Transcript
[00:00:00] Andony Melathopoulos: I think everybody knows by now that Monarch butterflies are experiencing a good decline here in north America. Now many people, volunteers, people listening to this show as well as researchers and organizations are committed to the recovery of these butterflies. But any strategy around butterfly recovery has to understand the mechanisms of decline.
[00:00:23] And that's why I'm so excited to introduce today's guest. Dr. James Tracy now Dr. Tracy. Post-doc in the Robert Colson lab at Texas a and M he's been working on some really innovative modeling to show a significant mechanism of Monarch decline that is collisions with butterflies on interstates.
[00:00:45] And he's also come up with some real. Amazing insights into where these collisions are occurring and how we might be able to reduce those collisions. So in this week's episode, we have Dr. James Tracy talking about how to understand the effect of interstate collision with Monarch butterflies this week on pollination.
[00:01:15] All right. Welcome Dr. Tracy to pollination. Hello, how are you doing fantastic. You gave a great talk at the anthropological society of America who has just left the sessions. We're here in Denver on monarchs. And just to begin with there's a lot of concern over Monarch butterflies and and their migration patterns.
[00:01:30] Can you tell us. About, I guess the other factor of this is that highways and other things are transecting this migration pattern. Can you tell us a little bit about some of the critical points in the migration pattern of these butterflies?
[00:01:42] James Tracy: There's something called the Texas, Oklahoma.
[00:01:45] Funnel. And that's where the spring monarchs come through this narrow area and they lay their eggs and Texas and Oklahoma. And then in the fall, monarchs come down through this narrow area and large numbers in directed flight and cross roadways. And there's actually some high roadkill mortality in Texas and Mexico.
[00:02:00] So to something we've been investigating for several years.
[00:02:03] Andony Melathopoulos: Okay. So let's just review that. So there's some areas where are really a lot. Butterflies are moving through. There's a lot of roadways and there's this potential for roadways having these impacts through collisions mainly. Can you so you've been looking at this question.
[00:02:18] And do you D conducted a research project? Tell us a little bit about how you how you measured. Is it possible to account for mortality of butterflies? Is it visible? How do you actually measure
[00:02:27] James Tracy: that? So we had a large survey area that two thirds of the Eastern half of Texas.
[00:02:32] What we did is set up 100 meter transects, every 30 to a hundred kilometers along major roadways. And so we might have around 200 transects in a fall period or a spring period when we were doing the surveys and we not only surveyed the dead monarchs and these a hundred meter transects, but the milkweeds that the Monarch larvae used as host and that are important nectar plants as, and also the non milkweed nectar plants.
[00:02:57] And there all, these are very common along the highways and they're very important. The Monarch. So there's a positive and negative aspect that we were looking at on these roadways. And
[00:03:06] Andony Melathopoulos: I imagine as you walk along the road side, is, are our dead monarchs visible? Or do you have to really look before you find them?
[00:03:12] James Tracy: Sometimes we wouldn't find any in a hundred meters and, but sometimes we'd find up to 95 dead monarchs. And that wouldn't be very visible. And sometimes these hotspots as we call them what stretch for miles, maybe the first year we did the surveys in 2016, there was about an 80 mile stretch of dead monarchs along interstate 10 in west Texas.
[00:03:30] That was very striking and textile personnel happened to be out there and saw it. And it was part of the impetus that got us funded for the last couple of years. Looking at this,
[00:03:41] Andony Melathopoulos: the department of agriculture concerned about these butterflies, the tech stock. Okay. Transportation. So much.
[00:03:48] Okay. I, so you've got this data where you have bee plant sorry, butterfly plants, and you've got a dead butterflies. How were you able to w how were you able to characterize, spatially, how different areas are priority? I imagine you saw a lot of variability.
[00:04:03] How do you boil that down into something that's useful for a department of transportation?
[00:04:07] James Tracy: So we really had to do random surveys. Because we didn't want to just concentrate on areas where there was a lot of roadkill that would buy us to study. So we did survey a large area, but sometimes we would stop and do extra surveys where we saw a lot of milkweed just to check and see if there was a lot of roadkill there too.
[00:04:24] So we made sure we had enough data to look for correlations and we did find the quarter. Where we have a lot of milkweed or a lot of non, non milkweed nectar plants. Sometimes in some years, we'd get a little bit more Monarch roadkill, but we don't know if it's really enough to offset that benefit of these plants that have for the monarchs.
[00:04:42] And that's something that needs to be looked at more.
[00:04:44] Andony Melathopoulos: And if I recall from your presentation, it, the presence or absence of those plants for one thing, but the real driver of mortality was something completely different sort of geographical and character. Can you explain those findings?
[00:04:56] James Tracy: So what we found is these large hotspots were located in west Texas along draws.
[00:05:02] Apparently monarchs will follow draws and arid areas because there's more moisture, more plants, nectar plants. And when they cross the roads in these draws, that's where we're getting the big hotspots on the coast. It was a totally different picture. The monarchs were crossing bay. And the causeways that cross those bases, where we were saying the high mortality and what we think happened, there is the monarchs followed a peninsula out into the bay to try to stay over the land.
[00:05:26] And that's those peninsulas carried the causeways and they stayed on those causeways and that's where they were getting killed.
[00:05:31] Andony Melathopoulos: Oh, that's fascinating. So the first one makes sense. You have these draws, maybe some more moisture, more plant density. And so they're coming down. These draws, they hit the highway and then they get hit.
