Tag Archives: Raptor Migration

First Autumn Raptor Migration Count in Singapore

by Tan Gim Cheong
This article was first published in BirdingASIA 28 (2017).
The write-up here is an expanded version with more figures and acknowledgements.
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Figure 1 – Part of a kettle of 82 OHB, Tuas South Avenue 16, Singapore, 8 October 2014. 

From 1 October to 16 November 2014 Singapore’s first autumn raptor migration count took place at Tuas South Avenue 16 (1.265ON 103.622OE), near the southwest tip of Singapore island, an area with many grassland plots that generate strong thermals during the day. The project was carried out by volunteer amateur birdwatchers but, due to a shortage of volunteers over the 47-day period, full coverage was unfortunately not achieved – observation times varied from two to eight hours per day while on seven days, no counts were made; overall, an average coverage of five hours per day was achieved. Nonetheless, the count was still useful in providing a baseline indication of the numbers and diversity of raptors that may be expected in Singapore during autumn migration.

Figure 2

Figure 2. Daily total of all migrant raptors. Note: no birds were recorded on 3 October, and no counts made on 13, 14, 16, 20, 21 and 29 October and 11 November.

A total of 3,667 raptors of 11 migrant species were recorded. Oriental Honey Buzzard Pernis ptilorhyncus (3,189 birds) accounted for 87% of the total. The Japanese Sparrowhawk Accipiter gularis (252 birds) was a distant second, making up 7%, while the remaining 6% comprised small numbers of nine species, including 15 Chinese Sparrowhawk Accipiter soloensis. Those three species were recorded throughout the period. A total of 11 Black Baza Aviceda leuphotes was recorded – one on 30 October, two on 1 November and eight on 12 November; six Peregrine Falcon Falco peregrinus – one each on 4, 6 and 8 October and 1, 5 and 16 November; three Common Kestrel Falco tinnunculus – one each on 1, 8 and 10 November; Booted Eagle Hieraeetus pennatus – singles on 18 and 24 October; Greater Spotted Eagle Clanga clanga – singles on 23 October and 13 November; and Osprey Pandion haliaetus – singles on 10 and 16 November. There was just one Black Kite Milvus migrans on 23 October, and one Common Buzzard Buteo buteo on 30 October. A further 183 raptors were unidentified.

Figure-3

Figure 3. Individual species totals.

Although Oriental Honey Buzzards were recorded throughout the period, there were two noticeable peaks: between 6-12 October (37% of the total) and between 7-15 November (40% of the total). Flocks of up to 80 birds migrated across the site by ‘kettling’ – circling together – in one thermal and gliding to the next, making this site one of the best places in Singapore to observe migrating raptors (eg. prior to the 2014 count, 745 Oriental Honey Buzzarsd were recorded on a single day, on 9 November 2013; an even higher number, 894, has subsequently been recorded, on 9 November 2015).

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Figure 4. Distribution of Oriental Honey Buzzards.

A count of 31 Japanese Sparrowhawks on 23 October 2014 was the highest one-day number of this species in Singapore. Most of these migrated singly, but up to three were observed kettling together. Chinese Sparrowhawk was encountered only in ones and twos; the largest group of Black Baza was a flock of eight, the remaining three comprised two together and a single. One notable record was a Northern Boobook Ninox japonica in flight on the afternoon of 1 November 2014 – it had probably been disturbed from its day-time roost.

The highest number of raptors recorded on a single day was 490 birds, on 8 October, with an average of 92 birds a day during the period. Notably, there was one day, 3 October, when no migrant raptors were recorded, even though the weather was fine. Reports of migrating raptors 4 km north of the count site, not seen by our recorders, suggest that migration occurred across a broad front, and some birds were not in visual range of the count site.

Figure-5

Figure 5. Distribution of Japanese Sparrowhawk.

The flight path also appeared to have shifted slightly compared with earlier years, when about half of the raptors flew south and the rest flew east-south-east. During the 2014 count, few raptors flew south; most flew east-south-east passing to the north of the observers. A survey of the wider area revealed that there was a new area of reclaimed land in the sea between Singapore and Malaysia, north-north-west of the count site, and birds were using the thermals it generated to cross the Straits of Johor; they passed further north of the count site than in previous years. The count site itself was reclaimed from the sea about 15 years ago, indicating that raptors adapt to the landscape altered by man to take advantage of available thermals.

Figure-6

Figure 6. Distribution of Chinese Sparrowhawk.

The peak hours for raptor movement were 12h00-16h00. Singapore is at the tip of continental South-East Asia, beyond which lie the Indonesian islands of the Riau Archipelago. Birds passing the site after 16h00 would find themselves flying over the sea as nightfall approaches, and might not have much time to find a suitable roosting site on the small islands scattered to the south.

The general direction of the flight path was from the north-west (Malaysia), then east-south-east towards Jurong Island (Singapore). By extrapolating the flight path, it would appear that most birds proceed directly to the Riau Islands without stopping in Singapore.

