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Is daar 'n gps wat baie klein is vir voëltjies?

Is daar 'n gps wat baie klein is vir voëltjies?



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Ek wonder of daar 'n baie klein GPS -toestel is wat op passante (of ongeveer 10 gram voëls) gemonteer kan word sonder om hul vlug te beïnvloed. Hierdie webwerf wys inligting vir vlermuis se GPS. Maar dit hou ook net 24 uur aan. Ek wonder of daar 'n ligte en lang batterylewe van ongeveer 2-5 gram is. Ek het dit ook gevind, maar het nie gevind of dit 'n lang batterylewe het nie.

Is daar 'n studie oor GPS wat klein voëltjies opspoor?


Die tegnologie is daar (nog) nie vir ontplooiings op voëls van 10 gram nie. Die grense vir GPS-tegnologie is rondom die 50 g-reeks, vir voëls. Hou ook in gedagte dat die kleinste houtkappers oor die algemeen nie kan oordra nie, dus moet u die diere herwin om u data op te haal.

Soos u vraag impliseer, is daar 'n sterk afweging tussen die gewig van die toestel en die batterylewe. Daar is GPS-toestelle wat so min as 1 g weeg, maar hul lewensduur is baie beperk (10 regstellings vir die 1 g-toestel; 50 vir 'n 1,1 g-toestel).

As 'n kanttekening: u vraag impliseer dat klein voetgangers 20 - 50 % van hul liggaamsmassa in die spoorsnyer kan dra sonder dat hul vlug beïnvloed word. Die etiese borde wat ek ken, beperk oor die algemeen spoorsnyers tot ~ 5 % van die massa van die dier.


Ouervoorsieningsgedrag by 'n kudde-lewende passerine, die Vinous-throated Parrotbill Paradoxornis webbianus

Die hoeveelheid voedsel wat ouers aan hul kuikens lewer, word beïnvloed deur verskillende lewensgeskiedenisseienskappe sowel as omgewings- en sosiale faktore, en hierdie belegging bepaal uiteindelik die huidige en toekomstige fiksheid van ouers en hul nageslag. Ons het die voorsorggedrag van ouers in die Vinous-throated Parrotbill bestudeer Paradoxornis webbianus, 'n spesie met 'n ongewone sosiale sisteem wat gekenmerk word deur kuddelewende, swak territorialiteit en veranderlike nesverspreiding. Ouervoorsieningstempo het 'n positiewe invloed op kuikenmassatoename gehad, wat daarop dui dat voorsieningstempo 'n effektiewe maatstaf van ouerlike belegging in hierdie spesie is. Mannetjies en wyfies het nessies teen ongeveer dieselfde tempo gevoer, en geen ander versorgers is by neste waargeneem nie. Ouers het voorsieningstariewe gekoördineer sodat hulle kuikens meestal sinchroon gevoer het. Die mate waarin ouers die verskaffing gekoördineer het, word egter geassosieer met hul sosiale omgewing, aangesien sinchronisasie positief verband hou met die plaaslike teeldigtheid en negatief tot die naaste buurafstand. Die tempo waarteen ouers nestelinge voorsien het, toon dieselfde verhoudings met sosiale maatreëls, omdat dit die grootste was by hoër digtheid en wanneer bure nader was. Besoektempo was ook verwant aan kuikenouderdom, maar nie aan broeigrootte, broeisgeslagsverhouding, ekstra paarvaderskap, lêdatum, temperatuur, ouers se liggaamskarakters, tyd van die dag of jaar nie. Ons kom tot die gevolgtrekking dat die sosiale omgewing van broeipare 'n belangrike rol speel in die bepaling van ouerbelegging, waarskynlik deur die gevolge daarvan op die geleenthede wat ouers het om met spesifieke eienskappe te soek.

Dit is 'n voorsmakie van intekeninginhoud, toegang via u instelling.


Vyf praktiese gebruike vir “Spooky” kwantummeganika

Kwantummeganika is vreemd. Die teorie, wat die werking van klein deeltjies en kragte beskryf, het Albert Einstein berug dat dit so ongemaklik gemaak het dat hy en sy kollegas in 1935 beweer het dat dit onvolledig moet wees.

Verwante inhoud

Die probleem is dat kwantumfisika skynbaar die gesonde verstand van kousaliteit, lokaliteit en realisme weerstaan. Byvoorbeeld, jy weet dat die maan bestaan, selfs as jy nie daarna kyk nie, dit is die realisme daarvan. Oorsaaklikheid vertel ons dat die gloeilamp brand as u met 'n ligskakelaar druk. En danksy 'n harde beperking op die spoed van lig, kan die verwante effek nie onmiddellik op 'n miljoen ligjare weg kom nie, volgens die omgewing. Hierdie beginsels breek egter op die kwantumgebied af. Miskien is die bekendste voorbeeld kwantumverstrengeling, wat sê dat deeltjies aan weerskante van die heelal intrinsiek gekoppel kan word, sodat hulle onmiddellik inligting deel en 'n idee wat Einstein laat spot het.

Maar in 1964 het fisikus John Stewart Bell bewys dat kwantumfisika eintlik 'n volledige en werkbare teorie was. Sy resultate, wat nou Bell’s Stelling genoem word, het effektief bewys dat kwantumeienskappe soos verstrengeling so werklik soos die maan is, en vandag word die bisarre gedrag van kwantumstelsels ingespan vir gebruik in 'n verskeidenheid van werklike toepassings. Hier is vyf van die interessantste:      

’n Strontiumhorlosie, wat in Januarie deur NIST en JILA onthul is, sal akkurate tyd vir die volgende 5 miljard jaar hou. (Die Ye -groep en Brad Baxley, JILA)

Ultra-presiese horlosies

Betroubare tydsberekening gaan oor meer as net jou oggendwekker. Klokke sinchroniseer ons tegnologiese wêreld en hou dinge soos aandelemarkte en GPS -stelsels in lyn. Standaard horlosies gebruik die gereelde ossillasies van fisiese voorwerpe soos slingers of kwartskristalle om hul ‘ticks’ en ‘tocks’ te produseer. Vandag is die mees presiese horlosies ter wêreld, atoomhorlosies, in staat om beginsels van kwantumteorie te gebruik om tyd te meet. Hulle monitor die spesifieke stralingsfrekwensie wat nodig is om elektrone tussen energievlakke te laat spring. Die kwantumlogiese horlosie by die Amerikaanse Nasionale Instituut vir Standaarde en Tegnologie (NIST) in Colorado verloor of wen slegs 'n sekonde elke 3,7 miljard jaar. En die NIST strontium horlosie, wat vroeër vanjaar onthul is, sal so akkuraat wees vir 5 miljard jaar—langer as die huidige ouderdom van die Aarde. Sulke supergevoelige atoomhorlosies help met GPS-navigasie, telekommunikasie en opmeting.

Die presisie van atoomhorlosies berus gedeeltelik op die aantal atome wat gebruik word. Elke atoom word in 'n vakuumkamer gehou en meet tyd onafhanklik en hou die ewekansige plaaslike verskille tussen homself en sy bure dop. As wetenskaplikes 100 keer meer atome in 'n atoomhorlosie inprop, word dit 10 keer meer presies—maar daar is 'n beperking op hoeveel atome jy kan indruk. Navorsers’ volgende groot doelwit is om verstrengeling suksesvol te gebruik om akkuraatheid te verbeter. Verstrengelde atome sal nie besig wees met plaaslike verskille nie en sal eerder net die verloop van tyd meet en hulle effektief as 'n enkele slinger bymekaar bring. Dit beteken dat die byvoeging van 100 keer meer atome in 'n verstrengelde horlosie dit 100 keer meer presies sal maak. Verstrengelde horlosies kan selfs gekoppel word om 'n wêreldwye netwerk te vorm wat tyd onafhanklik van ligging sal meet.

