|A note on the birds of the Ssese Islands, Lake Victoria
The Ssese Islands lie in the north-west part of Lake Victoria in Uganda. They comprise 84 islands of which Bugala is the largest. Bugala Island lies about 50 km WSW of Entebbe and about 3 km from the mainland at Bukakata. The island is about 50 km long and up to 5 km wide and holds the majority of the islands’ people. The economy is based on fishing, agriculture and forestry, with limited tourist facilities. The vegetation of the islands is principally a forest/grassland mosaic and a limited degree of cultivation. Forest cover is roughly 50%, much of it modified or secondary in character. Part of the mosaic is in Reserves designated by the Forest Department, classified as medium-altitude moist evergreen forest dominated by Piptadeniastrum-Uapaca and moist grass savanna (Forest Department Biodiversity Report No. 23, 1996). It appears that there is a significant level of illicit timber removal from the forest.
Lake Victoria has been heavily colonised by the Water Hyacinth Eichhornia crassipes since the mid-1980s. This is apparent on Bugala; much of the shoreline has a 3-metre wide strip of growth and there are numerous floating mats offshore. The floating mats are used by Little Egrets Egretta garzetta and Yellow Wagtails Motacilla flava for feeding, but the growth along the shoreline severely restricts suitable habitat for waders.
I visited Bugala Island from 6 to 10 February 1995; at that time, there was little published information of the birds of the Ssese Islands. Subsequently, the Forest Department Biodiversity Report No. 23 (1996) has been published, providing a review of the birds (and four other taxa) recorded in Forest Reserves on Bugala Island. This note supplements that report and summarises the available records from the islands. It also seeks to analyse the differences between the forest bird community on the islands and that in nearby mainland forests.
During my visit, I recorded birds seen both within and outside the Forest Reserves, but as the boundaries are not always clearly marked, observations cannot be allocated between inside and outside the reserves. Observation of birds was carried out with 10x42 binoculars in a cross-section of habitats, largely on the eastern part of the island around Kalangala and at the western end around Luku. The 92 species recorded are listed in Appendix 1, where the frequency and habitat are given. Further details of specific sightings are given in Appendix 2. Nomenclature throughout follows Britton (1980).
The Forest Department Biodiversity Report No. 23 (1996) records 89 species from three Forest Reserves on Bugala Island, plus 11 separately recorded from a fourth reserve on Bugala. The reports were compiled from 15 days of observation and mist-netting in September 1993. The same report also covers surveys of two nearby lakeshore forests on the mainland, Mujuzi and Jubiya. The report concludes that overall ‘the species composition of each of the reserves was found to be similar’, but ‘the Ssese Island forest avifauna has been observed to be less diverse than equivalent mainland forests’.
Additional information on the islands’ birds is given by Ingram et al. (1970), the report of a Southampton University expedition in July to September 1970 which studied mammals and birds on five islands including Bugala; netting of birds was undertaken but largely restricted to grassland bordering forest. Although the expedition spent eight weeks on the islands, including two weeks on Bugala, they recorded only 59 species (excluding doubtful records), including 30 on Bugala, having spent a substantial proportion of their time on other work. No significant species were recorded on Bugala that I did not see in 1995; species recorded by them on other islands and not recorded (by them or since) on Bugala include Black-headed Weaver Ploceus cucullatus and Weyn’s Weaver P. weynsi. Ingram et al. (1970) note that some species were common on some islands but absent on adjacent ones, especially weavers in apparently similar habitats.
Malcolm Wilson of the Queen Elizabeth National Park Bird Observatory has provided details (unpublished) of 78 species recorded from 17 to 20 October 1997, when he operated mist nets in degraded secondary forest close to a fishing village on Bugala Island. Notable records include White-backed Night Heron Gorsachius leuconotus, an immature seen at night by torchlight, a Bat Hawk Macheiramphus alcinus seen displaying and one White-bellied Kingfisher Alcedo leucogaster netted.
Records from the Forest Department Biodiversity Report No. 23 (1996), Ingram et al. (1970) and Wilson (pers. comm.) are also included in Appendix 1. I have separated certain records from Ingram et al. (1970) which appear doubtful; these records are listed in Appendix 3.
