Enrico Cavina (*)

“ Decision making “ of autumn migrations of Woodpigeons ( Columba palumbus ) in Europe : analysis of the abiotic factors and “focus” on Atmospheric Pressure changes .

Enrico Cavina (*)

• –

ABSTRACT

In thisdetailed paper we have tried todetect all thepossibleabioticdataon three areas oftransit ofwoodpigeons(Columbapalumbus)onautumn migration(Falsterbo SWEDEN -FRANCEPyrenees – ITALY Appennini mountains and valleys “CIC “- ), processing and reportingoftheirdata..
The"focus"was toidentifythe mainabiotic factor related totheweatherthat can bedefined as "thefinger pressing thebutton"forthe take-off flightofthefall migration fromnesting areasby bothtransit areas(stop-over). The analysis wasconducted oncensus datain transit,in the Archivesof the Observatory ofFalsterbo(Sv),Mountains Pyrenees(GIFS) in France, ITALY Club Italiano del Colombaccio – Progetto Colombaccio ( CIC). Basisofthetotal quantityofPigeonscountedin migrationof40 years (from 1973 to 2014 )is42.936.667 woodpigeons(Columbapalumbus)and more specificallyinthe subject of studyover the past 15years (1999-2013) 47peakswere identified(1-5days)migrationin Sweden,42peaks on thePyrenees , 12 in Italy : TOTAL 101 Peaks . Itwas possible to comparethese peakswiththe weather conditionsdrawnday by day andhour by hourdetailedby the Archivesof WeatherHistory.The analysis carried outmainlywith datarates ofincidenceof abiotic factorshas revealedthat thelikely"finger pressing the button" can be identifiedin raising of theatmospheric pressure (AP) : thisincreaseis a constant (92.62% Sweden-92.85% of the Pyrenees- 91,00% in Italy ) andmorein particular has beenwith variationsabove 10hPain75.80% of the peaksfor the sector"36/24 h" and76.19% for the sector"18 h"preceding thetake-off ..
The global analysisof all theabiotic factorsmakes it possible toconstructa number of hypothesesfor the interpretationof the"why"this happens.It is also emphasizedthat the sensorterminalof the variationsofatmospheric pressureisreadily identifiableof the Para-Tympanic Organ (PTO) of Vitali.as possible “biological” barometer.

Key words : woodpigeons’ migration , atmospheric pressure (AP) , take-off , decision making ,weather , abiotic factors

July 2014 updated NOVEMBER2014

INTRODUCTION

Many factors[51]-biologicaland abiotic factors [1web]-affect thedecision-making momentfor many migratory birdstoflymigration in autumn andspring.This moment ofdecision("decision making") occurs as thefirst “take-off” from the areas ofbreeding(autumn)and fromwintering areas(spring) and then always occursalong themigratory route until the arrivalin the destination area(wintering areas, breeding areas).[3-25-40-44]

The phenomenon of"I decide to go, at this very moment" occursin different waysforall species ofmigratory animals, andto interpret ithoweverwe have torememberthe complexityof the phenomenon of"Migration"(the mystery of migration) in various species of birds.

The "I decide to startnow"isactive in allmigrating birds-migrantsday and night, inthe shortormedium or longdistance , migrationalone or in groupormass(gregariousness) -who begin orcontinueafterstop-overmigrationunderthe stimuliof differentbiological andabioticfactors[ 1-2-3-4-30-57-77 ]..

Theornithologicalliterature[44-51] is rich ofstudiesfor all of thesevarious factors andrelated integrations such asphysiological, physical, genetic, ecological, ethological, biochemical etc... It'must be indicated ascomprehensive referenceandcurrent(2010), the work of M.S.Bowlin"Grand ChallengesinMigrationBiology"which contains 221references [ 51 - 2010].Spite ofthe wealth ofanalysisand specific researchonabiotic factors, it does not revealmany referencesand insightsuseful toidentifythe timeand theprecise motiveof the " decision making" for thetake-offnamely theidentificationof the "finger pressing the button" to start themigratory flight, if it exists as such.

