Effects of Human Persecution on European Raptors

EFFECTS OF HUMAN PERSECUTION ON EUROPEAN RAPTORS

, by Ian Newton Institute of TerrestrialEcology 12 Hope Terrace, Morningside EdinburghEI49 2AS Scotland

Abstract Persecutioncauses population declines only if it addsto the natural mortality and doesnot merelyreplace it. Largeraptor species with slowbreeding rates are lessable to withstandheavy losses than are smallspecies with fastbreeding rates. Over the last 150 years,persecution has eliminated some of the biggerspecies from large partsof Europe and is still responsiblefor restrictingthe distributionof others.In Britain over this period, the rangesof severalspecies have contractedand expandedagain with the rise and partialdecline in gamepreservation, with temporaryexpansions during two warswh, en gamekeeperswere otherwiseemployed. Persecution is still restrictingthe breeding range of the Golden Eagle, the Buzzard,and the Hen Harrier in the British Islesto abouthalf the potential. In somelists of bountypayments, certain species declined or disappearedin the re- cordsduring the operationof the scheme,suggesting that the killing itself reducedor exterminatedthem. But in otherlists, no declinesin numberskilled occurredover a long period, suggestingthat hunterswere merely croppingthe populationand causingno long-termdecline. The importanceof deliberatekilling of raptorsis shownby the large proportionsof bandedbirds that were later recovered,and by the proportionsof these recoveredbirds reported as shot.Recovery rates were ashigh (or higher)for someEu- ropeanraptors as for many game-birdand waterfowlpopulations exposed to regular huntingseasons. Widespread use of poisonon meat baits has had the most damaging effectson Europeanraptor populations, often where the procedurewas aimed primarily againstwolves or foxes.In recentyears, the mostcommonly used poisons include strychnine,phosdrin, and alpha-chlorolose.

Introduction In recentyears the effectsof humanpersecution on raptorshave receivedmuch less attentionthan the effectsof toxic chemicalsand land-usechanges. Yet persecutionis still restrictingthe distributionof severalraptor-species in Europe,and in someregions is practisedwith little lesszest than at its peaka centuryago. This paperis concerned with the extentof thiskilling and with its effectson populations,and is aimedparticu- larly at the North Americanreadership. It is not concernedwith whetherthe killing is justified,for thisquestion involves value judgements, which incorporate vested interests and personalpreferences. Largeparts of westernEurope are privatelyowned, so control operations are usually carriedout, not by governmentagencies, but by thousandsof individuallandowners and their "gamekeepers,"as well as by the huntersthemselves and by stockfarmers. Per- secutionof raptorsis widely acknowledged(Bijleveld 1974), but little scientificdocu- mentationof its effectsis available,partly becausemost reduction of numbersoccurred