Other works with information on the islands’ birds include the following. Williams (1967) contains a list of birds said to occur on the islands but gives no references; in view of the wide divergence of his list from other sources, it has not been included in this analysis. Hale Carpenter (1920) provides some observations, mainly of non-passerines, and notes that a number of families appeared to be absent. Britton (1980) specifically mentions the islands in the distribution of a few species. Despite a claim on the website uganda.com, I have found no reliable records of Shoebill Balaeniceps rex from the islands.
Overall, only about one third of the passerine species which occur in the Lake Victoria basin (as detailed in Britton, 1980) have been recorded on Bugala. Whilst undoubtedly there are further species to be recorded, the island’s avifauna is less diverse than that of the mainland, despite a wide range of habitats. As if to compensate, several species appeared to me to be more numerous than in similar areas on the mainland, including Blue spotted Wood Dove Turtur afer, Ross’s Turaco Musophaga rossae, Pygmy Kingfisher Ispidina picta and Snowy headed Robin Chat Cossypha niveicapilla. Derek Pomeroy (pers. comm.) notes that the apparent rarity of several species, including Little Swift Apus affinis, Grey throated Barbet Gymnobucco bonapartei and Copper Sunbird Nectarinia cuprea is also interesting.
The classification of forest species proposed in Bennun et al (1996) has been adopted for the purposes of analysing the forest species recorded on the islands and comparing them with those of the mainland. This classification is as follows:
FF Forest specialists: true forest birds, most characteristic of the interior of undisturbed forest, though they may persist in secondary forest and forest patches.
F Forest generalists: typically birds of forest edges and gaps, likely to be commoner there and in secondary forest than in the interior of intact forest.
f Forest visitors: not infrequently recorded in forest but not dependent upon it.
The classification of each forest species recorded from the islands is given in Appendix 1. Of the total of 154 species recorded on the islands, the list includes the following forest species:
Forest dependent: FF 11
Total FF + F 41
Forest visitors: f 31
Total forest species 72
I have some experience of the forests of western Uganda; the forested areas visited on Bugala appeared degraded and species-poor by comparison and a number of non-forest specialist species were recorded from the forest interior. These included forest generalists Yellowbill Ceuthmochares aereus and Little Greenbul Andropadus virens, which were more common than might have been expected in the interior, and forest visitors Paradise Flycatcher Terpsiphone viridis (the local variant of which is described in Appendix 2), Black-headed Oriole Oriolus larvatus, Grey-backed Camaroptera Camaroptera brachyura and Slender-billed Weaver Ploceus pelzelni.
A comparison of the forest species recorded from the islands with those recorded from nearby mainland forests is instructive. Forest reserves close to the western shore of Lake Victoria include Jubiya, close to the Ssese Islands, Mujuzi, some 40 km south west and Sango Bay (which includes Malabigambo) some 80 km to the south west of the islands. These forests are covered by Forest Department Biodiversity Reports, No. 23 (Jubiya and Mujuzi) and No. 20 (Sango Bay) (both 1996).
The total numbers of forest specialist species recorded from the islands and from each of these mainland forest reserves is as follows:
Classification: FF F
Ssese Islands 11 30
Jubiya 15 30
Mujuzi 13 19
Sango Bay 59 58
Total from all the above 61 62
Proportion of total
recorded on the islands: 18% 48%
Whilst the seasonal swamp forests of Sango Bay clearly have the most diverse forest avifauna, it is notable that the relative proportion of forest specialist species recorded on the islands is much lower than that of forest generalists. This is consistent with the occurrence within the forest interior of non-forest dependent species.
When the area within 40 km of Kampala is considered (Carswell 1986), the paucity of the islands’ forest species is underlined still further – Carswell lists 76 FF species and 68 F species. Of these, 26 FF and 20 F species occur at both Sango Bay and in the Kampala area, but not on the Sseses.
The islands’ avifauna varies significantly from that of the mainland. The number of forest species is much lower, with forest generalists (F species) rather than specialists (FF species) dominating the interior. More generally the diversity of passerines appears lower, but some species are much more common. Why might this be so?
Lake Victoria was formed about 750,000 years ago; fluctuations in the lake level may have caused Bugala Island to have been joined to the mainland as recently as 14,000 years ago. However, forest structures have changed significantly in the last 10,000 years due to climatic changes and the forest on the islands was largely removed by 1910 - the forests regenerated after an evacuation of the islanders following a sleeping sickness epidemic in that year (see Crul, 1995 and Forest Department Biodiversity Report No. 23, 1996). Thus it is likely that many of the island birds have colonised the islands following these changes, rather than having been present throughout.