Waarnemers sal 'n moeilike tyd hê om in kwantumkorrespondensie in te kap. (VOLKER STEGER/Science Photo Library/Corbis)

Onkraakbare kodes

Tradisionele kriptografie werk met sleutels: 'n Afsender gebruik een sleutel om inligting te kodeer, en 'n ontvanger gebruik 'n ander om die boodskap te dekodeer. Dit’s egter moeilik om die risiko van 'n afluisteraar te verwyder, en sleutels kan gekompromitteer word. Dit kan opgelos word met behulp van 'n potensieel onbreekbare kwantum sleutelverspreiding (QKD). In QKD word inligting oor die sleutel gestuur via fotone wat lukraak gepolariseer is. Dit beperk die foton sodat dit vibreer in slegs een vlak—byvoorbeeld, op en af, of links na regs. Die ontvanger kan gepolariseerde filters gebruik om die sleutel te ontsyfer en dan 'n gekose algoritme te gebruik om 'n boodskap veilig te enkripteer. Die geheime data word steeds oor normale kommunikasiekanale gestuur, maar niemand kan die boodskap dekodeer tensy hulle die presiese kwantumsleutel het nie. Dit is lastig, want kwantumreëls bepaal dat die "lees" van die gepolariseerde fotone altyd hul toestande sal verander, en elke poging om af te luister, sal die kommunikators op die hoogte bring van 'n sekuriteitsbreuk.

Vandag gebruik ondernemings soos BBN Technologies, Toshiba en ID Quantique QKD om ultra-veilige netwerke te ontwerp. In 2007 het Switserland 'n ID Quantique-produk probeer om 'n peutervrye stemstelsel tydens 'n verkiesing te verskaf. En die eerste bankoorplasing met behulp van verstrengelde QKD het in 2004 in Oostenryk plaasgevind. Hierdie stelsel beloof om hoogs veilig te wees, want as die fotone verstrengel is, sal onmiddellike veranderinge aan hul kwantumtoestande deur interlopers aangebring word. deeltjies dra. Maar hierdie stelsel werk nog nie oor groot afstande nie. Tot dusver is verstrengelde fotone oorgedra oor 'n maksimum afstand van ongeveer 88 myl.  

Close-up van 'n D-Wave One rekenaarskyfie. (D-Wave Systems, Inc.)

Super-kragtige rekenaars

'N Standaard rekenaar kodeer inligting as 'n string van binêre syfers, of bisse. Kwantumrekenaars oorlaai verwerkingskrag omdat hulle kwantumbisse, of qubits, wat bestaan ​​in 'n superposisie van state—totdat hulle gemeet word, qubits kan beide "1" en "0" op dieselfde tyd wees.

Hierdie veld is nog in ontwikkeling, maar daar is stappe in die regte rigting gedoen. In 2011 onthul D-Wave Systems die D-Wave One, 'n 128-qubit verwerker, gevolg 'n jaar later deur die 512-qubit D-Wave Two. Die maatskappy sê dit is die eerste kommersiële kwantumrekenaars ter wêreld. Hierdie eis is egter met skeptisisme ontmoet, deels omdat dit nog onduidelik is of D-Wave’s qubits verstrengel is. Studies wat in Mei vrygestel is, het bewyse van verstrengeling gevind, maar slegs in 'n klein deel van die rekenaar se qubits. Daar is ook onsekerheid oor of die skyfies enige betroubare kwantumspoed toon. Tog het NASA en Google saamgespan om die Quantum Artificial Intelligence Lab te vorm wat gebaseer is op 'n D-Wave Two. En wetenskaplikes aan die Universiteit van Bristol het verlede jaar een van hul tradisionele kwantumskyfies aan die internet gekoppel sodat enigiemand met 'n webblaaier kwantumkodering kan leer.

Hou 'n skerp oog op verstrengeling. (Ono et al., Arxiv.org)

Verbeterde mikroskope

In Februarie het 'n span navorsers aan die Hokkaido Universiteit van Japan die wêreld se eerste verstrengel-verbeterde mikroskoop ontwikkel, met behulp van 'n tegniek wat bekend staan ​​as differensiële interferensie-kontrasmikroskopie. Hierdie tipe mikroskoop vuur twee strale fotone op 'n stof en meet die interferensiepatroon wat deur die weerkaatsde strale geskep word—die patroon verander na gelang van of hulle 'n plat of ongelyke oppervlak tref. Die gebruik van verstrengelde fotone verhoog die hoeveelheid inligting wat die mikroskoop kan versamel aansienlik, aangesien die meting van een verstrengelde foton inligting oor sy maat gee.

Die Hokkaido-span het daarin geslaag om 'n gegraveerde "Q" af te beeld wat net 17 nanometer bo die agtergrond gestaan ​​het met ongekende skerpte. Soortgelyke tegnieke kan gebruik word om die resolusie van astronomie -instrumente, interferometers, te verbeter, wat verskillende liggolwe bo -oor mekaar plaas om hul eienskappe beter te ontleed. Interferometers word gebruik in die soeke na ekstrasolêre planete, om sterre in die omgewing te ondersoek en om rimpelings te soek in die ruimtetyd wat gravitasiegolwe genoem word.

Die Europese robin is moontlik 'n kwantum natuurlike. (Andrew Parkinson/Corbis)

Biologiese kompasse

Mense is nie die enigste wat kwantummeganika gebruik nie. Een leidende teorie dui daarop dat voëls soos die Europese rooikop die spookagtige aksie gebruik om op koers te bly wanneer hulle migreer. Die metode behels 'n ligsensitiewe proteïen genaamd kriptochroom, wat verstrengelde elektrone kan bevat. Soos fotone die oog binnedring, tref hulle die kriptochroommolekules en kan genoeg energie lewer om hulle uitmekaar te breek, en vorm twee reaktiewe molekules, of radikale, met ongepaarde maar steeds verstrengelde elektrone. Die magnetiese veld rondom die voël beïnvloed hoe lank hierdie kriptochrome radikale duur. Daar word vermoed dat selle in die voël se retina baie sensitief is vir die teenwoordigheid van die verstrengelde radikale, wat die diere in staat stel om effektief 'n magnetiese kaart te ‘sien’ wat op die molekules gebaseer is.

Hierdie proses word egter nie volledig verstaan ​​nie, en daar is 'n ander opsie: die magnetiese sensitiwiteit van voëls kan te wyte wees aan klein kristalle van magnetiese minerale in hul snawels. Tog, as verstrengeling werklik op die spel is, dui eksperimente daarop dat die delikate toestand baie langer in 'n voël se oog moet duur as in selfs die beste kunsmatige stelsels. Die magnetiese kompas kan ook van toepassing wees op sekere akkedisse, skaaldiere, insekte en selfs sommige soogdiere. Byvoorbeeld, 'n vorm van kriptochroom wat gebruik word vir magnetiese navigasie in vlieë, is ook in die menslike oog gevind, hoewel dit onduidelik is of dit vir 'n soortgelyke doel nuttig was of eens was.