65 RaptorResearch 13(3):65-78 66 RAPTOR RESEARCH Vol. 13, No. 3 between 1850 and 1900, before biologistswere interestedin recordingit. In recent years,too, killinghas become illegal in manycountries so, practiced subversively, it has provedhard to study.Moreover, in their effortsto understandthe birdsthemselves, biol- ogistshave generallyavoided working on populationsthat they knew were beingheavi- ly shot. HistoricalPerspective In an attempt to protect domesticstock, the killing of larger raptorswas officially encouragedin partsof Europeas earlyas the sixteenthcentury by paymentof bounties. This seemsto havebeen sporadic, however, and had no markedor long-termeffects on populations.It waswith the risein small-gamemanagement in the nineteenthcentury that persecutionreached its peak and spreadto the smallerspecies. Game shooting in- creasedin popularitywith the introductionof Pheasant(Phasianus colchicus) rearing, and againwith the improvementin the shotgun,from muzzleloader to breechloader. The objectiveof totalelimination of raptorpopulations was soon achieved for somespe- ciesover large areas. In many countries,the destructionof raptorsbecame an acceptedrural practice.No onein hisright mind was expected to passup the chanceto kill a hawk.This attitude was reflecednot only in the lack of protectivelegislation but alsoin the widespread paymentof premiumsfor birdskilled and in the employmentof gamekeeperswith the specifictask of destroyingpredators. In Britain everysizeable estate had at leastone keeper,and someidea of their total numberscan be gainedfrom Castle'sFishing & Al- lied TradesDirectory (1910) which lists 1,600 registered gamekeepers. This total excludes underkeepersand othersconcerned with "vermincontrol." The sameattitude persisted well into the twentiethcentury but, with socialand economic changes, increasing edu- cation,and the riseof a conservationmovement, public opinion is graduallychanging. It hasso far beenreflected in the abolishmentof manybounty schemes and in the in- troductionin onecountry after anotherof protectivelegislation. At the time of writing, fourteenEuropea_n countries afford full protectionto all birdsof prey,sixteen afford partialprotection (certain species, certain regions, or certainseasons), while onecountry (Malta) givesno protection(Conder 1977). The specieswhich receiveleast protection over the Continentas a whole includethe Goshawk(Accipiter gentilis), Sparrowhawk (A. nisus),Marsh Harrier (Circus aeruginosus), Buzzard (Buteo buteo), and Rough-legged Buzzard(B. lagopus),mainly as a resultof politicalpressure from hunters. In somecoun- tries, suchas Britain and France,legislation is still resistedor largely ignoredby the huntingfraternity. Effective law enforcementis difficulton privateland. Theoretical Considerations It is convenientfirst to considerthe conditionslikely to lead to reductionsin raptor numbers.The onlypermanent way to reducethe populationof anybird is to reduceits habitatand food supply. The alternativeentails holding numbers below the levelthat the environmentwill supportand removing birds year after year to counterthe effects of their breeding. Whethersustained killing leads to a long-termpopulation decline depends on whether killing replacesthe naturalmortality, or addsto it. Thus,if the increasedmortality from shootingis offsetby reducedmortality from naturalcauses, so that the numberof birdswhich die eachyear is aboutthe same,the populationwill not decline.But if the mortalityfrom shooting,or from a combinationof shootingand naturalcauses, exceeds Fall 1979 Newton--Persecutionof Raptors 67 that which would otherwiseoccur from naturalcauses alone, the populationwill decline.In practice,much depends on whenthe killingoccurs. Its effectis likely to be minimalin themonths following breeding, for thepopulation is then at itsseasonal peak, with manyjuveniles that would die anywayor dispersebefore the nextbreeding season. In suchcases, shooting has to be exceptionallyheavy if it isto do morethan merely crop an expendablesurplus. The effectof killingis greatestif it is doneat the startof a breedingseason, for thepopulation is thenat itsseasonal low, after most natural morta- lityhas occurr•t. Shooting at that time not only adds to thenatural mortality, but also concentrateson the breedingadults, the mostvaluable sector of the population,so that declineis rapid.It wasthrough the annualdestruction of breedingpairs that the populationsof severalspecies were wiped out overmuch of Britainbefore 1900. The tradi- tionalnesting places of thebirds were well knownto the landownersand their keepers, andmany Peregrine (Falco peregrinus) cliffs in the ScottishHighlands still show the re- mainsof stoneshelters, built by the keepersfor useas shootinghides. Probably some suchshelters are usedfor thispurpose today. The vulnerabilityof any raptoralso depends on how easilyit canbe killed.First, somespecies are fairly tame and easy to shoot;others use conspicuous perches and are easyto catchin leg traps;and yet otherseat carrion,so are easyto poison.Throughout Europe,it is the carrion-feedingspecies that have suffered most because they can be killed in largenumbers with minimumeffort. Secondly.,large speciesare inevitably moresusceptible to theeffects of persecutionthan