Monarch Migration: 2019

Guest Essay by Kip Hansen

featured_image_monarchsThe 2019 Fall Monarch butterfly Migration has begun and is in full swing.

Here in the Central Hudson Valley of New York, monarch caterpillars are still pupating and emerging as the Monarch Super-Generation.  The monarch pictured here is recently emerged and resting on a collard leaf in our garden in preparation for her journey.  She is one of a half dozen monarchs reared in protective custody by my family at the end of the summer here.  Five of the six have been females.

route_southMonarchs are now coming down from the north.  In my area, they pass down the Hudson Valley between the Catskill Mountains and the Taconics, coming down from southern Quebec and Vermont, headed eventually either to Mexico or, in some cases, southern Florida.  My personal observations show that the peak of the migration for the mid-Hudson Valley passed last week.  However, as of the first week of October, monarchs are still being sighted  heading south as far north as Hudson, New York.

The monarchs tend to flow down through New Jersey being funneled by geography to end up at Cape May at the very south-eastern tip of that state which is a favored monarch watching site during the migration.

This image shows the two flyways for monarchs heading south to mountain areas in the Mexican states of Mexico and Michoacan, as indicated by the star on the map:


Overall, this year seems like it is going to be another positive year for Eastern Monarch numbers.  Mid-year numbers of monarchs arriving in the northern breeding areas were up over last year, which was also an up year.

Table. First sightings north of 37N and east of 110W.

1–15 May 16–30 May 31 May–9 June Total sightings
2019 10.6% 63.3% 26.1% 1244
2018 24.7% 58.7% 16.6% 945

The percentages are of total first monarch sightings by date.

As of last year, monarch numbers were recovering nicely:


In the winter of 2018-2019,  over 300 million monarchs overwintered in Mexico.  While this year looks to do a bit better from the sightings reported of the southern migration, the actual number of monarchs arriving in Mexico won’t be known until after the middle or end of November and won’t be officially announced until January 2020.

The web site Journey North reports lots of monarchs migrating south this year —  down the  Eastern Flyway along the Atlantic coast and down both sides of the great Mississippi River.

Oddly, there are known disconnects between the numbers of monarchs sighted in northern breeding areas, monarchs sighted during the southern migration and the numbers arriving and overwintering in Mexico.  Some years there are lots of monarchs sighted  in the north but they fail to arrive in Mexico for the winter.  Some years, it is the other way around.   There are suspicions (and some evidence) that many monarchs are overwintering in southern Florida and along the Gulf Coast and it is known that many have settled in as year-around residents.   The Monarch Migration is still largely a mystery.

A slew of new papers on monarchs have just been published in a special issue of  Frontiers in Ecology and Evolution, “Research Topic:  North American Monarch Butterfly Ecology and Conservation”.   One of these shows that worldwide, monarchs are quite widespread and thriving:



Interestingly, monarchs around the world exhibit a wide range of behaviors regarding migration and overwintering.

“Monarchs worldwide exhibit varying overwintering and migratory behaviors (with migration potentially being an ancestral trait; Zhan et al., 2014). This variation creates a range of behavioral adaptive capacity. Eastern North American monarchs migrate upwards of 4,000 km every fall (Solensky, 2004), to overwinter in mountainous forests, which provide a unique, protective microclimate (Williams and Brower, 2015). Western North American monarchs also migrate in the fall, flying up to hundreds of kilometers to primarily coastal overwintering groves, which provide a slightly different specific microclimate (Jepsen and Black, 2015; Pyle, 2015). There are fewer monarchs in the western population, spread out among hundreds of overwintering sites (compared to fewer than 20 sites in Mexico; Vidal and Rendón-Salinas, 2014; Jepsen and Black, 2015). Western North American overwintering monarchs may also have a shorter diapause compared to those in eastern North America (Herman et al., 1989), and there may be differences in mating behavior at the different overwintering grounds (Brower et al., 1995).”

