Dangerous bird?! 

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

(Photo by: Jason)

Scientific name: Ardea cinerea-Common name: Grey Heron, Gray Heron--In latin, Ardea = Heron; cinerea = grey or ash coloured. (cinis means ashes) (Robinson, 2005)Robinson, R.A. (2005). BirdFacts: profiles of birds occurring in Britain & Ireland (BTO Research Report 407). Retrieved from http://blx1.bto.org/birdfacts/results/bob1220.htm ]]>. Hence, the bird is given the common name Grey Heron (or Gray Heron).- -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.

Biology

Grey Herons are usually solitary, although they may occur in small loose flocks occasionally (Jeyarajasingam, 2012)Jeyarajasingam, A. (2012). A Field Guide to the Birds of Peninsular Malaysia and Singapore (2nd ed.). New York: Oxford University Press.

Feeding Habits

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)Briffett, C. (1993). The Birds of Singapore. New York: Oxford University Press

Reproduction

In Singapore, Grey Herons probably can breed all year round (Tan, 2001)Tan, R. (2001). Grey Heron (Ardea cinerea).Retrieved from http://www.naturia.per.sg/buloh/birds/Ardea_cinerea.htm

Courtship

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)Tan, R. (2001). Grey Heron (Ardea cinerea).Retrieved from http://www.naturia.per.sg/buloh/birds/Ardea_cinerea.htm

Nest Building

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)Tan, M., & Vickerman, J. (2010). Bird Ecology Study Group Grey Heron in courtship mode. Retrieved from http://www.besgroup.org/2010/02/27/grey-heron-in-courtship-mode/

Breeding

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)Tan, M., & Vickerman, J. (2010). Bird Ecology Study Group Grey Heron in courtship mode. Retrieved from http://www.besgroup.org/2010/02/27/grey-heron-in-courtship-mode/

Hatching

Before the chicks can hatch after approximately 50 days, incubation of eggs by both parents happens for around 25 to 26 days (RMBR, 2012)Raffles Musuem of Biodiversity Research. (2012). Ardea cinerea. Retreived from http://rmbr.nus.edu.sg/dna/organisms/details/20

Parental Care

After hatching, chicks will remain in the nest for about 10 to 20 days (RMBR, 2012)Raffles Musuem of Biodiversity Research. (2012). Ardea cinerea. Retreived from http://rmbr.nus.edu.sg/dna/organisms/details/20

Flight Habits

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)Briffett, C. (1986). A guide to the common birds of Singapore. Singapore: Singapore Science Centre

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)Briffett, C. (1986). A guide to the common birds of Singapore. Singapore: Singapore Science Centre

Calls

Generally, the Grey Heron makes its call during flight, and produces a harsh “kraank” sound (Jeyarajasingam, 2012)Jeyarajasingam, A. (2012). A Field Guide to the Birds of Peninsular Malaysia and Singapore (2nd ed.). New York: Oxford University Press.

Description

Adult

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)Gan, J. (1997). The Nesting Herons of Sungei Buloh. Wetlands, 4(1). Retrieved from https://www.sbwr.org.sg/wetlands/text/97-4-1-2.htm

.

Adult

Grey Heron morphology. (Photo by: Jason, Labelled by Karen Chew)

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

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)Jeyarajasingam, A. (2012). A Field Guide to the Birds of Peninsular Malaysia and Singapore (2nd ed.). New York: Oxford University Press.

Juvenile

Grey Heron juveniles typically look similar to the adult. However, their colours appear duller, and their necks are more greyish in colour (Jeyarajasingam, 2012)Jeyarajasingam, A. (2012). A Field Guide to the Birds of Peninsular Malaysia and Singapore (2nd ed.). New York: Oxford University Press.

How to recognise a Grey Heron?

Grey Heron diagnosis. (Photo by: Eddy Swan, Labelled by: Karen Chew)

The Grey Heron is a relatively large bird that is hard to miss.- The diagnostic features include:- 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.

Features	Herons
	Purple Heron Purple Heron (Ardea purpurea) (Photo by: Dr. L. K. Yap)	Grey Heron Grey Heron (Ardea cinerea) (Photo by: Dr. L. K. Yap)	Great-billed Heron Great-billed Heron (Ardea sumatrana) (Photo by: Francis Yap)
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	Above: Grey Below: Black and Grey beneath	Above and below: Dark Grey

Where can we find Grey Herons?

Global Distribution

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)Jeyarajasingam, A. (2012). A Field Guide to the Birds of Peninsular Malaysia and Singapore (2nd ed.). New York: Oxford University Press.

Local Distribution

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)Lim, K. C., & Lim, K. S. (Eds.). (2009). State of Singapore's Wild Birds and Bird Habitats: A Review of the Annual Bird Census 1996 - 2005. Singapore: Nature Society (Singapore)

Spotting Grey Herons at Pasir Ris mangrove

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

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)Lim, K. S. (1992). Vanishing Birds of Singapore. Singapore: Nature Society (Singapore)

Conservation Status

Global: Least Concern (IUCN Red List)

Local: Nationally Threatened Species (Nature Society, 2011)Nature Society (Singapore) Bird Group Records Commitee. (2011). Checklist of the Birds of Singapore [Data file]. Retrieved from http://www.nss.org.sg/documents/Singapore%20Checklist%202011%20edition.pdf

Taxonomy

Classification Change

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)Sheldon, F. H., & Slikas, B. 1997. Advances in Ciconiiform Systematics. Colonial Waterbirds, 20(1): 106-114.

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.

Current Classification

Grey Heron adult in breeding colours. (Photo by: Nazrye)

- - Kingdom: Animalia ----Phylum: Chordata -------Class: Aves ----------Order: Pelecaniformes -------------Family: Ardeidae ---------------Genus: Ardea ------------------Species: cinerea --------------------Subspecies: ---------------------------------Ardea cinerea cinerea (Linnaeus, 1758) ---------------------------------Ardea cinerea firasa (Hartert, 1917) ---------------------------------Ardea cinerea jouyi (Clark, 1907) ---------------------------------Ardea cinerea monicae (Jouain & Roux, 1963) - - The subspecies of the Grey Heron are very similar, with only slight variation in some morphological characteristics such as shade of colour. Also, each subspecies appears to be found in distinct geographic areas around the world (Bower & Rabago, 2011)Bower, J., & Rabago, D. (2011). "Ardea cinerea"(Online), Animal Diversity Web. Retrieved from http://animaldiversity.ummz.umich.edu/site/accounts/information/Ardea_cinerea.html ]]>. - -

References

Discussion Area

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This page was authored by Chew Hui Fen Karen 
Last curated on 2012