornbill revealed the bird feeds on fruits on trees in the canopy and not on the ground. Five nests were found in disturbed secondary forests, while the sixth was beside a small stream not disturbed by human interaction. They also nested in logged forested areas and degraded forest areas, although the nests were not successful because of human interaction. The Rufous Necked Hornbill preferred broadleaf evergreen forests. The study concluded the Hornbill can co-exist with humans provided fruit trees, and nesting places are provided.
West Ghat, India
The changing habitats of the nesting locations and fruit tree availability have been affected by humans. A coffee plantation was studied. It recommended that fruit trees be planted as shade trees.
Central India
The Indian Grey Hornbill was distributed more widely than the Malabar Pied variety. The Indian Grey was found in most locations where old-growth trees and fruit trees were available. In urban areas, the hornbills were found on college campuses and other places where large old-growth trees were combined with fruit trees. The Malabar Pied was restricted to preserved rainforest areas.
Indonesia
The results of an Indonesian survey showed the retention of forest patches within a palm oil estate could support hornbills to grow and breed. A large number of ficus trees were thought to be the reason. Observations show the Rhinoceros Hornbill and the Black Hornbill feed on oil palm fruits.
Sumatran Hornbills
Results were surprisingly high in low canopy oil estates instead of high canopy forests. The data was probably due to fruiting fig trees in the area.
Mysore, India
In a study relating to the gut passage of seed from the time they are eaten to the time they are pooped out, it was discovered the viability of seeds were not affected by the Horn Bills. The times were between 5 and 536 minutes. The timing of gut passage is essential to determine seed dispersal.
Peninsular Malaysia
Horn Bills have been found in 112 locations in 12 states. The primary cause of their demise is logging. Peninsula Malaysia retains about 44% of its forests(2015) which the majority are in Pahang, Perak Terengganu and Kelantan. These four states have about over 50% of their forested areas remaining. The peninsula logs between 2,000-13,000 ha per year, depending on the state. States which have stopped logging altogether include Perlis, Malacca, Penang, Negri Sembilian and Selangor (2015).
This essay was adapted from several papers in the Sarawak Museum Journal December 2018