are small ones. This is partly because largespecies live at lowerdensities, but mainly because they have much lower breeding ratesand take longerto reachbreeding age (Newton1977). Following a 50% kill, a slow-breedingeagle population could take many years to recover,whereas a fast-breeding Kestrel(F. tinnunculus)population could be backin oneor two years.In the long- term,therefore, it is the small,fast-breeding species that are mostresistant to sustained killing.A thirdfactor influencing vulnerability is the sizeand distribution of the popu- lationto beginwith. Any smallpopulation which is localisedin a restrictedhabitat is moreeasily eliminated than a largepopulation that extendsinto remotecountry where it ishard to reach,Events over the last150 years have led to the fragmentationof many formerlywidespread populations. Such isolated remnants are vulnerable for anotherrea- son-namely,the reducedchance of immigrationwhich might otherwiseserve to counterthe effectsof, say,local persecution. Long-termTrends in BritishPopulations Thesevarious generalisations can be illustratedby referenceto the Britishraptors, whosehistory over the last 150 yearshas been well documented(Witherby et al. 1938, Baxterand Rintoul 1953, Parslow1967). Early in the twentieth century,five species were apparentlyeliminated completely for a periodas breeders.These species (and their approximatedates of disappearance)were MarshHarrier (1898),Honey Buzzard (Pernisapivorus) (1911), Goshawk(1889), Osprey (Pandionhaliaetus) (1908), and White-tailedEagle (Haliaeetusalbicilla) (1916). The first three had anywaybeen re- strictedto smallareas by habitatdestruction, so that their tiny populationswould have beeneasy to find andeliminate. But the White-tailedEagle was widespread and prob- ablynumbered more than 200 pairs;its extirpationwould have been facilitated by carrion feeding(and poisoning) and by a low breedingrate. It is not certainto what extent collectorsof skinsand eggs were involved in the final demiseof thesespecies, but there canbe no doubtthat it wasthe gamekeeperswho broughtthem to a low point original- 68 RAPTOR RESEARCH Vol. 13, No. 3 ly. Only they had the guns,traps, and poisonto do it. Four of the speciesconcerned later recolonisedfrom the Europeanmainland and have smallpopulations in Britainat the presenttime, and the White-tailedEagle is the subjectof a reintroductionscheme (Love et al. 1978). Severalother previously widespread species were muchrestricted in range,the Buz- zard to somewestern districts, the Hen Harrier (C. cyaneus)to the northernand west- ern isles,and the Red Kite (Milvusmilvus) to a tiny areain centralWales, where game preservationdid not take hold (fig. 1). Somepeople wrote of thesespecies as having "retreated"to remoteareas-perhaps from analogywith humanbehaviour under persecution-but with the birds no retreatingwas involved.Populations were wiped out from all but remoteareas where birdssurvived in no greaternumbers than previously. Underreduced persecution, the Buzzardhas since recolonised large parts of the coun- try; the Hen Harrierhas reoccupied many mainland areas. The Kite, however,has taken an extremelylong time of dedicatedprotection to reachits 1978level of 35 pairs.It was hamperedby an exceptionallylow breedingrate and the continueduse of strychnine baits(against crows and foxes)in the breedingareas (Moore 1957,Watson 1977, Davies and Davis 1973,Newton 1972, Sharrock1976). The Golden Eagle (Aquila chrysaetos)also suffereda considerablediminution in range,and its survivalthrough the worst period, in contrastto the White-tailed Eagle, couldbe attributedto its occupyingsome high, inlandareas which, at that time, were extremelyremote and hard of access.The Peregrinewas eliminatedfrom a few areas (e.g., the southernPennines) but had large reservoirpopulations on coastsand islands where it couldbreed free from persecutionand producerecruits to offsetthe lossesin other areas.The speciesleast affectedwere the Merlin (F. columbarius),Kestrel, and Sparrowhawk.These were the threesmallest, having the bestability to recoveryear after year from persistentkilling. Summarising,marked reductions in numbersand rangeswere associatedwith low and localisedpopulations at the start,with carrionfeeding, with slowbreeding rates, or with a combinationof thesefactors. Lesser reductions were associatedwith large populations living partly away from gamepreserving areas, little or no carrionfeeding, and high breedingrates. The Hen Harrier wasthe onlyspecies with a highbreeding rate that was markedlyrestricted by shooting,but the bulk of the populationnested in Red Grouse (Lagophs1. scoticus)preserves, and with its fearlessnest-defense, the harrierwould have beenespecially easy to shootat the nest. Persecutionremains a threat to the Britishraptors and is clearly the main factor restrictingthe presentrange of at leastthe Buzzard,the Hen Harrier, and the Golden Eagle,none of which occupymore than abouthalf their potentialrange in the British Isles,including Ireland. The Red Kite and others are low because, although perhaps no longerrestricted by persecution,they were reduced by it in thefirst place. Some species are unlikelyto achievetheir formernumbers in the foreseeablefuture because their habitatis no longerwidespread.

