Sumatra and Java in September 2023: 45 mammals including 12 primates, marbled cat and Javan slow loris

Trip report by Royle Safaris · September 2023

Trip report by Royle Safaris · Royle Safaris Indonesia tours

In September 2023 Royle Safaris ran a Sumatra and Java mammal tour led by Allin, with local guides at each forest. The group worked Gunung Leuser in northern Sumatra, then Gunung Halimun in West Java and sites in Central Java, and recorded 45 mammal species and 78 birds, including 12 of the 13 primates (Sumatran Orangutan, Thomas's Langur, Lar Gibbon, Javan Gibbon, Javan Surili, Javan Slow Loris), Marbled Cat, Sunda Leopard Cat, Hillier's Slow Loris and Great Argus. The report gives the route, species lists by site and photographs.

When September 2023
Where Gunung Leuser (Sumatra); Gunung Halimun, Central Java (Java)
Recorded 45 mammals incl. 12 primates, 78 birds
Led by Allin, Royle Safaris

Sumatra & Javan Mammal Tour

September 2023

Trip Report

Indonesia is home to a huge number of islands and a biodiversity which is largely unrivalled globally. Many of the larger islands are home to endemic species of all kinds and this tour visited forests in Sumatra and Java to see as many of these endemic mammals and other species as possible. The trip was focused on the north of Sumatra (Gunung Leuser National Park), and then Western Java (Gunung Halimum National Park and its surroundings) as well as Central Java (Prambanan Temple, Borobudur Temple, Kemuning, Denasri Pekalongan and other nearby areas).

The trip was led by Indonesian Allin and we hired various local guides at the forest locations, including Jaka & Adjit who run a great guest house in Gunung Leuser and work tirelessly day and night for our clients, Imam & Handa in West Java and then Adan in Central Java. With the help of these local guides our group (consisting of Ewan Davies, Warren Gilson and Judy Parrish) find a fantastic total of 45 mammal species including 12 species of primates out of a possible 13 – the 13th being siamang which was heard (notable primates aside from orangutan included two species of gibbons and slow loris seen) and some very nice surprises such as marbled cat, Sunda leopard cat. We also had some nice bird sightings including wonderful great argus pheasants and various other endemic species.

Gunung Leuser National Park

The trip started in Jakarta and with everyone deciding to arrive the day before the start of the trip we were able to get to Medan in northern Sumatra early and gain an extra evening / night looking for wildlife. We then spent a further 3 full days here, totalling 4 nights in Gunung Leuser. The group explored the park, surrounding forests and plantations and had some fantastic sightings with a lot of effort and good luck. Because of the level of human activity around Gunung Lesuer it was necessary to stay out and spotlight until very late (often around 4-4:30am) as very little is seen until at least 10pm. During the day in Gunung Leuser we had sightings of long-tailed macaque, Prevost’s squirrel, plantain squirrel, lowland slender squirrel, black-striped squirrel, horse-tailed squirrel (Ewan only), southern pig-tailed macaque, Sundiac silvered langur, Sumatran orangutan, Thomas’s langur, lar gibbon, long-tailed giant rat (seen feeding in the park during the day), Robinson’s squirrel and pale giant squirrel. In a nearby bat cave we also had sightings of diadem leaf-nosed bat, very likely arcuate horseshoe bat, greater short-nose fruit bat and a couple of very likely oriental house rats. During spotlighting there was also great luck with sightings of Sunda palm civet, three different Sunda leopard cats, marbled cat, small-toothed palm civet and the main target here, with two north Sumatra endemic Hillier’s slow lorises. The local guides also saw a Malay porcupine.

Gunung Halimum National Park & Surrounding Areas

Following on from Gunung Lesuer National Park, the group headed back to Java and the west Javan areas around the great forested hills of Gunung Halimum. Once again we would spend the days looking in the forests (particularly in the morning) and then again after dark. We were rewarded during the 3 nights here with sightings of west Javan ebony langur, Javan surili, black-striped squirrel, black-eared pygmy squirrel, groups of Javan gibbons, black giant squirrel, Javan treeshrew, three-striped ground squirrel and then at night we found red giant flying squirrel, Javan small-toothed palm civet (which seemed to be in courtship behaviour mode), diadem lead-nosed bat and common pencil-tailed tree mouse. We also found leopard tracks here as well as freshly killed Javan ferret-badger on the trail.

Central Java

From Gunung Halimum National Park the group headed east and into Central and Southern Java to find more mammals. The main focus in these areas would be the endemic Javan slow loris as we would spend time in places where many have been released back into the wild over the years and there are perhaps the best populations of them left in the wild.

