Monarch butterflies are third most commonly observed?

How come Monarch butterflies are the third most commonly observed organism on INat? Aren’t they supposed to be uncommon?

iNat started in California and the monarch butterfly migrations have been a massively popular thing to go see for many decades. That means there are millions of photos going back pretty much as long as there have been cameras.


also a very common introduced species in Australia


“there are millions of photos going back pretty much as long as there have been cameras.”

iNaturalist has only existed for a little over a decade and hasn’t really been big until the last five years. How many monarch uploads go back to “as long as there have been cameras”?

How many monarch observations are from 2020-2021, the alleged all-time nadir when there were (officially) fewer than 2000 monarchs left in the entire western US?

It’s terrible that we let facts get in the way of a good narrative!

1 Like

Monarchs are very photogenic. I’ve only seen one in person once, I think, but I made sure I photographed it. Meanwhile I see dozens of a butterfly called “common brown” in Australia every day at the moment, but only do an observation of one if I haven’t found anything more interesting that day.

(Just checked, and I actually have 2 observations of Monarchs. Both seen last summer.)


Personally, monarchs are my most observed species, and that does not include the captive ones I’ve raised. When I first realized this, I was a bit surprised, too. I think what contributes to it for me is that I try to document every single monarch I see, including eggs, caterpillars, and chrysalises. On hikes, I always check the milkweed plants but don’t necessarily make observations for all of them. I do for all the monarchs I find though. I should add, when I find an egg or caterpillar on my plants at home, that usually triggers a series of observations at different time points during the life cycle, so the number of observations I have does not necessarily equal the number of individuals I’ve documented.

Edit: Here’s an example, seven observations for the same individual making a chrysalis on the side of my house next to the milkweed patch in the yard.


As others have mentioned, the Monarch occurs on several continents. It is the migratory subspecies of North America that has seen a steep decline in population numbers (though other populations, e.g. Puerto Rico, also aren’t doing so great either). “Uncommon” is a relative term. For species with an allee effect, populations can be simultaneously quite high relative to other species but concerning low from a conservation standpoint.

Monarchs are a readily-identifiable, highly-charismatic species that will often visit people’s backyard. Because many people are familiar with the plight of monarchs in the U.S., they are more likely to take the time to document one when they see it.

Also, it’s important to note that breeding population and total population are two different metrics. Conservationists often refer to breeding population (i.e., adults), and iNat documents total population (i.e., includes eggs, larva, and pupae). Monarchs are an r-select species, which means they lay many eggs so that a relative few will survive long enough to reproduce.


it’s probably probably at least partly because IDs to subspecies are less common, but there were only 23 observations of the endangered migratory subspecies through the period you mentioned, most of which were in the eastern united states.


That 2,000 number was a snapshot number of the overwintering population. Monarchs naturally go through annual cycles of abundance. The winter count measures the population available for the upcoming breeding season, and 2,000 is a concerningly low number. iNat is a poor tool for measuring abundance under the best of circumstances, but what you are comparing are two extremely different metrics.

And not only that, but you are comparing the snapshot number to a (multi-)annual number.


At least where I live, Monarch populations vary wildly from year to year but in most years they are fairly common. In some years, they are probably the most common butterfly.


19 posts were split to a new topic: Monarch Populations

In my experience, most of my observations are bees and other pollinating insects, so I often encounter monarchs while snooping around flowers, so I’ve made it a habit to get an observation of them whenever possible. They are pretty large and charismatic butterflies that most people recognize, so I think a lot of iNatters are more inclined to get pictures of them.


Reposting this with permission and a few edits.

This is a great question! Ultimately, monarchs are the third most commonly observed species because they are very common. Andy Davis has done some slightly deeper analysis of the iNaturalist monarch data, focusing on the estimated summer range. Here’s the blog post: .

Even scientists commonly claim that monarchs are declining; however, monarch summer populations (the actual population) has not declined for as long as we’ve been monitoring it . Also, monarch populations exploded around 200 years ago and have not gone down recently . What about the claims that monarchs have declined by 90% or more? They come from studies that measure the area taken up by monarchs in Mexico, and we’ve actually known for a long time that monarchs could just be nesting more densely, giving the illusion of a decline. Even if the declines in Mexico are really that steep, there has been no correlation between “low” years of Monarchs in Mexico and “low” years of Monarchs in the Summer–it seems that Monarchs are able to hit a kind of carrying capacity every year regardless of how many of them start the northward migration in Spring.

