Introduction
KKOZ is one of the five zoos under umbrella of “The Zoological Park Organization under the Royal Patronage of His Majesty The King”, or ZPO. The ZPO is one organization under the Ministry of Natural Resource and Environment, which has as its principal mission the conveying of a conservation message to the public, especially youth. Conservation in zoos aspects is in zoos’ objectives; to give recreation in a zoological park environment, to transfer education through wildlife management, to help conserve wildlife in situ and to produce research works which help in answering conservation questions. Since the year 2000, Khao Kheow Open Zoo had a number of individual hornbills which had never been bred, or even attempted to pair. In the past, hornbills were often donated to the zoo and zoo people did not give them much attention or attempt to breed those hornbills. But the situation in the wild changed due to habitat loses and poaching, and new birds are very difficult to obtain from the wild. Zoos were the obvious place to breed those donated hornbills to replace the collection.

Khao Kheow Open Zoo had accomplished breeding hornbills which already paired in its previous research; Comparative Study of Captive Sympatric Paired Hornbill, in Relation to Nest box Materials, Dimension, Shapes and Installing Sites in 2000. One conclusion that was made from that study was that a strong pair-bond is one crucial factor to the success of breeding. While in situ conditions had produced a number of behavioral researches to start with, the zoos had planed to do induced paring in captive hornbills.

In natural behavior, the male will find a good nest hollow and defend it from other males or other animals. At the same time, that male will try to attract the female with “high-priced” feed such as lizards, snakes, birds or other protein-rich feed. The female is the chooser, or the one who finishes the paring process. The female will accept feed, sometimes just throwing away some of those “high-priced” feed to test the male’s ability to find food. Then, if the female is satisfied with the treat, she will follow him to the nest hollow site. The male will use the food to lure her to the exact place of the nest hollow, sometimes even throwing feed into the hollow, if the female is new to the paring process. She will, then, examine the hollow for aspects such as space, height and strength. If she is satisfied with the hollow, she will accept mating and the breeding process begins. In some cases, the male will also provide sealing material to attract the female too.

In the zoo, the research was designed principally to use the availability of nest boxes and availability of feed as tools to induce paring. Nest box installation method will be defined in detail into either side or both individuals to see if it will affect the attempt to start of the male, or acceptance of female, and how much effect will be measured. The feed availability aspect was performed through measuring the amount of feed-intake of both sides and then gradually reducing the amount on the female side, while increasing that on the male side. The assumption is if the male has “too much”, he will start to give away the pairing purpose, while the female will accept the male more easily for the feed’s sake.

We will gain information in terms of the degree of male attempts to feed and the female’s acceptance. In the end, the combined techniques will be used to see the ultimate result, “the successful paring”.

Objective
1. To increase breeding pairs
2. To guage the effectiveness of the nest box installation technique
3. To guage the effectiveness of the feed availability technique
4. To guage the effectiveness of the combined technique of the two methods Materials
• 6 individual Great hornbills (Buceros bicornis)
• 6 individual Rhinoceros Hornbill (Buceros rhinoceros)
• 5 individual White-crowned Hornbill (Berenicornis comatus)
• 12 individual Oriental Pied Hornbill (Anthracoceros albirostris)
• Individual paring cages for large hornbills: 13 cages
• Individual paring cages for small hornbills: 12 cages
• Nest boxes for large hornbills: 2 boxes
• Nest boxes for small hornbills: 2 boxes

Results in some success cases Neighboring cage organizing
In Great hornbills and Rhinoceros Hornbills, they were organized in the following diagram. From this organized system, each individual would have the opportunity to meet with opposite gender as much as possible. Female in cage 1 could have access to 1 male, female in cage 2 had access to 2 males, female in cage 4 had access to 2 male, female in cage 6 had access to 3 male and female in cage 8 had access to 1 male. After a period of observation, the female with the most potential was moved to cage number 6 to have more male to be chosen. The females with the least potential were moved to cage number 1 and 8. The male with the least potential was moved to cage 5.

Result and Discussion
Combining three techniques; nest-box installation, female feed reduction and provide “high priced” (such as mouse, lizard, gecko) feed to male can induce courtship behavior. Combining three techniques gave a better result than using each technique solely. Nest-box installation gave better stimulation than female feed reduction technique.

Using these techniques, we can pair 2 pairs from 8 Great Hornbills. (in 2 years; 1 in 200 and another 1 in 2001). We got 1 pair of Rhinoceros Hornbills from 6 individuals in 2001. In Bushy Crested Hornbills, we got 1 pair from 5 individuals in 2003-2004. This pairing took a long time due to the fact that the male had not reached puberty and was younger than female 4-5 year. In Oriental Pied Hornbills, we got 3 pairs in 2000, 2 pairs in 2001. We produced more than 20 chicks in the breeding program, this led to the next plan to release captive-born birds into the wild in 2004 to see if the captive-born can survive and reproduce in nature.

In case that female was ready but male was not ready, there were some behavior recorded such as: the female showing aggressive behavior by strongly pecking the male with her beak.

Because the main aim is to breed these valuable hornbills, we cannot design methodology which inlcudes every fine detail. The more important purpose is to breed than to know effects of each treatment, so we were trying in any way to accomplish that. However, from our observations and daily records, we can make some assumptions, which will be shown in appendix I.