Say Cheese: Wetland Wildlife Inventory

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HOST: This is the NOAA Ocean Podcast. I’m Marissa Anderson. Have you ever wondered what animals call coastal wetland areas home? In this episode, we explore how scientists across the National Estuarine Research Reserve System conducted the first-ever North American inventory of wildlife that reside in these habitats. It was done using cameras. And you might be surprised who showed up in their photos. Our guest today is Dr. Kenny Raposa, research coordinator at Rhode Island’s Narragansett Bay National Estuarine Research Reserve and lead scientist for the study. Let’s dive right in…

HOST: So let’s kind of start from the top. Could you give us the 30,000-foot view of what this project is about?

RAPOSA: [laughs] Yes, that’s a great view to start with. This project was the first-ever effort to use camera traps to inventory, assess, quantify wildlife use of coastal wetlands at a broad spatial scale. The scale we focused our study at was continental; we did sites all over North America.

HOST: Can you explain what you mean by “camera trap”?

RAPOSA: It’s a specific way of using — I think what everyones knows — as, you know, wildlife cameras or game cameras. You put them out in your backyard to look at animals around your house and in your yard. When you use those game cameras for science, using specific methods and protocols and analysis techniques, then we refer to them as camera traps. And that's what we used in our study.

HOST: How did this project come about?

RAPOSA: [laughs] Do you want the short version or the long version?

HOST: We’ll take the long version!

RAPOSA: [laughs] The longer version — and I’ll try to keep it relatively brief — but the way this came about initially was back in 2019, and at that time in our state, we had a couple large-scale marsh restoration projects going on. One was an older study, so that marsh was well on its way to recovery; and another restoration project that was quite new, so that marsh was just beginning its recovery, and at the same time, I had an intern that summer, and she actually had a little bit of extra time on her hands, so we worked together to figure out sort of a side independent project for her to do to help out the reserve, and of interest to her, and so again, long story short, we had these game cameras at the reserve that were not being used, and we thought that it might be fun and interesting — again not knowing what we’re getting in to — but fun to put these game cameras out at these marshes to see if wildlife use varied across the marshes in different stages of recovery. What we found was shocking in a couple of different ways. I was shocked that having not used these before, I was shocked at the quality of the data. So in just a very short time, just in one summer, we collected really quantitative data that we could use to show that the wildlife using these wetlands was statistically different, and it was even more shocking to me, the quality of the images that were coming back from these cameras. We knew that wildlife were using these wetlands, but I guess we never really thought about the diversity and richness that was out there, and so what we were seeing on these images coming back from the cameras was really kind of shocking to us. Just being able to see what was out there at night, and at different times of the day when we’re not out there was incredible to us, and so I think from that moment on, I was kind of hooked on using these things in wetlands both for science and for outreach and education. So then I thought that if we could use them here in Narragansett Bay, wouldn’t it be cool to do a broad-scale survey using these things across the entire reserve system.

HOST: So in the study, what animals have you captured with the photography?

RAPOSA: It’s almost easier to answer, like, what didn’t we see? We saw — again, this was a study at 32 sites in the U.S., Canada, and Mexico, just in the summer of 2022. And so with that effort we saw, I think it was almost 150 species across all these sites, which was much higher than any of us had expected. Again, this is wildlife, it falls into three categories; we saw mammals, birds, and reptiles using these wetlands. So by far, most of the species were birds, all sorts of different kinds, from raptors, you know, eagles and hawks and owls; wading birds like herons and egrets; water fowl; song birds, of course, etc, etc. For reptiles, we didn’t get that many of those, but what we saw were things like iguanas in the mangroves down in Hawaii and in the Caribbean; we saw snakes and lizards out in California marshes; and turtles and alligators in the Southeast. Things like that. And then for mammals, I think there were about 40 species of mammals that we found across the study. It ran the gamut. We saw a lot of ungulates, meaning deer, white-tailed deer, black-tailed deer, elk in the Pacific Northwest. We saw lots of canids, meaning dogs like coyotes, even gray wolves up in Alaska; bears; mountain lions; raccoons; otters. All sorts of different incredible mammals out in these wetlands. So we saw an incredible diversity and richness of wildlife in the wetlands.

HOST: That’s so fascinating. I’m sure through the use of these trail cams, it gives you the opportunity to see animals that you might not have encountered if you had scientists actually out there in the field trying to observe them live, right?

RAPOSA: I’ve been in coastal wetlands for my entire professional career, which spans 25 years, and you do see animals out there, but not very often. You might see some birds flying around here and there. The vast majority of the animals we found with the study are very cryptic, so they’re either really abundant at night, or they’re just sort of avoiding people in general, so it just sort of shows that there’s a lot more out there than you think.

HOST: Did you notice in the studies, were there any animals in particular that enjoyed the limelight more, if you will, and tended to show up on the cameras kinda more frequently?