“While these long-distance migrations are well-studied, many locations worldwide have non-migratory monarchs and year-round or winter breeding, including Central America (Ackery and Vane-Wright, 1984), southern Florida (Brower, 1961), along the Gulf Coast (Howard et al., 2010), and southern California (Satterfield et al., 2016), as well as throughout many Pacific Islands. Monarchs in Australia employ both migratory and non-migratory strategies concurrently (James, 1993), with monarchs breeding year round in a northeastern coastal area, but overwintering without breeding at two other sites (Smithers, 1977). This strategy of partial migration (where some individuals migrate and others do not) thus seems common throughout the monarchs’ worldwide range, although the proportion of migrants to non-migrants varies greatly.”

source:  Nail et al. (2019)


In California, the gathering of monarchs along the Big Sur to Santa Barbara coastal mountains showed very poor numbers for the winter of 2018-2019 — the lowest ever recorded — at < 30,000 overwintering monarchs counted in the Thanksgiving Count.  These poor numbers have resulted worries that the Western Monarch is in an “extinction spiral”.   It is important to remember that when referring to the “Western Monarch population”, most biologists are in fact referring specifically to the migratory/overwintering portion of the western monarch population.   They are talking only of the monarchs that gather and overwinter together at a large number of known sites along a very long and rugged coast.   The worry is for the Western Monarch Migration, and not really the western monarchs as an entire population.  How many monarchs are simply traveling to Mexico (one of their alternatives) or moving into Southern California and continuing to feed and breed for the winter is unknown — there is almost no body of science on the topic.   The monarchs may simply be finding alternative roosts that are not on the list of sites included in the Xerces Society Thanksgiving Count.  We just don’t know.  But a lot of effort is going into citizen-support science  to try and find out.  If you live in the United States or Canada, west of the Rocky Mountains, there are programs for online reporting of milkweed (necessary for monarch reproduction) and all the life stages of Monarch (eggs, caterpillars, butterflies and chrysalises)  which you can participate in — it is easy and fun.

Take Aways:

    1. Monarch butterflies (Danaus plexippus) make an intriguing biological study with their varying migration and overwintering behaviors.   How the supergeneration  comes into being and how these insects, many generations later on,  find their way to the same area of Mexico every year is entirely unknown.
    2. Monarch butterflies are not endangered, though there are lots of activists groups trying to get them declared so under the U.S. Endangered Species Act.
    3. The phenomenon of the great monarch migrations and overwintering roosts, especially for the Western North American population may waning as monarchs adjust to changing conditions with alternate behaviors, as they have done in other parts of the world.
    4. The needs of monarch butterflies are simple: patches of native milkweeds allowed to grow and flower along roadsides, railroad right-of-ways, in your gardens and the edges of fields.  Local efforts can make a big difference by educating State, County and Local governments about the need to leave the milkweed (or at least some of it) alone.
    5. In your own yards, planting butterfly-friendly gardens are a great way to help.

    # # # # #

    Author’s Comment:

    I like birds and butterflies and flowers.  Monarchs remain a mystery to me even after extensive study.  I like mysteries . . . .

    If the monarchs are migrating through your area (in the United States or in Australia), drop a comment and let me know.

    I write about the monarchs here at WUWT just because they are interesting.

     # # # # #


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October 3, 2019 10:31 pm

We raise monarchs as well noticed this year they did particularly poorly. About 2/3 didn’t emerge from the crysalis. We had a bad problem with parasitic flies this year which lay eggs in the caterpillars and emerge (and kill the host) in the pups stage.

Also it is interesting, being in Coastal Southern California we only see Monarchs in the Summer months. Supposedly they are overwintering somewhere close to me.

Reply to  marque2
October 4, 2019 6:54 am

Note: above – was typing on my cell phone – yes there are typos and missing periods. Apologies.

Reply to  marque2
October 4, 2019 6:13 pm

As a kid in Midland, 1960s, Michigan we gathered and raised, released Monarchs gathered in nearby city fields every summer. As an adult living around the same area and into central and northern Ohio is have not seen a caterpillar in years. They were easy to find, plentiful

Brian Valentine
October 3, 2019 10:41 pm

So plant more milkweed! We have. It does take special preparation in the mid-Atlantic, where we are, but can be done.

