Red-Legged Crakes in Singapore.

A Note on Red-Legged Crakes (Rallina fasciata) in Singapore

Image 1.  Adult at Singapore Botanic Gardens on 20^th May 2012.  By Francis Yap

This elegant, usually secretive rail is found year-round in Singapore’s forests and parks and is known to breed here.

It has a wide range and is understood to be present as a resident or breeding visitor or passage migrant or combination thereof in North-East India, Myanmar, Thailand, Vietnam, Peninsular Malaysia, Indonesia, Borneo and the Philippines.  It has recently also been found in Cambodia.

As a result of this large range the Red-Legged Crake’s current IUCN Red List Category is LC (of Least Concern)

A review of the available printed and online resources for this species tells us two things

• Compared with similar species present in Singapore such as Ruddy-Breasted Crake (Zapornia fusca) and Slaty-Breasted Rail (Lewinia striata) relatively little is known about it.
• There are only two places in its range where it is relatively easy to locate and see this bird – Singapore (numerous locations) and Thailand (Kaeng Krachan National Park, Western Thailand).

In this article, I will try to summarise the current gaps in our knowledge, put forward some new information from recent observations in Singapore and suggest how birders in Singapore might provide valuable information to further complete our understanding of this species.

The fullest account of the species is in, ‘Rails – A Guide to the Rails, Crakes, Gallinules and Coots of the World’ by Barry Taylor and Ber van Perlo (1998) which highlights the following gaps in our knowledge:

Juvenile:  Not properly described, probably similar to immature but duller, and more extensively white on underparts.

Movements:  These are not properly understood, but the species is both resident and migratory in its normal range.

Food and Feeding:  No information available.

Breeding:  Nest undescribed.  Eggs 3-6.  Both sexes incubate.  No further information available.

Habits:  Shy, retiring and difficult to flush. (…) Claims that the species is nocturnal may refer primarily to calling activity.

Social Organisation:  Assumed to be monogamous.

Social and Sexual Behaviour:  No information available.

The species description in ‘Handbook of the Birds of the World’ (now available online as http://www.HBWAlive.com) appears to derive directly from Taylor and van Perlo and does not add any significant new information.

From the species description in ‘A Photographic Guide to the Birds of Malaysia and Singapore’ by Morten Strange we read ‘Diet unknown. Nest has never been described.  May disperse outside breeding season but this has not been studied.’

The species data sheet from the Data Zone at http://www.Birdlife.org states:

Population size:  Unknown

Population trend:  Unknown

Vocalizations: The calls of the Red-Legged Crake are variously described as follows:

‘In breeding season calls at dawn and dusk, either a slow descending trill or nasal pek pek pek or clucking kunkunkunkunk..; advertising calls gogogogok at night.  (Birds of East Asia by Mark Brazil)

‘Territorial call (often at night) is loud, hard, rapid UH-UH-UH-UH-UH-UH…, every 1.5-3s.  Also, quacking nasal brrr, brr’ay or grr’erh. –  (Field Guide to the Birds of South-East Asia by Craig Robson)

‘Male territorial all is a loud rapid hard (6-9) note UH-UH-UH-UH-UH-UH…, repeated every 1.5-3s.  Females sometimes join in with sudden quacking nasal brrr, brr’ay or grr’erh notes. Often call during night.’  (A Field Guide to the Birds of Thailand by Craig Robson)

‘The territorial call is a loud series of nasal pek calls, repeated every half second at dawn and dusk in the breeding season (Robson).  A series of loud ehh calls followed by a loud trill most frequent at dawn and dusk (Jeyarajasingam).  (Field Guide to the Birds of Borneo by Quentin Phillipps and Karen Phillipps)

‘Calls at night.’ – (A Photographic Guide to the Birds of Malaysia and Singapore by Morten Strange)