'N Kort geskiedenis

Ongeveer 40 jaar gelede het 'n eenvoudige eksperiment wat in Toskane uitgevoer is, die verloop van navorsing oor voëlnavigasie verander: 'n groep duiwe met hul reuksenuwees is op 'n onbekende plek vrygelaat en het nooit teruggekeer nie. hul ongeskonde metgeselle het vinnig teruggevlieg na die hok (Papi et al. ., 1971). Op daardie tydstip is die reuksintuig as marginaal by voëls beskou en reukaanwysings is nog nooit ernstig in ag geneem onder die moontlike bronne van omgewingsinligting wat potensieel bruikbaar is vir 'n posisiebevindingsmeganisme nie. Om hierdie rede kan dit nogal vreemd lyk dat 'n toetsvrystelling met anosmiese duiwe selfs bedink is. Floriano Papi het daaraan gedink om die navigasievermoëns van anosmiese huisduiwe te toets, want hierdie gevoel was die enigste (saam met smaak) wat nog nie getoets is as potensieel belangrik vir navigasie. 'n Belangrike stuk inligting het egter uiteindelik die eerste poseksperiment met anosmiese voëls aangespoor. Terselfdertyd het Wallraff en kollegas ondersoek ingestel na die gedrag van duiwe wat in geslote voëlkelders grootgemaak is en wat aan verskillende omgewingsprikkels blootgestel is. Hul navorsing was daarop gemik om te toets of 'n uitsig oor die horison van kritieke belang was vir die duiwe om ongestoorde navigasievermoë te ontwikkel. Om voëls te toets wat in 'n voëlhouer met glasskerms opgevang is, en voëls wat in 'n volière omring deur 'n palisade verhef is, wat die volle uitsig op die horison verhinder het, het hulle verwag dat hulle slegs in laasgenoemde groep 'n gestremdheid sou waarneem. Die resultate was duidelik teen die verwagtinge: die duiwe wat die horison kon sien, maar beskut teen die wind deur glasskerms, kon nie huis toe kom nie. Daarenteen was voëls wat blootgestel is aan die winde wat deur die palissade gegaan het, onbelemmerd, selfs al was die uitsig oor die omgewing belemmer. Hierdie eerste resultate, wat later deur daaropvolgende eksperimente bevestig is, het gelei tot die hipotese dat 'n 'atmosferiese faktor' waarskynlik by navigasie betrokke sou wees (Wallraff, 1970). In die lig van hierdie resultate het die toets van die navigasievermoëns van anosmiese duiwe nie vreemd gelyk nie. Beide die resultate van Wallraff en Papi word verduidelik deur die 'reuknavigasie -hipotese' wat deur Papi voorgestel is (Papi et al., 1972): duiwe in hul tuisgebied kan een keer op die vrylatingsterrein windreuke in verband met windrigting leer hulle is in staat om die algemene reuke te herken en te onthou uit watter rigting hierdie reuke by die tuisgebied kom om die rigting van verplasing te bepaal (fig. 1).

Die bewyse dat reuke van plaaslike vrystellingsplek 'n bron van navigasie-inligting vir posduiwe is, is gedemonstreer in 'n elegante eksperiment deur Benvenuti en Wallraff (Benvenuti en Wallraff, 1985), waarin die voëls geflous is oor die reukinligting van die loslaatplek. Duiwe is vervoer in lugdigte houers wat geventileer is deur lug wat deur koolfilters gesuiwer is, na 'n vals vrylating waar hulle 'n paar uur lank die plaaslike omgewingslug kon inasem. Daarna is die voëls in suiwer lug vervoer na 'n nuwe plek wat in die teenoorgestelde rigting ten opsigte van die huis geleë is, aan nasale verdowing onderwerp en vrygelaat. By die vals vrylatingsplek het hierdie voëls die plaaslike reuke ervaar, terwyl hierdie soort inligting nie toeganklik was by die ware vrylatingsplek nie. Die voëls het na die 'vals tuisrigting' georiënteer, dit wil sê die tuisrigting vanaf die vals vrylatingsplek, terwyl die kontrolevoëls wat aan die plaaslike lug blootgestel is by die ware vrylatingsplek na die huis gerig is.


BESPREKING

Ons studie het beide veld- en laboratoriumdata gebruik om te ondersoek hoe 'n klein, insekvretende, sittende, groeplewende passerine, 'n waarskynlike kandidaat vir voëltorpor, in 'n energiek uitdagende omgewing oorleef. Oornag meting van Tb het aangedui dat vrylewende witbroodbabbelaars normotermie oor 'n wye reeks van gehandhaaf het Ta en het nie slenter of hibernasie gebruik nie. Aanvullende laboratoriumeksperimente met individuele en groepsverwante fisiologie het getoon dat kappertjies wat baber het, energieke voordele uit sosiale termoregulering, sowel as die gebruik van geïsoleerde haakneste, put. Ons bevindinge dui daarop dat heterotermie inderdaad ongewoon kan wees onder Austral passerines, en dat voëls met 'n meestal tipiese voëlfisiologie die aansienlike energiekoste van endotermie kan verreken met gedragstrategieë om hitteverlies te minimaliseer en 'n hele jaar deur bestaan ​​in 'n veranderlike omgewing te handhaaf.

Vrylopende babblers handhaaf 'n byna konstante Tb oornag, ten spyte van laagtepunte, dikwels onder nul, oornag Tbb. Die reeks van Tb, veld vir alle individue was <2.2°C onder alle omgewingstoestande, en het meer gevarieer tussen individue as 'n reaksie op omgewingstoestande. Alhoewel torporasie en winterslaap slegs in 'n klein aantal voëlgesinne selde waargeneem is (Geiser et al., 2006), word die vermoë om nagtelike hipotermie algemeen te sien, algemeen beskou (McKechnie en Lovegrove, 2002). Daar was egter geen bewyse dat hipotermie 'n belangrike deel van die baber se energieke strategie was nie, behalwe hul tipiese homeotermiese skotofasepatroon (Schmidt-Nielsen, 1997 Fig. 1). Babels het endogeen warm geword vir vertrek by sonsopkoms tot 'n soortgelyke Tb hierop by aankoms. Albei beteken aktiewe fase Tb (Tb, vertrek 40,4°C) en rusfase Tb (minimum Tb, veld 38.5°C) was soortgelyk aan dié vir ander normotermiese passerines (41.6±1.13 en 38.9±0.87°C, onderskeidelik Prinzinger et al., 1991). In die laboratorium het individuele babers by Ta=10°C gehandhaaf Tb slegs 1.0°C laer as by termoneutraliteit (38.6°C by Ta= 30 ° C), bereik deur 'n toename van 143% in MR (geakkommodeer deur verhoogde ventilasie VEk) en 'n afname van 15,7% in Cnat 'n tipiese endotermiese reaksie.

Wêreldwyd is nie-passerines en veral nagtelike spesies meer geneig om heterotermies te wees, en baie termoregulerende navorsing het op hierdie spesies gefokus (bv. Brigham, 1992 Körtner et al., 2001 Lane et al., 2004 McKechnie et al., 2007 Cooper et. al., 2008 Smit en McKechnie, 2010 Doucette et al., 2011, 2012). Slegs 'n handjievol studies het egter die nagtelike energieke strategie van vrylopende passante gedokumenteer, en nog minder het die kern gemeet Tb. Witkopmossies (Zonotrichia albicollis) 'n rusfase-onderkoeling het, met 'n vermindering van 3,4 ° C Tvel tussen die aktiewe en die rustydfase (Dolby et al., 2004) en die variasie in diels Tb van die dor-bewonende witbruin mossie-wewer (Plocepasser mahali) word toegeskryf aan seisoenale omgewingstoestande (Smit et al., 2013). Die enigste vergelykbare meting van kontinue, nagtelike Tb van 'n Australiese verbyganger in die koue is vir gevange-opgevoede jeugdige, donker bosse (Artamus cyaneurus Maddocks en Geiser, 2007), gemeet in buitelugvoëls. Hierdie voëls het oornag heterotermie gebruik Tb, min verminder met & gt5 ° C uit rus Tb, wat die skrywers as daaglikse vermorsing geklassifiseer het. Hierdie data, gebaseer op veltemperatuur of vir gevange voëls, dui daarop dat heterotermie onder passerines meer algemeen kan wees as wat tans herken word. As sittende, insekvretende voëls in 'n semi-droë habitat, het witbruin babbelaars eienskappe wat daarop dui dat hulle waarskynlik kandidate is vir skurftegebruik, en het inderdaad ander aanpassings soos sosialiteit en samewerkende teling wat geassosieer word met harde en onvoorspelbare omgewingstoestande. beskou as 'n goeie model vir heterotermie by voëls. Maar hul gebrek aan torpor, of inderdaad enige beduidende heterotermie, dui daarop dat voëltorpor-gebruik skaars kan wees, veral in vergelyking met klein soogdiere, as hul algemene fisiologie soortgelyk is aan ander passerines, en inderdaad ander voëls. In hierdie geval kan die gebrek aan data wat voeder -heterotermie kwantifiseer, nie net 'n gebrek aan navorsing op hierdie gebied verteenwoordig nie, soos tans aanvaar word (Astheimer en Buttemer, 2002 McKechnie en Lovegrove, 2002 Geiser et al., 2006).