Michael S. Kelly LS, BSA Ret.
October 3, 2019 10:50 pm

We have two butterfly bushes on our property in Norther Virginia, and this year were knee-deep in butterflies – especially monarchs. I had never seen so many, though my wife (who had butterfly bushes in California) said that it was not the most she had ever seen. At one point during the summer, I actually had to slow down as I drove up our road, just to avoid creaming all of the monarchs flying across in front of me. Very, very beautiful sight!

Reply to  Michael S. Kelly LS, BSA Ret.
October 4, 2019 1:10 am

You’re lucky. In the parts of Canada where I have lived, there are not nearly as many Monarchs. I don’t think I have seen even one all summer.

Timo, Not That One
Reply to  commieBob
October 4, 2019 5:48 am

I live in Toronto and I haven’t seen so many Monarchs since the 60s. I was thinking this is a bumper year. The city has planted milkweed in many city flower beds.

Reply to  Timo, Not That One
October 4, 2019 6:10 am

Timo ==> There have been encouraging reports from points north — glad to hear the Toronto is one of those with lots of monarchs this year. Well Done to your city officials for planting milkweed in the parks — many milkweeds are very decorative as well as being necessary for the monarchs.

Reply to  commieBob
October 4, 2019 8:47 am

CommieBob we use to see them all the way up in northern Ontario – but haven’t seen them in decades. Nor have I seen them when I moved to southern ON and now to out east Ontario. This province went on a milkweed eradication program and all the butterflies stopped showing up in summers. I use to see milkweeds all over the ditches all across this province now they’ve planted an invasive plant in it’s place.

Geoffrey Harris
Reply to  ldd
October 8, 2019 10:34 pm

Why did they do that? What was the point?

Reply to  Michael S. Kelly LS, BSA Ret.
October 4, 2019 5:18 am

Michael ==> Thanks for the report on monarchs in Northern Virginia!

Planting butterfly feeding bushes and flowers is a great way to boost monarch numbers.

Reply to  Michael S. Kelly LS, BSA Ret.
October 4, 2019 8:17 am

I’m in Virginia also. Central Virginia, north of Richmond.
Our two butterfly bushes and milkweeds have not attracted any more butterflies than previous years.

Looks to be a normal butterfly year here.

Phil R
Reply to  Kip Hansen
October 4, 2019 10:42 am

SE Virginia here, have a butterfly bush, several milkweeds (among other things for black swallowtails). have had monarchs sporadically, but fairly consistently, throughout the summer (at least later summer to recent). Haven’t seen any caterpillars, though have seen commonly in the past. Generally, seems to be about normal summer (informal observations, no counting, etc.) here. Would love to see a blast of monarchs sometime.

Phil R
Reply to  Phil R
October 5, 2019 10:40 am


Don’t know if you’ll see this, but thanks for the response. I’ll keep a watch on the back yard and let you know if it picks up any.

October 4, 2019 1:00 am

I used to keep these in my bedroom here in Southern Australia when I was a kid (much to mother’s chagrin) I don’t know if they even bother travelling north (warmer) in winter here. They are very adaptable.

Reply to  Mike
October 4, 2019 5:19 am

Mike ==> Good to hear from Australia! To hear US activists talk, you’d think monarchs were exclusive to North America.

Reply to  Kip Hansen
October 5, 2019 8:22 am

a friend has what we call Swan bushes and the monarchs love it, hers hatched out some weeks ago in Victoria SE Aus

adam selene
October 4, 2019 2:49 am

Last winter in Houston, my Monarchs spent the winter with sightings all the way through. However, the summer/fall count is way down with almost 0 pupating. Something moved in to my yard and decimated them.

Reply to  adam selene
October 4, 2019 5:22 am

Adam ==> Interesting to hear that monarchs are year-around residents in Houston. Your monarchs may have just moved north with the crowd — and then again, may have been heavily parasitized after spending the winter.

John Garrett
October 4, 2019 3:36 am

Kip— thanks. I will spend the day outside on the migratory route and will be looking for Monarchs. The Monarch’s multi-generational migration is a genetic miracle and, as you say, a grand mystery.

Reply to  John Garrett
October 4, 2019 5:23 am

John ==> Let meknow where you are and the results of your observation….