‘Details are from Coates & Bishop (1997) unless otherwise specified.  The advertising call is described as a loud staccato series of gogogogo notes, usually given at night but also during the day in rainy weather.  Birds also give a series of “devilish-sounding” screams, and very sharp girrrr and R R R R call.  The territorial call is a loud series of nasal pek calls, repeated about every 0.5s and given at dawn and dusk in the breeding season; this is apparently given by the male, and the female sometimes joins in with nasal notes (C.R.Robson in litt.).  There is also a long, slow descending trill, reminiscent of the Ruddy-Breasted Crake (Lekagul & Round 1991).  When two birds meet, there is a cacophony of scolding sounds.’  (Rails A Guide to Rails, Crakes, Gallinules and Coots of the World by Barry Taylor and Ber van Perlo).

It is always difficult to transcribe bird or animal vocalisations into words but it seems that the authors above are describing 5 or 6 different sounds:

1. Advertising call (at dusk and during the day after rain) – gogogogo or gogogogok or ehh or UH-UH-UH-UH-UH-UH-UH
2. Territorial call (dawn and dusk during breeding season – male only?) – pek pek pek or kunkunkunkunk
3. Female response to male territorial call (dawn and dusk during breeding season) – nasal notes or sudden quacking nasal brrr, brr’ay or grr’erh
4. Other call – long, slow descending trill,
5. Other call – girrr, R R R R, brrr, brr’ay, grr’eh, loud trill
6. Other call – devilish-sounding screams, cacophony of scolding sounds

There are few recordings of this species available online:

The Internet Bird Collection has no recordings.

Xeno-canto.org has 7 recordings – 5 from Singapore and 2 from Indonesia.

The Macaulay Library has 4 recordings – 3 from Singapore (2 of these are also on xeno-canto) and 1 from Malaysia

AVoCet has 2 recordings – both from Indonesia

Of these 11 separate recordings we can note that 5 were made between 18.45 and 19.05, 1 was made at 09.30 and one at 21.30.  For the remaining 4 recordings no time information is available.

It is too small a sample to draw any conclusions on what time of year the birds most often call nor whether some calls may be associated with breeding periods but we can note that the calls were recorded in 8 months of the year from March through to November.

These recordings seem to cover two distinct types of vocalisation:

1. A multi-note repeated call which could be described as gogogogok or UH-UH-UH-UH-UH-UH-UH or perhaps pek pek pek or ehh ehh ehh depending on the listener.  This is heard in 8 recordings. The number of notes in each call varies from 5 to 9 notes.  Sometimes there is a constant number of notes per call e.g. xeno-canto recordings XC364136 and XC57232 both have 5-note calls.  Sometimes the number of notes varies between calls e.g. the call of the individual recorded in Macaulay Library recording ML30627461 varies between 6 and 9 notes and the call in XC352336 varies between 7 and 8 notes.  The call covers a range of frequencies from 500Hz to 7kHz but most of the sound is between 1 and 2kHz as you can see in the Sonogram below:

2. A sharp single (squealing?) call followed by a descending growling/girrrr/trill. This is heard in six recordings.  In two cases this call comes before a series of gogogogok calls (XC364136 and AvoCet recording AV8465) and in one case after a series of gogogogok calls (XC366445).  I have also heard this call given on its own (pers ob).  This call is at a higher pitch than the advertising call and the main elements are between 3 and 4 kHz.

The available recordings do not currently seem to cover all the descriptions in the literature.

It is likely that some calls have yet to be recorded and published (for example the single nasal ‘kek’ call described by Yong Ding Li op cit) but it is also possible that some of the different transcriptions in the literature are in fact referring to the same call.  Perhaps there are only 3 or 4 distinct vocalizations rather than 5 or 6?

Visual Media:

In the Internet Bird Collection there are 19 videos from 3 locations:  Kaeng Krachan National Park in Western Thailand, Singapore Botanic Gardens and Hindhede Nature Park Singapore.  They show adult and juvenile birds bathing, walking or preening.  There are also 6 photos – 3 from Singapore, 2 from Thailand and 1 from India.

