Siberian Peregrines in southern Africa

From Arctic tundras to African dunesSiberian Peregrines in southern AfricaText by Andrew R. Jenkins and Alan StephensonPhotographs by Andrew R. JenkinsAcross its almost worldwide distribution,the Peregrine Falcon Falco peregrinusvaries in appearance andbiology to the extent that as many as 19 geneticallydistinct races are currently recognized.Populations of these subtly different forms aregeographically separate, and many are essentiallyresident within their respective breeding rangesthroughout the year.However, Peregrines living at northernlatitudes are forced southward by severewinter conditions on their breeding grounds,and the two northernmost races are highlymigratory. Pairs of F. p. tundrius and F. p. calidusannually vacate their territories on the tundrasof arctic North America and Siberia and travelthousands of kilometres south to spend theboreal winter in the tropics.An adult male calidus Peregrine feeding on a Rock PigeonColumba guinea on the dunes at Woody Cape in SouthAfrica’s Eastern Cape.62 PEREGRINE Falconafrica – birds & birding1997 – volume 2, number 4PEREGRINE falcon63

The secrets of Peregrine migrationExtensive ringing programmes, observations of migratingfalcons in areas where they are particularly concentrated,and studies using satellite telemetry have unlocked manyof the migration secrets of Alaskan and Canadian tundriusPeregrines, most of which overwinter in Central andSouth America. However, the origins, routes and destinationsof migratory Peregrines of the Asian Arctic are poorlyknown. These calidus Peregrines are thought to movesouth into central and southern Asia, the Middle East andAfrica. Birds crossing into Africa probably pass throughthe Red Sea region before fanning out to travel down bothcoastlines. They are apparently quite numerous on passagealong the coasts of Somalia and Kenya, and havebeen reported using oil rigs off the Angolan coast as huntingand roosting sites. Inland in North and Central Africa,specimens have been collected from Sudan, Cameroonand the Congo.Visitors to southern AfricaAuthentic records of calidus or other migrant Peregrines insouthern Africa are scarce. Andrew Jenkins (ARJ) searchedthe literature and canvassed a number of museums andornithologists in the region and could compile only 18acceptable calidus Peregrine records – five of which weremuseum specimens.One reason that so few migrants are recorded may bethat calidus birds are difficult to distinguish in the fieldfrom resident African Peregrines F. p. minor. Although thetwo races supposedly represent opposite extremes in thespectrum of Peregrine colour and size variation, casualsightings of Peregrines are often made under difficult circumstancesand seldom permit the observer time to studysubspecific details. Confusion is exaggerated by considerablevariation in plumage and size within each subspecies.Perhaps significantly, seven out of 10 sexed and aged calidusrecords from southern Africa are of adult females –those most obviously different from the region’s residentbirds.While problems with identification may reduce thenumber of migrant Peregrines recorded, data from theSouthern African Bird Atlas Project show no increase inthe frequency of Peregrine sightings over the summerperiod when the migrants should be in the region(October to March). Hence the paucity of contemporaryrecords, which exists even in the face of a growing The Alexandria dunefield is two to three kilometres wide and stretches about 50 kilometres along the coast from just north-eastof Port Elizabeth. The dunes reach a height of more than 100 metres in places, and only occasional patches of vegetationbreak the monotonous expanse of open sand.Possible migration route of Siberian Peregrines into AfricaThe broken red lines ( )indicate approximate routes ofnorthern Eurasian Peregrinestrapped on their breedinggrounds and satellite-tracked towintering areas in WesternEurope and Pakistan. Migrantsinto Africa may originate fromWestern Siberia.Kola Peninsula..Woody CapeKara Sea?.Taimyr Peninsulanumber of expert falcon enthusiasts active on thesubcontinent, is probably realistic, and only a relativelysmall number of migrant Peregrines travel as far as southernAfrica each summer.Falcons of the dunesIn the summer of 1992, Alan Stephenson (AS) had occasionto visit the Woody Cape Nature Reserve which straddlesthe Alexandria dunefield along the eastern shore ofAlgoa Bay, in the Eastern Cape. During this visit, he wassurprised to see at least two adult Peregrines apparentlyoccupying the long stretch of low, sandy cliffs which linethe beach to the north-east of Woody Cape. Subsequentvisits revealed that these or similar birds were present inthe area throughout that summer. AS noticed that thebirds differed from African Peregrines in their appearanceand in the way they flew. One bird, which he took to befemale, was obviously bigger than Peregrines he had seenbefore, and both seemed to have very pale undersides.When they flew around the dunes or along the shore theyseemed lazy, big-winged and