Work in Progress

The Black Harrier Work in progress Text by Odette Curtis, Andrew Jenkins Despite its striking appearance and & Rob Simmons Red Data status, the endemic Black Harrier remains little studied. Photographs by Andrew Jenkins 1 1 2 2 3 3 4 4 5 5 6 Black Harrier beats its way low Western Cape, initiated by staff and 6 7 across the windswept Strandveld associates of the Percy FitzPatrick 7 8 A of the Cape West Coast. Its ele- Institute of African Ornithology. The 8 9 gant shape and charcoal-black plumage, harrier has been the Institute’s logo 9 10 offset by striking white markings and since the early 1980s, but this new ini- 10 11 piercing yellow eyes, contrast starkly tiative is the first formal attempt to 11 common 12 with the monotonous greens and browns understand the harrier’s biology. uncommon 12 13 of the coastal scrub. It is a sight as There are only a couple of Black Harrier rare 13 14 unique to the Western Cape region as studies in the literature. One dates back to 14 15 the looming silhouette of Table 1981 and was a desk-top review of status 15 16 Mountain, yet this impressive and and distribution, while a more recent 16 17 endemic bird, newly inducted to Red study recorded aspects of breeding biolo- Opposite Banking against the after- 17 18 Data status, remains largely unknown. gy over two seasons in the West Coast noon sun, a soaring Black Harrier 18 19 National Park. Our goals are more ambi- shows its characteristic flight-pattern. 19 20 Better late than never tious. We hope to document fully the 20 21 The year 2000 saw the start of a research species’ breeding ecology and resource Below Black Harrier habitat in the 21 22 project on the biology and conser va- requirements, with a view to understand- Perdeberg area – fynbos patches in a 22 23 tion status of the Black Harrier in the ing its conservation needs better. This sea of grain. 23 24 24 25 25 26 26 27 27 28 28 29 29 30 30 31 31 32 32 33 33 34 34 35 35 36 36 37 37 38 38 39 39 40 40 41 41 42 42 43 43 44 44 45 45 46 46 47 47 48 48 49 49 50 50 51 51 52 52 53 53 54 54 55 55 56 56 57 57 58 58 59 59 60 60 61 61 62 62 32 BLACK HARRIER AFRICA – BIRDS & BIRDING OCTOBER/NOVEMBER 2001 BLACK HARRIER 33 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 24 25 25 26 26 27 Black Harrier life-cycle: a clutch of four eggs at Sally’s nest on the Slent farm, Perdeberg; a recent hatchling and two unhatched eggs; a female and her two three-week-old nestlings; a fully-feathered youngster, aged about six weeks. 27 28 28 29 29 30 requires that we work over as extensive agricultural areas, the transformation and they exhibit. More than a third of the son, Harry settled down to fatherhood close to the nests that we had under being caught by a provisioning harrier. 30 31 an area as possible, and that the study fragmentation of their natural habitat by world’s harrier species are, at least some- and together with Sally successfully raised observation, and at the Koeberg Nature The egg had disappeared when we went 31 32 spans a number of years. Having identi- agriculture is likely to be of little conse- times, polygynous. In other words, they three healthy youngsters. Reserve provisioning males were seen to to ring the nestlings at a later stage. 32 33 fied our ultimate objectives, we set our- quence. Given that standard farming breed in groups comprising a single We first met Harry when, contrary to make regular, very direct flights to areas Perhaps it hatched, only to provide a tasty 33 34 selves three more modest goals for the practices in grain-growing areas include male and multiple (usually two) fe- our expectations, he pounced greedily some distance away to the east, probably morsel for the hungry harriers? 34 35 year. We aimed to locate study areas with frequent crop-spraying, that harvesting of males. Polygyny has been mooted for onto our Bal-chatri trap baited with plump to the wheatfields that lie beyond the We should get a far clearer picture of 35 36 breeding har-riers in both natural and crops generally coincides with the middle Black Harriers, but has not yet been little mice (which were unharmed during West Coast road. harrier diet once we have been able to 36 37 man-altered environments; to capture of the harrier breeding season and that properly confirmed. In an attempt to this process and lived to tell of their What little information we were able to collect and analyse larger samples of 37 38 and mark adult birds for long-term obser- the Black Harrier is an exclusively ground- clarify this issue, we spent many hours heroic escape). This