Standaard fisiologie

Babbelaars het 'n tipiese endotermiese reaksie op Ta bo en onder termoneutraliteit in die laboratorium. 'n Byna konstante Tb is gehandhaaf deur 'n toename in metaboliese hitteproduksie op laag Ta. Hierdie toename in O2 vraag is geakkommodeer deur 'n toename in fR en VT eerder as EO2, wat tipies is van beide voëls en soogdiere (bv. Larcombe et al., 2003 Cooper en Withers, 2004). Termiese geleidingsvermoë bly byna minimaal onder die termoneutraliteit, maar neem toe by hoër Ta, net soos EWL, aangesien babbelaars hul hitte-afvoer verhoog het. Die PRWE van 17,5 ° C was besonder hoog en dra vermoedelik by tot die handhawing van die waterbalans in die afwesigheid van gratis water, en word ten minste gedeeltelik vergemaklik deur homeotermie by lae Ta.

Om die fisiologiese basis vir ons waarnemings van nagtelike homeotermie vir vrylewende babers die beste te interpreteer, is dit nodig om hul standaardfisiologie in 'n allometriese en filogenetiese konteks te ondersoek. Vir soogdiere, laag Tb en lae BMR korreleer met die gebruik van heterotermie en torpor (Geiser, 1998 Cooper en Geiser, 2008 Ruf en Geiser, 2014) en ons aanvaar 'n ooreenkoms in fisiologiese drywers tussen konvergent endotermiese soogdiere en voëls. Daarom het ons hier ons standaard fisiologiese data vir babers vergelyk met dié van ander voëls (tabel S6) met behulp van die 95% voorspellingsgrense (Cooper en Withers, 2006) vir konvensionele en filogeneties ingeligte allometriese regressies nadat Barker et al. (2016), met behulp van die filogenetiese boom van birdtree.org (Jetz et al., 2012, 2014) met die Hackett-ruggraat (Hackett et al., 2008).

Standaard Tb van babbelaars het statisties ooreenstem met dié van ander voëls, beide voor en na regstelling vir filogenie, net soos hul Cnat, wat daarop dui dat daar niks merkwaardigs is aan die isolasie van die babler of die hittebalans nie (fig. 7). Ons waarde van BMR vir alleenlopende witbruin babers (Mb 46 g) van 1,24 ml O2 g −1 h −1 was soortgelyk aan, maar laer as, die 1,51 ml O2 g −1 h −1 gemeet deur Chappell et al. (2016) vir die kastaiingbruin-bekroonde babbelaar (Pomatostomus ruficeps Mb 50 g), al het ons voëls 'n minder droë habitat en effens laer Mb, wat daarop dui dat daar geen stresreaksie is vir witbroodprateraars wat eensaam slaap nie. Witbruin babblers het 'n BMR wat slegs 64,0% van die voorspelde was Mb. Alhoewel dit binne die 95% voorspellingsinterval vir die konvensionele allometriese analise was, was dit onder die voorspellingsgrense nadat filogenie in berekening gebring is (fig. 7), wat daarop dui dat babers 'n laer BMR het as hul naaste familielede. Lae BMR word gekorreleer met 'n geneigdheid tot torpor (Cooper en Geiser, 2008), wat vermoedelik soortgelyke aanpassing aan 'n lae-energie strategie weerspieël. Ten spyte hiervan, het ons geen bewyse gevind van ongemak vir vrylewende babers nie, wat daarop dui dat hul lae BMR, tesame met strategieë soos sosiale termoregulering en geïsoleerde haakneste, voldoende is om hul energiebegroting te balanseer.

Allometriese en filogenetiese vergelykings van fisiologiese veranderlikes vir witbruin babers met dié van ander voëls. Tb (A), basale metaboliese tempo (BMR B), Cnat (C) en EWL (D) vir witbruin babers (swart simbole) in vergelyking met ander voëls (grys simbole sien tabel S6). Mb, liggaamsmassa. Filogeneties onafhanklike residue vir dieselfde parameters word in E–H getoon. Soliede lyne dui die kleinste kwadrate regressie aan en stippellyne die 95% voorspellingsintervalle vir elke allometriese verwantskap.

Allometriese en filogenetiese vergelykings van fisiologiese veranderlikes vir witbruin babers met dié van ander voëls. Tb (A), basale metaboliese tempo (BMR B), Cnat (C) en EWL (D) vir witbruin babbelaars (swart simbole) in vergelyking met ander voëls (grys simbole sien Tabel S6). Mb, liggaamsmassa. Filogeneties onafhanklike residue vir dieselfde parameters word in E – H getoon. Soliede lyne dui die kleinste kwadrate regressie aan en stippellyne die 95% voorspellingsintervalle vir elke allometriese verwantskap.

Standaard EWL was slegs 41,0% van die allometries voorspelde waarde, en statisties laer as dié vir ander voëls, voor en na die filogenie (Fig. 7). Lae EWL (soos lae BMR) word geassosieer met droë habitatte (Williams en Tieleman, 2005) en dra by tot hul hoë PRWE. Dit, tesame met die voorgevormde water van hul insekvretende dieet, kan die oënskynlike vermoë daarvan weergee om die waterbalans te handhaaf sonder om te drink, ten minste in die winter (T.K.D., persoonlike waarneming).

Sosiale termoregulering

Baie sosiale endoterme rus gemeenskaplik (Gilbert et al., 2010), en saamkuier kan 'n belangrike rol speel in die instandhouding van homeotermie. In uiterste gevalle is endoterme wat gemeenskaplik rus, verpligte sosiale termoreguleerders wat nie normaal kan reguleer nie Tb op laagtepunt Ta in die afwesigheid van spesifieke eienskappe (bv. McKechnie en Lovegrove, 2001). Witbruin babblers het altyd tydens die studie gemeenskaplik in die veld gekuier, maar selfs as hulle individueel in die laboratorium gehou is Ta so laag as 10 ° C, alle babers word gehandhaaf Tb binne 1,15 ° C van termoneutrale waardes. Daarom is babbelaars fakultatiewe sosiale termoreguleerders en alhoewel hulle individueel oornag in die natuur kan oorleef (Chappell et al., 2016), kry hulle aansienlike energieke voordele deur saam te kruip.

Die vermindering in energieverbruik van saamkuierige babbelaars, met 'n saamkuier MR 65–74% van individuele MR teen 'n ekwivalent Ta, is soos verwag vir ander saamkuilende endoterme (sien Gilbert et al., 2010, vir oorsig) en soortgelyk aan dié gemeet vir twee tot drie saamkuilende kastaiingbruin babbelaars, en sal waarskynlik selfs groter wees vir meer saamkuilende individue (Chappell et al. ., 2016). Vermoedelik speel die aansienlike vermindering in MR van saamkuierige babbelaars 'n beduidende rol in die balansering van hul energiebegroting en negeer gedeeltelik die behoefte aan heterotermie. Aansienlike variasie in minimum Tb, veld tussen individue (~2.1°C) is waargeneem vir vrylewende babbelaars (Fig. 2). Ligging binne die slaapnes beïnvloed waarskynlik oornag Tb daar kan 'n fisiologiese koste verbonde wees aan sosiale status as sosiale status posisie in 'n geskarrel bepaal. Dus, individuele variasie in Tb, veld kan sosiale status aandui, soos waargeneem vir vervet-ape (Chlorocebus pygerythrus McFarland et al., 2015).

Hoek nes eienskappe

Die energieke voordeel van verblyf in geslote neste is 'n verdere aspek van babers se nagtelike energie -strategie. Die Tslaapplek van onbesette babbel neste was dieselfde as Tbb, anders as die neste van gesellige wewers (Philetairus socius), wat voldoende groot en goed geïsoleer is om oornag bo omgewingstoestande te bly, selfs wanneer dit onbewoon is (White et al., 1975). Wanneer beset, die verhouding van Tslaapplek aan Tbb want kabbel neste is soortgelyk aan dié van eensamehout-witbruin mossieswewers (P. mahali Ferguson et al., 2002), met die TslaapplekTbb differensiaal toeneem as Tbb afneem. Die termiese geleiding van haan neste (C= 1,62 J g −1 h −1 ° C −1) was gelykstaande aan die konduktansie van groepe van twee tot drie saamkuierende babers (C=1.61 J g −1 h −1 °C −1 by 10°C), dus halveer slaapnes effektief die tempo van energie wat na die omgewing verlore gaan vir klein groepies saamkuierige babbelaars. Die isolerende eienskappe van mosswewer-nessies is 'n belangrike faktor om die homeotermie op 'n lae vlak te handhaaf. Ta (Ferguson et al., 2002) en bied vermoedelik soortgelyke energieke voordele vir witbrou-babbelaars.