October 4, 2019 3:46 am

Kip: In northeastern Vermont we had few monarchs the previous three years even though our property of meadow and field contains hundreds of milkweed plants. It is also prime nesting habitat for songbirds. This year we have had dozens of monarchs and they were still flitting about even after three light frosts. Maybe they are the tail end of the migration out of Quebec. I did not see any yesterday and we are under a freeze warning tonight and tomorrow night.

Reply to  Keith
October 4, 2019 5:42 am

Yes – we too have seen many monarchs in north-central Vermont. Seems like more than normal.

Reply to  Keith
October 4, 2019 6:07 am

Keith ==> Monarchs can take a light frosting but not a real Vermont-style killing frost. Hopefully your monarchs have taken the hint from the frosts and headed down my way, past Albany and down the Hudson River Valley.

Don K
Reply to  Keith
October 4, 2019 7:23 am

In years past, I used to see a few migrating monarchs every year about this time of year. I sort of mentally associate them with the blooming of Purple Asters which are the last of our native wildflowers to bloom here in Northwest Vermont. However, I haven’t seen a monarch in the Autumn for several years. On the other hand, I did see a couple in midsummer this year. This is not really good butterfly country as most farmers have given up trying to deal with a very short growing season and as a result there’s not a lot of open land. Mostly it’s either been paved and built over or has reverted to woodland. Oddly, the few butterflies I do see represent fairly diverse taxa so they are apparently hanging on somewhere around here.

Yep, there are frost warnings for most of the Adirondack area and Northern Vermont except the Champlain Valley for tonight and tomorrow night. I don’t think it’ll be brutally cold, but Winter is definitely coming.

Doug Huffman
October 4, 2019 5:14 am

Elsewhere is documented the suspicion that captive raised Monarchs are unable to navigate their migration route. That is a very subtle observation and easily disparaged by hobbiests.

Here, where I live, I expect milkweed to be soon declared an invasive. I watch carefully and notice few – no – heavily munched leaves.

Reply to  Doug Huffman
October 4, 2019 5:34 am

Doug ==> The “captive raised monarchs don’t migrate” science is very very weak — though not thoroughly discountable as yet. The real experiments needing done are captive raising, tagging and releasing to see if, in fact, captive raised monarchs do migrate (or not).

When they say captive raised, they mean specifically monarchs raised in butterfly farms and butterfly exhibits — they may in fact be breeding non-migrating monarchs by selectively (intentionally or not) using year-around resident monarchs from the south in their breeding programs.

What most “hobbyists” do is bring caterpillars inside, away from predators and parasitic wasps, feed them (best done using day length locations — not under artificial lighting), and then releasing them hours after the butterflies emerge from their chrysalises. There is no reason to believe that this practice is anything but beneficial — though it may not actually add much to monarch numbers.

steven F
Reply to  Doug Huffman
October 6, 2019 5:15 pm

milkweed is native to most of north america. Invasive plants are typically plants that are not native to a specific location. So I doubt it will be declared invasive.

October 4, 2019 5:47 am

Great article. We have 11 acres on the eastern side of the Blue Ridge near Culpeper VA. This year we have seen a tremendous increase of all types of butterflies.

Reply to  Tom Kennedy
October 4, 2019 6:14 am

Tom ==> Know your area — traveled through several times headed south — very Garden of Eden-ish there.

Great to hear good news from Culpeper on butterfly numbers.

Bruce Cobb
October 4, 2019 5:56 am

We have (or had) a stand of milkweed alongside our driveway, along about a 50′ stretch next to a banking. A couple years ago, I had to mow along the driveway as we were having the driveway sealed. So, the stand has been considerably reduced, but I think they’re returning. We noticed a half dozen or so of the monarch caterpillars on them. About a week or so ago, there was one flapping, upside down on the driveway. It was a victim of folded wing, due to a parasite known as Ophryocystis elektroscirrha (OE). That’s the understanding now anyway. One wing was already somewhat tattered, possibly from abrasion from the pavement. It was unable to fly. We have cared for it, knowing it will just die anyway. They seem to like gatorade, so it gets that, using a plastic scrubber set in a small, glass dish (actually a cover). The scrubber acts as a platform for it to perch on while feeding, keeping it dry. We used a cat carrier as a station, with various grasses and clover in it, and at first, it would manage to go about 30′ away, but it has become increasingly weaker. We put it in the carrier at night, bringing it inside, and put it outside, in the sun if possible. Yesterday was cloudy and very cool (low 50’s), so we kept it inside, but this morning it is sunny (quite cool though – 40’s), so we’ll put it outside in the sun. It probably won’t last much longer – maybe a day or so.
We had one a couple of years ago that we helped with the same problem. The infection was not as advanced, and it actually could fly some and eventually, after about 3 days it flew off. They are indeed amazing creatures.