Ingram et. al. (1970) suggest, when noting that certain species are common on one island and absent from an adjacent one, that if two species with the same ecological requirements are colonising a set of islands, the first to arrive may become established to the exclusion of the other. This could also explain the variations in population densities between the islands and the mainland.
Tropical forest birds have a poor ability to colonise new areas, especially over water. Diamond (1985) states that the dispersal ability is lowest in stable habitats such as tropical rain forest. Paulson (1994) showed that forest interior species (classified here as FF species) were less likely to cross cleared areas between forest patches than forest edge (F) birds. This may have resulted in F species filling niches on the islands taken elsewhere by FF species.
BENNUN, L., DRANZOA, C. & POMEROY, D. (1996). The forest Birds of Kenya and Uganda. Journal of East African Natural History 85: 23-48.
BRITTON, P.L. (ed.) 1980. Birds of East Africa. Nairobi: EANHS
CHAPIN, J.P. 1948. Varieties and hybridization among the paradise flycatchers of Africa. Evolution 2: 111-126.
CRUL, R.C.M. 1995. Studies and reports in Hydrology 53: Limnology and Hydrology of Lake Victoria. UNESCO Publishing: Paris.
DIAMOND, J.M. 1985. Population Processes in Island Birds: Immigration, Extinction and Fluctuation. In: Conservation of island birds (MOORS, P.J. ED), Cambridge: International Council for Bird Preservation.
FOREST DEPARTMENT BIODIVERSITY REPORT No. 20. 1996. Sango Bay Forest Reserves. Kampala: Republic of Uganda Forest Department.
FOREST DEPARTMENT BIODIVERSITY REPORT No. 23. 1996. Mujuzi, Sesse Islands and Jubiya Forest Reserves. Kampala: Republic of Uganda Forest Department.
FRY, C.H., KEITH, S. & URBAN, E.K. 1988. The Birds of Africa. Vol 3. London: Academic Press.
HALE CARPENTER, G.D. 1920. A Naturalist on Lake Victoria. London: T. Fisher Unwin Ltd.
INGRAM, M.J., MALPAS, R.C., HUMBER, D.P. & EYRES, J.P. 1970. Report of the Southampton University Expedition to the Sese Islands, Uganda 1970. Southampton University.
MACKWORTH-PRAED, C.W. & GRANT, C.H.B. 1960. The birds of eastern and north eastern Africa. African Handbook of Birds. Series 1, vol 2. 2nd edition. London: Longmans, Green & Co.
PAULSON, B.O. 1994. Movements of single birds and mixed-species flocks between isolated fragments of cloud forest in Ecuador. Studies on Neotropical Fauna and Environment 29(3): 149-160.
WILLIAMS, J.G. 1967. A field guide to the National Parks of East Africa. London: Collins.
ZIMMERMAN, D.A., TURNER, D.A. & PEARSON, D.J. 1996. Birds of Kenya and Northern Tanzania. London: Christopher Helm.
Peter Osborn MA MSc, Burns Farm, Fordyce, Banffshire, AB45 2DL, UK
Birds recorded on the Ssese Islands
All records refer to Bugala Island, except those in [parentheses] which are from other islands only.
