by Prof NG Soon Chye, Marc CREMADES, LAI Huimin
Hornbills in Singapore? (Past to present)
here used to be 3 recorded species of Hornbill found in Singapore. The Rhinoceros Hornbill (Buceros rhinoceros) was formerly recorded in Singapore by Ridley in 1898 (Raffles Bulletin of Zoology 2007) but the population died out since. The Helmeted Hornbill (Rhinoplax vigil) was extinct in Singapore by 1950 (Kemp, 1995). The last recorded sightings of the Oriental Pied Hornbill (native subspecies: Anthracoceros albirostris convexus) were in the 1920s. Then, after over 70 years, the Oriental Pied Hornbill (OPH) was seen again in a Singapore offshore island, Pulau Ubin in 1994, with a confirmed nest in 1997. There are currently 2 populations of Oriental Pied Hornbills in Singapore, one group in Pulau Ubin, a North-eastern offshore island with secondary forests, the other on mainland Singapore.
The Singapore Hornbill Project works with National Parks Board and Wildlife Reserves Singapore since 2004 to increase the knowledge of the Oriental Pied Hornbills for the conservation of these species. The initial priority of the study was to increase their numbers by providing suitable artificial nest boxes to substitute the natural cavity they need to nest in. Strategically, these nest boxes were set up in Pulau Ubin and Jurong Bird Park for captive birds and came equipped with cameras for 24hr observations of the nesting events. With 5 years of observations, we have provided 4 generations of artificial nest boxes. There are more than 20 nest boxes in Singapore mainland and 7 nest boxes on the offshore island of Pulau Ubin. From less than 15 wild birds in 2000, we have more than 60 individuals now in 2010. Within this population, there are at least 12 productive breeding pairs. The largest population observed reside mainly in the offshore island of Pulau Ubin. Results from the study in Singapore revealed that the annual nesting cycle of the Oriental Pied Hornbill begins in November/December, lasting till early April to late May. During this time, the pair will enter courtship and copulation phase after chasing away their young from the previous season. Subsequently, they will choose a suitable nest cavity after many inspections at different sites, before the female decides to seal the entrance of the cavity to prepare for nesting confinement (NPP-Nest preparation Phase and SP- Sealing Phase). After commiting to a nest, the female is entirely dependent on the male to provide food and nesting materials for her and the chicks. The average clutch size observed is 3-4 eggs (ELP- Egg laying Phase), with incubation period between 26-29 days (IP-Incubation Phase). The female stays inside the nest for up to 3 months, and during this time she will raise the chicks until they are almost 2 months old and ready to leave the nest (RCP- Rearing chicks Phase). The usual number of fledgings is 1-2 chicks, occasionally only 3. Our 24-hr observations of intra-nest behaviour and biology has confirmed this discrepancy of the number of fledgings with records of infanticide, usually followed by cannibalism. This is a relatively common occurrence, up to 30% of nests in each breeding season. Infanticide occurs usually in the smallest and weakest chick, though we have observed infanticide in larger stronger chicks. Nesting commitment exhibited by the breeding pair is characteristic of Hornbills, but can be incomplete with observed immature breaking out of the female, leading to possible predation or mortality of chicks.
Breeding successes recorded in the wild (collaboration with National Parks Board)
With the acceptance and success of the artificial nest boxes put up in the wild, the team has now improved the concept of nest boxes to not only allow the breeding of the birds, but to be equipped with better cameras (Figure 2) and electronic sensors to survey the important parameters during the breeding season. We gained an understanding of the activity inside the nest, the job of the male as the sole provider of food and the requirements during the breeding season (Table 1). With this knowledge, it will help various zoological organizations to improve their management and husbandry of keep hornbills in captivity.
The concept of the 'Intelligent Nest'
The idea of an 'Intelligent Nest' is to allow researchers to monitor the hornbills as closely as possible, with no disturbance to their natural breeding behaviour. The parameters under investigation include Temperature and Humidity, Carbon Dioxide and Oxygen levels; a total of 6 sensors (2 for each type) were installed to measure both the inside and outside of the nest (Figure 3).
This project aims to investigate the quantity of nesting materials brought by the male during the early stage of the nesting cycle, the type of food brought by the male for the female and chicks, and also the mass of food consumed by each individual on a daily basis. Weighing scales fitted strategically allows us to measure any weight changes and follow the breeding cycle of the pair (Figure 4). This is also supplemented by the aid of 24hr CCTV video recording of the nest and 24hr weight recording of the birds, all recordings include data from both inside and outside of the nest.
Re-introduction programs (release to the 'Wild' - collaboration with Jurong Bird Park) With the population of the Oriental Pied Hornbills coming to a healthy number, we hope to enhance the wild population with re-introductions and re-locations of existing populations. A pair of captive Oriental Pied Hornbill from the Jurong Bird Park was introduced into the area of the Southern Bukit Timah forest, on 12 December 2008. 3 April 2009: Fledging of female and 2 chicks to the wild. Reduce feeding amount gradually to encourage foraging in their new environment. The pair has since produced 5 chicks to the wild within 3 breeding cycles.
What is the future for Hornbills?
Hornbills, with its role as a seed dispersal agent, will participate in the regeneration of the Singapore forests. With the adaptability of this species to survive and breed in a densely populated county like Singapore, the study of the diet requirements of these species and the food resources of the habitat can help evaluate the capacity of the garden, greenery and forest to provide food for a sustainable population of hornbills in Singapore. The future management of these species will involve the improvement of the genetic diversity of the population with genetic studies tied in with re-location and exchanging individuals from different groups.
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