Te nouvèl la lokal yo, pou pi fò nan US la lès ak Kanada te tranble (gen) recently with reports of the irruption of Vanessa Atalanta – papiyon Wouj la Admiral T. Pandan ke sa a se yon evenman ki komen chak sezon prentan pou papiyon sa yo emigre nò soti nan lakou ivèrnaj yo nan sid Etazini an, chif yo absoli ane sa a yo stupéfiants. Gen byen literalman dè milye de Amiral nan lakou tounen nou an.
Se konsa, sa nan diferan ane sa a?
Gen anpil espekilasyon sou tan an sezon prentan cho (pi cho mwa mas sou dosye pou anpil kote) epi byen souvan yo anpil bagay nan move enfòmasyon yo ale ansanm ak kèk Antomoloji fotèy. Pifò nan sous yo nouvèl mwen te vini nan tout di te sezon prentan an cho pèmèt papiyon sa yo fleri ak repwodui nan nimewo nòmal. Sa se pa byen posib sepandan, V. atalanta overwinters as an adult. The southern states provide temps just warm enough for adult Vanessa butterflies to hide in the fall and be the very first to awaken in the spring to get a jump start on mating. Menm si papiyon yo te reveye nan mwa fevriye plant yo lame yo pa t 'moute (pye); papiyon yo nan jarden nou yo soti nan ane pase.
Men, sa ki si tan te fè jwe yon wòl nan sa a sik boom? Ane pase a te yon ane La Niña ak sezon fredi bèl ak twò grav nou an. Ane anvan an te yon El Niño, most of the eastern US was assaulted with winter and we suffered at the hands of the epic Chicago “snowpocalypse”. Petèt sa a konbinezon deprime nimewo popilasyon ase nan 2010/2011 ki Lè sa a diminye parazitoid chay, sa ki pèmèt pou pi gwo fekondite papiyon an jeneral nan sezon lete an la 2011. Moun sa yo ki papiyon ivèrnaj te Lè sa a akòde yon sezon ivè cho ki ta ka te pèmèt pou yon mòtalite sezon fredi pi ba. As the butterflies moved north this spring there were no frosty nights to cut into populations – just lots of hungry birds. Rezilta a ta dwe yon foul nòmal nan migrasyon papiyon.
But then again…
Despite butterflies being so popular and well studied there doesn’t seem to be a perfect grip on what conditions each of the Vanessa species prefer. varyab yo nan plant lame, seri popilasyon, move tan ak parazitoid tout jwe wòl enpòtan nan abondans ak distribisyon. Did the weather cycles of the last few years variably effect one species over another? Ki moun ki vle fè konnen ke pwojè PhD (soti nan lanfè)?
One of the best posts I’ve read is by Doug Taron over on Gaz Tapestry – he is skeptical of this warm weather theory. Critically this irruption is effecting only the population of the Red Admiral and any theory involving weather would also likely effect other migrant butterflies like the Vanessa virginiensis – the American Lady. He also points out that an abundant butterfly like the admiral has classic cyclical population booms and busts in sync with parasite populations. I recall another summer in the late 90’s of staggering Admiral populations. Parasites really do better explain what we see in our yards this spring. While the weather might not have caused the abundance of V. atalanta, there can be no denying that butterflies of all species have woken up much earlier this year.
As far as I recall, almost all temperate zone animals (and plants, Mwen sispèk) go thru boom and bust cycles. It’s pretty much the function/nature of the wildly variable environmental conditions of the ecosystems. Even the less common temperate zone species cycle but the effects are less noticed simply because of the lower population levels.
must have been a lovely sight, vanessa atlanta has been struggling in the UK for the past few years!!
A few years back you may have heard about the painted lady invasion in the UK very much the same as the USA i was counting well over 1000 an hour coming up the field from the english channel !
Quick question about la nina i believe the later part of 2010 was also la nina thats why the UK and northern USA had such cold weather