Effectson Population Evidencefor the effectsof persecutionon populationscomes from (a) recordsof numbers killed, (b) correlationsbetween changes in killing and changesin population,(c) recoveriesof bandedbirds, and (d) studiesof birdsfound dead. Fall 1979 Newton--Persecutionof Raptors 69

(a) Numberskilled The paymentof premiumsfor dead raptorshas often meant that goodrecords have beenkept of the totalskilled. The numberscan be impressive,as the followingexamples show: In Norway, 1846-1900,rewards were paid for 223,487birds of prey, which included 61,157 Goldenand White-tailedEagles up to 1869, droppingto 27,319 eaglesin 1870-99 (Johnsen1929). As late as 1963,bounties were paid on 168 eagles. In the Netherlands,1852-57, rewardswere paid for 219 "eagles,"12,787 "falcons," 2,828 "goshawks,"16,626 "sparrowhawks," 1,756 "buzzards,"and 5,017 "harriers," makinga total of 39,233 birds of prey, probablylargely migrants(Braaksma et al. 1959). In the Nordrhein-Westfalendistricts of Germany,1951-68, a total of 210,520rap- tors;in Lower Saxony,1959-63, a total of 38,432; in Schleswig-Holstein,1960-68, a total of 37,793; and at Hessen,1951-67, a total of 61,353 raptorswere killed for re- ward (Bijleveld1974). From a singleScottish estate at Glengarry,in 1837-40, the kills included98 Per- egrines,78 Merlins,462 Kestrels,285 Buzzards,3 HoneyBuzzards, 15 GoldenEagles, 27 White-tailedEagles, 18 Ospreys,63 Goshawks,275 Kites,and 68 harriers,making a total of 1,372birds of prey (Ritchie1920). More recentrecords from one 1,200-hahunting preserve in southernEngland, in 1952-59,list 344 Sparrowhawks(Ash 1960). Bijleveld(1974) has recently assembled from officialstatistics totals such as thesefor manyEuropean countries. He estimatedthat in the 20 yearsup to 1970several millions of raptorshad been killed on the Continentby game-birdhunters alone, with especially large numbersin Franceand Germany.The sheermagnitude of suchfigures has led somepeople to doubtthem, but they are repeatedin similarorder in regionafter region,and in eachcase feet or beak were requiredas proofof killing. Confusionsof speciesin bountyschemes were probablycommon, however. The annualfigures for par- ticular estatesor districtsoften included many more raptorsthan couldhave lived there at onetime, a testimonyto the effectsof movementsor to the existenceof neighbouring lessdisturbed populations, from whichnew recruitscontinually came. When cullingoccurred on migrationroutes, the totalswere oftenextremely large, but drawn from populationscovering a wide area. Each autumn in southwestFrance, an estimated30,000 to 50,000small raptors fall victim in the netsof birdcatchers(people whotrap finchesto keepin cages),and many others are killedin Pyrenneanpasses by "pigeonshooters." Among the ringedraptors reported from the region,21% came from Scandinavia,12% from Polandand Russia,12% from central Europe, 7% from south Germanyand Switzerland,7 % from northGermany, 11% from England,23% from the Low Countries,and 7% from France(Yeatman, in Bijleveld1974). The numbersalone tell us little about the effect of this slaughteron populations,ex- cept that in somecases they must have represented at leastthe bulk of the localstock. Comparingthe figuresof the presentcentury with thoseof the previous,the main differenceis in the reducedrepresentation of eaglesand other large speciesin many lists, andtheir completedisappearance from others.That thiswas in someregions due to the cullingitself is suggestedby the large initial kills, followedby a swift decline,as the killing continued.For example,at Tenterdenin Kent, England,an intensivecampaign 70 RAPTOR RESEARCH Vol. 13, No. 3 for "thethinning out of vermin"began in 1676,and in thenext ten years payments weremade for 380 RedKites, after which numbers dropped away rapidly, with annual totalsof 35, 13,2, and2 (Ticehurst1920). Likewise, the Scottish Glengarry figures in- cludedat leastfour species which were no longer present a centurylater, but for which thehabitat still seemed suitable (two have since returned). Evidently there have been longper. iods in recenthistory when raptor numbers in many European areas were well belowwhat habitats would support. In otherlists, there was no obvious decline in thetotals over many years, which sug- geststhat in theseareas the hunterswere merely cropping the populationsconcerned and causingno long-termdecline. This is indicatedin someofficial statistics from Aus- tria,which show that between 1948 and 1968, premiums were paid annually on about 12,000to 20,000birds (table 1). In thisand other parts of Europe,the cullby hunters was especiallygreat in the severewinters of 1961-63, when the birdswere more than usuallyvulnerable. Likewise, the 6,000Goshawks destroyed annually by Finland's 170,000hunters are thoughtto be causingno long-termdecline in the Goshawkbreed- ingpopulation, for mostof thesebirds are juveniles killed in thefew months following breeding(Moilanen 1976, Saurola 1976). Care is needed in usingonly the records of recentyears, however, because in anylong-running bounty scheme covering several species,one might expect there to be lesschange as the years go by, as the larger species are eliminatedat an earlystage to leavethe smaller,more resilient ones.

