By Washington Wachira
As I tip-toed behind a large Newtonia tree along the Karura River, I heard a spine-chilling scream! I aimed my binoculars upwards and marveled at the sight of a Harvey’s Duiker being grabbed by the largest African Crowned Eagle I have ever seen.
Turning right, I saw a large but gentle young eagle in a huge nest. Its white plumage stood out in the dark forest canopy as the parent put the duiker in the nest. The young bird quickly left with the hind limb of the duiker and headed for a feeding patch on a neighboring tree.
Birds of prey are avian predators characterized by their keen vision, strong hooked bills and powerful talons. They are often called “raptors”, a name derived from Latin the word rapere, which means to seize or take by force.
There is a wide variety of raptors — from Eagles, Hawks, Secretarybird, Kites, Falcons [including Kestrels], Owls, Buzzards, Vultures and Osprey. Africa has 89 diurnal raptors and 31 owl species. Eagles are especially famous, the largest being the Martial Eagle, and the most powerful, the African Crowned Eagle.
The Martial Eagle, scanning the savannah for gazelle fawns, the lightning-fast stoop of a Lanner Falcon swooping in for a sandgrouse, the smooth and silent flight of a Barn Owl skimming over farmlands for mice, the leisurely soar of a White-backed Vulture browsing the grasslands for carrion. Awesome!
Ecosystem health indicators
Raptors offer vital ecosystem services, helping to regulate the populations of their prey, including crop pests, and in the case of vultures, consuming carcasses rapidly to prevent the spread of diseases. Being on top of the food chain, raptors are very reliable ecosystem health indicators. Their success or failure points to the state of the environment where they occur.
The Kenyan capital, Nairobi, is considered a great place for raptors. With a one-of-a-kind urban national park next door, the metropolis hosts a variety of habitats that are home to a wide array of spectacular raptors.
The sight of bids nesting in urban areas is becoming more common due to rising global human population that has led to habitat changes. In Nairobi, the Great Sparrowhawks and Ayres’s Hawk-eagles have nested in various parts of the city, often close to schools, markets, golf courses, homes and hotels.
Large avian predators, like the African Crowned Eagle, often utilise very small forest blocks in Nairobi for nesting. Currently, there are five pairs of African Crowned Eagles occupying the greater Nairobi region.
The recent return of the eagles is largely due to proper care of forests around Nairobi, including the fencing off of some woodlands. One of these nests, at the edge of Nairobi
National Park, was abandoned by the local pair after the expansion of Lang’ata Road. However, with food available around the neighbouring forests, this pair has returned.
African Crowned Eagles are the top avian predators in Nairobi’s forests. Scientifically sound knowledge on the Crowned Eagles is essential for informed conservation policies and decisions on where roads, railways, power lines, wind farms and industries may be built.
A resident Augur Buzzard pair nested on trees near Muthaiga, along Thika Road, and White-backed Vultures have also attempted nesting on a tree along Lang’ata Road, near the Galleria Mall.
Black Kites have been observed in the Nairobi Arboretum and at Kenyatta University. This makes urban nesting a developing adaptational trait among different bird species.
Urban nesting sites are very important in a changing human world. Many habitat conversion activities are pushing species out of their breeding sites, forcing them to seek alternatives.
Human presence may serve as a predator deterrence strategy, increasing nest productivity and raising chick-fledging probabilities. Some species that have adapted to feeding strategies that are aided by human activities, including dumpsite scavenging, may also become more successful with urban nesting. Nests that are close to feeding sites are favourable as they reduce parent nest-absence and increase chick survival through parental protection and sustainable food availability.
All this makes Nairobi and other cities a very important place for birds of prey. The Ugandan capital, Kampala, for example, has a huge population of Hooded Vultures dwelling in the city and residents have gotten used to them.
What Nairobi’s expansion means for the future of raptors
A growing human population will certainly mean an increase in the amount of garbage around Nairobi. This will likely attract more Black Kites into the city. It is already evident that Nairobi has more Black Kites than all neighbouring towns. This may be good for the Black Kite population, but on the other hand, the species will likely outcompete the smaller raptors – such as Ayres’s Hawk-Eagles and Great Sparrowhawks for space and food.
As more power generating projects are implemented to meet increasing demand for energy, infrastructure installations such as wind turbines and high voltage pylons will threaten birds of prey. They will be at increasing risk of collision, electrocution and slicing by wind turbines.