long-tailed, and lacked theurgency and energy of the African Peregrine. When inpursuit of prey however, they took on a differentdemeanour and showed themselves to be fast, powerfulhunters, unmistakably Peregrines. AS recognized thatthese must be migrant calidus birds.Over the next five years AS made numerous visits toWoody Cape and adjacent areas of the dunefield. ThePeregrines were there each summer from about Novemberto March. He saw both adult and juvenile birds, and asmany as five or six individuals in the area at a time. Theadults seemed to prefer the coastal cliffs, whereas thejuveniles usually perched inland on the highest crests ofthe dunefield. The Peregrines were often in the companyof Hobbies F. subbuteo which also seemed to use the dunefieldas a perching and foraging area and generally outnumberedtheir larger relatives, with upwards of 10–20birds present in the vicinity on most visits. The numberof birds and their time of arrival on the dunes varied eachyear, perhaps depending on the weather and foragingconditions the birds experienced on their trip south.A bird in the hand...Since first encountering the dunes Peregrines, AS maderepeated efforts to trap one of these birds in order to studyit in the hand. They were generally skittish and difficultto approach, and they proved to be extremely trap-shy.However, in January 1995 his efforts were rewarded, andhe bagged a juvenile male. AS and ARJ got together tomeasure and photograph the bird, and to take a bloodsample with a view to perhaps confirming its identityusing DNA analyses.In appearance, it seemed to fit the profile for a calidusPeregrine. The literature suggests that calidus is the palestPeregrine subspecies, especially ventrally, with faint markingson the underparts, a relatively incomplete head-capand thin ‘malar stripes’ beneath the eyes, leaving thecheeks white. Overall, this bird was much paler than a1997 – volume 2, number 4PEREGRINE falcon65

305–330 millimetres), and longer than that of minor (average284 millimetres, range 275–300 millimetres), and itstail was more than two centimetres longer than that of atypical African Peregrine. With a wing area about 20 percent larger than that of a typical minor, its wing loading(body mass to wing area ratio) was about 15 per centlighter. The relatively long wings and light body of themigrant probably facilitate long-distance flying andreduce energy expenditure during migration.In the 1996/97 season, there were at least three birds inthe Woody Cape area, including an adult male which AStrapped in January 1997. Again we convened to recordthe bird’s vital statistics, photograph it and take someblood before ringing and releasing it. At 580 grams thiswas another fairly small individual, with a wing length of300 milli- metres and a slightly heavier wing loading thant h ejuvenile bird. It featured a striking contrast between darkslate dorsal plumage and white, lightly barred underparts.The malar stripe was quite broad but the cheeks werewhite.While these trapped birds were larger than AfricanPeregrine males, the size discrepancy was much less DestinationsThe literature suggests that Siberian Peregrines leave theirbreeding areas at the end of the northern summer in synchronywith the migration of their main prey species,mostly waterbirds, and that they follow these birds totheir wintering areas and continue to prey on them there.Hence, falcons visiting southern Africa might be expectedto frequent coastal estuaries where migrant shorebirdscongregate. Wader biologists report that the frequency ofPeregrine strikes at major southern African estuaries is relativelylow, but this may simply reflect the small numberof migrant falcons which make it this far south.It is difficult to account for the attraction which theAlexandria dunefield apparently holds for calidusPeregrines. The area features a unique habitat, with largeexpanses of open sand offering little cover for prey.Perhaps the dunes constitute a particularly favourablehunting area for the migrant falcons, where they areunlikely to encounter territorial residents? Also, WoodyCape is conveniently situated for falcons to hunt pigeonsmoving over the sea between the mainland and BirdIsland, and migrant passerines and waders travellingalong the coast and crossing Algoa Bay.A juvenile female African Peregrine trapped in the southwesternCape (above) and a juvenile male calidus trappedat Woody Cape (right). Note the thicker malar stripe, morecomplete, dark ‘helmet’, and darkly streaked underparts ofthe African bird. The migrant has a significant amount ofwhite on the head, quite thin malar stripes and pale, faintlystreaked underparts.typical juvenile African Peregrine. Its chest and belly wereoff-white with light streaking, its back chocolate-brownwith the dorsal feathers broadly edged in buff. The malarstripe was quite thin and the cheeks were pale, but themost telling feature was the amount of white on its head,which extended from a broad, pale noseband to conspicuouswhite eyestripes and large, white patches on the nape.Siberian Peregrines are also