Vir sommige spesies, veral nagvoëls en vlermuise, word slaapplekke met gunstige helling, aspek en ingangsrigting gekies om passiewe opwarming toe te laat of om basking te vergemaklik (bv. Geiser et al., 2004 Turbill en Geiser, 2008). Dit was nie 'n strategie wat deur babbelaars gebruik is nie, aangesien daar geen voorkeur in die rigting van die nestoegang was nie, en babbelaars het endogeen warm gemaak voor sonop. Terwyl kabbelhakneste by voorkeur in die boonste derde van hul gasheerboom gebou word, maak die variasie in gasheerboomsoorte en werklike hoogte van die gasheerbome dit onwaarskynlik dat mikroklimaatoorwegings belangrik is. 'N Voorkeur vir die bou van neste in digte bome kan 'n energieke voordeel inhou, aangesien digte blare wind kan afwyk en stralingswarmteverlies kan verminder (Walsberg, 1986), maar nesplek kan ook 'n strategie teen roofdiere wees.

Termoregulering

Die gekombineerde gebruik van sosiale termoregulering en gemeenskaplike haakneste maak wesenlike energiebesparing moontlik vir witbruin babers. Minimum oornag babbel Tslaapplek is bereken om tussen 6,8 en 15,4 ° C te wissel, dus is die omvang van MR's vir voëls in hierdie neste bereken tot 1,78-2,44 ml O2 g −1 h −1. Ekstrapoleer die lineêre verband tussen Ta en O2 onder termoneutraliteit vir eensame voëls buite nes na hulle TaAs 'n babelende baber in 'n hok nes 'n energieverbruik van slegs 55-65% van die blootgestelde voëls onder dieselfde omgewingstoestande het, sal dit selfs laer wees vir groter groepe (bv. Chappell et al., 2016). Met ander woorde, klein groepies gemeenskaplike nesmaakbabbelaars by 'n Ta van -3 tot +15 ° C en a Trusplek van 6,8 tot 15,4 ° C sou 'n MR -ekwivalent hê aan dié van 'n enkele blootgestelde voël by a Ta van 17,6 tot 24,3 ° C. Hierdie aansienlike energiebesparings, tesame met die voëls se intrinsiek lae BMR, sal 'n belangrike rol speel in babbelaars wat hul daaglikse energiebegroting balanseer, en vermoedelik enige vereiste vir verdorring in hul energiek uitdagende omgewing ontken. Daarom, ten spyte van 'n algemeen tipiese termiese fisiologie van voëls, laat die energie en gedrag van die witbroodprater instandhouding van homeothermie toe, en stel dit voor dat heterotermie nie 'n voorkeur-energietiese taktiek is vir voëlspesies wat dit kan vermy nie.


Die innerlike lewens van voëls

Tweet tweet! Ons praat van voëls en die ongelooflike dinge wat hulle kan doen. Ons kyk vandag na vyf van die coolste onlangse verhale in voëlgenetika: kolibries dryf hul blitsvinnige vlug, 'n geen wat migrasie beheer, hoekom mans verskillende kleure vir wyfies het, hoe ligbesoedeling mossies sieker maak en die voël duisende jare lank vasgevang is onder die Siberiese ys.

In hierdie episode

00:31 - Hoe kolibries hul vinnige vlug dryf

Hoe kolibries hul vinnige vlug dryf Ariel Gershman, Johns Hopkins School of Medicine

Die kolibrie is die kleinste ter wêreld. Hulle kan eintlik in die lug sweef, en uniek onder voëls, kan hulle agteruit en onderstebo vlieg. Die vinnigste van hulle slaan meer as tagtig keer per sekonde sy vlerke. Al hierdie lugakrobatiek vereis 'n paar unieke truuks van energie en metabolisme - en Phil Sansom het gehoor van Ariel Gershman aan die Johns Hopkins School of Medicine, wat probeer uitvind wat in hul gene dit alles moontlik maak ...

Ariel - Ons stel regtig belang in iets wat kolibries doen, genoem metaboliese vloed. They are able to maintain this extremely high metabolism, and extremely high blood sugar, that for most humans would be considered as diabetes but hummingbirds are able to do this without getting any of the ailments associated with diabetes, like blindness, and kidney disease, and all of these other problems that humans who maintain this persistently high blood sugar often experience.

Phil - What's the flux part of that? Is it flux like changing really quickly?

Ariel - The flux is just this rapid shift that they're able to do. So when hummingbirds are eating, they're eating sugar from nectar, and they're able to use the sugar almost entirely to fuel their metabolism, or how they break down that sugar to make energy. But then once they stop feeding, they have to rapidly switch their metabolism to be able to use this fat that they store in their body to then be able to get energy, and power this extremely expensive hovering flight that they're able to do. And so if they weren't able to switch this metabolism so quickly, from their fed state to their fasted state, then they wouldn't be able to continue flying.

Phil - Oh my God, it almost sounds like one of those animals that hibernates in winter and then does all their eating in the summer, but over the course of what, minutes?

Ariel - Yeah. Over the course of 30 minutes is how quickly they're able to switch this fed to fasted metabolism.

Phil - What exactly are you doing to look into this metabolic flux, as you called it?

Ariel - We first had to actually sequence and put together their entire genome. And once we had the whole genome together, we then had to figure out where genes in the genome are. Because only about 1% of the genome actually codes for genes that end up making proteins. And then what we did was we sequenced all of the hummingbird RNA. If you can imagine. the genome is kind of like the blueprint for how to build the organism, whereas the RNA is more like what's actually being made to allow the organism to survive and persist.

Phil - How are you doing this here then, with both the DNA and the RNA?

Ariel - What we mainly focus on is called long read sequencing. Some people call it third generation sequencing. The typical, or the gold standard of DNA sequencing, is this second generation sequencing right now. And in second generation sequencing, it's extremely accurate, but we're only getting small pieces of DNA at a time. Where in third generation sequencing, we're actually sequencing these really, really long molecules of DNA. And if you can imagine, when you're putting together a puzzle, it's a lot easier to put together a puzzle with less pieces that are bigger than a puzzle with more pieces that are smaller. However we lose a little bit of the accuracy with long read sequencing, so it's more likely that there will be mistakes.

Phil - Do you do anything to compensate for that?

Ariel - Yeah, we do. Once we have the entire structure from the long read data we go in and we correct it with the accurate short read data. This is a process that in the field we call hybrid genome assembly.

Phil - Wow. And just for context, how big is the job? How many genes does a hummingbird have?

Ariel - Oh, a hummingbird has around 20 to 30,000 genes. Not that much different than a human actually.

Phil - That's, yeah, quite a few genes to get through.

Ariel - Yeah. And it's actually not even the region of the genome that codes for genes that's the hard part it's really the rest of the genome, that we don't really know a lot about what it does, that's actually the hard part for genome assembly, because a lot of the genome is made up of repetitive DNA. And if you can imagine, if you have the same puzzle piece that fits in multiple locations, you really don't know where it actually goes.

Phil - And what do you do in that situation?

Ariel - The longer reads actually really help us out a lot there. Because when we have the repeat, if we can get the information on either side of it we can anchor it to the right region of the genome.

Phil - These hummingbirds, then, you're giving them a nice big meal, then taking a bunch of blood to get all their DNA and RNA, or what?

Ariel - We're actually taking their liver and their muscle tissue. So those are the really important metabolic tissues.

Phil - With all this incredible third generation sequencing, what are you finding in there?

Ariel - Wow. I wish I had like the cure to diabetes or something crazy. but we're finding a lot of differences in expression in thyroid hormone, which is along the lines of what we expected. What we're really looking for and hoping to find is these glucose transporters. Not a lot is really known about how glucose, sugar, actually gets into the hummingbird cells and how it happens so quickly. Hummingbirds don't seem to have a lot of these genes that humans have that allow sugar to enter our cells. So how was it entering in hummingbirds? We don't know yet. And we're really hoping to figure that out.