RAPOSA: [laughs] There were. I will say we’re in the process of publishing a paper from the study right now and so I’m working up all the data and doing all the analysis. One of the things we did is we quantified the abundance of all the species we saw across the study and at the individual sites. And so looking back at those data, we have them tallied by the most abundant species listed in descending order. And so I’ll just read a few of them, so the most abundant species we saw by far across the survey was white-tailed deer; so they made up about 40% of all the animals that we saw out in these wetlands. So deer were extremely abundant in these wetlands within their range, which is all over the East Coast, in the Gulf of Mexico, and into the Great Lakes. So white-tailed deer were by far the most abundant. Followed by things like raccoons, particularly down in the Southeast — very abundant down there. Coyotes were surprisingly common at wetland sites across all the coasts in our study. Things like great blue heron, Columbian black-tailed deer or mule deer out on the West Coast, crows and ravens, surprisingly feral pigs — so wild hogs — were extremely abundant at half a dozen sites mostly focused in the Gulf of Mexico and out in Hawaii. And on and on, great egret, Canada goose, red-winged black bird, and even turkeys were quite common across the study as well. Those were some of the most abundant species that we saw from this effort.

HOST: I had the opportunity to visit the albums where they had some of the photos and I encourage everyone to look at it, it was so interesting. It’s funny, you see some of the animals kind of doing their own thing, going about their business, but some, I guess, kind of caught the camera and were curious about it, and had like some good selfies, if you will. So that’s very entertaining.

RAPOSA: [laughs] Ah yes, no doubt about it, deer in particular like to take selfies; cattle down in Texas were good at that, yeah. A lot of them are not shy.

HOST: It’s great that with the advances in technology with these trail cams that they can just provide such insight into these habitat areas and then also the secret lives of the animals that live there.

RAPOSA: That’s really what this shows, is that, you know, again — even for us that are out there — it’s shocking to see what’s there when we’re not there.

HOST: What have been some of the challenges, if any, that you’ve encountered in this study?

RAPOSA: There were definitely challenges. I’d say the number one challenge by far was the — and I kind of expected this, but not to the degree that it turned out to be — it was challenging just to process all the images themselves that came back to me from these cameras. So again, these cameras take photos, they’re motion detection cameras, and they're out taking a picture anytime something triggers the sensor. So they end up in wetlands where there's a lot of moving grass and leaves and shrubs and such. They end up taking a lot of images where there's nothing in them, no wildlife in them. But you still have to go through all those images to look for wildlife even if there’s nothing there. So I never tallied how many images there were across the entire study, but I estimate there’s gotta be at least 150,000 or so that came back that we had to go through. And there's a number of different ways to go through images and process them. We did it very old school, where we just did it all back at the Narragansett Bay Reserve. I did about 90% of it myself with help from a few summer interns. And I never quantified how long it took me, but it was shocking how long it did take me to process all those images and identify the species that were in there, count them, and all that kind of stuff. That was a huge challenge, just going through all the images. Another one, more generally, was just sort of — again, we worked with 32 sites across the continent — and so it was challenging in a way to just make sure — it was just me at my site in Rhode Island — trying to coordinate all these people doing the work across all these different diverse sites. So, challenging to make sure that they were doing things the way we needed them to do them to ensure that the data would be comparable across the sites. We wrote a protocol for them to all follow and by far most of them did, but it was still challenging to make sure that everyone was doing what we needed them to do, from just based at my site here in Rhode Island.

HOST: Yeah, I can’t imagine the length of time for just reviewing the photos. Animals too, they also have great camouflage, so you really need to be able to focus and really analyze each individual photo to make sure you’re not missing anything.

RAPOSA: And it was really challenging in another way because again, I know the wildlife species here in New England pretty well, but we were trying to identify these things across, you know, out in California, in Alaska, in Hawaii, and the Caribbean. So there were so many species I had no idea what they were, so we ended up having to work with experts at each individual site, to go back and forth, and have them really help me identify what we were seeing. So it took quite a long time to do that.

HOST: And were there any species in particular that kind of surprised you that resided in a specific location?

RAPOSA: Quite a few! But I mean, and again, just keep in mind, I’m very — I’ve done most of my work in New England, and I have no idea what’s going on in a lot of these other sites. So it really was surprising to see things like Asian mongoose all over the mangroves out in Hawaii, and to a lesser extent, in the Virgin Islands. I would have had no idea you have mongoose in these wetlands. Armadillos down in Texas. I mean, that was shocking for me to see those animals. Another one was, and again, I think it's well known to folks at those sites, but for me it was really shocking to see the amount of feral animals, feral and domestic animals using these wetlands. So I mentioned feral pigs, they’re really abundant at sites — say, down in Texas and the Southeast, where they do a lot of damage to the marshes through trampling and digging. Cattle — quite abundant down in Texas as well. So, just surprising to see all these feral, domestic species using the wetlands, which we don’t really see here up in New England.

