|"Dangerous" Grey Heron at bay. (Photo by: Jason)|
The Grey Heron may be a descendent of the dinosaurs, but usually does not cause harm to humans. Nonetheless, even as young juveniles, Grey Herons display some "aggressive" behaviours towards their parents and siblings.
--------------------------------------------------------Ferocious or harmless? Find out for yourself below.
Name and Etymology
Scientific name: Ardea cinerea-Common name: Grey Heron, Gray Heron--In latin, Ardea = Heron; cinerea = grey or ash coloured. (cinis means ashes) (Robinson, 2005)
-The Grey Heron was first described by Linnaeus in the 10th edition of Systema Naturae (1758). The type specimen originated from Sweden, and the original description can be found here.
Grey Herons are usually solitary, although they may occur in small loose flocks occasionally (Jeyarajasingam, 2012)
Grey Heron striking at prey in water. (Photos by: Jason)
Grey Herons are excellent predators, feeding on food such as fishes and frogs (Briffett, 1993)
|Fancy a food delivery? (Photo credit: Jason)|
]]>. From laying of eggs to chick hatching, and finally the young leaving the nest, the whole progression takes around three months (Gan, 1997)
In Singapore, Grey Herons probably can breed all year round (Tan, 2001)
]]>. The process of courtship starts with the male Grey Herons, as they begin to collect nesting materials (e.g. twigs) after arriving at a suitable nesting site high up on trees. While defending their respective sites from other males, the male Grey Heron tries to attract the opposite gender (Tan & Vickerman, 2010)
Despite being solitary most of the time, especially during feeding, Grey Herons adopt a more sociable character during the breeding season, typically forming breeding colonies among tall emergent trees (Tan, 2001)
]]>. The nest is typically a platform made of sticks and branches (Tan, 2001)
Once the courtship process is successful, the Grey Heron couple proceeds to build their nest. Males will collect and bring the nesting materials, while the females will be responsible for constructing the actual nest (Tan & Vickerman, 2010)
|Grey Heron carrying nesting material. (Photo by: Jason)|
]]>. Around 3 to 5 pale blue coloured eggs are laid (RMBR, 2012)
After completing the nest construction, mating occurs, where the males will attempt to mount on the back of the females, balancing by spreading out their wings (Tan & Vickerman, 2010)
]]>. During incubation, the parents take turns to forage for food, ensuring that there is always one parent performing the duties of egg incubation and nest guarding at all times (Kwong 2010)
Before the chicks can hatch after approximately 50 days, incubation of eggs by both parents happens for around 25 to 26 days (RMBR, 2012)
|Grey Heron parents at nesting site. (Photo by: Jason)|
]]>. They are being fed by their parents, which regurgitate their swallowed food (Kwong, 2011)
After hatching, chicks will remain in the nest for about 10 to 20 days (RMBR, 2012)
Older chicks or juveniles will usually produce "begging" calls for food, and peck at their parents’ throats using their bills to stimulate regurgitation (Kwong, 2011)
|Grey Heron adult with chicks. (Photo by: KS Kong)|
Interestingly, like other birds in its family, the Grey Heron bends and curves its long neck into a distinct “S” shape during flight, making it look deceptively shorter in height. On the other hand, its legs adopt a stiff straightened posture, positioned below its tail (Briffett, 1986)
|Grey Heron in flight. (Photo by: KS Kong)|
]]>. This is especially important for Grey Herons living in the northern side of the globe, which flies and migrate southwards over a long journey during winter.
During both take-off and landing, Grey Herons are usually rather clumsy. Nonetheless, they can steadily fly long distances by flapping their wings slowly and deliberately (Briffett, 1986)
|Grey Heron clumsy landing. (Photo by: Dr. L. K. Yap)|
]]>. Nevertheless, they are also able to make different calls in variation with the activity involved, such as during mating. When startled, these birds can make deep guttural calls as well (Davison & Yeap, 2010)
Generally, the Grey Heron makes its call during flight, and produces a harsh “kraank” sound (Jeyarajasingam, 2012)
There is no difference in the general morphological characteristics between males and females . However, in terms of weight and size, males weigh approximately 1.5 kilograms while females are lighter and smaller (Gan, 1997)
Height: 90 to 98 cm-
Head: White, with conspicuous eye streak below eye.Black plumes appearing like a thick band runs across the head from top of eye to nape-
Bill: Yellowish, long and pointed-
Neck: Long and white coloured, many irregular black streaks of unequal length on foreneck-
Body: Underside of body mainly white-
Legs: Generally brown-
Wings: Broad and round. When wings are folded, upperwing appears to be fully grey.In flight, Primaries and Secondaries look black or grey.-
Wingspan: Up to 2 metres
Breeding Adult Changes
|Breeding colours transition in Grey Heron adults. (Left photo by: Jason; Right photo by: Nazrye, Labelled by: Karen Chew)|
]]>. Similarly, this occurs for both the males and females.
