BIRDS OF PREY AT PHINDA PRIVATE GAME RESERVE
Monitoring the density and breeding success of eagles and other birds of prey, is a useful way of determining the health of an ecosystem, because these predators can only thrive when the food pyramid they depend upon is intact. Around the world, raptors are among the first creatures to disappear when habitats are modified by mankind, and their food base collapses, although some species such as Black-shouldered Kites and Barn Owl may flourish or even explode in numbers (albeit temporarily) when monocultures such as grain crops (which attract large numbers of rodents) replace natural habitats. Most raptors have specialised requirements when it comes to breeding, whereas as other species are more adaptable.
Over several months of observation, I have been able to document the occurrence of at least 32 active nests, for 15 bird of prey species at Phinda. This should be regarded as a minimum figure, however, since nest sites of the smaller raptors and owls are notoriously difficult to find, and not all of the reserve has been surveyed thoroughly. Of particular interest, is the absence of any vulture breeding activity at Phinda, even though three species regularly nest in the adjacent (and much older) Mkhuze reserve. Smaller owls are rarely seen and also seemingly absent as breeding birds (again in contrast to Mkhuze where African Scops-Owl and African Barred Owlet are abundant in similar habitat) This might be attributed to the paucity of nesting sites at Phinda, as birds with similar nesting requirements such as hornbills and rollers are either rare or absent.
As Phinda matures into a fully restored wilderness landscape, so we might expect the full complement of raptors, including vultures, to return and settle at maximum density. Such an event would rightly be regarded as a greater conservation success than the introduction of any of the larger mammals, no matter how threatened they might be, in a regional sense. Large eagles and vultures cannot be conserved in a single protected area, or even in a conservation block because they range far and wide onto farmlands where they are vulnerable to direct persecution. In this regard, Phinda can also play a role in educating the neighbouring farmers and rural communities about the many benefits that birds of prey have for both natural and agricultural landscapes, as well as teach them ways to limit or prevent the predation of small livestock by birds of prey.
In this article, I provide details on the species for which I have evidence of breeding. I also list the raptors for which breeding is suspected or possible, as well as those that range onto Phinda only as vagrants or seasonal non-breeding migrants. It is to be hoped that present and future rangers and guides will carefully note and document the breeding activities of Phinda's birds of prey, as well as their diet, on an ongoing basis so that an increasingly accurate picture of their density and ecological role can be determined. Wahlberg’s Eagle
This intra-African migrant visits Phinda between late August and March, with pairs returning annually to their nests, which are repaired and lined with green leaves prior to egg laying. Ten nest sites were recorded at Phinda in 2005, with four pairs known to raise young. A single egg is laid in August or September, with an incubation period of about five weeks. The youngster is ready to fly after a further 10 weeks, and will beg noisily from its parents during the first few weeks of independence. Most nests were situated in taller trees along drainage lines, with one on the fringe of the sandforest. The stick nests are always situated on a fork below the tree canopy, usually at a height of about 10m. Trees used at Phinda were Sycamore Fig Ficus sycamoros (4), Red Bushwillow Combretum apiculatum(2), Fever Tree Acacia xanthophloea, Brack Thorn Acacia robusta (2), White Milkwood Sideroxylon inerme (1) and Newtonia Newtonia hildebrantii (1). During 2002, a total of eight nests were found in the south of Phinda alone, at a density of 7.19km2 per pair (Kilpin, 2003). Wahlberg's Eagles spend their non-breeding months in the northern savanna zones of Nigeria, Cameroon, Chad and Sudan.
Yellow-billed Kite
The Yellow-billed Kite is another intra-African migrant, although not all of the birds visiting southern Africa between August and March will breed. There are five known nest sites at Phinda, although no information is available on the numbers of young raised. All nests were situated below the canopy of trees along well wooded drainage lines and rivers. The average height of nests was just under 8m. The most common tree used for nesting was Weeping Boerbean Schotia brachypetala (3) with Natal Mahogany Trichilia emetica (1) and Brack Thorn Acacia robusta (1).