Key Forest classification
C = caught, with number of individuals (shown only for the following groups)
P = present FF Forest specialist
X = injured bird brought by local resident F Forest generalist
? = recorded as "identification uncertain" f Forest visitor
1970: July - September Ingram et. al. (1970)
1993: September Forest Department (1996)
1997: October Wilson (unpublished)
1995: February the author
Species Forest 1970 1993 1997 1995 Frequency and habitat 1995
White Pelican Pelecanus onocrotalus P
Pink backed Pelican Pelecanus rufescens P P Common
Long tailed Cormorant Phalacrocorax africanus P P P
Greater Cormorant Phalacrocorax carbo P P P P Common on lake
Grey Heron Ardea cinerea P P
Goliath Heron Ardea goliath [P] P P
Black headed Heron Ardea melanocephala P One in cultivation
Squacco Heron Ardeola ralloides P
Cattle Egret Bubulcus ibis P P Common with livestock
Green-backed Heron Butorides striatus C2
Little Egret Egretta garzetta P P P P Common on lakeshore and floating weed
Yellow billed Egret Egretta intermedia P P Common on lakeshore and farmland
White-backed Night Heron Gorsachius leuconotus P
Hamerkop Scopus umbretta [P] P P P One at lakeshore
Open billed Stork Anastomus lamelligerus P P P Common near fishing villages
Saddle billed Stork Ephippiorhynchus senegalensis P
Hadada Bostrychia hagedash P P P P One on lakeshore
Sacred Ibis Threskiornis aethiopica P
Egyptian Goose Alopochen aegyptiacus P P P
Red-billed Teal Anas erythrorhyncha P
Yellow-billed Duck Anas undulata P
Palm nut Vulture Gypohierax angolensis P P P One over forest
African Marsh Harrier Circus ranivorus P
Harrier Hawk Polyboroides radiatus f P P P Three over forest
Common Buzzard Buteo buteo [X] P Common over forest/grassland mosaic
Long crested Eagle Lophaetus occipitalis f P P One in cleared forest
Crowned Eagle Stephanoaetus coronatus FF P
Fish Eagle Haliaeetus vocifer P P P P Common along shoreline
Black Kite Milvus migrans P P P P Common near habitation
Bat Hawk Macheiramphus alcinus F P
Hobby Falco subbuteo P
Scaly Francolin Francolinus squamatus F P
White spotted Pygmy Crake Sarothrura pulchra F P P
Ringed Plover Charadrius hiaticula P Restricted to open shore
Common Sandpiper Actitis hypoleucos [C1] P C2 P Common on shoreline
Wood Sandpiper Tringa glareola P C4 P Restricted to open shore
Greenshank Tringa nebularia P P
Green Sandpiper Tringa ochropus C1 P Restricted to open shore
Black winged Stilt Himantopus himantopus P Restricted to open shore
Water Thick-knee Burhinus vermiculatus C1
Grey headed Gull Larus cirrocephalus P P
White-winged Black Tern Chlidonias leucopterus P
Gull billed Tern Gelochelidon nilotica P P Common on lake
Tambourine Dove Turtur tympanistria F C2 C1
Lemon Dove Aplopelia larvata FF C2
Afep Pigeon Columba unicincta FF P P Heard once in forest
Ring necked Dove Streptopelia capicola f [P] P
Red eyed Dove Streptopelia semitorquata f P P Fairly common in cultivation
Blue spotted Wood Dove Turtur afer f P C1 P Common in forest and cultivation
Green Pigeon Treron calva F P P P Three in forest and trees in cultivation
Grey Parrot Psittacus erithacus FF P P P One pair in forest
Eastern Grey Plantain Eater Crinifer zonurus P P P Common in cultivation and edge areas
Ross’s Turaco Musophaga rossae F P P P P Common in all areas with trees
Didric Cuckoo Chrysococcyx caprius [C2] P C1 P Common in all areas with trees
Emerald Cuckoo Chrysococcyx cupreus F P P P Fairly common in forest
Klaas’ Cuckoo Chrysococcyx klaas f P
Red chested Cuckoo Cuculus solitarius F P P P Common in forest
Yellowbill Ceuthmochares aereus F C2 P P Common in forest and woodland
Blue headed Coucal Centropus monachus P
White browed Coucal Centropus superciliosus [?C1] P P P Common in bush
Fiery-necked Nightjar Caprimulgus pectoralis F P
Little Swift Apus affinis P P Small flock at a single location, nesting on
Eurasian Swift Apus apus P
White-rumped Swift Apus caffer P
Speckled Mousebird Colius striatus P
Narina’s Trogon Apaloderma narina F P
Giant Kingfisher Ceryle maxima [C1]
Pied Kingfisher Ceryle rudis P[C31] P C6 P Common at lake shore
Malachite Kingfisher Alcedo cristata C1 P C2 P Pair in grassland at roadside bank
White-bellied Kingfisher Alcedo leucogaster FF C1
Shining-blue Kingfisher Alcedo quadribrachus FF C1
Striped Kingfisher Halcyon chelicuti P Three on trees in cultivation
Chestnut-bellied Kingfisher Halcyon leucocephala f P
Blue breasted Kingfisher Halcyon malimbica F C10 C1