Table1. OfficialAustrian Game Statistics on Birdsof PreyKilled Between 1948 and 1968

Accipiters Harriers Buzzards Total 1948 10,943 386 3,482 14,811 1949 11,406 821 3,757 15,984 1950 13,181 973 5,252 19,406 1951 13,385 674 4,770 18,829 1952 13,533 757 4,152 18,442 1953 13,788 902 5,479 20,169 1954 12,567 695 5,157 18,419 1955 12,024 694 4,757 18,475 1956 12,952 1,068 5,922 19,942 1957 11,967 838 5,071 17,876 1958 11,518 1,033 5,315 17,866 1959 11,886 1,045 5,606 18,537 1960 12,558 908 6,173 19,639 1961 12,983 921 6,825 20,729 1962 13,838 944 7,590 22,372 1963 11,399 911 7,293 19,603 1964 10,755 879 5,872 17,506 1965 7,109 615 4,826 12,550 1966 7,162 695 4,661 12,518 1967 8,922 596 5,292 14,810 1968 9,262 569 5,823 15,654 (FromBijleveld [1974], derived from Oesterreichisches Statisticisches Zentralamt.)

(b) Changesin persecutionand populationstatus The evidenceis of two kinds:First, the distributionof a speciesover a widearea fits withvariations in persecution.Second, some marked improvement in thestatus of a spe- ciesfollows a knowndecline in killing.The Buzzardin Britainprovides an exampleof Fall 1979 Newton--Persecutionof Raptors 71 bothkinds of correlation. In 1800 the species bred throughout thecountry, but by 1860 it hadbeen eliminated from all but a fewwestern district, by 1954it hadspread consid- erably,and by 1970it hadspread even fi•rther (fig. 1, Moore1957, Sharrock 1976). Thesechanges correlate with changes in the intensity ofgame preserving, helped in later yearsby a changein attitude.A particularlydetailed survey in 1954showed that the distributionof Buzzards at that time closely mirrored the contemporary distribution of gamekeepers.,Thebird was commonest in districts where game keepers were scarcest andabsent altogether from districts where keepers were numerous (nesting habitat was availablethroughout). Further evidencefor the influenceof gamekeepingon British raptor populations cameduring the 1914-18 and 1939-45 wars,when many keeperswere employedon other things.At these times all raptors (exceptperhaps the Peregrineduring the 1939-45period) increased and extended their range,and for the commonerspecies the changeswere reflectedin the numbersof nestlingsringed each year by amateurbird- ringers(Newton 1972). There wasa big increasein the numbersof Sparrowhawksand Merlinsringed within two yearsof the war'sstarting and a rapid drop to formerlevels within two yearsof the war'sending (fig. 2). The numbersof nestlingsringed must to someextent have reflected the numbersavailable for ringing,the increaserepresenting the combinedeffects of improvedpopulation and breedingsuccess, under lessened gamekeeping.It wasalso during this war that the Hen Harrier becameproperly reestab- lishedon the Scottishmainland, nesting largely undisturbed in the youngforestry plan- tationswhich had appearedsince it was here before.Early naturalistswrote about a similarincrease in raptorsduring the 1914-18war, but ringingwas not sufficientlyde- velopedto documentit. In both wars increaseswere not confinedto Britain but oc- curredthroughout Europe. Wolves and other mammal predators gained a similarrespite and alsospread. More recently,Weir (1978) noteda markeddecline in Raven(Corvus corax) numbers in part of northernScotland, associated with the useof poisonedmeat baits. In 1964-68, beforepoisoning started, 16-17 pairsbred in the studyarea, and 10-11 producedyoung eachyear. By 1977,however, when poisoning had been continued for severalyears, the populationwas reduced to 5 pairsand 1-2 producedyoung. Dead Ravenswere found in eightof the vacatedterritories, in someinstances together with GoldenEagles. Where persecutionwas insufficientto eliminatepopulations, it sometimesaffected their age structureand breedingsuccess, as was apparentamong Golden Eagles else- wherein Scotland.Sandeman (1957) compared the breedingin deerareas, where eagles were not persecuted,with that in grouseand sheepareas, where they were persecuted (table2). In deer areas,there was no instanceof an eaglelacking a mate,but in sheep and grouseareas eight such instances were recorded.In deerareas there was no instance of an adult eaglepaired to an immaturepartner, but in grouseand sheepareas there werefour suchinstances. Both these features were symptomsof excessivekilling. An immaturepartner in a pair meantthat either the pair did not lay or that they pro- ducedinfertile eggs. The meansize of successfulbroods was the samethroughout, but the overallbrood size, when pairs that raisedno youngwere takeninto account,was 0.6 in deer areasand 0.3 in grouseand sheepareas. In theselatter areas,killing was sup- pressingthe breedingoutput so much that the populationcould not havebeen sustained without continuedimmigration. In populationssubjected to even lesspersecution, the removalof breedingbirds does little morethan createtemporary gaps, which are soon 72 RAPTOR RESEARCH Vol. 13, No. 3

Table2. Effectsof HumanPersecution on GoldenEagles, South Grampians, Scotland 1950-56

Mean brood- Mean brood- Numberof Territory One member sizein sizein territory with only of pair successful all years onebird immature nests nests Deer areas (no persecution) 35 0 0 1.4 0.6

Sheep& Grouse areas(much persecution) 63 8 4 1.4 0.3 (From Sandeman1957.) filled by new recruits.Or it may reducebreeding rate, but not enoughto causepopu- lation decline. Widespreadshooting over decadesseems also to have affectedthe behaviourof indi- vidualraptors and their reactionsto man,perhaps partly throughthe selectiveremoval of the tamer individuals.This differenceis apparentfrom comparisonof, say,the Afri- can populationswith the Europeanones. The African onesgenerally show themselves more,nest in closerassociation with man,and allow a muchcloser approach before tak- ing flight than do their Europeanequivalents. Perhaps the extremein tamenessis found in the GalapagosHawk (Buteogalapagoensis), which will allow observersclose enough to read the colourbands (M.P. Harrispers. comm.). Shooting seems also to haveaffect- ed nestdefense behaviour, which is muchless vigorous in Europethan in otherparts of the world.The differenceis especiallymarked among Goshawks and Peregrines.

(c) Band recoveries Comparedwith mostother birds, not only are morebanded raptors recovered, but very manyof the recoveredbirds are reportedas shot or trapped.For the commonBrit- ishspecies, the percentageof bandedbirds that were later recoveredvaried from 7% to 14%,and the proportionsof thesereported as killed were ashigh as68% dependingon species(tables 3 and 4). The proportionsrecovered were greaterthan thosefor some waterfowl and gamebirds exposedto proper huntingseasons and for recognizedpest species.Only largewaterfowl and CormorantsPhalacrocorax showed a higherrecovery rate, the formerbeing legally hunted or speciallystudied, and the latter killed as pests. After 1954,when protectivelegislation was introduced for raptors,the proportionsre- portedas killed declined(table 4). Thisdecline may havebeen genuine, or it may have been due to manypeople's omitting to report the birdsthey had killed or falsifyingthe causeof death.In both periods,birds reported as "found dead" may haveincluded some killedby man. Similaranalyses of Europeanrecoveries also indicated the importanceof persecution in the overallmortality of reportedbirds (table 5 and6). They alsoreflected the region- al variationsin shootingpressure. Among Kestrelsringed as nestlingsin Holland, in- tentionallykilled birds formed 82% of all recoveriesfrom Belgiumand France, but only 10% of thosefrom other west Europeancountries. The mean annualmortality calcu- lated from the two setsof recoverieswas significantlydifferent, at 59% and 44% (Cav• 1968).In somespecies, the recoveriesimplied a differencein warinessbetween young and old birds or in the extent to which they came near human settlement,for more of Fall1979 Newton--Persecutionof Raptors 73

