she knew about local monarchbehaviours in recent
years. Could she explain the type of behaviour
we observed years agoon theGiant’sTomb? She
tellsme the eventwe came acrosswas a
roosting
,
and explains the pilots crossing the channel were
streaming
toward their congregation.
Streams are the paths betweenmigrationpoles
which are spreadout over easternCanada on
the northern end andMexico in the south.“You
will see those roosting formationswhen the
temperature drops between 10 to15°C,” says
Armstrong.“If it’s 5°C they can’t even crawl.”
Themonarchs simply gather upuntil ideal flight
conditions resume. Roostings canbe found in the
same places year after year.Audrey shared stories
of roosting sites in theGrey-Bruce andManitoulin
Island areas. In 2007, she found a roostingonGrey
County Rd.1 inKemble,ON.“One of the reasons
roostingbehaviour is little known is due to the
fact that it canbe difficult to spot, especially in
mid September, theway they fold themselves back
in leaves as they begin to change colour in late
summer,” she says.“From that [Kemble] roosting,
wewere able to tag some, and estimate a count
of around 700.”She said a year later they found a
secondmonarchgroup roosting at the same site.
“Generally you’ll see thempassing throughGrey
Bruce aroundmid-August tomid-September.”
Another roosting foundnear the SaugeenRiver
yielded an estimatedpopulationof 2000.Armstrong
facilitates educational workshops through the
MonarchTeacher Network, informingpeoplewhat
they cando tohelpmonarchbutterflies by building
up their habitat.
Not only does themonarchmigrate fromMexico
to easternCanada, it takesmultiple generations
topull this off. Last February,monarchpopulations
spikeddramatically from the record lows of the past
three years;MonarchWatch, a groupbasedout
of theUniversity of Kansas, estimated200million
monarchs over-wintered inMexico.Amonth later,
awinter storm ravaged colonies inMexico, leaving
butterflies frozen to trees anddeadon the forest
floor.Armstrongbelieves it is difficult todetermine
howhard the stormwill hit themonarchpopulation
because they had just begun their northward
migration.A single stormdemolishingpopulations
at any stop along their route is just one ofmultiple
challengesmonarchs face.Armstrong adds:
“Habitat loss is likely the largest threat tomonarch
populations.”
Sowhat definesmonarchhabitat? FromMexico
toCanada, themonarchmigration streams along
patches ofmilkweed.The life cycle of themonarch
butterfly depends onmilkweed. Eggs are first laid
upon the underside ofmilkweed leaves andhatch
into larvae.Themonarch caterpillar eats the leaves
until entering the chrysalis stagewhere it cocoons
itself, usually on the underside of the leaves.Then
finally the butterfly emerges into adulthood, all
within around 20-32days.Themonarch lives in
symbiosiswith themilkweedplant andwhen
changes tomilkweeddensities occur along their
migrationpaths, it can severely affect any one of
themultiple generations completing the journey.
“Loss ofmilkweedhabitat occurs formany reasons,
mostly changes in landuse,” saysArmstrong.
“Clearingof fields and removal ofmilkweed along
roadsides play a role in this.Monoculture practices
andherbicide alsohave an impact.”Themonarch
is not a local resident, but iswithus for an integral
part of its life cycle, andGrey-Bruce andManitoulin
are very important stops along theirmigration
route.“The bestmessage you cangive people is
thatwe can all do something tohelp,”Armstrong
stresses.“If youhavemilkweed at home, leave it
there, and if youdon’t have it, plant it.Once found
on the Province of Ontario’s noxious plants list,
milkweed seeds cannowbe foundon the shelves at
nurseries—that’s a big step.”
TheMonarchWatchWaystationprogram
(monarchwatch.org)was developed to create
habitat formigratingmonarchs. Registering your
yard allows you to establishhabitat formonarchs,
aswell as tag them.Thismeans they canbe
potentially identified andmonitored. Seed kits can
alsobe purchased fromhere that include varieties
of nativemilkweed aswell as native nectar plants
as a food source for adultmonarchs.
Themonarch is a threatened species yet so far has
rolledwith all the punches and continues to loft
along fromone generation to the next.We can
all help keepan eyeout for roostings in the trees
on cooler summer days.We can identifymilkweed
plants, protect them, andpay attention towhat
other plants adultmonarchs are feedingoff, and
protect themalso. I know formyself that after
speakingwithAudreyArmstrong, I justmight have
topaddlebackout toGiant’sTomb Islandona cool
August night.
To learnmore aboutwhat you cando to create
habitat formonarchs, check
forworkshops in your area.
– Scott Parent
"We can all do something to
help. If you havemilkweed at
home, leave it there, and if you
don’t have it, plant it.”
Late-summermilkweedwithburst seedpods.Themonarchbutterfly life-cycledepends onmilkweed. WILLYWATERTON.
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MOUNTAINLIFEBLUEMOUNTAINS
SUMMER2016
