What: Butterfly populations have been declining at an alarming rate, raising concerns about the broader implications for the environment. Experts from Binghamton University are available in this live virtual event to discuss the causes of this decline and what it may signal for the health of ecosystems.
In addition to being beautiful and inspiring art, said Grames, butterflies also play a vital role in pollination, helping to pollinate food and flowers and contributing to the health of ecosystems around the world. This study could help drive important conservation efforts, such as prioritizing species for the and/or
When: Wednesday, March 5th at 2 PM ET
Where: Newswise Live Zoom Room (address will be included in follow-up email)
Thom Canalichio:
Hello and welcome to this Newswise Live virtual press briefing. We are here today with a researcher from Binghamton University to discuss an embargoed research paper that is under embargo. It's getting published tomorrow, Thursday, March 6 at 2pm in the Journal of Science. So for any media on the call, we ask that you hold off on publishing anything about that until that embargo date and time again. That's Thursday March 6 at 2pm Eastern Time. After that, you can publish about this. I'm here with Dr. Eliza Grames from Binghamton University. She's an Assistant Professor, and she worked as a co-author on the study, and we're going to go ahead and talk about it. So Dr. Grames, please tell us about the findings of this study in the butterfly population decline.
Dr. Eliza Grames:
Yeah. So the study that we put out was a big analysis of population trends for all butterflies that occur in the contiguous United States. And what we found is that over the last 20 years, from 2000 to 2020 we have lost one out of every five butterflies in the US. So it's a 22% decline over only 20 years, which is a pretty shocking rate of decline in such a short time span.
Thom Canalichio:
And tell us a little bit about the importance of butterflies as a species, what this indicates for the health of the environment, as well as their role in things like pollinating crops. Why is it important to look at a species like butterflies?
Dr. Eliza Grames:
Yeah, so butterflies, they're absolutely incredible. We've got in the U.S. part of the first step of this project was figuring out just how many butterfly species there are in the United States, so that we knew where to start for our analyzes. And as it turns out, there are 650 butterfly species whose ranges overlap with the United States. So that was our starting point. And these species fill so many different roles in ecosystems. So they're pollinators for many of our wild plants. They're herbivores, so at their caterpillar stage, they're really important in terms of actually being eating plants and food resources. And then they also are food for insectivores like birds. So they play a lot of really important roles in ecosystem function. But I actually think even more so than that, that those services that we get from them, the benefit that we get most from butterflies, is that they're really, you know, they inspire us. They motivate us. We're amazed that they can fly. You know, everyone's captivated by the migration patterns of the monarch, and they've inspired so many songs and poetry and literature. And so I think in terms of, like humans' connection to butterflies, they're one of the insects that we do feel that connection with. And so thinking of them as broader indicators of what's going on with insects in general, it's a good way to get people to actually care about the insects, which we often refer to as the little things that run the world because of their important roles in ecosystems.
Thom Canalichio:
They certainly are one of the most charismatic insect species for us to be looking at in this kind of question. And you mentioned something that intrigues me, that the importance of their development in the caterpillar stage also has important impacts on the environment, an important role to play. Tell me a little bit about that, because I think many people might just hone in on the flying butterfly, you know, fully formed phase of things. What is unique or special about the caterpillar phase that plays an important role here?
Dr. Eliza Grames:
So a lot, yeah, we do. We focus on the flying butterflies because they're the ones that we interact with more. It's really difficult to find butterfly caterpillars. They're often really, really well camouflaged. So adult butterfly so the female will lay eggs on their host plant often, and then the caterpillars are reared on that plant and only eventually leave once they do become adults, and so, yeah, at that stage, you know, we're often not thinking of it, but that's the stage at which they can be prey for insectivores, or that they're doing most of their herbivory, whereas once they get to the adult stage, they're mostly just flying around. Or potentially, some species are relying on nectar.