Reply to  Bruce Cobb
October 4, 2019 6:18 am

Bruce ==> Thanks for sharing your monarch story with us. Nature is a hard master for many of its species — all competing with one another — the monarchs are prone to several parasitic infections and are prey for many other life forms. Somehow, balance is achieved and maintained. Thanks for chipping in on the side of the monarchs.

Natalie Gordon
October 4, 2019 5:57 am

Monarchs have been just plain missing in my part of Manitoba, Canada. (For those of you weak on Canadian geography we are about 200 miles straight north of North Dakota and nowhere near Toronto.) We have abundant natural pasture habitat for butterflies thick with milkweed. In the past we always had lots of monarchs. It was common to take a walk down the roadside and see showy milkweed plants and almost each one would have a monarch caterpillar on it. They were frequent visitors to our garden and often found on the grills of automobiles. Alas it has been about five years since I have seen even one monarch. My husband saw one single monarch late this summer. The milkweed are still here in abundance so it is not lack or or changes in habitat here. There is something else going on with monarchs and it is not good.

Reply to  Natalie Gordon
October 4, 2019 6:26 am

Natalie ==> The fact that your locale hasn’t had monarchs for a few years is not necessarily an indication of how monarchs are doing on a continental scale. Weather plays an important role in where dispersing monarchs end up in the far northern reaches of their breeding range. Prevailing winds can land them hundreds of miles from their traditional breeding grounds.

Last year was a very good year for monarchs overall (Eastern monarchs — which would breed in your area). And this year is looking good from mid-year reports.

Population dynamics are complicated at the best of times, and at the edges of ranges, can be downright mystifying.

Thanks for the Manitoba Report — even if it is a “negative” sighting — all data is valuable.

Gary Pearse
October 4, 2019 6:12 am

Overall in Quebec and Eastern Ontario, we’ve had a cool, short summer. At a friend’s cottage, we had ~10C nights inthe first week of August. At home we have an outdoor plant that usually produces big floppy red flowers the size of a catcher’s glove (forgotten its name) that only managed a pathetic sprig of green and the black currants fell off the plant still green. I saw only the odd monarch in the city.

Speaking of mysteries, I mentioned under your last report that the main Ontario flyway crosses Lake Erie. They gather at Point Pelee (Canada’s southernmost point – same Lat as N California) in mid September and wait until north winds are above a certain strength to assist them across Lake Erie.

Reply to  Gary Pearse
October 4, 2019 6:35 am

Gary ==> Interesting weather report — while the rest of North America was apparently having an unusually warm September.

Thanks for the CBC report from last years Point Pelee National Park migrating monarch roosts.

This year, Point Pelee is reporting high numbers:

Let us know if there are further reports for this years migration….would be interested in seeing comparative, year-to-year, numbers.

Gary Pearse
Reply to  Kip Hansen
October 4, 2019 8:24 am

Kip, here is a report on this years flights from Canada. Apparently a large number.

Gary Pearse
October 4, 2019 6:24 am

Perhaps if people knew milkweed flowers were very tasty (like asparagus) they might encourage growth and leave some for the monarchs. A liitle known fact: during WWII, the fluff from milkweed gone to seed was collected to fill life vests and for ” down- filled” jackets, etc. It is better insulation than goose down. There is a company in Nebraska that makes parkas, etc. using it.

Reply to  Gary Pearse
October 4, 2019 6:41 am

Gary Pearse ==> Fascinating — yet another reason to encourage milkweed cultivation in home gardens and on public lands. I’ll have to try the recipes next year for milkweed shoots!