It 's obvious thatthe biological condition(physiological, hormonal, metabolic, physical) [7-13-36]whichhas beenmaturingin the daysbefore the migration("zughunrue")[85], thisisthe basis on whichthe commandwill actto go .We must alwaysremember that among theabiotic factors, the length of daylight (photo-period) [8-37-40-60-72]isprominent factorthataffects thepineal glandand resulting various neural correlations . It'also obvious that the timingof optimal migrationdepends on otherabiotic factors[2-3-86],just as the environmental conditionsandmainlythe status of theweatherin placeorexpected: It is imperative – for the birds - todeal withthe migratory flightin the best conditionsofsafetyand possiblyless fatigue. just as the environmental conditionsandmainlythe status of the real or expected weather.[12]

Butthe main questionfor the focusof our research is: < while consideringthe variousvalence of decisionof all factors-biotic and abiotic-can weidentifyafactor that mostof the otherrepresents "thefinger pressing thebutton " forthetake-off ofmigratory flight ? >. [16-34-35-39-45-48-60-67-71]

Andit is well-known andwidely studied[38-44-51] the abilityof migratory birdsto predict the weather, andthis also applies totheresident birdsaboutthe behavior-especiallyalimentary-in the area of residence .Itis also known thatthe extemporaneous weather depend on several factors-atmospheric physicalandfirst of all theatmospheric pressure(AP ); as well asthe climatic conditionsoflong period, mostly seasonal, depend on thetemporaloscillationso-called"North Atlantic Oscillation -NAO" (and correspondingElNinofor the Pacific) characterized bycyclic fluctuation(fluctuation)of the differencesofPAat sea levelbetween twovast areas ofland-ocean hemisphere: climaticconditionactsstronglyonbiotic factors.[6-31-32-67-82-89 ]

In severalscientific papers[38-44-51] aimed at studyingthe correlationbetweenmeteorological factorsand migration ,it isalmostalways givengreater prominence toAtmospheric Pressure"low", whose arrivalwould be perceivedby themigrationsothatthey cananticipatethe advance of thefaceof bad weather.It does not seemto have beengiven a lot ofimportancetostudythe variations(properlyvarying degrees) of theatmospheric pressure – growing- [39-45]thatoccurjustbefore the arrival oflowatmospheric pressureandbad weather: the study of thisspace-timevariationsbefore thelowering of theAP andof the take-off, there that must be better analyzedin detail.

We shouldgive importanceand emphasizethe supposedanatomical basisor "biological barometer" whichisthe Para-Tympanic Organ of Vitali(PTO)that in addition tobarometric functionswouldalsofunctionas altimeter[17-18-20-21-22-23-24-29-80-83]..

In previousnotes publishedon the Web (Aggiornamenti 11.11.2013

)[74-79] we hadhighlighted someimportant conclusionsaboutthe correlations betweenmass migrationandelevationsof theAP in the hours beforethe take-off forWoodpigeonsand also forthe Woodcock(Scolopaxrusticola) [79-74-78]..

In thisdetailed workwe have tried todetect all thepossibleabioticdata (***)on two areas oftransit ofWoodpigeons(Columbapalumbus)onautumn migration(Falsterbo SWEDEN -FRANCEPyrenees), processing and reportingofthem.

(***)The data wereextracted from thefree consultationto the Webasreported by theweb-sites of theinstitutionalFalsterboBird Observatory(extreme southern tip ofSweden) and on the mountainsPyrenees(France- and with respect tometeorological datafrom the websiteWeatherUnderground"WeatherHistory", in full respect of intellectual propertyandcopyright, usingpublic dataonly forscientificstudyand correlationsandnon-commercial use, andcitingsourcesas with allscientificbibliographies[01-02-03]. We have received official permissions from the sources ( Sweden-France – Italy – USA )

The"focus"has beenmain-for us -to identify,if possible,a set ofnumerical and statistical datasuch as toconfirmwhat has already beendetectedinpreviousNoticepublishedon the Web (Aggiornamenti 11/11/2013) [74-75-77-78]: theAP risessignificantlyin the48-18hour period beforetake-off migration.
We anticipateasdiscussedlaterin the analysis andconclusions: among all the factors affecting thedeterminismof the take-off formigration, higher-mostly sudden–AP seems to represent"the finger pressing the button".