During these 4 days we would visit various locations including Pramban Temple where we found plantain squirrel as well as several nice birds including endemic Javan mynah, Javan sparrow and Javan munia. Next was the world famous Borobudur Temple complex where we had sightings of more plantain squirrels and more birds, then in the nearby rice paddy-fields here we had a Javan mongoose sighting. At night we visited some of these forests where Javan slow loris have good populations (we will not disclose the name of these forests as the slow loris are still a target of poaching for the pet trade), over the course of the time here there were sightings of Javan slow loris (one with slow loris researchers working with them here and then in a second location 2 more individuals seen), Sunda colugo (3 seen) and Javan flying squirrel (6 of these amazing endemic mammals seen) as well as a good number of birds. Further locations we visited during the day included Petungkriyono where we saw Javan gibbon, east Javan langur, Javan surili (the southern/central subspecies fredericae which is a very rare sighting) and long-tailed macaques and then large flying foxes and Eurasian wild boar in Mendolo.

All in all, a very successful trip resulting in a great list of 45 mammal species and 78 bird species.

So below is a list of our sightings, it was mostly a mammal focused trip, so the bird list is lacking as no real time was spent on finding and ID’ing birds and next to no effort was made for reptiles and amphibians (hence their absence from the sightings table).

For anyone interesting in exploring Java, Sumatra or other islands in Indonesia for mammals specifically or other groups of wildlife (or just general species) please just contact us at info@royle-safaris.co.uk and we will happily provide information and answer any questions as well as preparing any tailored itineraries you may wish.

Sundiac Silvered Langur Photo: Royle Safaris

Eastern Javan Lutung Photo: Royle Safaris

Western Javan Lutung Photo: Royle Safaris

Long-tailed Macaque Photo: Royle Safaris

Diadem Leaf-nosed Bat Photo: Royle Safaris

Arcuate Horseshoe Bat Photo: Royle Safaris

Javan Small-toothed Palm Civet Javan Small-toothed Palm Civet

Robinson’s Squirrel Photo: Royle Safaris

Yellow-and-black Broadbill Photo: Royle Safaris

Mammalwatching by Vehicle Photo: Royle Safaris

Mammalwatching by Foot Central Java – Javan Mongoose Searching

Species List

Mammals

	Common Name	Binominal Name	Gunung Leuser NP	Gunung Halimum NP	Central & South Java
1	Javan Small-toothed Palm Civet	Arctogalidia trilineata		*
2	Small-toothed Palm Civet	Arctogalidia trivirgata	*
3	Black-striped Squrrel	Callosciurus nigrovittatus	*	*
4	Plantain Squirrel	Callosciurus notatus	*		*
5	Prevost's squirrel	Callosciurus prevostii	*
6	Pencil-tailed Tree Mouse	Chiropodomys gliroides		*
7	Greater Short-nosed Fruit Bat	Cynopterus sphinx	*
8	Sunda Colugo	Galeopterus variegatus			*
9	Fawn Roundleaf Bat	Hipposideros cervinus	*
10	Diademed Leaf-nosed Bat	Hipposideros diadema	*	*
11	Lar gibbon	Hylobates lar	*
12	Javan gibbon	Hylobates moloch		*	*
13	Malayan Porcupine	Hystrix brachyura	*
14	Javanese Flying Squirrel	Iomys horsfieldii			*
15	Three-striped Ground Squirrel	Lariscus insignis		*
16	Long-tailed Giant Rat	Leopoldamys sabanus	*
17	Long-tailed Macaque	Macaca fascicularis	*	*	*
18	Southern Pig-tailed Macque	Macaca nemestrina	*

	freshly dead
	*
*
		*
	tracks only
*
*
	*
*
	*	*
*
*
		*
	*
*
	*
*
*
*
*
		*
heard only
		*
*
	*
	*
		*

19	Javan ferret-badger	Melogale orientalis
20	Black-eared Pygmy Squirrel	Nannosciurus melanotis
21	Hiller's Slow Loris	Nycticebus hilleri
22	Javan Slow Loris	Nycticebus javanicus
23	Leopard	Panthera pardus
24	Southeast Asian Palm Civet	Paradoxurus musangus
25	Marbled Cat	Pardofelis marmorata
26	Red Giant Flying Squirrel	Petaurista petaurista
27	Sumatran Orangutan	Pongo abelii
28	Javan surili	Presbytis comata
29	Thomas Langur	Presbytis thomasi
30	Sunda Leopard Cat	Prionailurus javanensis
31	Large Flying Fox	Pteropus vampyrus
32	Malaysian Field Rat	Rattus tiomanicus
33	Pale Giant Squirrel	Ratufa affinis
34	Black Giant Squirrel	Ratufa bicolor
35	Arcuate Horseshoe Bat	Rhinolophus arcuatus
36	Horse-tailed Squirrel	Sundasciurus hippurus
37	Robinson's Squirrel	Sundasciurus robinsoni
38	Lowland Slender Squirrel	Sundasciurus tenuis
39	Eurasian Wild Pig	Sus scofra
40	Siamang	Symphalangus syndactylus
41	East Javan Langur	Trachypithecus auratus
42	Silvery Lutung	Trachypithecus cristatus
43	West Javan Langur	Trachypithecus mauritius
44	Javan treeshrew	Tupaia hypochrysa
45	Javan mongoose	Urva javanica

	Common Name	Binominal Name	Gunung Leuser NP	Gunung Halimum NP	Central & South Java
1	Javan Myna	Acridotheres javanicus			*
2	Common Myna	Acridotheres tristis	*