was the first of five collect on harrier diet (and this took the remains, and when we have completed 38 39 vations (and to take blood from both nesting bird, it would seem unlikely that watching interactions between breeding birds that we managed to trap during the form of prey remains collected from more observations. However, initial 39 40 adults and their pairs attempting to breed in fields of harriers. Both of our study areas featured 2000 season. Once in the hand, these beneath favourite perches and roosts and im pres sions indicate that, while agricul- 40 41 offspring to determine paternity); and to wheat or barley could ever fledge signifi- concentrations of breeding birds, in birds were weighed, measured, ringed and direct observations of prey delivered to ture may fragment and impinge on Black 41 42 study breeding biology and success, cant numbers of young. Our preliminary which the closest nests were about 100 marked with brightly coloured patagial nests), suggested that harriers fed mostly Harrier nesting habitat, it could also ben- 42 43 including a preliminary assessment of investigations do indeed suggest that metres apart. Even under these ‘semi- tags (plastic flaps attached to the leading on rodents, small birds and the occasional efit the species by providing particularly 43 44 mating systems. these problems may largely exclude har- colonial’ conditions, we recorded only edge of one wing). Individuals tagged in reptile. Interestingly, the harriers at good foraging conditions. On this basis, 44 45 riers from farmland. one instance of confirmed polygyny: this way were distinguishable hundreds of Koeberg were predominantly rodent eat- the key to Black Harrier conservation 45 46 Living in a sea of grain Despite scouring much of the Overberg the antics of a male dubbed ‘Harry the metres away and were key in our behav- ers, while those at Slent seemed to take seems to lie in achieving an optimal bal- 46 47 A regrettable feature of the Fynbos Biome region for breeding harriers, we found no Harrier’ were studied at length during ioural studies. We also took blood samples mainly birds. The most frequently record- ance between cereal croplands and patch- 47 48 (which forms the core of the Black active nests in or close to grain fields, and the formation of his threesome. from these birds and from any young that ed prey at Slent was Common Quail es of undisturbed, natural vegetation. 48 49 Harrier’s breeding distribution) is the all of the 19 nests we located were in rela- Harry met Sally some time before we they produced during the season. We Coturnix coturnix, while Red Bishop 49 50 extent to which natural vegetation has tively pristine vegetation. Ultimately, we started to monitor the harriers at Slent hope to use these and subsequent samples Euplectes orix was also on the list of prey The road ahead 50 51 been transformed into horizon-spanning identified two principal study areas: the Farm, and the couple had already pro- to determine which males are fathering species. This suggested to us that the Slent Given sufficient enthusiasm and fund- 51 52 swathes of cereal croplands. It is unclear area inclusive of the Koeberg and duced a splendid clutch of four eggs. which broods, as it was entirely possible harriers did much of their foraging some ing, this promising start should see the 52 53 to what degree, and in what way, the har- Jakkalsfontein nature reserves on the What Sally didn’t know (or did she?) was that, given the mêlée of courting harriers distance from the Perdeberg (where quail Black Harrier project run for another 53 54 rier population has been affected by this West Coast, and Slent Farm and the that Harry had a little bit on the side. His we sometimes observed, some males may are uncommon and bishops not record- three to four years. During this time we 54 55 wholesale modification of its habitat. In Perdeberg Conservancy, just north-west newly acquired mate, Harriette, gained have copulated with females other than ed), probably in the grainfields that sur- hope to continue the intensive monitor- 55 56 order to shed some light on this all- of Paarl. Harry’s attention during Sally’s protracted their ‘wives’. round the mountain. In one remarkable ing of marked breeding birds in our core 56 57 important conservation management vigil at nest one, and soon produced a instance, a small, non-harrier egg (proba- study areas, and simultaneously develop 57 58 issue, we went to some lengths to locate When Harry met clutch of three eggs at nest two.

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