Habitat loss from other infrastructure projects such as road and railway construction will also negatively impact vulnerable raptor populations in Nairobi and beyond.
Other threats facing raptors in Nairobi include poisoning, forest degradation, pollution, illegal hunting and competition for prey with bush meat poachers.
Types of raptors found in Nairobi and the roles they play
Nairobi has a wide variety of birds of prey. Their roles in the ecosystem range from prey numbers regulation, carrion eradication, disease control and rodent control.
The birds include Owls such as Pearl-spotted Owlet, African Wood Owl, Verreaux’s Eagle-Owl, Marsh Owl and Spotted Eagle-Owl that help regulate rodent populations in the city. A rare Owl, the Pel’s Fishing Owl, has also been recorded here.
Falcons include species like Lanner Falcon, Amur Falcon, Eleonora’s Falcon, Sooty Falcon, Barbary Falcon, Red-footed Falcon, Eurasian Hobby, African Hobby, Common Kestrel, Greater Kestrel, Lesser Kestrel, Dickinson’s Kestrel, Pygmy Falcon [to the south], Taita Falcon [extreme south] and Peregrine Falcon.
Eagles range from the largest three — Martial Eagle, African Crowned Eagle and the rarer Verreaux’s Eagle. Relatively smaller eagles such as the Steppe Eagle, Tawny Eagle, Long-crested Eagle, Eastern Imperial Eagle [very rare], African Hawk-Eagle [rare], Ayres’s Hawk-Eagle, Wahlberg’s Eagle, Lesser Spotted Eagle, Booted Eagle and the Greater Spotted Eagle also inhabit Nairobi at different times in a year.
Another group of eagles is the Snake-Eagles with round faces and bare tarsi, which include Black-chested Snake-Eagle, Western Banded Snake-Eagle [rare in the region] and Brown Snake-Eagle.
Eastern Chanting Goshawks are common to the south, but the related Dark Chanting Goshawks are very rare. Accipiters, characterized by their long tails and slender bodies that help them maneuver around bushes as they hunt. The generalist-feeding goshawks include Shikra, Gabar Goshawk and African Goshawk.
Specialist-feeders, focusing on avian prey, include the Little Sparrowhawk, Ovambo Sparrowhawk, Rufous-breasted Sparrowhawk and Great Sparrowhawk. Kites include the African Black-shouldered Kite and the Black Kite.
Vultures — nature’s clean-up crew — include the Lappet-faced Vulture [Kenya’s largest vulture], White-backed Vulture, Palm-nut Vulture and Ruppell’s Vulture. Some vulture species are now almost extirpated from Nairobi, including the Egyptian Vulture and Hooded Vulture.
Without these vultures, Nairobi would be a stinking ecosystem with many pathogens that would cost the economy billions of shillings to manage epidemics.
Buzzard species, famous for rodent hunting, include the Augur Buzzard and Steppe Buzzard. Mountain Buzzards are infrequently seen along the Kiambu-Nairobi boundary.
Lizard Buzzards and Eurasian Honey Buzzards can also be seen occasionally. The very rare Long-legged Buzzard has also been recorded. Others include the Bateleur and African Fish Eagle, known for their short tails in relation to their wings.
The Secretary bird [a snake-hunter], and the African Harrier-hawk, known for its double-jointed feet that enable it to hunt lizards from crevices and raid other birds’ nests has also been seen. A rare Osprey has been sighted occasionally scouting in the local wetlands.
Harriers include the Eurasian Marsh Harrier, African Marsh Harrier [no recent sightings], Montagu’s Harrier and Pallid Harrier. The beautiful African Cuckoo-Hawk, seen in the Ngong-Karen forests, should not be forgotten. Bat Hawks have also been sighted around Limuru, Karen, Rosslyn and Zimmerman areas.
Nairobi residents have an obligation to ensure the continued survival of raptors because of the important role they play in ensuring ecosystem balance.
Habitats must be preserved by curbing forest degradation, reclaiming wetlands and refraining from converting grasslands to farmlands and residential estates. Many recreational facilities are habitats for raptors. Golf courses for example host nesting trees for local species. Golf course and resort managements can work together with the conservation community to improve public awareness on the importance of birds of prey.
Corporations need to step up support for avian species conservation through, for example, adopting forests, reforestation and fencing off of woodlands. Local support for research and citizen-science will ensure essential data is available to inform conservation decisions.