Other Migrants

Other migrants recorded during the count were: Oriental Pratincole Glareola maldivarum (327), Pacific Golden Plover Pluvialis fulva (76), Pacific Swift Apus pacificus (25), Blue-tailed Bee-eater Merops philippinus (11), White-shouldered Starling Sturnia sinensis (10), Ashy Bulbul Hemixos flavala (9), Red-rumped Swallow Cecropis daurica (5), Bridled Tern Onychoprion anaethetus (2), Streaked Bulbul Ixos malaccensis (2), Eurasian Curlew Numenius arquata (1), Indian Cuckoo Cuculus micropterus (1) and Schrenck’s Bittern Ixobrychus eurhythmus (1).

Acknowledgements

Sincere thanks go to all the volunteers who helped with the count: Alan Owyong, Alan Yeo, Alfred Chia, Alvin Yeo, Chong Boon Leong, Con Foley, Danny Lau, David Awcock, Diana Jackson, Doreen Ang, Francis Yap, Frankie Cheong, Frankie Lim, Han Yong Kwong, Horst Flotow, Jacky Soh, Jane & Terry Heppell, John Spencer, Lau Jia Sheng, Laurence Eu, Lawrence Cher, Lee Ee Ling, Lee How Sung, Leslie Fung, Lim Kim Keang, Lim Mui Soon, Low Choon How, Nicholas Tan, Ron Chew, See Toh Yew Wai, Subha & Raghav Narayanswamy, Tan Chee Keon, Tan Kok Hui, Timothy Lim, Wing Chong, Woo Jia Wei and Yap Euhian.

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Singapore Raptor Report – Late Spring Migration, April-June 2016

WBSE, 210616, Sentosa, James Tann

A rare photo of an adult and a young White-bellied Sea Eagle “cartwheeling” over Sentosa, 21 Jun 16, by James Tann.

Summary:

On 21st June, James Tann captured a rare series of photos of two talon-locked White-bellied Sea Eagles ‘cartwheeling’ through the air over Sentosa. Some books described this as ‘talon-grappling’ and ‘tumbling’. Interestingly, an adult and a young eagle was involved in this instance whereas this behaviour is usually attributed to mated pairs but only mature adults have been known to form breeding pairs.

Now, for the migrants. Five migrant raptor species were recorded in the April to June period. Four of them – the Osprey, Oriental Honey-buzzard, Japanese Sparrowhawk and Peregrine Falcon were also recorded during last year’s late spring migration. The notable addition this year was the Rufous-bellied Eagle: a juvenile was photographed at Lorong Sesuai on 23 April enjoying a meal.

Of the 14 orientalis  Oriental Honey Buzzards recorded, 11 were juveniles (there were 10 in the same period last year), one was an adult female while the remaining two were not aged. Most of the juveniles were moulting their flight feathers (most were showing new P1 & P2, counting from the inside). It is worth mentioning again that juveniles are known to ‘over-summer’ in the tropics.

Only one Japanese Sparrowhawk, an adult female, was recorded on 2nd April. Two Ospreys were recorded at Sungei Buloh Wetland Reserve in Apr and May, but none in June; elsewhere, there was a record at Singapore Quarry in Apr and another record at Seletar Dam in May.

Two Peregrine Falcons were recorded in April – one at Pulau Ubin on 8th and another at Chinatown on 21st. An ernesti Peregrine Falcon returned to its usual haunt at the rooftop of buildings at Church Street on 26 May and a juvenile, likely also ernesti, flew over Punggol Barat on 15 June.

Back to the resident raptors. The usually encountered resident raptors were all present. Notable records included the locally rare Crested Serpent Eagle which was recorded thrice in April (Kent Ridge Park, Ubin & Bidadari), twice in May (Sungei Tengah & Malcolm Road), and once in June (Chancery Lane).

Also, April to June was a good quarter for the Crested Goshawks – in April, two juveniles were photographed at the leafy compounds of the Singapore Zoo and an adult male was seen collecting twigs at the Southern Ridges where two nest structures were seen; in May, the species was recorded at the Botanic Gardens and Bishan; and in June, a total of four juveniles from two different nests were recorded at the Botanic Gardens.

Many thanks to everyone for sending in / sharing their records; and to  James Tann for the use of his photo.

For the full report in pdf, please click Singapore Raptor Report, Late Spring Migration, Apr-Jun 2016

8th Singapore Raptor Watch Report

compiled by TAN Gim Cheong

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Oriental Honey Buzzard at Tuas South Avenue 8, 15 Nov 15, by Tan Gim Cheong.

 

The 8th Singapore raptor watch was held on Sunday, 15 November 2015 and involved 61 participants – the largest number of participants thus far. The weather forecast was for rain throughout the island. By noon, showers had passed through most of the island, leaving the rest of the day overcast – not the best weather conditions to observe raptor movements! We counted 320 raptors representing 6 migrants species and had 143 sightings of 5 resident species; a further 70 raptors could not be identified. There were 10 raptor watch sites and the numbers counted at each site varied from a low of 9 to a high of 124.