thought to be one of thelargest forms of the species – appreciably larger thanAfrican birds. The bird AS had trapped was not particularlylarge. It weighed 570 grams and was only slightlyheavier than most South African minor males (which averageabout 530 grams, and range from 500–610 grams) andwas rather light for a calidus male which reportedly averagemore than 700 grams and range from 678–740 grams).However, its wing-length measurement (310 millimetres)was about right for calidus (average 314 millimetres, rangeAn adult male African Peregrine (above) trapped on theCape Peninsula, and an adult male Siberian Peregrine(right) trapped at the Alexandria dunefield. The Africanbird is typical of the subspecies, and features a coloured‘wash’ with dense spotting and barring on the lower chestand belly and a pale ‘bib’, broad malar stripes and a full,black head-cap. The calidus bird has a slightly narrowermalar stripe and is conspicuously whiter and more lightlymarked below.than we had expected and both were well within the sizerange of minor females. Russian ornithologists have suggestedthat male calidus Peregrines migrate further thanfemales, and are more likely to venture south into Africa.If this is the case, and most of the southern African visitorsare males, our observations suggest that size may notbe a good criterion for separating migrant from residentbirds. Apart from ‘jizz’ differences which are probablyonly apparent to an experienced observer, we found thatthe best distinguishing feature in the field is probably thewhiteness of the entire ventral surface on calidus birds,compared with the white ‘bib’ and darker belly presentedby minor. Greyer upperparts and narrower malar stripesmay not be strictly diagnostic of calidus.66 peregrine Falconafrica – birds & birding1997 – volume 2, number 4PEREGRINE falcon67

Above The Siberian Peregrine (left) shows a noticeably whiter, less heavily marked belly and underwing than the AfricanPeregrine (right).OriginsRecent efforts to investigate the migration routes of EurasianPeregrines have shed some light on the possible origins ofvisitors to southern Africa. Four birds were fitted with satellitetransmitters in 1994 at their breeding grounds on theKola Peninsula in north-western Russia by an American biologist,Charles Henny, and his team. All four birds overwinteredin western Europe. Further east along the Arctic Circle,a female from the Taimyr Peninsula was tracked to her winteringgrounds in Pakistan by workers from the FalconFacility of the National Avian Research Center, Abu Dhabi(interestingly, a male trapped in this area weighed 625grams, a figure which compares favourably with the weightswe recorded in South Africa).This rather limited evidence could suggest that falconsmoving down into Africa originate from somewherebetween Kola and Taimyr, in the region of the Kara Sea. InNovember 1996, Dr Bernd Meyburg of the World WorkingGroup on Birds of Prey & Owls (WWGBP) informed us of afemale calidus Peregrine which had been trapped and satellite-taggedon southward migration through Saudi Arabia.She was tracked on passage down to a point just north ofPaarl in the Western Cape,where she apparentlyspent the austral summer.Unfor tu nately, duringher stay in theBoland, she apparentlyshed her transmitterpackage and Mey burgwas unable to followher on herreturn journeyand estab-ROGER DE LA HARPE/ABPLLeftThe AfricanPeregrinelish the whereabouts of her home. This summer, theWWGBP tracked two more females tagged in Saudi Arabia,but these birds migrated only as far as East Africa.Conservation implicationsLittle is known of the conservation status of SiberianPeregrines. While populations in some areas are probablysubstantial, there is evidence that their reproductive performancemay be impaired by organochlorine contamination,which caused Peregrine populations in the United Statesand Europe to crash in the 1960s and ’70s. These chemicalsare used in pest control, but have been outlawed in mostFirst World countries because of their persistent toxiceffects on the environment. They are still used in lessdevelopedcountries, including some African states, and itis conceivable that calidus Peregrines accumulate these poisonson migration.We hope to fit satellite transmitters to Peregrines visitingthe Alexandria dunefield in future summers in orderto establish the path they follow on their return journey,and on their entire migration route in subsequent years. Ifwe can track sufficient individuals from this popularsouthern destination, we may be able to determine wherethey might be exposed to pesticides and other dangers ontheir annual pilgrimage from Arctic tundras to Africandunes.AcknowledgementsAndrew Jenkins would like to thank Mr Steven Phelpsand Peregrine Properties for sponsoring his travel coststo Port Elizabeth.Alan Stephenson would like thank the Western RegionDistrict Council for allowing him the time to studythe Peregrines at Alexandria, and the Officer-in-Chargeat the Woody Cape Nature Reserve for permittingaccess to the dunes.68 PEREGRINE Falconafrica – birds & birding