Bird movements aro - International Bird Strike Committee

BIAD STRIKE COMMITTEE EUROPE
ascE23/wP 57
London, 13 -17 may 1996
BIRD MOVEMENTS AROUND AIBPORTS: A CRITICAL ISSUE tN THE
SPECIFICATION OF AVOIDANCE SYSTEMS
Luit S. Buurma
ANLAF Flight and Ground Safeiy Division
Natural Environfr ent Section
P.O. Bor 20703
2500 ES The Hagle
SUMMAAY
ouant iylns, quarilying and predlctins low levcl b rd 'novements is the key issue
hamDerino the certifcation or bnd sfiike prev€ntlon mc.sures i. rhe conrro zone of
airports as we as en route . Bnd conrol at rhe runway tsclf is atre.dy succestu at
many ai.ports. Less w de spread, and limn€d to m tary aviat on, blt technica y
speakinorpclor mproveme.t,6r€ larse scale warn.g sysrems ndicatlng mass bnd
mrgranon. Howcver, the'botrom up' and top dow.' .pproach roqether do by lar not
solve.ll bnd strike problcms A geoo.aphlcalcomparson or the (tow tevet) atrttude
drstriburion ot milltary b rd strlkes lrom EUFaASE indicat.s a missi.g li.k, jLsr ourside
vsLa range but also below the covefage of most radars. Thls risk ls posed by tocat bnd
lrghts ov€r up to some tens ol kilomerers especla ly in coasral and wertand areas.
l.tesratcd.adar a.d visual obscrvations in The Netherlands show th.t a so a signiic.nr
part or onq distance nigratory I ishts may occlr .1 low evel, evcn ar niqht. Locat and
migralory flghts may accumulate along topos.aphical baiiiers or leading lines ar
ocaiions considered lor anport consrrucrion.
Thls prescntatio. is a plee Jor the c assiiicarion of rhese complex problems. This sholtd
happen rn slch a manner that existing ornitholoeica know edOe w help to develop
r!es oi thumb to be used in intearalcd bnd avoidance systems. There are iund6menial,
psycholoOicalas wc as polticalreasons why operatio.. bnd predlctio. models shoull
bc backed Lp by bnd detection devces. Problcms with wild ge€se winrering in The
Nelherlands m:yserve as an example.
Key Words: Slalistics, M itaiy Aviatio. Locallr,lovements, Brd Popu atons, Deteclion, Radar
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Becker (1996) summarized the discussio. n the Low LevelWG on 'en route
b rd st. ke preveniion d!r ng thc last ten years. He is perfectly right in his
conclusion that we should hcad lor an lntegrated approach, combi.i.g
geographical, b olog cal, weather and radar data . My staremcnr ol today s rhar
we on y can make such inte9rated prevention operat onaly stable whef we
succeed n classifvino and subsequenty standardislna the d ffc.€nt prevention
eements. In olhcr wo.ds: we must develop a.d speak ihe same ang!age in
order to communicate abour the .redictab c and non o.edic.r"ble aspects of the
bnd strlke risk. Predictab e risks arc in principle open ior.e iiiablc prevenlive
measures rcsult ng in a quanrlflab e risk reduction. A!t also the .ema ning .on
pr€d ctab o types of b rd danger can be brought under control to a ce(ain
extcnt, Remote sensifg of bird movcrncnts has a proven porenrial in rea 1me
warning systems (B!urma& Brldeicr 1990, Lcshem 1994). Th s p.per aims ro
stim! ate berter comm!n cat on on the mproveme.i of nvoid..cc sysrems by
Jocussing on the crillca iss!e ol ow evel bira ilgfr,
Evidence from military stalistics
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B rd control at the runwav itself is a ready s!ccesful ai many airporrs. Less
wde spread, and llmred ro mi(ary aviation, b!r techn cally speakng ripe for
mprovement, are large sca c warning sysrems ndic.ri.a mass b rd migrario. n
h gher airlayers. However, the 'bonom l]p'a.d 'lop.down'approach rogerher do
by f.r not solve all bird strike problems. A gcographicalcomparlson ol rhe (low
levc ) altitude disrribution of mllilary bird strikes from EUFBASE indrcares a
s!bstantial p.oblem, jusr outside visual range but .lso below lhe coverage of
mosl .adars: iigure 1. Thls risk is posed by loca b rd f ights over up to sorne
tens of kilometers, especia ly n coaslal and wcaand arcas.