Table 3. Percentageof BandedRaptors Recovered Compared with Other Birds in the British Banding Scheme

Raptors Recognisedquarry-species Osprey 11 RedGrouse 11 Red Kite 11 Partridge 5 Marsh Harrier 11 Pheasant 7 Hen Harrier 9 Mallard 17 Montagu'sHarrier' 14 Teal 18 Sparrowhawk 10 Wigcon 16 Buzzard 7 Snipe 5 GoldenEagle 8 Woodcock 8 Kestrel 12 Woodpigeon 10 Merlin 11 Peregrine 8 Song-birds Residentspecies 1-4 Owls Migrant species • 1 Barn Owl 17 Little Owl 9 TawnyOwl 9 Long-caredOwl 7

Recognizedpest-species Crow 7 Magpie 6 Bullfinch 2 Cormorant 20 (From Spencerand Hudson1977.) Note:The table excludesswans and geesein which the recoveryrates have been inflated by detailedstudies; swans are alsoespecially likely to be found after death.

Table4. Proportionsof British-BandedRaptors Reported as Deliberately Killed Beforeand After 1954, When ProtectiveLegislation Was Enacted

Up to 1954 After 1954 Total Reported Total Reported recovered as killed recovered as killed Hen Harrier 25 20% 148 10% Montagu'sHarrier 19 68% 24 50% Sparrowhawk 166 60% 71 16% Buzzard 33 48% 173 14% GoldenEagle -- -- 18 28% Kestrel 175 41% 457 10% Merlin 73 52% 107 16% Peregrine 16 56% 55 22% Figuresare minima,and it is not knownwhat werethe true proportionsof recoveredbirds that werekilled. Sparrowhawkand Kestrelto 1969,other species to 1976-77. the birdsrecovered in their first yearhad been shot or trappedthan of thoserecovered in later years.Among Goshawks in Fennoscandia,the figureswere 87% and 78% for first-yearand olderbirds, and among Kestrels in Hollandthey were 34% and 19%(Hog- lund 1964, Cav• 1968). 74 RAPTOR RESEARCH Vol. 13, No. 3

(d) Studiesof carcasses Among35 raptorsof variousspecies found dead or disabledin northeastScotland in 1964-69,20% hadbeen killed by man (Weir 1971).In a studyof Buzzardsin the same area,Picozzi and Weir (1976)used a traineddog in regularsearches for poisonedbaits andfor deadbirds. They found 52 deadBuzzards in the period1964-72 and ascertained the causeof death in all but five: 29 (54%) were poisoned,and 9 (15%) were shotor trapped,making a minimumof 69%killed by man.Of the 42 birdsaged, 27 (64%)were in their firstyear. Between 1968 and 1972,the authorsfound poisoned baits on 12 of 15 estateswithin 30 km of the studyarea, together with 28 Buzzardcarcasses. In four years beforepoisoning started on two of theseestates, they found6 adult pairseach spring with 2.3 pairson averageproducing fledged young annually. After poisoningstarted, therewere only4 pairs,with 0.5 pairsproducing fledged young annually. The Buzzard waslegally "protected" during the periodconcerned. Table 5. Proportionsof RaptorsRecovered in EuropeanBanding Schemes That Were Reportedas Killed by Man

Countryof Total Reported banding recovered askilled Reference Black Kite Switzerland 279 80% Schifferli 1967

Sparrowhawk Britain 226 48% Glue 1971 Denmark 81 71% Shelde 1960

Goshawk Finland 532 92% Haukioia& Haukioja 1970

Buzzard Fennoscandia 473 62% Olsson 1958 Germany 50-80% Mebs 1964

Kestrel Britain 632 18% Glue 1971 Switzerland and Finland 416 65% Schifferli 1965 Netherlands 245 23% Cav• 1968

Peregrine Sweden 199 48% Lindberg1977 Finland 46 78% Mebs 1971 Germany 107 43% Mebs1971

Table6. Recoveriesof Birdsof PreyBanded in Finland

% recovered Numberringed birdsshot 1913-62 % recovered or trapped Goshawk 1,006 27 78 Sparrowhawk 1,724 17 49 Marsh Harrier 208 11 65 Rough-leggedBuzzard 164 13 67 HoneyBuzzard 242 13 45 Buzzard 803 9 49 Peregrine 195 22 62 Kestrel 2,135 6 53 Osprey 800 4 67 (From Nordstrom1963.) Fall 1979 Newton--Persecutionof Raptors 75