Phil - Do you have any personal favourite theories at the moment?

Ariel - I think that this glucose transporter that we're looking for that we don't think is present in hummingbirds. I think that it might be there, it's just that it's in a region of the genome that's so repetitive that previous people who have studied it, haven't been able to find it because of this repeat problem.


Bespreking

The experience-dependent reaction to displacement lends support to Perdeck's paradigm of migratory bird orientation (10). A navigation system presumed to be based on experience has also been shown in caged adult migrants (27, 28). However, previous experiments that tested migratory orientation in cages suggested that juveniles are able to compensate for the displacement. Because adult birds are able to compensate, juvenile birds are supposedly in the process of constructing a navigational map along the migratory route (18). The difference between our study and previous ones could be due to the use of orientation cages, where birds remain within a cage while attempting to depart for migration (22), or alternatively, it may be that our juvenile birds were displaced outside the maximum range of their map that is under construction.

Our study is the first to document age-specific reorientation movements after a continent-wide displacement and within the first hours upon release. It seems highly unlikely that the adult birds used path integration during the displacement to reorient. A path integration system becomes very imprecise over the long distances our birds were displaced.

The results provide insights into the nature of navigation during long-distance migration. On the basis of one migratory journey from Alaska to southwest North America, white-crowned sparrows obtain information that allows them to reach their wintering ground from an area that their normal migratory route does not encompass. Gaining and retaining such information is presumably adaptive because it would allow them to reach their wintering grounds after natural displacements. Juveniles, on the other hand, continue in the species-specific migratory direction after displacement. This suggests that, during migration, homing to a known location is triggered only by reaching that final destination and, possibly, after spending time in it. Because the juvenile birds were caught en route, neither stopovers nor partial travel on the southerly migratory route in the first year seems to trigger homing back to the migratory route. Furthermore, our experiment indicates that the navigational map of adult white-crowned sparrows encompasses at least the continental U.S. and allows them to correct for vast displacements very rapidly (within days, at least), hinting that migratory birds may possess a global navigational map. Even though adult white-crowned sparrows return to a specific winter home range, at this large scale the “map” may just provide a bird with a sign on a gradient, e.g., letting the bird know whether it is east or west of its goal, as observed previously by Åkesson et al. (17).

Currently, magnetic cues seem the most likely candidates for the basis of a map stretching this far (29). However, the small difference in geomagnetic intensity across longitudes in North America makes magnetic intensity an unlikely candidate for distinguishing between the east and the west coast, and celestial or olfactory cues cannot be ruled out (30).

In the past, studies of navigation in passerine birds have generally been restricted to the laboratory because of limitations on field-based study (30). We have demonstrated that it is possible to study the navigation behavior of small migratory birds in the field and provide insights into their behavior. These results demonstrate that the ability to track small animals continuously is essential to gain an understanding of the behavior of free-living migrants. Ultimately, a complete understanding of the mechanisms used by adults and juvenile passerine birds will require a global tracking system for small animals (23).


Metodes

Study extent description: This dataset covers four representative habitats within the Sierra Nevada mountain range: Pyrenean oak forest, thorny thickets on the edge of the forest, common juniper and Spanish juniper scrublands, and high-summit ecosystems. These ecosystems were selected based on criteria of singularity and ecological functionality in the context of Sierra Nevada (Barea-Azcón et al. 2012, 2014) and can be described as follows:

Pyrenean oak forest: Mediterranean woodland composed mainly of relict Quercus pyrenaica and some dominant scrubland species (i.e. Berberis hispanica, Prunus ramburii, Rosa canina, Crataegus monogyna and Adenocarpus decorticans). These forests show strong evidence of past management that has determined their current structure and diversity. This management is based on mainly charcoal production, pastureland creation, and wood harvesting until the 1950s, so that the current trees are mostly resprouts of individuals 60 to 70 years old. The target localities (n=4) are located at an average elevation of 1650 m a.s.l. (1600-1750 m a.s.l.) and are distributed in the southern, western, northern, and eastern slopes of Sierra Nevada, reflecting all the ecological conditions of the Pyrenean oak forests in the study area (Pérez-Luque et al. 2013).

Thorny scrubs: Typical areas dominated by thorny thickets on the edge of the forest or as result of recent colonization of abandoned arable lands. Berberis hispanica, Prunus ramburii, Rosa canina, Crataegus monogyna are dominant but accompanied by other species such as Lonicera arborea of selfs Sorbus spp. This open habitat is very important for breeding birds in the study area and also for winter-visiting species due to a great production of fruits from the end of the summer to the beginning of winter. Transects (n=4) in this habitat are located between 1450 and 2060 m a.s.l. (average: 1790 m a.s.l.).

Common juniper and Spanish juniper scrublands: vegetation in these localities is composed mainly of common juniper (Juniperus communis), Spanish juniper (Juniperus sabina). Cytisus galianoi en Genista baetica are also important species in these ecosystems. These scrublands rarely exceed 60 cm in height and appear intermingled with rocks and stony ground. Transects (n=4) located in this ecosystems cover an elevational range from 2000 to 2300 m a.s.l. (average: 2150 m a.s.l.).

High-summit ecosystems: composed by typical Alpine landscape. These ecosystems are characterized by rocky outcrops that originated from glacial activity, pastureland, small snow beds, and glacial lagoons. The four transects representing this Mediterranean high-mountain habitat span an elevational gradient from 2280 to 3100 m a.s.l., with an average elevation of 2580 m a.s.l.

Sampling description: The sampling procedure was the line-transect method (Verner 1985), with a bandwidth of 100 m, with 50 m on each side of the line (Barea-Azcón et al. 2014). Each 50 m band was divided into five ranges parallel to the line transect (comprising a 10 m width each one). A total of 16 transects were sampled with lengths of 1.9 to 3 km (Table ​ (Table2). 2 ). Sight and sound records within the sample area were considered contacts. All transects were sampled in the early morning, under appropriate climatic conditions. The observer walked at a constant speed of 2 to 4 km/h. Transects are repeated at least once per month, snow cover permitting. This implies that the sites located at the higher elevations were sampled only from late spring to early autumn.

Tabel 2.

Information about transects sampled to collect data included in this dataset.

Transect nameLength (m)Habitat typeLongitudeLatitudeProvinceMunicipalityElevation (m asl)
Robledal de Cá༚r2556Pyrenean oak Forest -3.4292 36.9532GranadaCá༚r1736
Robledal de Dílar2553 -3.4779 37.0582GranadaDílar1605
Cortijo del Hornillo3044 -3.3680 37.1246GranadaG࿎jar Sierra1585
Dehesa del Camarate2805 -3.2537 37.1797GranadaLugros1575
Dehesa del Río Dúrcal3292Thorny thickets -3.4825 37.0255GranadaDúrcal2033
Collado de Matas Verdes2237 -3.4470 37.0909GranadaMonachil1918
El Purche1944 -3.4780 37.1311GranadaMonachil1453
Lanteira2515 -3.1725 37.1409GranadaLanteira1794
Collado del Sabinar2745Juniper scrublands -3.4184 37.1199GranadaG࿎jar Sierra2036
Campos de Otero2264 -3.3930 37.1100GranadaG࿎jar Sierra2143
Loma Papeles2539 -3.3401 37.1434GranadaG࿎jar Sierra2113
Dehesa de las Hoyas2436 -3.3173 37.1724GranadaG࿎jar Sierra2074
Laguna Seca2530High-summit ecosystems -2.9615 37.0992GranadaHuéneja2295
Aguas Verdes2431 -3.3589 37.0540GranadaCapileira3149
Hoya Mora2046 -3.3771 37.0896GranadaG࿎jar Sierra2407
Papeles alto2309 -3.3098 37.1357GranadaG࿎jar Sierra2420

Method step description: All data were stored in a normalized database (PostgreSQL) and incorporated into the Information System of Sierra Nevada Global-Change Observatory. Taxonomic and spatial validations were made on this database (see Quality-control description). A custom-made SQL view of the database was performed to gather occurrence data and other variables associated with occurrence data, specifically:

Bird Count: number of individuals recorded by the observer within transect (see Sampling description)

Distance: distance of the contact (bird) from transect line. The distance was estimated by eye.