Woodland Kingfisher Halcyon senegalensis [C1] P
Pygmy Kingfisher Ispidina picta f C2 C39 C4 P Common in cultivation, forest edge and
White throated Bee eater Merops albicollis f P P Common at forest edge
Eurasian Bee-eater Merops apiaster P
Little Bee eater Merops pusillus [P] P
Madagascar Bee eater Merops superciliosus [C2] P
Blue breasted Bee eater Merops variegatus [C14] P P Three in grassland
Black and White Casqued Hornbill
Bycanistes subcylindricus F P P P P Common in forest and cultivation
Crowned Hornbill Tockus alboterminatus f [C1] P P P Fairly common at forest edge
Grey throated Barbet Gymnobucco bonapartei F P One at forest edge
Yellow-rumped Tinkerbird Pogoniulus bilineatus F P
Pogoniulus subsulphureus FF P
Brown-eared Woodpecker Campethera caroli F P
Cardinal Woodpecker Dendropicos fuscescens P One at woodland edge
Yellow crested Woodpecker
Mesopicos xantholophus FF P P One at forest edge
Striped Swallow Hirundo abyssinica [C2] P P Common in pairs
Angola Swallow Hirundo angolensis [C28] C1 C2 P Common in small groups
Eurasian Swallow Hirundo rustica P P P Common and numerous
Banded Martin Riparia cincta P Fairly common: grassland by lakeshore
African Sand Martin Riparia paludicola [P]
Sand Martin Riparia riparia P P Common in small numbers
Black headed Oriole Oriolus larvatus f C2 P Common in forest
Pied Crow Corvus albus P P P P Two near habitation
Little Greenbul Andropadus virens F C135 C15 P Common in forest
Yellow throated Leaflove Chlorocichla flavicollis f [?C5] C2 P Common: trees in grassland & cultivation
Common Bulbul Pycnonotus barbatus f C3 P P Common
Blue-shouldered Robin Chat Cossypha cyanocampter F P
Red-capped Robin Chat Cossypha natalensis F P
Snowy headed Robin Chat Cossypha niveicapilla F [C7] C34 C1 P Common in cultivation
Sooty Chat Myrmecocichla nigra P P Restricted to rocky, grassy slopes
Whinchat Saxicola rubetra P Common in grassland
African Thrush Turdus pelios f P P Common in cultivation and undergrowth
Reed Warbler Acrocephalus scirpaceus P Common in cultivation
Yellow breasted Apalis Apalis flavida f P P? [A pale apalis at the forest edge was
possibly this species]
Grey backed Camaroptera Camaroptera brachyura f C1 C35 C1 P Common in woodland and forest
Olive-green Camaroptera Camaroptera chloronota FF C2
Winding Cisticola Cisticola galactotes C1 C1 P Common: grassland, adjacent cultivation
Croaking Cisticola Cisticola natalensis P Small group in long grass
Grey capped Warbler Eminia lepida f C2 P One in cultivation
Green Hylia Hylia prasina F P
Willow Warbler Phylloscopus trochilus f [C1] P P Common: cultivation, bushed grassland
Green Crombec Sylvietta virens F [?C1] C5 C2 P Two locations in forest
Spotted Flycatcher Muscicapa striata P C1
Black-and-white Flycatcher Bias musicus f P
Wattle eye Platysteira cyanea f C1 P P Common in woodland
Black-throated Wattle eye Platysteira peltata F C11
Paradise Flycatcher Terpsiphone viridis f P[C10] C28 C11 P Common in trees and forest
Richard’s Pipit Anthus novaseelandiae C1 P Two on rocky and sandy grassland
Yellow throated Longclaw Macronyx croceus C1 P Restricted to grassy slopes
African Pied Wagtail Motacilla aguimp P P P P Common in cultivation
Cape Wagtail Motacilla capensis P Two in clearings
Yellow Wagtail Motacilla flava P P Common and numerous in all open areas
and on floating weed
Red-backed Shrike Lanius collurio P
Lesser Grey Shrike Lanius minor P
Splendid Glossy Starling Lamprotornis splendidus F P P One seen over forest
Collared Sunbird Anthreptes collaris F C3 C1 P Fairly common at forest edge
Olive bellied Sunbird Nectarinia chloropygia F P Fairly common in bushy areas
Copper Sunbird Nectarinia cuprea f P One in bushed grassland
Blue throated Brown Sunbird Nectarinia cyanolaema FF P
Red chested Sunbird Nectarinia erythrocerca P P Common in cultivation and bush
Olive Sunbird Nectarinia olivacea FF [C29] C83 C7 P One in forest
Scarlet chested Sunbird Nectarinia senegalensis f P P Common: bushed grassland, cultivation
Superb Sunbird Nectarinia superba F P
Variable Sunbird Nectarinia venusta f [C1] P
Green headed Sunbird Nectarinia verticalis F P P One in cultivation
Yellow White eye Zosterops senegalensis f [C10] C4 P Common in woodland
Slender billed Weaver Ploceus pelzelni f [?C30] C58 C1 P Common in forest and cultivation
Black necked Weaver Ploceus nigricollis f C5 P P Three singles/pairs in forest and woodland
Orange Weaver Ploceus aurantius f P[C79] C8 C6 P Two colonies in villages, both with P.