Theseand othersurveys show that a high proportionof the deathsof birdsthat fall into the handsof biologistscan be attributedto directkilling by man.Whether they are representativeof all deathsdepends on how typicala samplewas found. One can easily imaginethat in the sameareas some birds might die in waysin which they would be unlikelyto be found(for example,killed and eatenby predators).This meansthat the role of humanpersecution in the overallmortality may be exaggerated.Band recoveries sufferfrom th6gs•tmedrawbacks when used to indicatecauses of death;but both meth- odsgive usefulcomparisons with resultsfrom otherbirds and showthe prevalenceof persecutionon sparse,protected populations. Studiesof localpopulations could not be expectedto reflectthe generallevels of per- secutionbecause biologists normally select study areas so as to avoid it. Nonetheless, humaninterference was the commonestcause of both adult mortality and nest failure recordedin manystudies. In someearly Britishwork on Sparrowhawksand Merlins,it accountedfor every nestover a several-yearperiod (Owen 1916-22, Rowan 1921-22). In more recentwork on Sparrowhawks,Buzzards and Kites, it accountedfor at least 7%, 8%, and 9%, respectively,of all clutchesand for at least21%, 34%, and 15% of all failures(Newton 1976,Tubbs 1971, Davies & Davis 1973). Methodsof Killing When the gun is used,birds are oftenshot at the nestor at any other time they ap- proachwithin range.In partsof Europeit wascommon to set out a live EagleOwl (Bubobubo) and shoot from a hideany raptorsor crowsthat cameto mobit; or to wait at concentrationpoints on migrationand shootat the passingbirds (Biileveld 1974). As for traps,the commonesttypes are leg trapswith springiaws that snaptogether when thebird stepson a centraltreadle, holding firm until the bird is removedor dies.They are placedon nests,around carcasses, or on naturalor artificialperching places, as in the poletrap. For eaglesand otherlarge species in opencountry, it is usualto build a smallmound of stoneson whichto placethe trap. Anothertype is the cage-trapwith two compartments,in one of whichlive pigeonsor other animalsare placedto act as decoys;in the otherthe raptoris caughtalive when it stepson a treadleto releasethe lid. Situatednear woodland,such traps are especiallyeffective against accipiters but needdaily attentionto keepthe decoysfed and watered.They are sometimesknown as "SwedishGoshawk traps." Regardingpoisoning, raptors are sometimeskilled deliberatelyin thisway and some- timesincidentally during attempts to get rid of otheranimals, such as wolves and foxes. Widespreadpoisoning alone has caused serious declines, as shownfrom (a) the coinci- dencebetween the periodsof poisoningand decline,(b) the findingof corpsesat bait, sometimesin numberslarge enough to form the bulk of a localstock, and (c) the pres- enceof poisonsat lethal levelsin tissues.Several cases have been documentedin recent yearsinvolving local populationsof eagles,vultures, and others(Biileveld 1974, Men- delssohn1972). One strikinginstance was the virtualdisappearance in recentdecades of the once-commonGriffon Vulture (Gypsfulvus) from Romaniaand Bulgaria,linked with the widespreaduse of strychninefor wolf control.In one Romanianarea sixty White-tailedEagles were picked up in oneweek, and in anotherarea ten EgyptianVul- tures(Neophron percnopterus) were found dead at a singlebait (Biileveld1974). The main poisonsused include the traditionalstrychnine, the more recent organ- ophosphoruspesticide known as phosdrin or mevinphos,and the narcoticalphachloro- lose.Instances of secondarypoisoning are knownfrom all thesecompounds. When used 76 RAPTOR RESEARCH Vol. 13, No. 3 in eggs,they kill a few raptor species(mainly harriers), but are very effectiveagainst corvids,whereas on meatbaits they kill very manyraptors. The adventof alpha-chloro- losehas led to a greatincrease in the illegalpersecution of Britishraptors because, com- paredto other poisons,this materialis relativelysafe to use.Many instancescame to light in 1971-76from analysesperformed by governmentagricultural departments of carcassesfound by amateurnaturalists (Brown et al. 1977). Most carcasseswere found duringMarch-May each year, which is whengamekeepers and shepherdshave a blitz on"vermin." Different poisons were favoured in differentregions, depending partly on localavailability.

Literature Cited Ash,J. s. 1960. Birdsof prey numberson a Hampshiregame preserve during 1952-9. British Birds 53:285-300. Baxter,E., and L. J. Rintoul.1953. The birds of Scotland:Their history, distribution, and migration.Oliver & Boyd,Edinburgh. Biileveld,M. 1974.Birds of preyin Europe.Macmillan Press, London. Braaksma,S., W. H. Th. Knippenberg,and V. Langenhoff.1959. Enigebroedvogels in Noord-Brabant. Limosa 32:206-212. Brown, P.M., P. J. Bunyan,and P. I. Stanley.1977. The investigationand pattern of occurrenceof animal poisoningresulting from the misuseof agriculturalchem- icals. ]. Forens. Sci. Soc. 17:211-221. Cave, A. J. 1968. The breedingof the Kestrel,Falco tinnunculus L., in the reclaimed areaOostelijk Flevoland. Netherlands ]. Zool. 18:313-407. Conder,P. 1977. Legal statusof birdsof prey and owls in Europe.Proc. ICBP World Conf. on Birdsof Prey, Vienna, 1975:189-93. Davies,P. W., and P. E. Davis. 1973.The ecologyand conservationof the Red Kite in Wales. British Birds 66:183-224, 241-270. Glue, D. E. 1971. Ringingrecovery circumstances of smallbirds of prey. Bird Study 18:137-46. Haukioia,E., and M. Haukioia.1970. Mortality rates of Finnishand SwedishGoshawks (Accipitergentilis). Finnish Game Research 31:13-20. H/Sglund,N. 1964. Der Habicht Accipitergentilis Linn• in Fennoscandia.Viltrevy 2•:195-270. Johnsen,S. 1929. Rovdyr-og rovfuglstatistikkeni Norge. BergensMuseum Arbok 2:5-118. Lindberg,P. 1977.The PeregrineFalcon in Sweden.Proc. ICBP World Conf.on Birds of Prey,Vienna, 1975:329-338. Love, J., M. Ball, and I. Newton. 197•. SeaEagles in Britain and Norway.British Birds 71:475-481. Mebs,Th. 1964.Zur Biologieund Populationsdynamikdes Mausebussards (Buteo buteo). ]. Orn. 105:247-306. 1971.(Death causes and mortalityrates of Peregrines[Falco peregrinus] calcu- lated by Germanand Finnishband-recoveries). Die Vogelwarte26:98-105. Ger- man, with Englishsummary. Mendelssohn,H. 1972. The impact of pesticideson bird life in Israel. ICBP Bull. 11:75-104. Moilanen,P. 1976.Goshawks and pheasants.Suomen Luonto 6:315-318. Fall 1979 Newton--Persecutionof Raptors 77