Thom Canalichio:
And I imagine that to some, to some, depending on what plants we're talking about, caterpillars eating those plants might be considered a pest if it's, you know, a plant in your yard or in your garden. But what is important about that role in the greater, wider ecosystem, that caterpillars devouring leaves on plants is actually an important thing
Dr. Eliza Grames:
If we didn't, if we didn't have insect herbivores, then the world would just be completely green, right? That's one of the core questions in ecology, is, why is the entire world not just covered in plants, because they can photosynthesize and produce their own energy? And so, yeah, it really comes down to herbivory. And, you know, sometimes we think of, you know, ungulates or a deer who are browsing on plants. But really the bulk of herbivory is done by insects, insects who are really, really important herbivores.
Thom Canalichio:
So then going into the mature winged butterfly phase of life, for these creatures, they play a very important role in pollinating, and what other kinds of things and what is important for people to understand about their role in all of that?
Dr. Eliza Grames:
Pollination is one of the main ecosystem services that we get from insects. I don't know off the top of my head, what percent of plants are pollinated by insects as opposed to other insect pollinators, sorry, pollinated by butterflies as opposed to other insect pollinators, the pollination service is the main one that we get from insects.
Thom Canalichio:
Now, what do you think are the drivers of this decline?
Dr. Eliza Grames:
So we weren't in this study, able to exactly link drivers or anthropogenic stressors to the population trends, but there were some general findings that came out that kind of hint at what might be driving butterfly declines. So the first one is that in the Southwest region of the US, so New Mexico, Arizona, that's where we were seeing the steepest declines. That's also the hottest and driest part of the country, and it's also been warming up and drying out at quicker rates than other regions due to climate change. And so we think there's potentially a signal of drought there. Drought is really important for butterflies and insects in general, because they have really, really high surface to volume ratios, right? There's not a lot of like ‘juice’, I guess you could say inside an individual insect, relative to how big they are, and so they're really prone to desiccation in drought conditions. And then drought also affects their food resources, affecting host plants, which of course, then will have cascading effects up onto insects. So we think that might be a really important driver. Another regional signal that we saw is that insecticides in the Midwest are probably driving a lot of the insect declines there. There was a paper that came out last year by one of the status of butterfly's working group members, Braden van Danes, who was looking specifically within the Midwest, what's driving population declines there. And he found that insecticides more so than any other driver of decline more so than habitat loss, more than climate change, insecticides were the number one driver of butterfly declines in the Midwest and then in other parts of the US, there's a less clear signal as to what the key culprit is, although there are kind of indications that climate change might be driving declines in especially the Southeast, where we're seeing less severe declines for species that are occurring both the Northern and Southern part of the US. So comparing their population trends in the Northeast to the Southeast, we're seeing less severe declines in the Northeast. And so that's potentially indicating that species are moving northward due to climate change and slightly more buffered in the northern parts of their range. But again, we weren't able to conclusively test that as just kind of a general signal that leads to these sorts of hypotheses. But what might be driving declines, in general, with insects, declines are driven by many, many different factors, and it's typically not just one stressor acting individually. It's everything all together.
Thom Canalichio:
Tell us a little bit about the methods to the study you're looking at multiple over time population studies. What kind of methods were employed for your analysis across these different studies, and what were the methods of each individual study like for people to understand a little bit about that?
Dr. Eliza Grames:
We would be here for hours if I told you about the methods of every individual study. There was, I think it was 76,000 different surveys that went into it. There were 12.6 million individual observations of butterflies that went into the analyzes. So it was a massive amount of data aggregation, some of the key data sources that went in were what are called Pollard walks. So there's a lot of states that do regional butterfly monitoring using what's called these Pollard walks. They were initiated by someone named Ernie Pollard, who started doing these in the UK. And the idea is that you walk in a straight line, so you walk the same transect every single time you go back to survey, and you picture that there's a five meter box surrounding you, and you count every single butterfly that flies into that box to try to get sort of a density estimate. So that was one of the types of data sources that came in, especially from statewide monitoring programs. There was also one of the longest running. Actually, I think it is the longest running butterfly biodiversity monitoring program anywhere, which is Art Shapiro's transects in Northern California. So this is a set of sites that Dr. Art Shapiro has been visiting every two weeks, and counting the butterflies there since 1972 for some sites. So it's really temporally intensive, how much data is there. And then the third kind of key source of data that went in was the North American Butterfly Association (NABA), 4th of July counts. This is a citizen science, or participatory science program, where people go out in the area where they're most familiar with and they count all the butterflies that they can see during one single day, once a year, within a circle. So you have a fixed radius circle, and then you count everything that you see there. And that is where we get a lot of the really good spatial replication, because people have been doing these surveys also, they started in the 70’s, but have gotten much more popular in recent decades. And so that's why the analyzes are from 2000 onwards. That's when more and more of these circles, the NABA circles, is what we refer to them as. These are the Fourth of July butterfly counts that people have been going out and doing those surveys, which was a huge source of data that went into the analyzes.