The occurrence and measurement data were accommodated to fulfil the Darwin Core Standard (Wieczorek et al. 2009, 2012). We used Darwin Core Archive Validator tool (http://tools.gbif.org/dwca-validator/) to check whether the dataset met Darwin Core specifications. The Integrated Publishing Toolkit (IPT v2.0.5) (Robertson et al. 2014) of the Spanish node of the Global Biodiversity Information Facility (GBIF) (http://www.gbif.es/ipt) was used both to upload the Darwin Core Archive and to fill out the metadata.

The Darwin Core elements for the occurrence data included in the dataset were: occurrenceId, modified, language, basisOfRecord, institutionCode, collectionCode, catalogNumber, scientificName, kingdom, phylum, class, order, family, genus, specificEpithet, scientificNameAuthorship, continent, country, countryCode, stateProvince, county, locality, minimumElevationInMeters, maximumElevationInMeters, decimalLongitude, decimalLatitude, coordinateUncertaintyinMeters, geodeticDatum, recordedBy, day, month, year, EventDate.

For the measurement data, the Darwin Core elements included were: occurrenceId, measurementID, measurementType, measurementValue, measurementAccuracy, measurementUnit, measurementDeterminedDate, measurementDeterminedBy, measurementMethod.

Quality control description: The sampling transects were georeferenced using a hand held GPS device (WGS 84 Datum) with an accuracy of କ m. We also used colour digital orthophotographs provided by the Andalusian Cartography Institute and GIS (ArcGIS 9.2 ESRI, Redlands, California, USA) to verify that the geographical coordinates of the transects were correct (Chapman and Wieczorek 2006).

For field identification, several field guides were used (De Juana and Varela 2000, Jonsson 2001). The scientific names were checked with database of the IOC World Bird List (v 5.52) (Gill and Donsker 2015). We also used the R package taxize (Chamberlain and Szocs 2013, Chamberlain et al. 2014) to verify the taxonomical classification.

In addition, we performed validation procedures (Chapman 2005a, 2005b) (geopraphic coordinate format, coordinates within country/provincial boundaries, absence of ASCII anomalous characters in the dataset) with DARWIN_TEST (v3.2) software (Ortega-Maqueda and Pando 2008).


The data behind mysterious bird deaths in New Mexico

Last week, the Rocky Mountain states experienced a strong storm that brought with it snow, near hurricane force winds, and unseasonable record-breaking cold temperatures. In Albuquerque on September 8, it was sunny and a record-high 96ºF. The next afternoon, a severe windstorm tore through the region. The Albuquerque airport measured windspeed of over 70 mph, and temperatures plummeted to historic lows. Albuquerque broke a 100-year record low temperature when the mercury dropped to 40ºF. While snowfall was heaviest in the northern Rockies from Montana to Colorado, New Mexico received several inches of heavy, wet snow as far south as the Sandia Mountains east of Albuquerque.

Migratory bird casualties in Velarde, NM on 13 Sep 2020. Image from video posted on Twitter by Austin Fisher.

My colleagues and I spent the morning of Thursday 10 September picking up dead birds in the Sandias. We found several dead Empidonax flycatchers of three species, a Vesper Sparrow, and a Townsend’s Warbler. Some birds were wet from the overnight snow, but others were completely dry, huddled in the corners of buildings. A Dusky Flycatcher sat dazed in the parking lot.

We first thought little of it: mortality is expected for migratory birds, and we didn’t find more than a handful of carcasses. But social media told a grimmer story that night. We read reports of widespread mortalities across the state: dead swallows along a bike path in Albuquerque, a half-dozen Empidonax flycatchers and swallows in one park in Clovis, and a local news report of 300 carcasses recovered by researchers from New Mexico State University and nearby White Sands Missile Range. It was soon apparent that a significant mortality event had occurred.

But one video on Twitter recorded by local journalist Austin Fisher stood out to me: several dozen swallows dead in an arroyo in Velarde, approximately 40 miles north of Santa Fe. It was only when I reached out to Austin for the purposes of this report that I realized the video wasn’t taken the week before during the cold snap, but rather the previous night, on 13 September. To see it for myself, fellow ornithology grad student, Nick Vinciguerra, and I drove the hour and a half north that night.

When we arrived at midnight, we found a macabre scene. Several hundred Violet-green Swallows were strewn across the bank of the Rio Grande. Dozens of birds had stuffed themselves into the few natural cavities, and many more were dead amongst the vegetation. In total, we found 305 individuals of six species, all of which were insectivores: 258 Violet-green Swallows, 35 Wilson’s Warblers, six Bank Swallows, two Cliff Swallows, one Northern Rough-winged Swallow, a MacGillivray ’ s Warbler, and two Western Wood-Pewees. These proportions are similar to what was reported by researchers at NMSU.

Nick Vinciguerra collecting Violet-green Swallows on the banks of the Rio Grande River at midnight in Velarde, NM.

Several hypotheses are emerging to explain this mass mortality event in New Mexico. Recently, heightened attention has been given to the possibility that historic wildfires across western North America are to blame, and wildfires certainly pose a major disruption to migratory birds. For instance, a wildfire could cause birds to flee an area before they’ve replenished their fat stores. Indeed, anecdotal reports from banding stations suggest that wildfires contribute to unusual migrant influxes into areas that are free from fire. Michael Hilchey, a volunteer bander at the Rio Grande Bird Research Station in Albuquerque, noted a significantly higher volume of migrants over the past two weeks than has been over the last 10–15 years. Smoke is covering nearly all of the lower 48 states, and while we experienced heavy smoke in Albuquerque the night before the storm arrived, fires are not new or unexpected during the height of fall migration. Indeed, wildfires are common and increasing in frequency.

There is, I believe, a much more plausible reason for large numbers of birds to die during migration: lack of food.

The 55–60ºF temperature swing observed in New Mexico combined with hurricane force winds and with wet snow very likely caused hypothermia in some birds, especially juveniles. Furthermore, cold temperatures also affect the food supply for insectivores, as insects (which become dormant or dead) are then covered by snow. Certainly, they are not flying through the air, as swallows and pewees need. Dave Leatherman, a former entomologist for the state of Colorado, noted marked behavioral differences in foraging insectivorous birds during the week’s snowstorm. In addition, a 2007 study by Ian Newton found that unseasonably cold weather can have a negative effect on migrating birds. While cold temperatures and snow cut off the food supply for naïve migrants, resident birds not stressed by migration typically have both fat reserves and local knowledge of where to find shelter.

Notably, and understandably, this type of die-off commonly affects swallows. In several documented cases of swallow mortality events (Newton 2007), a sudden drop in temperatures caused insects to become dormant (and stop flying). In Kazakstan during the fall of 2000, cold and snow killed thousands of Barn Swallows (Berezovikov and Anisimov 2002). Severe cold snaps in 1931 and 1974 killed “hundreds of thousands, possibly millions” of swallows and martins in central Europe (Alexander 1933, Ruge 1974, Bruderer and Muff 1979, Reid 1981, Newton 2007). Specifically, Newton (2007) states, “When short of food in cold weather, swallows and swifts often seek shelter in buildings, huddle together for warmth, and may suffer from hypothermia and starvation. Other migratory insectivores also die in such conditions, but less conspicuously.”

The 305 individuals laid out at the Museum of Southwestern Biology that Nick Vinciguerra and I collected from Velarde, NM on 14 Sep 2020. All individuals will be deposited as specimens in the museum’s Bird Division for future research and education.

Sudden and dramatic unavailability of food caused by a historic and drastic cold snap is, I believe, a more parsimonious explanation than a widespread, smoke induced, mass mortality event. While we do not have data on how fast smoke inhalation would kill birds hundreds of miles away from the fires themselves, what we do have are data from the 258 Violet-green Swallows that Nick and I collected in Velarde this week.

Satellite imagery showing smoke from wildfires in the western U.S. on 9 Sep 2020. Image © NOAA.