Moore,N. W. 1957.The pastand presentstatus of the Buzzardin the BritishIsles. Brit- ish Birds 50:173-197. Newton,I. 1972.Birds of preyin Scotland:Some conservation problems. Scottish Birds 7:5-23. 1976.Breeding of Sparrowhaxvks(Accipiter nisus) in differentenvironments. ]. Anim. Ecol. 45:831-849. __. 1977.Breeding strategies in birdsof prey.Living Bird 16:51-82. Olsson,O. 195g'.'Dispersal,migration, longevity, and death causes ofStrix aluco, Buteo buteo,Ardea cinerea, and Larus argentatus. Acta Vertebratica1:91-189. Owen,J. H. 1916-22.Some breeding habits of the Sparrowhawk.British Birds 10:26-37, 50-59, 74-86, 106-115; 12:61-65,74-82; 13:114-24; 15:74-77. Parslow,J. L. F. 1967.Changes in statusamong breeding birds in Britainand Ireland. British Birds 60:2-47. Picozzi, N., and D. N. Weir. 1976. Dispersaland causesof death of Buzzards.British Birds 69:93-201. Ritchie,J. 1920. The influenceof man on the animallife in Scotland.Cambridge Uni- versity Press. Rowan,W. 1921-22. Observationson the breedinghabits of the Merlin. British Birds 15:122-129, 194-202, 222-231,246-253. Sandeman,P. W. 1957. The breedingsuccess of Golden Eaglesin the southernGram- pians.Scottish Nat. 69:148-152. Saurola,P. 1976.Mortality of FinnishGoshawks. Suomen Luonto 6:310-14. Schelde,O. 1960.The migrationof DanishSparrowhawks (Accipiter nisus (L.). Dansk. Orn. Foren. Tiddskr. 54:88-102. Schifferli,A. 1965. Vom Zugverhaltender in der Schweizbrutenden Turmfalken, Falco tinnunculus,nach den Ringfunden.Orn. Beob.62:1-13. 1967. Vom Zug Schweizerischerund DeutscherSchwarzer Milane nach Ring- funder. Orn. Beob. 64:34-51. Sharrock,T., ed. 1976. The atlasof breedingbirds in Britain and Ireland. BritishTrust for Ornithologyand Irish Wildbird Conservancy. Spencer,R., and R. Hudson,1977. Report on bird-ringingfor 1975.Bird Study,Suppl. 24:8-14. Ticehurst, N. F. 1920. On the former abundance of the Kite, Buzzard, and Raven in Kent. British Birds 19:96-104. Watson,D. 1977.The Hen Harrier. Poyser,Berkhamsted. Weir, D. N. 1978.Effects of poisoningon Ravens,Buzzards and GoldenEagles in Scot- land. British Birds 71:227-228. Witherby,H. F., F. C. R. Jourdain,N. F. Ticehurst,and B. W. Tucker.1938. The hand- bookof Britishbirds, vol. 3. Witherby,London. 78 RAPTOR RESEARCH Vol. 13, No. 3

• D•strrbutionof

• I•13-6 per 100sq miles •1•>1pair per100 sq l•,,es but<1pa,r per •] 1-2per100sq m,les

[] >lpa•rperlOOsqNobreedlngb•rds miles 10sqmlles []

Figure1.--Distribution of breedingBuzzards in Britainin 1954(left) compared to the contemporarydistribn- tion of gamekeepers(right). From Moore 1957.

1'5--

•Wartlme•

• Persecution Persecution

1'0- DDT

• D•eldr•n

•.,•'-,,,.._...... _•.•,,,,. ß i i 1930 1940 1950 1960 1970 Figure2.--An index,based on ringing,of the outputof youngSparrowhawks in Britainshowing the tempo- rary increaseduring the war, associatedwith the declinein gamekeeping.The indexis the percentagethat nestlingSparrowhawks formed of all nestlingbirds ringed in Britaineach year. Re-drawn h'om Newton 1972.