Bird srrikes may i.dic.re rhe yeat rcLn.l avercge anitude disrriburron oi bnds
(almost) inespective ol the time spend and disrance covered by ai.cratt €t
d llerent he ghts. Th s s on y thc casc whcn wc sclccl so ca led 'local strikes
e.g. d!rlng Iake off, landrng and overshoot (Buurma 1984), D!rlnlt these ilghl
phases the 1i!ht path oi the :i.craft has a lixcd ang c 1{) the ea(h s!riace. The
Europea. Miirary B rd St ke D.iab.se (EURBASE, see also Bu!rma & Dekker
1996) olfcrcd thc posslb lity to compare this selecrion (N=2582) lrom iive
wcst-c!ropean ai. lorces, In f g!rc 1 wc f ttcd curves rhrou!h the a t tudc
dlsrribuio.s in 100 ft classes. The resu rs look .ather slmular, bul when we
nspecrhe curves closer i.e. at 3o0 it (ca 100 m) and comparc the rwo
exvemes, GAF and BAF, we f nd thal the UK birdsrrikes at thls hcicht are rhree
timcs mo.c frcquenthan thosc ovcr Gcrmany. The concluslon is therctorc that
ihe FAF nol only suffcrs trorll a h gher bird slr ke rate (see Bulrma & Dekker
1996), blt las the curves are percentua ) a so from a d lferenl lype ot risk than
the GAF. Appareft y the blrd popu allo. aDove and around the British lsles,
which ls domlnated by coasrar and wel and species, fles hi!hcr and ai a larger
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546

sc€le than thc average blrcl .bove the E!ropcan mainla.d This becomes evcn
more obvio!s whe. we check thc oilrer air forccs a.d bird d str b!tion maps
Evidence from bndlstlike) distribution maps
Fi.stly, Jigure 2 shows a parI of the BSCE birdrisk map lndicatins zones oi ight,
moderate and heavy b rdstrike r sk. This i.ternario.aL map, deve oped n the
Sevenlics under the lcadership of Dr' J H ld, is bascd on best profcss onal
iudgemcnt abo!I 'rotal bird mear densities' lr cLear v indicates how ihe marn
bid areas are concenlratcd in the f at wcllands along thc coast a.d ln I ver
delra's. lt is also obv ous that RAF and RDAF are mostlv contionted wth these
blrd.ch zones whilc FAF 6nd GAF {n this o.der) have rhelr ow levelilving over
the lcss risky ln and, where wetla.d specles are much sca.cer. This sequencc ol
air lorccs i!lly iits with tlie seq!encc of lhe curvcs in iig!re I
Thc co(e arlon betwccn the type of c!rve and thc air fo.ce llviFg area can bc
deta led fu(her when wc ook al lhe RNLAF, having a posltlon in the m dd e, on
the map as wcl as amofg thc altitude clrvcs The centrc oI I ving act vllY of
this a r force s n the SE part of tlie country, avoiding thc dc.se human
populat on nr rhe fertile pol.lers below sc. evel in thc wesr' Fig!rc 3 (top)
shows thc bnd sanctlar cs and b rd str ke r sk map itom lhe AIP Ncther ands.
The clashed Ine denotes tlre bou.dary betwccn heavv and moderat€ risk irom
i gure 2. Five a rtrases are plottcd as rectang!lar black figurcs The lavcrage)
helghi of cach symbol glvcs the bird strikc r.te as w€Ll 6s the trend over the last
10 ye€rs. Goin! from ESE to WNW rhe ilve bascs show a. Incre.se In average
local b r.i sfi ke .ate co(espondlng to the i.cr€asc ln ge.eral bird de.sitv. The
salest base .ear the border wnh GernanY (Twentc AFa) and thc trase wlth the
h ghesr b rd str ke r.t o lLec!warden AFB) wcre subjectcd 10 .n equal v rnlense
bkd sr.ike p.cvcnlio. p.o!..m. Ai TW we wcrc zble ro app v hab ial
mo.iif catio. slccesiu ly (Dekkcr& Van der Zcc 1996), but al LW we st ll have
ro aeve op:ddit onal preventlon me.s!res Herc the nearbv waadensea/ o.e Dr!
nature arca, generates tidal mass movcmenls oi birds far .Land Fu(her, thc
very fen le grass ands ot the rcgion aro!nd thc base atiract big numbcrs or
'culturc
following' spec cs among !!lls, d!cks and waders A spcc al and
grow ng prob em are geese n winler (see b€ ow)
Thc problems at LW AFB correspond w th rhose at Schiphol alrporl near
Amsterdam. Qf course both a rile ds have Ju I rime Airpo( Bird Coflrol bul a so
the spatlaL planni.g a.d bird attract.g develop'ne.ls n a certarn arca qq!0q
thc a rport must bc considered (Klavcr 1994, B!!rma 1994a). The prescnl
EUFBASE dala do rellect the f.cr that ocal bird movemenrs n wclla.d areas
!s!ally occur at such a scale that struct!ral meas!res a.c polillcallv mpossib c
This is becominO vcry apparent ln the present Duch debat where to crcate a
second major airpo(. All possible locar ons {black dots with white asterlsk) arc
.ear important b rd sa.ctuaries or in zones wherc m g.atorv birds rend to
conccntrale. Flgure 3 (bottom) il!srrai€s thc classical v cw on au!mn
migratio. {taken from T nbergen 1949). Our own .adar sr!dv nc.r Hook ol
Holland (Buurma& Va. Gasteren I989) shows an cven molc hle.se tlvifg
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548

activity parallello the coastline over land and sea in a zone ot over 1O km wide.