SITE Tuas South Ave 16 Tuas South Ave 12 Tuas South Ave 8 Japan-ese Garden Kent Ridge Park Telok Blan-gah Hill Park Halus Wet-lands Ubin Puaka Hill Ubin Pekan Quarry Changi Busi-ness Park Grand Total
TOTAL 33 14 124 47 78 69 26 99 34 9 533
Figure 1 : Total count/sightings by Site

Of the 10 sites, all the eight sites from last year were maintained, a big thanks to all raptorphiles, especially the site leaders. Two sites were added – Tuas South Avenue 12 and Tuas South Avenue 8 – to supplement Tuas South Avenue 16 in order to cover as much ‘sky’ as possible in the west, knowing that the raptors migrate across a broad front at Tuas.

 

Figure 2

Figure 2 : 2015 Raptor Watch Sites. (source of basemap – maps.google.com.sg)

Raptor activity was ‘slow’ the whole day, the weather conditions a dampener no doubt. The small increase in the late morning was mainly due to a flock of Black Bazas at Telok Blangah Hill Park, while the jump in the afternoon was mainly due to the movement of 108 Oriental Honey Buzzards migrating across Tuas South Avenue 8.

Figure 3

Figure 3 : Raptor numbers by 1-hour time periods (migrant raptors only)

 

The six migrant species recorded included, in descending order, 181 Oriental Honey Buzzards, 96 Black Bazas, 31 Japanese Sparrowhawks, 9 Chinese Sparrowhawks, 2 Peregrine Falcons and 1 Common Kestrel. The 34 unidentified Accipiters were most likely migrants as well. The 36 unidentified raptors on the other hand, could be migrants or residents. The migrant raptor of the day would be the Common Kestrel – formerly considered a rare migrant, recently upgraded to ‘uncommon’ – photographed at Tuas South Avenue 12.

The main bulk of the Oriental Honey Buzzards (OHB) were recorded at Tuas South Avenue 8, which had 114 birds. Nearby Tuas South Avenue 12 only had 9 OHB while Tuas South Avenue 16 had 4 OHB. Japanese Garden had 23 OHB and Kent Ridge Park 13 OHB. Small numbers were recorded at another 3 sites, whereas none were recorded at Pekan Quarry (Pulau Ubin) and Changi Business Park.

As for the Black Bazas, 39 were at Telok Blangah Hill Park, 34 at Puaka Hill (Pulau Ubin), 18 at Kent Ridge Park and 5 at Pekan Quarry. The Japanese Sparrowhawk was recorded in single digits at eight sites, but none at Tuas South Avenue 16 and Pekan Quarry. The uncommon Chinese Sparrowhawk was recorded from three sites only – Puaka Hill (5 birds), Kent Ridge Park (3 birds) and Telok Blangah Hill Park (1 bird). The Peregrine Falcon, another uncommon migrant, was only recorded from Tuas South Avenue 12 and Japanese Garden.

S/N Species (Migrants) Count
1 Oriental Honey Buzzard Pernis ptilorhyncus 181
2 Black Baza Aviceda leuphotes 96
3 Japanese Sparrowhawk Accipiter gularis 31
4 Chinese Sparrowhawk Accipiter soloensis 9
5 Peregrine Falcon Falco peregrinus 2
6 Common Kestrel Falco tinnunculus 1
Total Migrant Raptors 320
   
1 Unid. Raptor 36
2 Unid. Accipiter 34
Total Unidentified Raptors   70
Figure 4 : Migrant and Unidentified Raptors Counted

For the resident species, the counts should be considered as ‘sightings’ rather than as individual birds as the same birds may visit the same site more than once. This is especially so for the more common resident raptors and less so for the rest. There were 68 sightings of the Brahminy Kite, 46 sightings of the White-bellied Sea Eagle, 15 sightings of the Black-winged Kite, 11 sightings of the Changeable Hawk Eagle and 3 sightings of the Grey-headed Fish Eagle. Similar to the year before, the Grey-headed Fish Eagles were only seen at Pekan Quarry (Pulau Ubin).

S/N Species (Residents) Sightings
1 Brahminy Kite Haliastur indus 68
2 White-bellied Sea Eagle Haliaeetus leucogaster 46
3 Changeable Hawk Eagle Spizaetus cirrhatus 11
4 Black-winged Kite Elanus caeruleus 15
5 Grey-headed Fish Eagle Ichthyophaga ichthyaetus 3
Total Sightings of Resident Raptors 143
Figure 5 : Resident Raptors Counted
Figure 6

Figure 6 : Raptor Sub-totals by Category (migrant /unidentified /resident) by Site

Summary

Number of raptors
– 320 migrant raptors counted.
– 70 unidentified raptors.
– 143 sightings of resident raptors.

Number of species
11 species counted, including:
– 6 migrant species.
– 5 resident species.

A complete breakdown of the species counted at each site is shown in the table below:

Figure 7

Figure 7 : Raptor numbers by Site and break down of Species

Thanks to all the 61 wonderful people, both leaders and participants, for spending their Sunday sitting out the rain and bearing with the gloomy weather to count the raptors that were willing to show themselves. National Parks Board staff and NParks volunteers also participated.  The following fantastic people led or assisted in the raptor count:

Figure 8

For a pdf version of the report, please click 8th Singapore Raptor Watch – 2015.