October 4, 2019 6:41 am

I’ve seen an occasional Monarch where I live in Southern CA but they are few a far between. I suspect most land owners in my area aren’t too keen on having Milkweed on their property because of the amount of horses there are. We did have a big showing of Painted Ladies this past spring that was pretty spectacular. At times there were so many in the air it looked like falling leaves.

Reply to  Kevin
October 4, 2019 6:48 am

Kevin ==> The Painted Ladies were in a “superbloom” condition this spring in Southern California . I like your description — “like falling leaves” (which we get here in the Northeast).

Monarchs settle in for the long-haul and are less visible when they are not forming massive roosts. Monarch numbers have been down pretty drastically in the west over the last few years.

Reply to  Kip Hansen
October 4, 2019 7:53 am


It’s been awhile since I’ve traveled up the coast of CA to see the Monarchs. My favorite place to go is Pismo State Beach (near Grover Beach). Perhaps this coming winter I’ll make it up there again. My daughter keeps asking when are we going to see the butterflies again. Hopefully we won’t be disappointed.

October 4, 2019 6:54 am

Best year ever for me in terms of monarchs. Just the other day had around 40 or so on the mexican sunflowers. I do have tons of milkweed in my garden as well. Located in PA.

Bruce Cobb
October 4, 2019 7:02 am

There was a disturbing story 9 days ago about thousands dead on Kent Island, MD:
The suspicion is that spraying for mosquitoes may have caused it. Although officially, they are saying that spraying is in too small a quantity and is not known to affect them, it does seem the suspicions are warranted. Perhaps testing is being done now to figure out the cause.

Reply to  Bruce Cobb
October 4, 2019 7:05 am

Bruce ==> Hmmm…interesting report — do follow-up and let me know if they discover anything specific.

Chris Hagan
October 4, 2019 7:32 am

The windmills in California will chop them all up.

steven F.
Reply to  Chris Hagan
October 6, 2019 5:25 pm

I live near a overwintering site and their is a major wind fram in the area. It was built in the 80’s and there is nothing to suggest the wind turbines are having any effect. Numbers in the late 90’s were quite high. Today there are not as many but the last strong drought ended a couple of years ago. So hopefully there will be more this year.

Steve Keohane
October 4, 2019 7:49 am

Oddly, in west central Colorado at 6600′, I’ve been seeing Monarch catepillars even yesterday. We’ve had three frostly nights so far, as low as 23° yesterday morning. It seems very late to b seeing them.

Steve Keohane
Reply to  Kip Hansen
October 6, 2019 5:59 am

Hi Kip, Yes, I’m west of the divide, south of Glenwood Springs. I don’t have a clue which way they fly. It is very mountainous here, I assume they would follow altitude, ie. the direction of water drainage as opposed to up and down the topography to follow a compass direction.

Joshua Peterson
October 4, 2019 8:19 am

In southern New Hampshire, we have seen a lot of Monarchs this year, more than I’ve seen in any recent years. Every milkweed seemed to be getting eaten; I saw multiple plants eaten down to the stalk due to the number of caterpillars. I’ve seen adults passing south for about a month now, though not as many now. A couple passed me in the yard Tuesday.

October 4, 2019 8:29 am

Are the Australasian and American Monarchs the same species? In the Galapagos , just a few miles between islands caused the finch species to diverge, as Darwin famously observed. But with the Monarchs thousands of miles of Pacific Ocean separate the two populations.
Were they introduced by humans in one of the two areas?

Reply to  Kip Hansen
October 4, 2019 11:58 am

Kip, Thank you

Reply to  m
October 5, 2019 9:47 pm

m – Australian Monarchs (we call them Wanderers) showed up and down the east coast after a cyclone in 1871 – they are thought to have blown in from New Caledonia where they had been introduced. The Wanderers found lots of weedy milkweeds and they have been doing fine ever since. Give them enough time and they may diverge from the American types, but probably more from genetic drift than selection as the foods and habitats aren’t so different.

October 4, 2019 8:35 am

I suspect that the butterfly simply follows %RH

my report on natural climate change coming up is a must read:

October 4, 2019 8:56 am

Just saw one yesterday in the warm afternoon. It stopped to fuel up on clover in the grass.