3	Common Sandpiper	Actitis hypoleucos			*
4	Common Iora	Aegithina tiphia			*
5	Cerulean Kingfisher	Alcedo coerulescens			*
6	Javan Blue-banded Kingfisher	Alcedo euryzona			*
7	Javan Plover	Anarhynchus javanicus			*
8	Brown-throated Sunbird	Anthreptes malacensis			*
9	Javan Trogon	Apalharpactes reinwardtii		*
10	House Swift	Apus nipalensis		*
11	Great Egret	Ardea alba			*
12	Grey Heron	Ardea cinerea			*
13	Purple Heron	Ardea purpurea			*
14	Great-billed Heron	Ardea sumatrana			*
15	Javan Pond Heron	Ardeola speciosa			*
16	Great Argus	Argusianus argus	*
17	Javan Frogmouth	Batrachostomus javensis			*
18	Eastern Cattle Egret	Bubulcus coromandus			*
19	Olive-backed Sunbird	Cinnyris jugularis			*
20	Zitting Cisticola	Cisticola juncidis			*
21	Cave Swiflet	Collocalia linchi			*
22	Large-billed Crow	Corvus macrorhynchos	*	*	*
23	Freckle-breasted Woodpecker	Dendrocopos analis			*
24	Orange-bellied Flowerpecker	Dicaeum trigonostigma	*
25	Scarlet-headed Flowerpecker	Dicaeum trochileum			*
26	Ashy Drongo	Dicrurus leucophaeus		*
27	Black Drongo	Dicrurus macrocercus	*
28	Common Flameback	Dinopium javanense	*
29	Little Egret	Egretta garzetta			*
30	Sunda Forktail	Enicurus velatus		*
31	Javan broadbill	Eurylaimus javanicus		*
32	Common Moorhen	Gallinula chloropus			*
33	Zebra Dove	Geopelia striata			*
34	Javan Kingfisher	Halcyon cyanoventris			*
35	Gray-and-buff Woodpecker	Hemicircus sordidus	*
36	Grey-rumped Treeswift	Hemiprocne longipennis		*
37	Black-winged Flycatcher-shrike	Hemipus hirundinaceus	*
38	Pacific Swallow	Hirundo tahitica	*		*
39	Javan Bulbul	Ixos virescens			*
40	Banded Kingfisher	Lacedo pulchella		*

41	Pied Triller	Lalage nigra			*
42	White-capped Munia	Lonchura ferruginosa			*
43	Javan Munia	Lonchura leucogastroides			*
44	White-headed Munia	Lonchura maja			*
45	Java sparrow	Lonchura oryzivora			*
46	Flame-fronted Barbet	Megalaima armillaris			*
47	Coppersmith Barbet	Megalaima haemacephala			*
48	Blue-throated Bee-eater	Merops viridis	*
49	Rufous Woodpecker	Micropternus brachyurus	*
50	Blue Whislting-thrush	Myophonus caeruleus	*
51	Eyebrowed Wren-babbler	Napothera epilepidota		*
52	Red-bearded Bee-eater	Nyctyornis amictus	*
53	Ashy Tailorbird	Orthotomus ruficeps	*
54	Javan Scops Owl	Otus angelinae			*
55	Eurasian Tree Sparrow	Passer montanus			*
56	Stork-billed Kingfisher	Pelargopsis capensis	*
57	Scarlet Minivet	Pericrocotus speciosus			*
58	Chestnut-breasted malkoha	Phaenicophaeus curvirostris	*		*
59	Glossy Ibis	Plegadis falcinellus			*
60	White-browed Crake	Poliolimnas cinereus			*
61	Black-backed Swamphen	Porphyrio indicus			*
62	Yellow-crowned Barbet	Psilopogon henricii	*
63	Red-throated Barbet	Psilopogon mystacophanos	*
64	Sooty-headed Bulbul	Pycnonotus aurigaster			*
65	Orange-spotted Bulbul	Pycnonotus bimaculatus		*
66	Asian Red-eyed Bulbul	Pycnonotus brunneus	*
67	Yellow-vented Bulbul	Pycnonotus goiavier			*
68	Cream-vented Bulbul	Pycnonotus simplex			*
69	Raffles's malkoha	Rhinortha chlorophaea	*
70	Wreathed Hornbill	Rhyticeros undulatus			*
71	Spotted Dove	Spilopelia chinensis		*	*
72	Crested Serpent-eagle	Spilornis cheela		*
73	Collared Kingfisher	Todiramphus chloris			*
74	Gray-cheeked Green Pigeon	Treron griseicauda			*
75	Pink-necked Green Pigeon	Treron vernans			*
76	Wood Sandpiper	Tringa glareola			*
77	Common greenshank	Tringa nebularia			*
78	Red-breased Crake	Zapornia fusca			*

Photos from Allin & Warren Gilson

Places visited in this report

Gunung Leuser National Park

This trip report was written by Royle Safaris and is reproduced with their permission, with their photographs. See Royle Safaris Indonesia tours for their trips and more reports. Back to resources.

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