{Image 2: Adult and juvenile at Singapore Botanic Gardens 26^th Feb 2014.  By Francis Yap}

On the Oriental Bird Images database of the Oriental Bird Club there are 25 photos – 14 from Singapore (of 3 to 4 different birds), 6 from Thailand and 4 from Malaysia.  One of the images from Singapore taken by Jonathan Cheah Weng Kwong in February 2006 at the Singapore Botanic Gardens shows an adult bird with a fat worm in its beak.

The 4 images from Malaysia are a series of photos of a roadkill bird taken by Amar-Singh HSS in Ipoh, Perak.  They are probably the best available set of images showing plumage details and reproduced below with the kind permission of the photographer.

Sightings:On the Singapore Birds Project website, there are 6 images and on the Singapore Birds website there are a further 2.  Of these 7 are from the Singapore Botanic Gardens and one from Lorong Halus.

A review of the records on eBird over the past 10 years shows the following number of sightings:

Vietnam – 1, Cambodia – 1, Thailand – 11, Peninsular Malaysia – 8, Malaysian Borneo – 8, Indonesia – 4, Myanmar- 0, Philippines – 0.

Such low numbers would indicate rarity (said to be the case in Vietnam and Cambodia) and/or difficulty of location and observation (inaccessibility of preferred habitat/shy and unobtrusive nature of the species) and/or lack of observers (although Thailand, Vietnam, Indonesia and Malaysia have good numbers of contributors to eBird).

However, the situation in Singapore is very different – for the first four months of 2017 there are 25 eBird records of probably 15-18 different individuals from Sungei Buloh, Kranji Marshes, Bukit Timah Nature Reserve, Hindhede Nature Park (including a high count of 5 by Martin Kennewell), Macritchie Reservoir Park, Venus Loop and Singapore Botanic Gardens.  This would indicate that this species in Singapore is neither rare nor especially difficult to locate.

We can summarise the gaps in our knowledge of this species as follows:

1. Appearance: Plumage and physical differences between male and female are not well described. It may be that there are insufficient consistent differences to make field identification of the sexes reliable.  There are now a number of good images of juvenile birds which were not available to Taylor and van Perlo but the plumage of immature birds is still not well understood – some images available show very grey adult-sized individuals – are these young birds?
2. Movements: It is not fully understood to what extent they are migratory and dispersive.
3. Habits: To what extent is this species nocturnal or crepuscular or diurnal?
4. Social and Sexual Behaviour: No information.
5. Breeding: – No information on nests or nesting habits
6. Population Trend: No information
7. Food and Feeding: No information
8. Voice: Number of distinct vocalisations not clear in the literature. Insufficient number of published recordings to clarify this.

Some new information:

Three recent encounters with this species in Singapore can help to start filling in the gaps:

1. On 24^th March 2017 I came across 2 adult birds foraging in damp leaf litter amongst rotting logs in Hindhede Nature Park, Singapore at 17.30. I was able to observe them for approximately 10 minutes. During this time they remained silent and there was no significant physical interaction between the two birds.  One bird had slightly lighter patches on the crown and side of the head and seemed to have a slightly shorter bill than the other.  They walked very slowly amongst the leaf litter, they did not peck repeatedly or scratch with their feet.  From time-to-time each bird would lower their head, peer down between the leaves and come up with a thin grey worm about 8-10cm long which was quickly swallowed. During the period of observation each bird caught approximately 5 worms.  No other food was seen to be taken.  It is possible they were feeling vibrations through their feet.

This observation coupled with the photo of a bird feeding on a worm in Singapore Botanic Gardens in 2009 by Jonathan Cheah Weng Kwong confirms that earthworms make up a part of the Red-Legged Crake’s diet.  Their activity also accords with the description given on the Singapore Birds Project website: “Forages by carefully walking through wet areas of secondary growth and forest, and picking up food items with its bill from the wet ground and leaf litter.”