It occurs also at nighi, and includes loca and regionalrnovements. At present
the discussion focusses upon creating new land in the North Sea along the
coa$ (figure 4). The complication is not only that such hugh inffastructural
works usually overlap with the birds flyways bur a so that these wofks atmost
always create new bird concentration areas themselvesi
Local fe€ding and roosting llights tollow patterns and time schedules that can
be measured and to a reasonable extent be predicted. A wealrh of biotogical
knowredge on the behaviour of most bird species is already available in the
literature. lt should therefofe be possible ro model the spatial and temporal
aspects of the fying behaviourof the main catesofies ol common blrd species.
The most cruclal aspect is fLying height, which wil be dependent of wlnd,
thermal conditions, type of landscape and especlally dlsrance to be covered.
llustraiive is the growing winrerpopulation ol the Whire fronled goose in the
vicinity of Leeuwafden AFB (figure 5). NE of the city of Leeuwarden rhere is a
3ke area (black)where 40.000 white fronts gather for the ntght. They feed on
the grasslands in the su(oundifgs and reg!larly cross the flighr path ol {mosrty
The number of White fronied geese near Leeuwarden have grown fiom 2.000 in
ihe Sixties to the present figure. This parat ets the rotaL n!mber w nrering in The
Netherlands which grew to almosr a millon indlviduals. However, this does nol
imply that we can conslder the sp€cies as a pest species tn the wav Attan &
Feare 1994 did while discussing cont.o measufes aga nsi {era Canada goose,
The fecent Concorde and AWACS accidents will undo!btly invoke a campalgn
against resident Canada geese around akports- Blt our Whire fronts are
migrants trom an hugh eurasiatic breeding range and subjed oi concern in the
international conservation debat (Aubrecht 1994). Sporls hunting may be a
scanng instrument when planned spalially in a proper wav. But so far we do not
know how rhis affects the daily f ight pattern three dimensionatty, In case rhe
birds cross rhe huni ng area at higher flight levels the birdstrike .isk may
increase in stead of decreasel
Given the growth of the h!man population, the value of €xisting nature res€rves
increases and parallel with th s the populariry of birds, Moreover, ihere is fast
growing political basis for creating'new naru.e'in combinarion with integral
wat€rmanagement {B'rurma 1994a). Consequently, the political basis for
measures to reduce total poplJlation size of a certain blrd species has almost
disappeared. This fact togerher with the findlng rhat the scale or tocat and
regional bird movemenls is much bigger than often rhought, m!st lead to
'sharing
the ak'as a rewarding prevention option. This brings us back to the
aim of this paper: the future of bird avoidance svstenrs.
550

adar in avoidance systems
In figure 6 the curves of figure 1 are combined with attitudtnat ranges ot b rd
control: en foute, around and on anpons. Avoiding birds in the air is difftc!h
because many bird movements occur betow rhe coverage of most tong range
surveilance radars {stippted) and just above the acquisition .ange of rh; visual
observer (shaded). To make ir even worse. tow tevet btd fying activtry is oflen
in big flocks as food rinding is a very sociat affair, especia y i; wefland a.eas
where water rabte dynamics creares a ftuctuating and palchy availabitiry of
food. A thorough map/calendar approach is of course the lirst srep in pianning
new airpo(s or aircrait flying routes. aut this information atone is too static f;r
day-to d€y bkd strike prevention. For each headache species the daity and
seasonal flying partern shoutd be known. In principte a tot of bi.d activity can be
predicted by a dynamic modet fed bV certain environmentat parameters, aut
scientific generalizations are lsua ty not enough to predict how each species w I
adapt to specific localconditions. Additionat rutes of thumb about spatiat fying
behaviour in reation to wearler, topography etc. are neeneo.
l. practice the onty ,rnodets,ihai do exist are very experienced b rd contro|ers
gvinglheir'best profess onatjudgeme.r,_ Howevef, this iype of antictpation is
primarily based on whar can be mentaty reconsrruct€d from visua observarion.
This is usually imlled to rhe a rport itsetf and 10 the towest 5O meters (Buu.m.,
Lensink & Linnartz 1986). Bur even he.e a big bird fock may sudenty appear.