Northern Brown throated Weaver Ploceus castanops f P Common in cultivation
Black-headed Weaver Ploceus cucullatus [C1]
Vieillot’s Black Weaver Ploceus nigerrimus f C1 C3 P Common in villages and forest
Weyn’s Weaver Ploceus weynsi F [C2]
Grey-headed Sparrow Passer griseus P P P Common in villages
Pin tailed Whydah Vidua macroura P P Widespread: cultivation, bushed grassland
Common Waxbill Estrilda astrild [C4] C1 P P One pair in grassland
Black bellied Seed cracker Pyrenestes ostrinus F C3
Black-and-white Mannikin Lonchura bicolor f P P P Three pairs in cultivation
Bronze Mannikin Lonchura cucullata [C1] P P Common on short grass and cultivation
Additional details of sightings during my visit are as follows:
Grey Parrot: only one pair of this noisy and conspicuous bird was recorded, at the western end of the island. Ingram et al.
(1970) record this species as present on all islands and particularly numerous on the smaller Bubeke Island
; the Forest Department Biodiversity Report (1996) states that the species was relatively abundant but under severe pressure from hunters.
Black-and-white Casqued Hornbill: a female was seen to rob two nests in a colony of Vieillot’s Black Weavers, probably taking young. The hornbill picked a hole in the side of the nest, then inserted its bill forcing the hole wider. An accompanying male took no part.
Didric Cuckoo: a young Didric Cuckoo was seen to be fed by a Slender-billed Weaver. Fry et al.
record weavers as the main hosts for this species; the Slender-billed Weaver is listed as a host but no incidence is given. Both cuckoo and weaver are widespread on the island.
Paradise Flycatcher: Chapin (1948) considered the birds of the Ssese Islands to be a separate subspecies T. v. restricta.
The plumage of the male is the normal chestnut and blue-black, but with the central pair of tail feathers pure white. Approximately 85% of about 25 sightings were of this form; one bird had the white tail feathers edged black. As noted above, this species was regularly seen in the forest interior; in the reduced light conditions, the white tail was particularly conspicuous.
Orange Weaver: Mackworth-Praed & Grant (1960) state that this bird often nests in association with other species. Two colonies were seen, both in small trees in villages (one by the veranda of the ‘lodge’ in Kalangala) and both with Vieillot’s Black Weavers.
Doubtful records from Ingram et al. not included in Appendix 1:
Fischer’s Lovebird Agapornis fischeri
C1 Britton does not record feral birds from Uganda
Eurasian Nightjar Caprimulgus europaeus [C2] The timing of the record (undated, but approx. mid-late August) would be exceptionally early
Fischer’s Greenbul Phyllastrephus fischeri [C41] Does not occur in Uganda, per Britton. The ubiquitous Little
Greenbul was not recorded by Ingram et. al.
Orange tufted Sunbird Nectarinia bouvieri [?C1] Recorded as identification uncertain
Eastern Double collared Sunbird Nectarinia mediocris [C1] Does not occur in Uganda, per Britton
Little Weaver Ploceus luteolus [C3] Habitat preferences suggest that this may have been P. pelzelni
Quailfinch Ortygospiza atricollis [?C1] Outside range given in Britton, recorded as identification uncertain