Thom Canalichio:
Are these kinds of surveys, something that citizens can get involved in, to support if they're interested in What's that process like?
Dr. Eliza Grames:
Yeah, absolutely. You just find your closest Fourth of July butterfly count. You find out who's organizing it, and you ask if you can go and help out. One of the other really lovely things I think about the Fourth of July counts is that you don't have to be an expert, so some people are just interested in butterflies, and they tag along. You don't have to be able to identify every single species. Somebody is there who is an expert and really knows the local butterfly species. And so you can learn about what's in, sort of your backyard, while also contributing data to platforms that then let researchers work with and analyze that data.
Thom Canalichio:
And speaking of our own backyards, what are the kinds of things that people can do to have a positive impact on supporting butterfly and insect populations in general?
Dr. Eliza Grames:
So that one of the things that I think is a really kind of positive message related to insect conservation is that the things that we do in our own backyards actually do benefit insects and can help local populations rebound. The easiest thing to do, at least, I think it's the easiest thing to do, is to have a slightly messy backyard, so don't mow the entire backyard. Leave a little strip of wildflowers at the back for pollinators. Leave bushes, leave native plants. Little piles of sticks are actually really, really beneficial for a lot of insects. So not necessarily for butterflies, but a lot of solitary bees use those resources for nesting and just kind of having that diversity of habitats in a yard can really let populations rebound.
Thom Canalichio:
So over the time period covered by this analysis, you've estimated a total of 20% decline compared to 25 years ago, the potential impacts of that or the threat that that represents to the ecosystem or to the healthy environment in general. What are your thoughts about what kind of takeaway we should have about what that means?
Dr. Eliza Grames:
Yeah, I think losing one out of every five butterflies over 20 years should be a big wake up call to people, because, you know, these, these clients, are not stopping. We stopped the analyzes in 2020 because that's when we pulled the data from the database, but declines have obviously continued since then, and also started long before we were actually monitoring species. I like to think of it in terms of the scale of human history and how we've been changing the land around us. So if you think back to the Industrial Revolution, and then again, after World War Two, there was a really rapid burst in how much humans were changing the world around us. And so all of those changes are certainly going to have impacts on biodiversity, and especially on insects. Some of the longest running monitoring programs in the world, while one of them is Art Shapiro's transects in Northern California, which started in 1972, the UK butterfly monitoring scheme started in 1976 and that seems, I mean, it is. That's fantastic. Those are really wonderful long term butterfly monitoring programs. But I always come back to the fact that that's fully a decade after Silent Spring was published. So we already knew that there was huge ecological collapse occurring before we even thought to start monitoring species. So that 20% decline, well, 22% decline over just 20 years. It's really, really sobering, especially to think about what was lost before then and what we're continuing to lose as climate change and habitat loss and insecticides and agricultural intensification continue to accelerate,
Thom Canalichio:
What kind of research into this area is next to dig deeper into this?