African Crowned-Eagle
This huge and powerful eagle is always associated with forest, so the riverine forest and sandforest at Phinda provides ideal habitat. The distinctive whistled call, given in aerial display, betrays the presence of this otherwise secretive raptor. There are four nesting pairs at Phinda, with each having raised young over the past few years. Eggs are usually laid between July and October, prior to the wet season. Although two eggs are normally laid and incubated (for about 50 days), only one nestling survives to fledge. Three pairs have nests along drainage lines in the south of Phinda and there is one pair nesting in the northern sandforest. The average height of these nests is around 14m, with large bulky nests usually well-hidden below the canopy. The sandforest pair have their nest in a large Torchwood Balanites maughamii at a height of about 20m. In the south of Phinda, near the shallow volcanic crater, a pair has its nest about 12m up in a Sycamore Fig Ficus sycamorus; this pair has an alternate nest just 5m up in a Weeping Boerbean Schotia brachypetala on top of a massive Hamerkop nest. They did not, however, use this nest as it is close to a main road, and there may have too much disturbance. On the banks of the Mhlosinga River, a pair have a nest some 15m up in a Fever Tree Acacia xanthophloea. Not far from Mountain Lodge the remaining pair have taken over a Bateleur nest, after their previous nest site in a large dead Sycamore Fig was blown over. This new nest is in a Fever Tree at a height of about 12m. The four Phinda nests are separated from one another by distances of between 4 and 7km, which is a higher than average density for this species. The recorded prey of African Crowned-Eagles at Phinda is diverse, with francolin, spurfowl, guineafowl, Vervet Monkey, Red Duiker, Suni and even fawns of Nyala and Impala being recorded over the past few years.
Martial Eagle
Two nests of this species have been found at Phinda, just 7km apart (well below the average of 20km or more). One nest is 12m up in a Sycamore Fig Ficus Sycamorus growing in a drainage line not far from Zuka Lodge. The other is 8m up in a Red Bushwillow Combretum apiculatum near the crest of the Ubombo hills; it is clearly visible from Phinda Rock Lodge in winter when trees are leafless; this pair had a previous nest about 2km away on the other side of the hills, in a dead Fever Tree. Martial Eagles typically lay their single egg in May, June or July, and this pair was provisioning their nestling with monitor lizards and other prey items during August 2005, when it was estimated to be about three months old. As elsewhere in their range, Martial Eagles at Phinda feed largely on monitor lizards, hares, mongooses, spurfowl, guineafowl and small or young antelope.
African Fish-Eagle
Two pairs have nest sites along the Mzinene River at a distance of some 8km from one another. Both are in Fever Trees Acacia xanthophloea about 12m high. Only one of these pairs raised a nestling in 2006.
Bateleur
Two breeding pairs of this conspicuous eagle are known at Phinda. One nest site is about 12m up in a Black Monkey Thorn Acacia burkei in the north. The other is about 15m up in a Fever Tree Acacia xanthophloea growing along a drainage line at the foot of the Ubombo hills in the south. These two pairs are 22 km apart. The pair in the south had their former nest taken over by African Crowned-Eagles, and rebuilt 3km from there.
African Harrier-Hawk (Gymnogene)
This unusual raptor is regularly seen, but only two nest sites have been located. One is 15m up in a Fever Tree Acacia xanthophloea along on the Mzinene River. The other is 8m up in an unidentified tree in riparian thicket along drainage line.
Southern Banded Snake Eagle
The small stick nest of this eagle is notoriously difficult to locate but the resident status of this localised bird strongly suggests that it breeds at Phinda. Based on repeated observations, there could be as many as four pairs here, with possible sites on the Munyawana drainage line close to Bumbeni Dam, Munyawana close to Zulu road (could be the same pair), the Mzinene River close to Bamba, and one in the northern sandforest. Individuals have been seen carrying snakes purposefully, as though provisioning a nestling or mate, and repeated vocalisations and display flights is further evidence of breeding.
Brown Snake-Eagle
A nest was reported some years ago in the Ubombo hills, but has not been active in recent times.
Lizard Buzzard
A single Lizzard Buzzard nest has been found, although there must be many more as this small raptor is common and frequently encountered at Phinda. The active nest was situated at a height of 10 m in a Black Monkey-Thorn Acacia burkei.
