The 'sealed cavity' nesting by Oriental Pied Hornbills at Taiping Lake Gardens. part 1.

April 03, 2026

Background There are approximately 62 recognized species of hornbills in the world, divided between Asia (32 species) and Africa (30 species. These birds belong to the families Bucerotidae (60 species) and Bucorvidae (2 species) with 26 species listed as threatened or near-threatened with extinction. While the ‘sealed cavity’ nesting method is a signature trait of most hornbill species, it is not universal across the entire family. African ground hornbills (shown below) do not seal their nests.

Nesting requirements I have been fascinated by the breeding protocol of hornbills where the female is ‘imprisoned’ for 3 months with the sole purpose of raising offspring. I live on Penang island where there are currently no endemic hornbills. Langkawi Island which is in a similar longitude only 60-70 nautical miles north has multiple species of hornbills some of which have impressive numbers. The common belief is that the reason for the lack of hornbills on Penang island is; 1. Habitat loss and fragmentation, 2. Need for mature trees 3. Not enough fruiting trees to support them 4. Disturbance by high people population density. Personally I think most of these theories are wrong. There are many fruiting trees that support troops of langurs, the population density is confined to certain area and there is considerable undisturbed forested areas. The nesting of Oriental Pied hornbills in Taiping, as described below, demonstrates that the nesting pairs care little for their close proximity to human activity. There are a number of mature trees BUT most likely the wrong sort of tree. Nesting depends on suitable hollows in trees and these are in short supply. Singapore had Oriental Pied Hornbills breeding on offshore islands and when nest boxes were distributed on the mainland the species became relatively common there. This indicates that suitable tree cavities are the rate-limiting factor. The mature Rain trees in Taiping have cavities generally when branches has fallen and left a hole. The trees have been somewhat artificially preserved as an integral component of the Lake attraction.. My photographic efforts to record the breeding cycle led me to Taiping where in 2026 there were at least 7 active Oriental Pied hornbill nests in the Rain trees around the Taiping Lakes where many people run, walk and exercise every day

My photographic documentation is confined to the Oriental Pied Hornbill (Anthrcoceros albirostris), showing the female and the male (in flight).

It is a relatively small black and white species with a whitish-yellow bill and ‘helmut’. Fortunately it’s conservation status is of ‘least concern’. . Over a period of three breeding cycles I followed several nests to record events in the raintrees in the Taiping Lakes area, which is a valuable asset in that city. As mentioned the female spends a heroic period (3 month) sealed into the nest cavity while most males I have observed are very hard working and show great concern for their family. There are various stages to the breeding cycle; 1. The female hornbill enters the nest cavity and completely seals herself inside within a soil, excrement and saliva barrier that has a feeding slit. This takes 5-9 days. 2. The female after 4-6 days then lays 3-4 eggs with a rest period of 3 days between each one. 3. Each egg hatches after an incubation period of 27-28 days. 4. There are then around 55 days of feeding where the male arrives at the nest with a variety of food. With the female and possibly 3 growing chicks the nest cavity must be quite tightly packaged. 5. After 3 months incarceration the female escapes the nest. In one observation 2 chicks left soon after and later the same day a third chick fledged. In a previous observation on Pulau Ubin the female left the nest several days before the chicks. In the 2026 season in Taiping I observed 5 different nests, Four of these were relatively easy to photograph. I will refer to them as the carpark nest (shown below),

the toilet nest,

the fallen nest,

and the zoo nest.

Why seal the nest? The male and female work closely together to build the slotted barrier wall. They use, soil, saliva, excrement and fruit-derived fibre to build the ‘wall’. Its primary function is the stop predation of the young chicks. The male from the toilet nest did not go far to collect soil as there was some renovation work nearby with exposed soil.