MATERIALS ANDMETHOD
Preliminarilyagainwe reaffirmthe respect andthe attribution of"intellectual propertyandcopyright"to theinstitutionalwebsitesthathave collectedthe"numerical counts" andmade it available forstudyand research (Falsterbo Bird ObservatorySWEDEN - ITALY Club Italiano del Colombaccio ) and for theweatherthe classic Historical Archives(WeatherUnderground: Weather History).
The comparative methodologyand integrative analysisofmeteorologicalandornithological datadoes not appearin the literatureor on the webto bepublished by the websitesthat we have mentioned. We believethat our research-presentedhere-hasalsothe intention of givingmorevalue to the workofdata collectioncarried outby thesewebsites,as abasicbibliographic factor. [01-02-03].We have received (September 2014) official permissions from the sources ( Sweden-France – Italy – USA )

Theglobal base ofstudy concerns themigrationof amulti-yeartotal(Sweden-Pyrenees)of38,105,479Woodpigeons(Columbapalumbus)[44]surveyedintransit migrationin40 years (1973.2013) and 4.831.138 (10 years) in Italy.
Thespecific basisofretrospectivestudyconcerns themigrationof42.936.667 Woodpigeonsin the last 15years (1999-2013) surveyedin transitat Falsterbo-Sweden (10.760.141 withan annual average341 576) andon the passesof the Pyrenees-France (27,345,338 withannual average1,823,022) and Appennini mountains-valleys-Italy ( 4.831.138 with annual average 483.138 in ten years 1998-2007 )

The averageannualglobal(Sweden+France)transit’scensusin 15years is2,164,598birds, which -compared with thecensus(Birdlife.org 2014) in forceps 27000000-51000000ofwoodpigeons breeding in Europe-isrespectively's8.01%(about 27 million)and4.24%(about 51 million)of all Woodpigeons inEurope .

Itwas possible to relatethese15-year period/ 10-year period ,correspondingto theperiod of 15years for whichWeatherHistoryprovides all theweather dataand astronomicalday by day andhour by hoursince 1998. Realizinginpapersome card- modelsusefultocompare the databothornithologicaland concerning the weather, we were able toevaluate differentabiotic factorsthat affect thedecision-making momentof take-off during the migrations,so we haveconsideredintheautumn-takeoff fromnesting areas(Sweden,Scandinavia, North-eastern Russia) and then by thetotalareaofthe stop-over prior to transitingthe Pyreneesin France. [01-02-03],and Russia-Central Europe-Balkans total areas ( long-medium-short distance) of stop-over prior to transiting in Italy [93]

SWEDEN -nesting area
The population [50]ofWoodpigeonsnestingin Swedenis estimated at980,000pairs (1.960:000 heads)moreconcentratedin the south ofSwedenbelow theLatitude60 °31'applied (Falen) to the Latitude57° 65'applied (Falsterbo) 800 kmto the southofFalen, andaroundLatitude57°43'applied (Göteborg) about 330km north ofFalsterbothis databeingvalid reference pointto consider-afterthe take-the transitsurveyedinFalsterbo.
The area betweenthese last twolatitudesshould therefore correspondto the areaoffledgingfor the birdsnested there and for birds intransitorstop-overs comingmorefrom the north (Scandinavia): Falsterbooverto pick up thetransitfrom Swedenis locatedon a routein front ofthe wholemigrationfromScandinaviaand alsofrom East/Northeaston the routeRussia-Baltic Countries.

In the period1973-2013(40 years)in Falsterbo(Sweden)have passed 10,760,141Woodpigeonsasdocumented, with an annual averageapplied (over 40 years) of262 459birds.[01]
In the period1999-2013applied (last 15 years) have passed5,123,647Woodpigeons-which represents43.01%of the totalof 40 years -with an annual averageof 15years of341 576birds, as equivalentto an increase of5450% compared to the averageapplied (262 459 birds)of the 40years in total.
The detailed analysis(1999-2013)ofdailytransitsmonitored(last week ofSeptember - October-the first 15 days. November) hasallowed the identification of47peaksof migrationin 15 years.Each peakmigrationhadminimum duration of 1day anda maximumof 5 days.In the47peaksidentifiedmigratorybirdshave passedcounted3,972,053, which represented-thepeak-the77,52% of the entiretransitof5,123,647birds,with an annual averageapplied (peak 1x1 year )84 511birds.