October 4, 2019 9:01 am

Another interesting fact is that Painted Lady butterflies perform a similar seasonal migration from central Africa to Europe and back. Somehow they survive crossing the Sahara Desert! Painted Ladies are present here in the central Appalachians (USA), but don’t here perform such a migration.

Fred Harwood
October 4, 2019 9:15 am

Here in SW Massachusetts, we have seen more monarchs than we can remember in our 75 years.

Kent Noonan
October 4, 2019 9:20 am

This year we only saw 1 monarch. Usually we see hundreds, the western migration. Here in southern Oregon, we have had milkweed growing for many years to support the migrating monarchs. I suspect the migration pattern has shifted, and the impact of last year’s low numbers in California for winter. Many would blame climate change, but any change here is so small as to be unmeasurable (if you look at the raw data, not the “adjusted”. Even the adjusted data shows small warming.). Loss of habitat is likely; pesticides, predators, parasites, all are more significant right now. Winter for the past couple years has been very mild here, so climate is unlikely. I wonder how sensitive to smoke they are? This year was very clear, but last year was the worst I can remember.

October 4, 2019 9:57 am

It is amazing how insects smell stuff. You only have to open a can of soda….

Bennett Dawson
October 4, 2019 9:58 am

Lots of Monarchs in Northern Vermont this year. I have acres of open meadow with hundreds of milkweed plants. Almost all had 2-3 Monarchs fluttering around the tops. There are a LOT of butterflies migrating from my area!

Bennett Dawson
Reply to  Kip Hansen
October 5, 2019 3:50 am

They left about a week ago. Thanks for the great article!!!

October 4, 2019 10:37 am

I live in Colorado Springs. This fall, I’ve only seen a few Monarchs (which is normal for this area). Last year, for some reason, we were teeming with Monarchs. The predominant butterflies migrating through this area are Painted Ladies, which were very numerous this year.

David Joyce
October 4, 2019 11:57 am

I’ve seen several Monarchs near the coast, north of Boston over the last few weeks. They definitely seemed to be going places. I am a soaring pilot and love to speculate about how soaring birds can find and use lift so well. Astonished that something with so little processing power is able to utilize much finer scale turbulence, and winds to essentially soar for thousands of km. Organisms do the darndest things.

October 4, 2019 12:01 pm

odd here in central maine I have only seen 5 or so of them. usually see more.

October 4, 2019 4:16 pm

NY has had an excellent burst of migrating monarchs this week, the peak day being Oct 2. Central Park had monarchs all over, congregating on late flowering shrubs to feed. There were as many as 20 butterflies on a single shrub, overwhelmingly monarchs, plus bumble bees.
Other butterfly species were in very much lower numbers.

October 4, 2019 4:16 pm

I have noticed a total lack of Black and Yellow Garden Spiders (Argiope aurantia), recently.
When I was a kid (47 years ago), we would catch grasshoppers and throw them into the spiders webs.
Now it is all “orb weavers”, no garden spiders or grasshoppers.
Maybe the shrews got the upper hand lately ?

October 4, 2019 4:20 pm

We still have monarchs in Southern Maryland as of today. Are they migrating? I don’t know.

Beachbum Charlie
October 4, 2019 4:34 pm

I’m on the beach on Topsail Island, NC, about 30 miles north of Wilmington, NC. Monarch migration is in full swing, with 5 – 10 flying over the dunes every minute. Many stop to enjoy the beach morning glories, beach goldenrod and Mexican beach blanket flowers blooming on the dune. Quite a show, delicate strength, stalwart perseverance.

Chris Carleton
October 4, 2019 5:03 pm

We live near Ottawa and have a two acre property. In the five years we have lived here this has been the best year ever for monarchs. In late August and early September they were everywhere on our property. I quite enjoyed pointing out their beauty to our two young grandsons.

Bruce Carter
October 4, 2019 6:50 pm

My wife and I were commenting on the number of Monarchs here in Fairfield CT this year.

The most we’ve seen in years….