In contrast to the yellow bills, the bills of the breeding adult Grey Herons can turn to a brilliant pink or dark orange colouration. Also, the legs of the breeding adults turn from brown to pink colour (Jeyarajasingam, 2012)
|Grey Heron juvenile. (Photo by: Ronald Yip)|
Grey Heron juveniles typically look similar to the adult. However, their colours appear duller, and their necks are more greyish in colour (Jeyarajasingam, 2012)
How to recognise a Grey Heron?
The Grey Heron is a relatively large bird that is hard to miss.-
1) White head with a distinct thick black line running from its eyes to its nape-
2) White long neck-
3) Foreneck bearing streaks of black lines-
4) Distinct grey coloured wing upperparts
Other than the Grey Heron, two other species of large herons can be found in Singapore. Due to their similar big sizes and style of flight, they may be confused with each other. Features used to differentiate between the three species of heron are listed below.
|Size||Large (80 - 90cm)||Larger (90 - 98cm)||Larger (114cm)|
|Head and Neck Colour||Rufous||White||Dusky Grey|
|Wing colour||Above: Ash Grey|
Below: Chestnut lining
Below: Black and Grey beneath
|Above and below: Dark Grey|
Where can we find Grey Herons?
Globally, Grey Herons have a wide range of distribution. They can be found in Africa, Europe, temperate Asia regions such as Japan and China, as well as in South and Southeast Asia such as Philippines and Singapore (Jeyarajasingam, 2012)
|Global distribution of Grey Herons. (Photo retrieved from: © Discover Life and original sources)|
]]>. Most of the Grey Herons sightings occur along the northern coasts. These include the pockets of mangrove areas that are currently present, such as Sungei Buloh Wetland Reserve and Pasir Ris Mangrove (Lim & Lim, 2009)
The Grey Herons dwell in habitats close to water. In Singapore, they can be found at mangroves, mudflats, ponds, canals, reservoir and coasts (Lim & Lim, 2009)
|Recorded sites of Grey Heron in Singapore. (Map from Google Maps; Locations mapped according to Lim & Lim, 2009)|
Spotting Grey Herons at Pasir Ris mangrove
|Personal Grey Heron sightings and respective photographs taken at Pasir Ris mangrove. (Left image: Map powered by streetdirectory.com; Right images and labellings by: Karen Chew)|
Other than the Sungei Buloh Wetland Reserve, another site where Grey Herons can be easily spotted is Pasir Ris Mangrove. This is probably due to heronries established on the tall trees along the perimeter of the mangrove and Sungei Tampines river. One of the heronry is situated at the forested area with many tall trees, marked by the "red star" in the map. Due to the location of the heronries, the best spot to view and photograph Grey Herons is probably at the small Hut next to Sungei Tampines, marked by the "purple diamond" in the map above. Other than the heronries, the birds can also be seen to rest and feed at the mudflat (brown rectangle) and canal (red rectangle) areas as shown in the diagram above.
Threats in Singapore
|Flying Grey Heron at Sungei Buloh. (Photo from: Ronald Yip)|
]]>. This demonstrates the harmful impact of rapid development on the Grey Herons.
The most significant threats that Grey Herons face in Singapore are the loss of habitats and nesting sites. Before the year 1990, there used to be a big breeding colony of approximately 70 pairs of breeding couples at the Kranji River System. However, the habitat and nesting site was lost to the construction of a new transmission station for the Singapore Broadcasting Corporation (now known as Mediacorp) (Lim, 1992)
At present, although these large birds have adapted rather well to pockets of remnant areas next to water bodies, they are still vulnerable in the face of constant developmental threats to their habitats or nesting sites.
Global: Least Concern (IUCN Red List)
Local: Nationally Threatened Species (Nature Society, 2011)
According to the 2011 Checklist of the Birds of Singapore by Nature Society (Singapore) Bird Group, the Grey Heron is listed as a Common bird, and is a Resident Breeder in Singapore.
|Grey Heron chicks. (Photo by: Ronald Yip)|
]]>, and the arguments and issues revolving the organisms in this order were not resolved for a long period of time.
Originally, Grey Herons belonged to the order Ciconiiformes. This was an order in which the families were constantly disputed upon, because the families under this order appears to share similar characteristic with families in orders, such as the Pelecaniformes. Ciconiiformes was thus seen as a taxon resembling a "dumping ground" (Sheldon & Slikas, 1997)
However, in the Year 2008, a paper published by Hackett et al. surfaced as a solution to many phylogenetic relationship problems between many groups of birds. In their study, nuclear DNA sequences from 19 independent loci were obtained from 169 species of birds, and subsequently aligned and analysed. As a result, many genus that were once under Ciconiiformes were regrouped to be under Pelecaniformes (Brown & Harshman, 2008)
|Phylogenetic relationships in the 'Water Birds' clade. From left, boxed in red are the respective order, family and genus of the Grey Heron. (Image adapted from Tree of Life web project, Labelled by Karen Chew)|
Importantly, many past books and websites grouped the Grey Herons under the Ciconiiformes order, while updated websites listed them under the order Pelecaniformes. Thus, one should take note of the classification change in order to avoid confusion.
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This page was authored by Chew Hui Fen Karen
Last curated on 2012