In the last 5years (2009-2013) there has been asignificant increase in thetransit migration: 2,265,395birds (44,21% of the total to15.) and1.8488 millionof thesewood pigeons(81.61% of the total 15., and 36.08% of the total 47peaks)have passedin 16(out of 47)peakswith an average of115 555to1x 1peakyear with anincrease-in the last5 years -of36.73% compared to the average valueof84 511birds on15 yearseveryone.
Last year of observation-2013-844 710woodpigeonshave transited and of these723 490(86,64% of total / year)divided into5peaks: in 2013compared to thebreeding populationestimated at980,000pairs (1.960:000 birds)[communication personalin 2013by AndersWirdheimComunicationOfficerSOFBirLifeSweden] the2013transitin Falsterbo(844 710 -2013) represents43.09% of breeding birdsin Sweden.It should be emphasizedthe exceptionaltransitin2 days(11-12October 2013) of450 800wood pigeons.

Last year of observation-2013-844 710woodpigeonshave transitedthese723 490applied (86,64% of total / year)divided into5peaks: in 2013compared to thebreeding populationestimated at980,000pairs (1.960:000 birds)[communication personalin 2013by AndersWirdheimComunicationOfficerSOFBirLifeSweden] observedthe2013transitin Falsterboapplied (844 710 -2013) represents43.09% of breedingin Sweden.It should be emphasizedthe exceptionaltransitin2 days(11-12October 2013) of450 800wood pigeons.
It is therefore clear that the transit(43.09% of nesting birds ) is not the wholebreeding populationin Swedenthat transit likely(about57%)across thesea to theBaltic coastformigratory routesnotmonitored.Itshould also beborne in mind thatFalsterboalso welcomestransitsfromthe largestnesting areasinthe North and East(the Scandinavian Peninsula, Russia).
The data collectedin Falsterbo, however, areextremelyimportantto define the typeof take-off time(the time when "the finger presses the button") and relatetoabiotic factors-mainly for weather-occurredpreciselyin the area of​​takeoff.
We must say thatthisarea-North/Northeast-Falsterboistoplace the cursor overa radius ofabout 300 kmcompatiblewith transitsoccurring afterthe take-off at a speed of50-70km /hduring the dayofthe flight.[01-02-03- 10]

The analysisof abiotic factorshas also beenextendedin ourretrospectivestudyareafurther northinSweden(latitude60 °31'-Falen) and also further southintheirobservation(latitude57° 65 'Falsterbo) without being able todetect by thefull-paper cards incomparison-significant elementsfor further studybecausethe findingsare similaror analogousfor the weatherandnodifferences with respectto the data collectedatLatitude57°43‘ (Göteborg), andso we decided nottoreport them in thistext.

Wetherefore considered it is acceptableto reportthe findingsobtainedfrom the historicalweather(WeatherHistory -Weatherundergound) for the area of Swedenaround andbelow theLatitude57°43'(Göteborg).[03]
On this basis,settingofnumerical and statisticalanalysis, we performed ourcollectionof meteorological data(andastronomical)[03] andornithological[01-02]to compare-onpaper forms (more than 500) -the"peak migration" withthe weather conditions48h/36/24/12hand 1 /hbeforetake-off on the day ofmigration, day by day of migrationpeaksof 15 years in Falsterbo.

With this method47peaks(15a.-1999/2013-min.1g.5gg-max)were analyzed :the media(1 picco x 1anno) of84,511birdsand relativemaximum increasesthe averagethathas reached115,555birds(1 to ./15°.) and thenin the last 5years we see an increase of36.73%.
Indetailtablesapplied at the end of Bibliography , it could be controlledrawnumerical dataevery dayof the 47peaks for eachyear of the15 years (1998-2013 Sweden-France-Italy).