[00:05:40] But the second one's a little bit more puzzled. I'm coming down the coast and they hit a peninsula. Why are they getting hit on the causeways?
[00:05:46] James Tracy: It looks that they'll stage themselves and sometimes form reus around these peninsulas before they cross the bay. So the gathering in large numbers, and then they probably follow these peninsulas and try to hug the land instead of getting out of open.
[00:06:00] And maybe even hugged the causeways. And of course that's where they're going to run into cars.
[00:06:05] Andony Melathopoulos: All right. So I guess the implication of this work, there's two things that come to mind. The first one is this week, a relationship between plants and roadsides that they're having a Monarch.
[00:06:15] Milkweed and nectar plants on roadsides in may, maybe the benefit outweighs the re the,
[00:06:22] James Tracy: yeah, we think it probably does. The correlations are very weak, but that's all we need to look at is how many monarchs do you get per per milkweed plant along a roadside area versus how many dead monarchs do you get?
[00:06:33] When you have more milkweed plants. And we think it's probably going to be a benefit to have those milkweed plants and ectropion. But
[00:06:40] Andony Melathopoulos: the big area seems to be where you have these draws, these hotspots, where mortality is occurring. Can anything be done? Can department of transportation do any kind of mitigation on existing road roadways to lessen this.
[00:06:55] James Tracy: Yes. Textile is a very interested in trying to do something about this and what they wanted us to look at is something called flight diversion nets. And these have been used in Taiwan successfully to reduce road mortality by over 85% for the migratory purple Crow butterfly. They fly in large numbers over this bridge every spring, but when they put up the nets, they cut.
[00:07:16] The mortality by 85%. We think that thing, the same thing would work for the monarchs. And they're wanting to test that out along interstate 10, where we have these hotspots and also along the causeways where we have on the.
[00:07:29] Andony Melathopoulos: Can you describe these nuts? I'm having a hard time envisioning what this might look like on the side of a road.
[00:07:34] James Tracy: So the nets are made out of an orange shade, cloth, tarp they're 12 foot high, and they're meant to be sturdy. And the winds that you can get along the coast and out in west Texas, but also something that the air can pass through, but definitely the monarchs would want to pass over. And if they keep can keep their height, it's cross the inner.
[00:07:52] Which is the key, which is the interstates are very wide out there, then maybe we can reduce some mortality.
[00:07:58] Andony Melathopoulos: Fantastic. And I guess the final question I have for you is you showed at the beginning of your talk, the decline in monarchs across the U S how do you have any sense of how important this a roadkill mortality is in the scheme of.
[00:08:11] James Tracy: Yeah. So the there's been a 75% decline of monarchs in the last 25 years. And we fit at an exponential model to that. It shows that there's a 7% annual decline and so 7% of the monarchs are. And those are going down annually, but we found out that over a third of that 7% can be attributed to roadkill in Texas roadkill comprises is about 2.5% of the overwintering population.
[00:08:36] So 2.5% is a big part of the 7% decline. This is
[00:08:40] Andony Melathopoulos: great. Thank you so much for your work. And I'm looking forward to seeing more findings out of this research. It's certainly of a national importance. Very much. Excellent. I did get.
Monarch butterflies have been experiencing declines in North America. In this week’s episode we hear about the significance of monarch butterfly collisions on interstates and an innovative method to reduce this source of butterfly mortality.
Dr. James Tracy is a postdoctoral fellow in entomology working in Dr. Robert Coulson’s Knowledege Engineering Laboratory. He received a Master of Science in Entomology from Kansas State University in 1986 and a Bachelor of Science in Entomology from Texas A&M in 1983.
James is interested in insect ecology related to the use of insects in biological control of pest or invasive organisms. He also is interested in landscape ecology involving applications of species distribution modeling using Geographic Information Systems (GIS). James’ thesis project involves studying landscape-level interactions between introduced tamarisk beetles (Diorhabda spp.; Coleoptera: Chrysomelidae) and the federally endangered southwestern willow flycatcher (Empidonax traillii extimus) that will nest in tamarisk in the southwestern U.S. Three species of tamarisk beetles were introduced into the western U.S. for biological control of invasive tamarisk along rivers from 2001–2009. Part of his research involves developing megascale (1 km resolution) species distribution models using climatic data and Old World distributions for three species of tamarisk beetles and combining these models with dispersal models to predict arrival of beetles in areas with flycatchers. Another part of research involves developing microscale (1 m resolution) flycatcher habitat suitability models for simulating both the negative effects of tamarisk beetle defoliation and tamarisk dieback and the positive effects of habitat restoration measures on the habitat suitability of the flycatchers at specific locations.
James has 22 years of experience working as a biological science technician (insects) for the USDA Agricultural Research Service in Temple, Texas in a weed biological control laboratory under Dr. C. Jack DeLoach. Their primary research involved the use of tamarisk beetles in biological control of tamarisk. While at USDA, James published a monograph on the taxonomy and biogeography of tamarisk beetles. His Master’s thesis project at Kansas State University involved studying the reproductive biologies of Ooencyrtus spp. egg parasitoids (Hymenoptera: Encyrtidae) useful in biological control of squash bugs (Anasa tristis, Heteroptera: Coreidae).
Links Mentioned:
The Knowledge Engineering Laboratory (KEL) is a facility of the College of Agriculture and Life Sciences at Texas A&M University