2. On 26^th March 2017 I came across a Red-Legged Crake calling with the ‘advertising’ call at 19.00 on the Petai Trail in Macritchie Reservoir Park, Singapore. The bird was in damp undergrowth in an area of secondary forest about 3m from the boardwalk which runs along the edge of the reservoir.  I was able to locate the bird briefly by sight to confirm the identification.

I began recording and noticed that the call was being answered by another bird                 concealed in emergent vegetation at the water’s edge on the other side of the                        boardwalk. I was unable to locate the second bird by sight.

The reply call was one I had not heard before.  It might be described as a low-                     pitched sharp exhalation of breath – it does not seem to fit any of the descriptions in        the literature.

This calling and answering continued for approximately two minutes after which the first bird continued calling alone.  After 3 minutes 24 seconds of recording the first bird made a loud sharp squealing note (describe as a ‘sharp hiccup’ by some observers) followed by a descending girrrrrr call lasting 4.5 seconds.  As this call finishes the second bird makes the same 2 calls of approximately the same duration but at a higher pitch (see extract from Sonogram page 5 above).

After this the birds were silent. From the increasing volume of the calls it was clear that the birds were gradually moving towards each other.  Owing to the lack of light and the density of the undergrowth I was unable to confirm by sight if they encountered each other.  The recording is available on xeno-canto.org No: XC366445 and can be listed to here. (double-click on icon) (There are some sudden changes of volume in the recording as I had to turn the microphone through 180-degrees to record each bird).

• embedded mp3 file)
• Link to xeno-canto recording with sonogram)

http://www.xeno-canto.org/366445/embed?simple=1

It is difficult to draw any firm conclusions from this recording other than it adds a third distinct vocalization to the two already covered by the currently available recordings.  This third vocalization may or may not be one of those described by the authors cited above.

As there are distinct differences between the vocalizations made by each bird it is certainly possible that this was an encounter between a male and female and may be behaviour associated with the breeding season for this species.

3. On 16^th May 2017 nest-building was observed in Singapore (location not disclosed to avoid disturbance). The nest was constructed on the ground under a small plant.  The materials used seemed to be exclusively dried leaves collected from the ground.  One bird collected the materials and carried them to the nest location where the second bird (probably the female) tucked them under itself. A single white egg was seen.

Suggestions for further study:

It seems likely that Singapore is the best place to improve our knowledge of this species as there are several easily-accessible locations where they can found with a reasonable degree of certainty.

They have been recorded at: Bishan Park, Bukit Batok Nature Park, Bukit Brown, Bukit Timah Nature Reserve, Central Catchment Nature Reserve, Hindhede Nature Park, Kranji Marshes, Lorong Halus, Lower Peirce Reservoir Park, Gardens by the Bay, Mount Faber, Nee Soon Swamp Forest, Pulau Ubin, Punggol, Sembawang, Sime Forest, Singapore Botanic Gardens, Singapore Zoo, Sungei Buloh Nature Reserve, Tyersall Woods and Venus Drive Trails.  This wide range of locations demonstrates that although considered primarily as a forest-dweller it is not restricted to old growth and does visit disturbed and newly-created habitats.