All the GRAPHICS are also available on-line at G+ :

The analysisof abiotic factors(weatherand astronomical)[5] was similarlyin-depth detail48h/36/24/12hof1.2days before thetake-off of the first day of thepeakrecordedin the counts. Unfortunatelyby the ornithological archives we cannot control thetimesofcountingat Falsterbo, and thenthe reference istothe rawdaily count , which is stillhighly significant.

For this analysisof abiotic factors, we've compiledall the specificpaper-cardsusefultocollectthe temporal changesof suchfactorsand thenrelate themto thetake-off of the peak. In addition,we have analyzedin detail thegraphical diagrams(verifiableon archivesof WeatherHistoryexaminingthe specific date) representing the trenddetailedintemperaturefor24h, A.P, wind speed, wind direction. Readingonthisgraph it canalsoaffectedbysome error indetail, however be overcomeby reading the WH tableshour by hour (raw numerical data).

Exactlythe analysisis more completehavingfree accessto the tablesof WeatherHistorythatallows you to read: temperature(mean,maximum and minimum), humidity (average), atmospheric pressureat sea level, windspeed and direction, visibility, conditionsweather(overcast, rain, fog, rain, etc..) These figures are verifiableevenhour by hourof thedayexamined ina given location.We haveextrapolatedfrom thetwilight hoursandat night(7-11pm) andthe hours of thedaytake-off at 7am and11.50amlate in the morning, herealso analyzingthe parametersof temperature,atmospheric pressure, wind conditions ,weather.
As forthe astronomical datacardsallow you todetectthe WeatherHistorydawnhours, extensionof visible light,day length, and more specificallyforthe lunar phasesapplied (new moon, growth, full,lowering ) the percentage ofsurfacemoonlighted .

Aclear and comprehensivesummaryof the sequencesand integrationof all these data, it is not so simpleto implement, butthe essentialand significant data can be detectedanalyticallyand criticallyon ournextshowinTables.

The tablestend to highlightthe variations betweenday/ sprior totake-off and the dayofitsTake-offandtransit

THE numeric TABLES are reported also in GRAPHICS ( English) following the Tables

TABLE ( A ) - data collected in Archives of FALSTERBO (Sweden) as by

ABIOTIC factors

(Migration counts ) copyrights permission 3rd September 2014 from Lennart Karlsson

10.760.141 woodpigeons counted 1999-2013 ( 15 years ) – 47 peaks of migration

The readingon thetablesof the mainnumerical data (raw numbers and percentagesofthe sector)has been set upto highlightany changes inspreadsfroma baseline(virtual "zero"tothe atmospheric pressure) andto comparethe findingswith accuracy"day/ sprior totake-off "and" dayof the take-off andtransitobservation. "
The analysis is conductedon 47peaksdetectedmass-migrationat Falsterbo-Sweden in autumnfor 15years (1999-2013). [01-41]
Theabiotic factorsanalyzed and reportedin Tableswere:general weather conditions, wind (direction and strength), visibility, day length, temperature, humidity, atmospheric pressureat sea level(expressed in "hectopascal " with the symbolhPa- seeWikipedia).
Allpeakswere identified during migrationdated by OrnithologicalObservatoryFalsterbo(Sweden- andrelatedto thedetailedweather data(andastronomical) drawn from the archivesHistoryof Weather[03-7-41](WeatherUnderground -
RESULTS(Sweden)
From reading thetableswe can highlightthe followingprominentor not.
1) Weather conditions: 74.46% of the peakscorrespond toslightlycloudyorclear days.
2) Wind-strength-41of 47 peaks with winds offorcebetween6-25km /h, thenmostlymoderate andevenly distributedproperlyin the daysoftransitin peaks.
3) Wind-direction-42.55% of the peakswithfavorablewindspredominantlyfrom the Northand Easton the dayof the passage; 38.29% of the peakswithunfavorablewindspredominantlyfrom the southand west; 14.89%of the peaksunder conditions ofmoderatevariabilityand /orcalm winds.
4)Visibility:6-10kmin'89.36% of peak.
5) Length of Day: calculatedinmid-Octoberbetween10h and10h45'.
6)Temperature:-average temperature between6-20°on average,mild- 89, 36% of peaks
7)Humidity: prevails in absolute termsbetween60-100%.
8) Moon: percentage of the lunar surfaceilluminatedover 40%in61,70% of peak
9)Atmospheric pressure:changesinglobal growth(1 ° -30 °) in92.62% of the peaks,variationsingrowthofover 10hPadifference in72,72% (48-24 hprior totake-off) and 78,72%in the 18hours before, to be regarded asthe dawnin the study areaoccursat around7am andthewoodpigeons typicallymovefrom the woods about30'-60 'after sunrise. About thetimeof the take-off and other environmental factorsplay important rolesand temporalscope ofan overnight stop, such as night-time temperature, humidity, clear skiesorcloudy, rain,wind,moon phase.
The values​​oftheirbaseat7-11pm (Twilight Night) thenight beforethe take-off point to aAtmospheric pressureinhPabetween1011-104053.43% of peak.
The samevalues​​in the morningof the take-off andtransit(7-11am) show that 75.45% of the peakswithdifferential values​​higher than1010hPa..