October 5, 2019 11:14 am


Attempting to understand the ways of Nature is a constant joy, at least in my life. Helping others to understand more about the natural world — not the Kiplingesque “Just So Story…” versions usually offered in Nature programs found in the media and on the ‘Net, but the real scoop as best we know so far — is important to me. I think true understandings make the world a better place and make people better people.

The great Monarch Butterfly migrations of North America are a brilliant mystery which the biological sciences are still working hard to try to comprehend. I’ll try to keep readers here updated as more and more is discovered.

If you come across anything interesting in the field, please drop me an email at my first name at i4 dot net. Thank you in advance.

Thanks to all who have filled us in on their Monarch Migration experiences — and when and where they are seeing monarchs. Don’t stop posting these sightings below, I’ll read them all and respond as I can.


Thanks for reading.

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October 5, 2019 10:00 pm

Hi Kip – Thanks for the update on the North American Monarchs. Here in the hinterlands of the Sunshine Coast in Queensland, Monarchs were active all winter – the only large butterfly that was. Jezebels (Delia negrina & argenthona), made their usual midwinter appearance and some of the small darts and blues were around, but the other large butterflies (Orchard Swallowtails, for example) have only started showing up with the spring.

It is the second year of drought here, so I expect Monarch numbers will be in some decline, although the milkweeds and cottonbushes they feed on are fairly vigorous weeds. Still it is dry enough that even the weeds are stressed.

Reply to  DaveW
October 6, 2019 11:44 am

DaveW ==> Thank you — your year-around Monarchs are part of the Monarch Mystery. Do let me know how the monrchs do over the next month or so with the droughty conditions… can email me at my first name at

October 6, 2019 11:55 am

I’ve seen two Monarchs in Amarillo TX, in the last week of September. None this past week, but we got so much rain that it may be holding them back. I suspect we will see more, given the strong cold fronts anticipated this week.

Ann Plattner
October 6, 2019 12:49 pm

I am so happy to find this site and report. I am in Baltimore, Md, and while we are not so far from northern Va., it’s worth mentioning that I play golf and that during the last week of September there were easily ten or more Monarchs that I noticed on the course. Something I would have noticed before, had it happened. So I hope this bodes well! Thanks for your site and the information.

Jeff Mitchell
October 6, 2019 3:54 pm

I live in Orem, Utah. We have milkweed in our front flower bed. We saw several monarchs this year. None laid on our plants.

David Joyce
October 6, 2019 7:26 pm

On Saturday, at Sterling Airfield, MA saw 2 monarchs heading South. The winds that day were generally from the west but at the airfield they were from the South. Wished them well.

David Joyce
Reply to  David Joyce
October 6, 2019 7:27 pm

And I’m going to look up milkweed seeds. We get monarchs in our back yard a lot, not sure why.

Myron Mesecke
October 7, 2019 7:26 am

About three years ago I contacted via email a scientist that studies Monarchs. I had some questions and comments pertaining to urban land use changes and whether any of them had an impact on Monarchs or other migrating insects. I noted that newer residential areas have much smaller lot sizes, houses are closer together and at least for central Texas 4 foot high chain link fences have been replaced by 6 foot high wooden privacy fences. I also mentioned how fewer homeowners plant gardens.
The scientist said that Monarchs fly high enough that buildings and fences in close proximity to each other is not an obstacle for them. But he did share my concern when it came to food and water sources for Monarchs in large cities.
He said that large cities have become a serious obstacle along the migration paths. They lack enough food and water sources and Monarchs suffer fatigue and risk death because the miles and miles of urban sprawl are too large for the Monarchs to traverse without food and water. There may be plenty of trees and grass lawns but those don’t sustain Monarchs.

He calls cities Green Deserts.

Rich Lambert
October 7, 2019 11:48 am

Kip, I was at the beach on Oak Island south of Wilmington, NC today. Quite a few Monarchs feeding on flowers near the beach.

Johann Wundersamer
October 13, 2019 10:06 pm

“There are suspicions (and some evidence) that many monarchs are overwintering in southern Florida and along the Gulf Coast and it is known that many have settled in as year-around residents. The Monarch Migration is still largely a mystery.”

Ain’t durence [ years ] as routes of wanderings “a coupled system of nonlinear functions with chaotic behaviours”.

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