As noi all blrd controtters are eqlalty experienced and atert, and as they cannot
overvrew the whole aiiport, ihere is a gap in tho markel for detecl on devices
oaseo on remote sensrno such as radar.
radar in avoidance systems
The above mentioned gap in the marker is growing surely but s owty as rong as
we are not at)re to quantify rhe bird strike risk betler and to show convincingty
the amo!nr of risk reduction. Air traffic conlro ers do not wish ro accept
addillonal responsibilities when the btrd information is nor very ctearty indicared
and well derined. Obviousty, not every singte smaI or medium sized b rd can
kept under controt. Thus, rhe equ pment shou d be abte 10 tndicate whether the
amount ot bird meat in a cerlatn air vot!me exceeds a ce(ain agfeed vatue.
Figufe 6 is a propos:lro reduce the many options or apptying remole senstng
into three altitude/scate ctasses on the basts of rhe spaital disrribution oi b rd
slrikes. ls!ggesr the fotowng terminotogy,
A. 2-D on airoort bird flock deteciton Certain ground radars do have the
capacity to monitor birds or cou d be adjusred 10 do so {schaefer 1969). Given
the limiled range needed 6tso off-the shelve marine radars with a reptaced
anlenna, to .a ow t\e bear and ircrea\e qdin, mrght be .porred. Ihe n a n
p oD em 6 grou-dctLtrer r"d-cr o1, bJt sopli\r.carFd new techro,ogy is abte to
solve this satisfactority.
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a. 3-D airport vicinitv bird co.irot Thts has been adopted during rhe tgth BSCE
meeting in Madid (see Buulma & Brudere. j99O) as rhe ideats;tution. The
radar needed should be abte ro trace individuat bird itocks interfering with
aircraft flight pathes tLow Levet Search, LLSe) as we as to monrtor bnd
densities by volume scanning (High Leveisampting HLSa) (Buurma 1994b).
C. aroe e miorir,on :qa
monrori.o Vaaous rada,s can be uspd ro ger inde\
I gures or rarge scate bird migrarion, M,hrarv air dere.se ano ai, lfa c coni.ol
radars are atready used for many years in the west european birdtam system.
Modern weather radars and wind profiters offer cha|enging new possib tities.
The main problem stiJt is catibration.
Allan, J.B. & C.J.F€:re {1994). FeratCanada geese (Branla canadensis)as a
hazard ro aircraft in Europer options for management and control.
aSCE22/wP3:25,42.
Aubrecht, G. (1994). Waterbird and wettand conservaiion - |WRB,s qtobal
nelwork and rhe cu,rent sta.e o, rhp i.rp.na.olat R"msar Co;eltion dnd
Bonn Convenrion. BSCE22tWp6:55-62.
Becker, J. (1996). How to get retab e information on the bird strike .isk
BSCE23/WP 8 hhis meeltnol
Buurma, L.S. {1984'. KeV facrors deler. n.ng btrdsr1,e ar d ricts. J. o.Avration
Saferv, Vol 2 nr 1:91-'l07
Buurma, L.S. (1994a). Superab!ndance in birdsrrrenos, weitands and aviation.
aSCE22/WP4:43-50.
B!urma, L.S. (1994b). High bird densiries assessed by radar, a ROBTN report.
BSCE22lWP32:223-242.
auurma, L.S. & B.Brudeier 0990). The apptication of radaf ror bird srrike
reduction. aSCE20/Wp36:273 445 (,radar bookref ).
Buuma, & A. Oekker (1996). ''1.S.
EUBBASE: potenriat lessons fiom mitirary bird
strike statistics. aSCE23AVP6 {rhis meetino).
BLUrma. L.s. & H. v€n -casrere.
{19891. M,graroi,i b ros a.d obctac es atong
-
tne coasr of the Dutch province Zuid Holand, RNLAF,report, 1j7 pp.
Buurma, t.S., R, Lensink & L.c. Linnartz (1986). Aftitode of di!rnat broa; ,ronr
mrgratron over Twenrej a comparison of rada. and visual obseruations in
O.iober 1984 | n Dur.h. I 19. su-narvJ. I rosa 59:169.182.
DeLke . A. & F.t-. van de, Zee {1996J. B ros a-d s,.sstdld on a rpo,r\.
BSCE23/WP30 (this meeting).
Klaver. A {t9-94j Ndrure d g.,L sa.e.y a conrjover5y.
BSCE22/WP5:51-54
Leshem, Y. (1994). Twenty,three years of bird strike danrage in the tsraet Air
Force 1972 1994. BSCE22twp22t 193-.t62.
Schaefer, G.W. (1969). An airport bird derection radar for reducing bird hazards
_.
to arcraft. Wond Conf.on aird Hazards ro Aircratt, Kingsron, Caoada.
Tinbergen, L. (1949). Vogels onderweg. Schetema & Hotkema, Amsrerdam.
554