HOST: Were there any other interesting trends that you noticed so far?

RAPOSA: Yes, there were. So again, the main goal of the study was to do this first sort of basic inventory and survey of wildlife across these sites. In addition to that, we also asked some specific questions about how and when these animals were using these wetlands. So we looked at sort of spatial and temporal patterns of wildlife use of the wetlands in the summer. So, from those questions, we saw some really clear patterns. Like over time, we saw what species of wildlife were using the wetlands based on the time of day. Birds, for example, almost exclusively used these wetlands during the day. And like I mentioned, you can see some of them flying around when you’re out there. But mammals were the exact opposite. Almost all of the mammal species are skewed to being most abundant at night. They’re very nocturnal; some of them are crepuscular, using them during the dawn and the dusk. But by far most of them were at night. So we saw that clear pattern there: birds during the day and mammals at night. We also looked at wildlife use across the tidal patterns, the tidal cycle. And from there, we saw that abundance and richness was dramatically higher in these wetlands at low tide, when the marshes are not covered in tidal water. And at high tide, when they are flooded, the wildlife was much less abundant and less rich. Not to say that there aren't wildlife using those wetlands at high tide, because there are herons and egrets up there foraging; there are water fowl, ducks and geese and things like that up there in the marshes as well when they’re flooded. But by far, abundance and richness were much higher in these wetlands at low tide. And then we did some simple habitat comparisons as well to see, to look for spatial variability and how these wetlands are used by wildlife. And so, we found a couple of things there, we found that — we call it habitat heterogeneity — but basically, when there is a number of different habitats in one wetland, compared to a wetland with just one or a smaller number of habitats. When the habitat diversity is higher, so is the wildlife. More species and more of them like to use these wetlands when there are a lot of different habitats in there to use. And then we also compared wildlife using the wetland habitats themselves to wildlife using what's called an ecotone. And so it's basically this narrow habitat band that straddles between the wetland and the upland. It's basically where the wetlands are sort of migrating into the uplands over time. And so we compared wetland wildlife versus ecotone wildlife, and we found that there were no clear patterns there, but we saw that there was a lot of variability in how wildlife use these habitats from site to site. Meaning in some sites, it was more wildlife species and abundance in the wetlands versus the ecotone, whereas at other sites, it was the exact opposite pattern, more animals up in the ecotone versus the wetland.

HOST: That’s really interesting to note, that how the diversity of the wildlife increased if the wetland area itself kind of had a diversity of ecosystem.

RAPOSA: Yup, yeah for sure. Again we — most of the cameras were placed in wetlands that just had just one habitat type, it was in essence vegetative salt marsh. But a number of cameras had in their view field the vegetation as well as, like, bare areas or salt marsh pools that hold water throughout the tidal cycle. Pans that are sort of degrading areas, and so when you have features like that within the marshes, within the wetlands, there was noticeable increase in the species that use the wetlands. In particular, things like raccoons loved to forage in these bare areas, and in these pools. Wading birds are foraging in the pools as well. So yeah, when there’s more habitats in the marsh, you tend to see more species of wildlife.

HOST: Why is it important to study species living in these environments?

RAPOSA: In this case, it's a huge knowledge gap. There's so much work with camera trapping wildlife in terrestrial habitats over the last decades, but almost nothing’s been done in coastal wetlands. And so this was just a first stab. I think it was important to do this study because we just didn’t know what kind of animals and wildlife were using these wetlands over space and time. That was one of the reasons we did this, but like I also mentioned, I think it's — another reason it’s important to do this now, is that we are, in fact, seeing these wetlands degrade and lose area over time. There's a lot of stressors on these wetlands. One of the main ones is accelerating sea level rise; these marshes just can’t keep up with sea level rise, and so they are sort of drowning in place in many regions. There’s other stressors as well. If we are losing these wetlands over time, and projections in the future suggest that we are going to lose them at a more rapid rate, then I think it's important to know what we might also lose in terms of their ability to support coastal wildlife. So that's sort of, I think, another reason we did this study now. We wanted to set the baseline for what's using these wetlands now so we can better understand in the future what might be lost as these wetlands degrade over time.

HOST: In addition to that, I just feel it's such a great way to also promote awareness of these environments and the species that live there with the public, that just having the photos, the albums, getting to see the animals — I think it just really appeals to a lot of people.

RAPOSA: Yup, we’ve worked with some outreach folks that are associated with the reserve to do just that. I think you’ve seen those photos yourselves, and so we are exploring different ways to get these photos out so that they’re accessible by the broader public. Yes, absolutely, you know, I’m interested in the data and the science that we can use these cameras for, but of equal value is the outreach and the education that these photos can provide.

HOST: This is the NOAA Ocean Podcast. Visit our show notes for the links to the photo albums from this wildlife study and to learn more about the importance of coastal wetlands. Thanks for listening, and don’t forget to subscribe to us in your podcast player so you never miss an episode!