African Goshawk
A single nest site has been found in riparian thicket in the Hamerkop drainage line. This accipiter is common at Phinda and more pairs must be breeding although their nests are always very well hidden in evergreen trees and hard to locate. Adults call repeatedly as they perform aerial display flights above their territories, and this is another way of determining abundance.
African Cuckoo-Hawk
This unusual raptor typically builds a frail, loosely-built nest of twigs, well hidden by foliage, in the crown of a tall tree. An adult was observed carrying unidentified prey as though provisioning a nestling or mate, and juveniles have been seen on several occasions so breeding is all but confirmed.
Secretarybird
A single pair of Secretarybirds have two alternate nest sites on the marsh; one nest is on the crown of a 5m Scented Thorn Acacia nilotica, and the other on top of a 10m high Umbrella Thorn Acacia tortilis.
Spotted Eagle-Owl
This is the most common owl in the south of the reserve with one pair nesting in an eroded gully on the ground at Ammonite Dam, and another at Spukupuku. We suspect that there are several other pairs nesting in the rocky areas of the Lebombo hills.
African Wood-Owl
Surprisingly, there are no confirmed breeding records at Phinda (this owl nests in tree cavities), but it is vociferous throughout the year in the northern sand forest where several pairs must surely hold territories.
Barn Owl
One pair was found breeding in a Hamerkop nest on the Munyawana River. During 2004 and 2005, the numbers of Barn Owls have picked up substantially. This is due to the increase in their rodent prey.
Raptors which may be resident and may breed at Phinda, but for which there is no concrete evidence:
Long-crested Eagle
Tawny Eagle
African Marsh-Harrier
Gabar Goshawk
Shikra (Little Banded Goshawk)
Little Sparrowhawk
Black Sparrowhawk
Verreaux's Eagle-Owl
Pel’s Fishing-Owl
White-faced Scops-Owl
Marsh Owl
Raptors which occur regularly or sporadically at Phinda, but are not resident and are not thought to breed in the reserve (although they are known to breed nearby):
White-backed Vulture (breeds at Mkhuze)
Lappet-faced Vulture (breeds at Mkhuze)
White-headed Vulture (breeds at Mkhuze)
Bat Hawk
Palmnut Vulture (breeds at Kosi Bay and Mtunzini)
Tawny Eagle (breeds at Mkhuze)
African Hawk-Eagle
Black-chested Snake-Eagle
Jackal Buzzard (breeds on cliffs above Jozini dam)
Rock Kestrel (breeds on cliffs of Lubombos and perhaps on old crow nests in electricity pylons)
Lanner Falcon (breeds on cliffs above Jozini dam and perhaps on old crow nests in electricity pylons)
Peregrine Falcon (race minor) (may breed on cliffs above Jozini dam)
African Grass-Owl
African Barred Owlet (breeds at Mkhuze)
African Scops-Owl (breeds at Mkhuze)
Raptors which are rare and visit Maputaland only as vagrants; and not thought to breed in the area:
Cape Vulture
Hooded Vulture
Dark Chanting-Goshawk
Ayre’s Hawk Eagle
Booted Eagle
Raptors that are non-breeding migrants from Eurasia, but which visit Phinda during the wet summer months:
Osprey
Eurasian Honey-Buzzard
Black Kite
Pallid Harrier
Montagu’s Harrier
Steppe Buzzard
Lesser Spotted Eagle
Steppe Eagle
Amur Falcon
Sooty Falcon
Eurasian Hobby
Peregrine Falcon (race calidus)
Acknowledgements: Duncan Butchart provided input into this article.
References and further reading:
Tarboton, W. A Guide to the Nests and Eggs of Southern African Birds. Struik, Cape Town.
Steyn,P. 1982. Birds of Prey of Southern Africa. David Philip, Cape Town.
Kilpin, A. 2000. Preliminary Owl Survey at Phinda. Ecological Journal 2:206-208. CC Africa, Benmore.
Kilpin, A. 2001. Notes on Wahlberg's Eagle breeding activity at Phinda. Ecological Journal 3:108-110. CC Africa, Benmore
Posted: Birds by Daryl Dell, Date: 5 January 2011
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