Discussion(Sweden)
The synthesisof this first partofretrospectiveresearch-againnotingtheintellectual property andcopyrightof our"sources"ofinformation retrieval(Falsterbo and WeatherHistory)-herebelowis discussed. [01-02-03-1-67]
In theautumnmigrationofwoodpigeons (Columbapalumbus)[47]inScandinavia(Falsterbo-Sweden) analyzed15 years(1999-2013) abouttheabiotic factorsthat affectin determiningthe decision of themigratory flight(instantaneous"decision making" of the take.off) from the nesting area andsurrounding areaspertaining tothe factor that mostnearly-absolute-identifies with "the fingerthat pushesthe button"is certainly theimportanceof changes (over 92%) ingrowth of the atmospheric pressurewhich 78.72% occursin the 18hours prior totake-off withdifferential values​​above1010hPa. [30-41-43-47]
However,we must point outthatas partof the 47peakshave beenthere-thoughrare6.38%-situations in whichthere has been noincrease inatmospheric pressureor evenreversedforvalues​​lower:thismeans that theincrease inAtmospheric pressurecan not be consideredafactorwithabsolute value, though extremelysignificant.[03]

It seems interestingin this regardincludeashort noteregarding whathappened in Italy(areaofforeststopoverMesola-Ferrara) in October2012:the collected dataarehighlysignificanteven ifreported asepisodic [78-79]
Theearlypeak(2-3Oct)foundin the woodsMesola(Romagna) was preceded bya fall in theATMOSPHERIC PRESSURE7-8mBdays28 to 29 Septemberin the areas(Central Europe -Eastern Europe-Balkans) suppositoryorigin, andthenin the afternoon ofSeptember 30(the day beforethe arrivalinMesola, about Pigeons30-50000), there was an increaseof10mB.
No significantchanges inTEMPERATURE(Notewe are still inSeptember)
As to the secondpeak(30 to 31 October) asreportedon theAdriaticcoasts(Delta-Romagna -Marche)withstrongcontinuousinputof flocksfrom the Adriatic(Balkans coast), we consideredin anticipationthatthe Central-EasternBalkans(Bosnia and Croatia)there would be afall ofATMOSPHERICup to996mBfor4 to 5 November(and relatedheavy rainfall) andthenin the days beforeyou couldprovidea migration ofpeoplestillstop-overin the Balkans.
In fact, theOctober27-28-29in thesupposedoriginoftheATMOSPHERIC PRESSUREdeclinedmodestlybut4-5mB(then 4 to 5 Novemberhas fallento 992mB) until 1016,thenOctober 30israisedin the afternoonof October 30,the day before thepeak ofOctober 31(massive arrivalof flocksfrom the Adriatic
In fact,in the 48hprior to thepeak ( 300.000 birds in takeoff from the forest between 3am-8am Full Moon ) there has been arushofPr.Atm. from990hPato 1016hPa (26 hPawell-documented variationin thegraphsWeatherHistoryofFerrara)[03-77-78]..