If a lack of food contributed to the mortality event, birds would have less fat and no protection against hypothermia. Indeed, of the hundreds of birds we assessed, none had fat stores on their bodies. Furthermore, many birds also showed signs of breast muscle atrophy, which points to starvation and dehydration. The average mass of an adult male Violet-green Swallow is 14.4 g females are slightly lighter at 13.9 g. In addition, I used an open-access museum collections database, Vertnet, to find data on thirty specimens collected July–September, and their average weight was 15 g. We weighed 234 swallows which showed only minor signs of decomposition, and their average mass was dramatically lighter: 9.5 g, or about two-thirds the weight of normal birds. Though we have yet to perform any toxicology analyses or inspect their lungs for signs of smoke inhalation, I think it is safe to say that these birds were starved and succumbed to hypothermia. When USFWS autopsies of other birds are reported in the coming weeks or months, we suspect they will reveal a similar cause of death.

Christopher Witt, Professor at UNM and Director of the Museum of Southwestern Biology, waxed poetical with me this week about how fall 2020 has brought a spectacular array of fall migrants to Albuquerque, noting that it’s been the “Best I’ve seen in years.” As a birder myself, I also benefitted from this better than average migration with my lifer Blackpoll Warbler on the University of New Mexico campus this week. Our influx of migrants may or may not have been due to wildfires, but I have no doubt that they were affected by the extreme cold and high winds in New Mexico. Though the fires and extreme weather events are influenced by human-induced climate change, it is unlikely that the wildfires alone caused the death of thousands of birds in New Mexico.

A comparison of body mass from the birds we salvaged on 14 September 2020 with that of other Violet-green Swallows collected during fall migration across the North America, downloaded from Vertnet, an open access biodiversity database. Both outlier points on the right refer to specimens that had little to no fat stores.


Higher elevation birds sport thicker down 'jackets' to survive the cold

Sahas Barve, a Peter Buck Fellow at the Smithsonian's National Museum of Natural History, led a new study to examine feathers across 249 species of Himalayan songbirds, finding that birds living at higher elevations have more of the fluffy down--the type of feathers humans stuff their jackets with--than birds from lower elevations. Published on Feb. 15 in the journal Ecography, the study also finds that smaller-bodied birds, which lose heat faster than larger birds, tend to have longer feathers in proportion to their body size and thus a thicker layer of insulation. Credit: Suniti Bhushan Datta

Feathers are a sleek, intricate evolutionary innovation that makes flight possible for birds, but in addition to their stiff, aerodynamic feathers used for flight, birds also keep a layer of soft, fluffy down feathers between their bodies and their outermost feathers to regulate body temperature.

Using the Smithsonian's collection of 625,000 bird specimens, Sahas Barve, a Peter Buck Fellow at the Smithsonian's National Museum of Natural History, led a new study to examine feathers across 249 species of Himalayan songbirds, finding that birds living at higher elevations have more of the fluffy down—the type of feathers humans stuff their jackets with—than birds from lower elevations. Published on Feb. 15 in the journal Ekografie, the study also finds that smaller-bodied birds, which lose heat faster than larger birds, tend to have longer feathers in proportion to their body size and thus a thicker layer of insulation.

Finding such a clear pattern across so many species underscores how important feathers are to a bird's ability to adapt to its environment and suggests that adding down may be a strategy common to all songbirds, or passerines as they are known to researchers. Furthermore, finding that birds from colder environments tend to have more down may one day help researchers predict which birds are most vulnerable to climate change simply by studying their feathers.

"The Himalayas are seeing some of the fastest rates of warming on Earth," Barve said. "At the same time, climate change is driving an increase in the frequency and intensity of extremely cold events like snowstorms. Being able to accurately predict the temperatures a bird can withstand could give us a new tool to predict how certain species might respond to climate change."

Using the Smithsonian's collection of 625,000 bird specimens, Sahas Barve, a Peter Buck Fellow at the Smithsonian's National Museum of Natural History, led a new study to examine feathers across 249 species of Himalayan songbirds, finding that birds living at higher elevations have more of the fluffy down--the type of feathers humans stuff their jackets with--than birds from lower elevations. Published on Feb. 15 in the journal Ecography, the study also finds that smaller-bodied birds, which lose heat faster than larger birds, tend to have longer feathers in proportion to their body size and thus a thicker layer of insulation. Carla Dove, who runs the museum's Feather Identification Lab and contributed to the study, said she was excited to work together with Barve to use the Smithsonian's collections in a new way. "Sahas looked at more than 1,700 specimens. Having them all in one place in downtown Washington, D.C., as opposed to having to go to the Himalayas and study these birds in the wild, obviously makes a big difference. It allowed him to gather the data he needed quickly before the COVID lockdowns swept the globe, and then work on the analysis remotely." Credit: Chip Clark, Smithsonian.

The research was inspired by a tiny bird called a goldcrest during a frigid morning of field work in the Sho-kharkh forest of the Himalayas. Barve found himself wondering how this bird, which weighs about the same as a teaspoon of sugar, was able to flit about the treetops in icy air that was already numbing his fingers. Shoving his hands back into the pockets of his thick down jacket, the question that formed in Barve's mind was "Do Himalayan birds wear down jackets?"

To answer that question, Barve and his co-authors used a microscope to take photos of the chest feathers of 1,715 specimens from the Smithsonian's collections representing 249 species from the cold, high-altitude Himalayan Mountains. Then, Barve and his co-authors used those super-detailed photos to determine exactly how long each feather's downy section was relative to its total length. The team was able to do that by looking at the fluffy downy section of each feather close to its base when compared to the streamlined ends of most birds' feathers.

After meticulously logging the relative lengths of all those downy sections, Barve analyzed the results and found that the smallest birds and the birds from the highest elevations, where temperatures are at their coldest, tended to have the highest proportion of down on their body feathers. The analysis showed that high-elevation birds had up to 25% more down in their feathers, and the smallest bird had feathers that were three times as long as the largest birds, proportionately to their body size.

Past research suggested that birds from colder habitats sported added downy insulation, but Barve said this is the first study to analyze this pattern for such a large number of species in cold environments and across 15,000 feet of elevation.

Barve led a new study to examine feathers across 249 species of Himalayan songbirds, finding that birds living at higher elevations have more of the fluffy down--the type of feathers humans stuff their jackets with--than birds from lower elevations. Published on Feb. 15 in the journal Ecography, the study also finds that smaller-bodied birds, which lose heat faster than larger birds, tend to have longer feathers in proportion to their body size and thus a thicker layer of insulation.The research was inspired by a tiny bird called a goldcrest during a frigid morning of field work in the Sho-kharkh forest of the Himalayas. Barve found himself wondering how this bird, which weighs about the same as a teaspoon of sugar, was able to flit about the treetops in icy air that was already numbing his fingers. Shoving his hands back into the pockets of his thick down jacket, the question that formed in Barve's mind was "Do Himalayan birds wear down jackets?" Credit: Jennifer Renteria

"Seeing this correlation across so many species makes our findings more general and lets us say these results suggest all passerine birds may show this pattern," Barve said. "And we never would have been able to look at so many different species and get at this more general pattern of evolution without the Smithsonian's collections."

Carla Dove, who runs the museum's Feather Identification Lab and contributed to the study, said she was excited to work together with Barve to use the Smithsonian's collections in a new way. "Sahas looked at more than 1,700 specimens. Having them all in one place in downtown Washington, D.C., as opposed to having to go to the Himalayas and study these birds in the wild, obviously makes a big difference. It allowed him to gather the data he needed quickly before the COVID lockdowns swept the globe, and then work on the analysis remotely."

Barve said he is following up this study with experiments looking into just how much insulation birds get from their feathers and then will tie that to the feather's structure and proportion of down. One day, Barve aims to develop a model that will allow scientists to look at the structure of a feather and predict how much insulation it gives the bird—a capability that could help researchers identify species vulnerable to climate change.

Dove said the potential to use these results to eventually understand how some birds might cope with climate change highlights the importance of museum collections. "We have more than 620,000 bird specimens collected over the past 200 years waiting for studies like this. We don't know what our specimens will be used for down the line that's why we have to maintain them and keep enhancing them. These specimens from the past can be used to predict the future."