TL;DR: monarchs aren’t uncommon.

1 Like

Some thoughts I have that I haven’t seen as clearly in other comments:

One predictor of high species observation counts on iNaturalist is how easy it is to identify. In my experience, many people get their start in interest in identifying insects by learning about the Monarch-Viceroy mimicry, and a large number of people who are casual outdoor nature people are excited to talk about the differences between those species. To me, this means there are a lot of people actively identifying and checking these records. A large large number of insect records will never be identified to species, either because the field marks are less clear or because of a small identifier community, or other similar reasons.

A related reason, in my opinion, is that monarchs are huge compared to a lot of other butterfly species at a lot of their life stages and, as adults, have large wings. I would guess this makes it easier to capture good photographs that have clear field marks. There are fewer butterfly eggs and chrysalis photos than adult pictures, and I’d bet a lot of those egg and chrysalis photos are monarchs, or disproportionately because people know where to look and what to look for. The same goes for caterpillars – another thing I see is that there are some species that people love to photograph as caterpillars and others that are typically photographed as adults. Monarchs benefit from both.

There’s a lot of interest in milkweed-associated communities and monitoring of those areas is often done systematically by classrooms, community groups, and casually. I would guess it’s not a coincidence that common milkweed is the 10th most common species of plant observed, but I’d be shocked if that really was reflective of the proportional number of plants that most people interact with that are common milkweed. Many other milkweed-associated insects benefit from this, including the milkweed bugs (which I’ve used in my own research because of the high number of photo-documented observations).

Somewhat off the cuff, but all that to say, there are more reasons than just true abundance that would lead to species being the most commonly observed.


IMHO this is the answer.

Look at Great Blue Herons - They’re common, but they’re not as common as American Robins, and yet they have more observations than Robins. If I took and posted a picture of every robin that I saw, I’d probably be posting 5-6 robins a day because they just hang out in my yard, constantly. But Herons? I post every heron that I can see. They’re uncommon enough to not be boring, they’re big, they’re charismatic, and they’re not particularly shy.

I fully imagine something similar is going on with Monarchs. Charismatic, easy-to-identify species with a lot of public interest are just naturally going to attract the interest of more people.


That is a great point, but I think the original question is why monarchs are number 3 globally when they’re supposed to be uncommon. Just like in the heron and robin situation, it isn’t that monarchs are uncommon and just observed a ton, it’s that they’re common and they’re observed disproportionately compared to other common species.

1 Like

Are they really that uncommon though? They’re declining, and threatened, but uncommon? This is just from a quick google, but it shows over 300k butterflies counted for just the western monarch count in 2022 (west coast USA)

I agree, they’re not uncommon! I said “it’s that they’re [monarchs] common and they’re observed disproportionately compared to other common species.”

They aren’t actually declining, either. Their populations have been stable based on summer counts for the past 30 years, and genetic data shows they haven’t declined in the past 70 years (though they did have a huge population boom around 200 years ago). The combination of all the data suggests that monarchs are at an all time global population high, and even the migratory subspecies in North America is near a historic population high.

Ah sorry, I misread your post! I get what you’re saying.

Its good to hear they’re not declining - though I still worry about habitat destruction.

1 Like

Whilst it may not be the case with monarchs, rare species are often over observed relative to common species in many ways. For many people spotting a rare bird/fungi/etc is a specific goal. Which means they will go to known hotspots for the observations, often with specific individuals ending up with many different obs. Where as a common species, may be over looked, because its too obvious.

Monarchs though, are more of a mascot species, in terms of insects its probably one of the most commonly known in the world. In many countries where they have been introduced (And probably in native ranges as well) its a common project to get some eggs/cocoons, and raise them and watch them grow. You can buy kits online, or look at online community groups. Often I see posts like “We have too many catipillar for our swan plants, anyone want some free catipillars”. So that will inflate numbers as well.