1. Status: In Singapore the Red-Legged Crake is classified as an Uncommon Resident Breeder / Winter Visitor.  To what extent is the resident population in Singapore supplemented by migrants?  Annual censuses are not going to help establish this.  We need year-round recording of occurrence to see if the population significantly increases for a certain part of the year.  There are probably too few observers contributing to eBird in Singapore at the moment but increased use of this tool (even for simple one-off sightings) would be the quickest way of getting this data.  Over the long term this can also be used to establish population trends.
2. Movements: To what extent do they range around Singapore?  It is my experience that some birds are to be regularly found in the same quite small area but is this true for the whole year?  This more accurate positional data can be recorded on and extracted from eBird.
3. Habits: Is it mainly nocturnal or just crepuscular or is it often active during the day (perhaps when feeding young)?  Nearly all of my encounters have been between 5.30pm and 7.30pm (with only 2 early in the morning) but looking at the images available it is clear that many of them were taken during full daylight hours (for example Francis Yap’s photos above were taken at 11.52am and 10.24am respectively) and we also have a recording of a bird calling at 09.30am.  Perhaps the birds often seen in daylight at the Singapore Botanic Gardens are very much the exception?
4. Appearance: New photos (especially of two birds together) and the study of the existing images available would help define any significant differences between the sexes and to better describe juvenile birds.  Singapore has a large bird photography community and there are no doubt many unpublished images which could be collated and studied.
5. Food and Feeding: Descriptions of feeding behaviour and photos/videos of them feeding would be very valuable.
6. Breeding Behaviour: Descriptions of courtship behaviour, dates of appearance of juveniles.  The breeding birds at Singapore Botanic Gardens provide us with a good opportunity to start collecting this information
7. Vocalisations: The current dataset is small but can be studied in more detail to analyze frequencies and time intervals for the various calls.  This may lead to the ability to distinguish between male and female birds.

As mentioned by some authors this species tends to call more frequently after rain and this is also my experience so visits after rain to look for recording opportunities are more likely to be fruitful.  It is clear that calls are frequently made at dusk and one recording by Yong Ding Li confirms they call at night but currently we lack any recordings to confirm that this species calls at dawn and, when they do, what calls they make.  Do they call all year-round?  Currently there are no recordings for December, January and February.  More recordings are needed.  It is easy to load these on to xeno-canto and make them publicly available.

The author would welcome any contributions of photos, audio recordings, sight records, behavioural descriptions and offers of collaboration from the Singapore birding community to help the further study of this species.

marcel finlay

 Singapore, May 2017

Email: marcorovetti@btinternet.com

Thanks to Francis Yap and Amar-Singh HSS for kind permission to use their photos, Seng Beng Yeo for the nesting information and to Lim Kim Chuah and Alan Owyong for their assistance.

References: 

The Avifauna of Singapore by Lim Kim Seng (Nature Society Singapore, 2009)

‘Notes on the Distribution and Vocalizations of the Red-Legged Crake (Rallina fasciata) in Singapore’ – Singapore Avifauna Volume 23 No 4 (Nature Society Singapore Bird Group, 2009)

A Guide to the Birds of Wallacea – Sulawesi, The Moluccas and Lessa Sunda Islands, Indonesia by Brian J. Coates and K. David Bishop.  (Dove, 1997).

Birds of Myanmar by Kyaw Nyunt Lwin and Khin Ma Ma Thwin (Silkworm Books, 2003)

Rails – A Guide to the Rails, Crakes, Gallinules and Coots of the World’ by Barry Taylor and Ber van Perlo (Pica Press, 1998)

Pocket Checklist of the Birds of the Republic of Singapore by Lim Kim Seng. (Nature Society (Singapore), 2007)

Birds of East Asia by Mark Brazil. (Christopher Helm, 2009)

A Photographic Guide to the Birds of Malaysia and Singapore by Morten Strange (Periplus, 2002)

Field Guide to the Birds of South-East Asia by Craig Robson (New Holland, 2005)

A Field Guide to the Birds of Thailand by Craig Robson (Bloomsbury, 2016)

Field Guide to the Birds of Borneo by Quentin Phillipps and Karen Phillipps (John Beaufoy Publishing, 2011)

www.Birdlife.org – Species datasheets.

www.eBird.org – species distribution maps

www.xeno-canto.org – voice recordings

www.avibase.com – summary of available voice recordings

www.avocet.com     voice recordings

www.hbwalive.com – (online version of Handbook of the Birds of the World by Lynx Edicions) – general species data

www.nparks.gov.sg – (Singapore bird checklist)

https://singaporebirds.com – (species info page)

https://singaporebirds.blogspot.sg  – (species info page)