Dr. Eliza Grames:
So some people are now looking more into the rare species and subspecies, so things that have really isolated populations where we didn't have as good of data before. Another thing that's come out of this is that we knew that there's 650 species that should occur in the US, but we only had monitoring data for 554 and of those 554 only 342 we had sufficient data to estimate the trend. And so that gives us a really great priority list of where we should go and do monitoring. So for the species that had a little bit of data, but not enough to estimate a trend, we need to go out and we need to do population censuses. And then also prioritizing where we do monitoring so many of the species that decline the most are in the Southwest, and so we really need to get boots on the ground and go and monitor butterflies, especially in southern Arizona, southern New Mexico, and then the Rio Grande Valley down in way south Texas, because that's where we're potentially losing a lot of species, but we don't have the data to understand it. And then the other angle of research, which is much more focused on policy, is figuring out, how do we prioritize these species? So now that we have population trends, we need to be able to do something about it and you know, support and promote conservation activities that will benefit these species, but trying to figure out where we begin on that list of things that's declining, that's a big, big question to figure out.
Thom Canalichio:
Any media on the call, you are welcome to ask any questions. Please chat those to us, and I'll ask them for you. With these populations, with these particular subspecies that have been harder to track or seem to maybe be more elusive. Does that indicate, in your opinion, that they might be threatened in some way, and how is that being tracked, which species, maybe, are in danger of extinction or other kind of threats.
Dr. Eliza Grames:
Yeah, absolutely. I'm very concerned about the species that are in that really a high declining category, where some species have lost 98-99% of their abundance since 2000 but also, yeah, the species that we didn't have the data for, potentially, they've already declined to the point of rarity. And so the way that we assess species for their risk of conservation or their risk of extinction is through the IUCN Red List. That's the most standard way of determining what species may or may not be most at risk of extinction. And the kind of key things that need to feed into these assessments is you need to know where species occur. So you need to have a range map, which we now have for all 650 butterfly species in the United States. So that's a great starting point, because once you have a range map, even if you don't have good population trend data, you know if it's kind of a narrow range, really restricted species, where threats that cover a portion of their range will potentially affect a lot of the population. You can also look at how threats are changing within a species range. So if some species are occurring in areas that have experienced more climate change or more agricultural intensification, we might be more concerned about them. So the range maps are really, really key to this assessment process. And then the other thing that is really, really good to have when you're doing an assessment of extinction risk is the population trend estimate. And so now we have trend estimates for 342 species. So that lets us go in and formally assess whether they are, you know, are they least concern, are they near threatened, are they vulnerable, are they endangered, are they critically endangered? So those two pieces of information give us a lot, a lot of what we need to know to be able to assess species for extinction risk. And then the third thing that you need is you need to know something about the habitats, the ecology, like, what does this species need to be able to persist? And that's a little bit trickier, because you have to find it in the literature. You have to dig through sometimes century old books when they describe these species about where they found them and where they occur. And so that's, that's an ongoing process. And there's, you know, so many species, it's hard to actually have individual experts do those assessments. So the IUCN butterfly and moth specialist group, who's the group that oversees all the red list assessments for butterflies and moths globally has started working with classes, especially entomology classes or conservation biology classes to get those assessments done. This semester, I'm teaching a conservation biology class at Binghamton University, and students in the class, for their kind of primary assignment for the semester, they've each been given a species and they're doing that Red List assessment. And one of the groups in the class actually ended up working on Julia Skipper, which is Nastra julia. And it didn't have a population trend estimate that they could find anywhere in the literature, but there's an estimate for it in this paper that's coming out tomorrow. So starting on Monday, they'll be able to fill out that section of the extinction risk assessment, because now we know that species is declining at more than 90% since 2000.
Thom Canalichio 24:37
Speaking of one of those species, a question in the chat here from Barbara Moran at WBUR in Boston. Welcome Barbara, thank you for your question. She asks about the Florida white, one of the butterflies in this report. It indicated that the decline was 100%. Does that mean it is extinct?
Dr. Eliza Grames 24:55
For that particular species, Barbara, I can look into it and email you about it. It's possible that it still exists. It still persists in other parts of the world, many of, especially the South Florida species, are also found in Mexico, like in the Yucatan, with kind of similar habitat, or elsewhere in the Caribbean, and so it's possible that it's not extinct, but it's extirpated from North America, which is a local extinction.*
*Nb: Within the United States, the Florida White has declined by 99.98% since 2000. It is still found in the US (i.e. it is not extirpated, but these analyses suggest it has declined precipitously) and is also still found in Central and South America.
