Black-crowned Night Heron: Breeding colony

“Glimpsed Black-Crowned Night Herons (Nycticorax nycticorax nycticorax) on my way to run a pediatric community/disability clinic and came back to investigate. In Peninsular Malaysia Black-Crowned Night Herons are uncommon expect at certain nesting sites.

“This nesting colony of Black-Crowned Night Herons is at a large ex-mining pool, deep inland (>50 km from the coast) and not near any mangrove (usually nesting site). There were at least 40 adults (possibly closer to 50) in three groups (25, 15, 5) spread over 20 meters.

“I spent the entire morning with them (cooked in the sun) and took close to 500 shots. They were breeding and I was privileged to see many forms of courtship behaviour.

“This one with eggs visible – at least three (left). The clutch size is usually three but can extend to six eggs.

“Courtship ritual 1: Mutual billing (below left). The fluffed up nature of both birds suggest excitement and courtship. At first I thought this was the male feeding the female (on the nest) – either as part of a courtship ritual or because she is confined to the nest. But on further reading and review – this is described in the literature as ‘mutual billing’. Saw this a number of times.

“Courtship ritual 2: Advertisement display or song and dance display. This male was repeatedly bobbing his head, stretching his neck out and lifting one leg to attract a female (just out of picture below him) (above right).
When his head was level with his feet, he would vocalise “quak” – this is called the ‘snap-hiss vocalisation’ and ‘It has been suggested that these displays provide social stimulus to other birds, prompting them to display. This stimulation in colonial species may be crucial for successful reproduction.’

“Courtship ritual 3: Twig ceremony (below left). This pair has bonded – see the evidence of the pink legs as a sign of bonding. Nest building is initiated by the male (on the lefts) – either a new nest or restore an old one. As part of courting or soon after, the male collects sticks and presents them to the female – the ‘wig ceremony’. Once accepted the pair works the twigs into the nest. This male displayed the twig for close to one minute, bobbing his head up and down, showing of the twig in many different directions before the female finally accepted it.

“Courtship ritual 4: Allopreening (above right). This cozy couple have already started a nest and were excitedly rubbing each other with some preening. Notice how excited the male is on the left.
The colony had a number of juveniles of various ages/stages.

“A first year juveniles in flight (below left)). It is documented that juveniles first have grey eyes which turn yellow/amber as opposed to the bright red eyes of adults. But all the ones I saw had red eyes.

“The colony had a number of juveniles of various ages/stages. These are 2nd-3rd year old juvenile (above centre). Again notice the eye should be yellow/amber but are red. This chap (above right) did not have the clean and bright plumage of adults. Possibly a sub-adult, close to 3 years old.”

Dato’ Dr Amar-Singh HSS
Ex-Ming Pool, 20 Km outside Ipoh City, Perak, Malaysia
2nd May 2009

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