Thom Canalichio 25:29
Great. Thank you. What other questions anybody might have? Please feel free to chat those to us. Thank you for that question. Barbara, big fan of WBUR. With people potentially creating some sort of pollinator-friendly habitats in their own yards and gardens. What kind of resources are available to learn about what proper species that might be, or techniques to accomplish that?
Dr. Eliza Grames 26:00
Yeah, that depends on where in the US you live. So you want to be planting native wildflowers that would normally occur in that area. So of course, it depends on where you live. The Xerces Society for Invertebrate Conservation has really fantastic resources listing what plants you might want to put in your garden for which state you live in, depending on what you want to support. So if you want plants that are going to benefit butterflies, they'll have a long list of things that you could pick up locally and plant. They also list what other species benefit. So you can find species that not only benefit butterflies, but also benefit bees or beetles. So it's a really fantastic resource that they've put together in terms of Yeah, figuring out what we should be planting in our backyards.
Thom Canalichio 26:43
And what kind of things should people not do in order to prevent unnecessary eradication of important insects?
Dr. Eliza Grames 26:52
Yeah, so I think in general, with pesticides, we spray a lot more pesticides than we really need to. And it's not just agricultural pesticides or insecticides that affect butterfly populations. It's things that we spray around our own homes. And so trying to figure out ways to limit that would be something individuals can do. One of the issues that we have, especially with trying to understand the effects of pesticides on butterfly populations around other insects, is that we don't have good data to understand how individuals are using pesticides. So what are the rates of pesticide application in residential and urban areas? We don't really know. So most of what we understand about the effects of pesticides comes from agricultural areas.
Thom Canalichio 27:40
Do you have a favorite butterfly species?
Dr. Eliza Grames 27:43
I do not. I try not to pick favorites for all the species that I work on, because I think that they're all really important. There are a few, kind of, like individual species, though, that I have a little bit of a soft spot for, because they represent, you know, really interesting questions or case studies. So one of those is the West Coast lady (Vanessa anabella). This is a species that occurs across most of the western United States. I did my postdoc out in the western US, and so I know the butterfly is out there a lot better, actually, than I know the ones at Binghamton and in this species. So it's super wide ranging. Covers most of the west coast. It's a habitat generalist. It's, you know, it used to be a really common backyard butterfly for many people, and it has declined just precipitously throughout its entire range. Everywhere that we have monitoring data for it, it is declining at really consistent rates. I came out in this study that it has declined in abundance since 2000 by over 80% and so that's really, really concerning, because from sort of a classical conservation perspective, we mostly focus on species with small ranges that are really restricted habitat specialists, or specialists in other ways, where maybe they have really limited diet, and it's none of those things. So it would not have been on our radar for something that needs immediate conservation action, if it weren't for looking at the population trends, because for everything we know about its life, history, and biology, it should be doing fine, but it's really declining very steeply.
Thom Canalichio 29:16
One final question, if you could tell me, what would you like for the general public to know about why this is important.
Dr. Eliza Grames 29:24
Yeah, the key takeaway that I take from this study is that, you know, we've lost one out of every five butterfly since the year 2000 and that alone, to me, if you think about, you know, what, what butterflies were there decades ago, what did we lose before then we should really appreciate the butterflies that we do still have. So when you go out and go on a walk or out on a hike and you see butterflies around you, you know, just think of how many used to be there, but also appreciate the ones that we do still have, and that we should be working to conserve those
Thom Canalichio 29:59
Great! Thank you so much Dr. Grames. For the media on the call, we'll share the recording and transcript of this discussion. If you have further questions, you can send them to Dr. Grames via John Brhel, the communications contact. I've put his name and email in the chat with that, I'd like to say thank you to everyone at Binghamton for helping to organize this. Thank you very much Dr. Grames for coming on and sharing everything. And to everyone, thank you very much for attending. Namaste and good luck.
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