Agrifood Safety Produce Bites

How Risky Are Birds to Produce Safety?

April 01, 2022 Michigan On-Farm Produce Safety
Agrifood Safety Produce Bites
How Risky Are Birds to Produce Safety?
Show Notes Transcript
Alison Work:

Hello, and welcome to the agrifood safety produce bites podcast, where we discuss all things produce safety, and dive into the rules and regulations surrounding the Food Safety Modernization Act Produce Safety Rule.

Olivia Smith:

I'm Olivia Smith. I'm a postdoctoral researcher at Michigan State University.

Phil Tocco:

I'm Phil Tocco. I'm with Michigan State University Extension. I'm based in Jackson County, but I cover the entire state with respect to on farm produce safety. I'm just curious a little bit about your background, Olivia, like where you're from, and what you've been doing and that kind of thing.

Olivia Smith:

I'm from Southeast Michigan, Lenawee County, and then, I've been gone a while, like, I went to Ohio State for a master's and then Washington State University for a PhD and then University of Georgia for a postdoc. And then I came MSU wanting to be back in Michigan. So that's kind of my journey back here.

Phil Tocco:

And how much of your role currently is in produce safety? Is it mostly just bio control, or do you do a lot of food safety stuff?

Olivia Smith:

I have been working maybe 50% of my time is dedicated to trying to understand how to manage birds, thinking about food safety issues, how big of a risk they really are, and then how to reduce that risk. And then maybe the other half is a mixture of bird, pest control services. And then there's another project that's totally unrelated to birds and agriculture.

Phil Tocco:

Well, cool. So I'm curious because I've always thought about birds being pretty monolithic. All the birds that I've ever known have had some, I mean, I always think about birds as being salmonella vectors, they've all got, in every piece of poop that comes out of a bird, it's gotta have salmonella in it. I expect it if one piece of poop is one thing, lots of poop is still just as bad as one piece of poop. So I'm curious, you're telling me that's not the case? You're telling me that, that there's some differential risk involved in that?

Olivia Smith:

Yeah, so maybe to start with salmonella, we actually haven't found much salmonella in bird feces that, you know, that's obviously a concern for farmers. But in the work that we've done, it's pretty rare at about .5% of the birds that we tested their feces had salmonella, so it's actually pretty uncommon.

Phil Tocco:

Okay, so I guess my question then is if if salmonella isn't the issue with birds, is there a food safety issue with birds? I mean is it like a different bug?

Olivia Smith:

Yeah, I guess, maybe not a zero or one answer. So with the birds, the most common foodborne pathogen that we find is Campylobacter, which is thought to be a wild bird commensal, meaning that it's, it just kind of coexists with them and doesn't cause them any problems. And e coli also is pre tty rare. It was even stack specifically as we were looking at was even less common than salmonella. So Campylobacter seems to be the most common in birds. And then what we were interested in also was kind of thinking beyond if the birds have the pathogen or not. And then thinking about, you know, for example, you could have a fly catcher, and the fly catcher could be in your forest right next to your crops, and then if that fly catcher, maybe it has salmonella, but if it's not actually flying into the crops, and it's not moving the salmonella onto the crops, so we were interested in thinking about how common it was that birds would both have the pathogen and then move into the fields and actually deposit the pathogen on the crop.

Phil Tocco:

Okay. So, if I'm trying to rank risk, or if I'm trying to think about risk of a particular population, I've really got to think about more than just, I got lots of birds. There's a problem, I have to think about maybe what kind of birds they are. What other key things should I grow or think about in terms of determining whether or not a population is really going to cause a problem versus one that's just kind of, you know, just there?

Olivia Smith:

Yeah, I think, um, the first thing that I think is important to think about, which is kind of where we started with our research was thinking about the farm's context. So are you a farm that is right next to a feedlot or are you a farm that's in the middle of a forest? If you're a farm that's in the middle of the forest, your birds probably aren't a huge issue. But if you're a farm, and you're right next to a feedlot, the birds are probably going into the feedlot where they could be picking up the pathogens. So kind of step one would be, where am I? Is it an environment that likely has the pathogen in it? Or am I in a pretty natural setting that might not have the pathogen? And then the second step is the types of birds that are there. So are your birds, the types of birds that are going to be foraging amongst cattle feces, which is pretty risky, as opposed to birds that are up in the tree canopy, which probably have pretty low exposure? And then kind of your third thing to think about is, are the birds actually foraging in my crop or not? And if they're not in their crop, then they're probably not going to contaminate it.

Phil Tocco:

Okay, cool. It's interesting. Now, is there a way we can rank each of these different things? Or are they all the same risk sort of profile so that if I've got one that's really high probability, or like for instance, let's say I'm close to a feedlot and and maybe I don't see a lot of birds in my in my produce? Is it one of those things where one cancels out the other? Or is there one that's like, this is a super huge contributor to risk so I need to really worry about this one first?

Olivia Smith:

In terms of specific bird species to be concerned about?

Phil Tocco:

Whether it's bird species, whether its behavior, whether its prevalence, any one of those things? Is one of those more important than the others is I guess what I'm asking, and if so, what would be the most important?

Olivia Smith:

Yeah, that's a really interesting question that, I'm gonna say, first of all, I'm not entirely sure kind of where the inflection point is between having a lot of pathogen and being in the crop a lot. But I think what we're trying to think about is kind of the interface of those two, so kind of the joint probability of them having the pathogen and being in the crop, and then where is that the highest?

Phil Tocco:

Cool, okay. You're basically doing cutting edge research, so we're kind of at the edge of our knowledge base, and we keep pushing it. So I totally understand. "I don't know" is a perfectly good answer to that question. Anyway. The other thing, too, that that I saw, when I was reading some of your stuff, you use this word co management. Help me understand what that means, and how your work could help me achieve it.

Olivia Smith:

Yeah, so we are really interested in trying to figure out how to manage birds and agricultural systems for all of the good and bad things that birds do. So birds, for example, can eat Spotted Wing or soft low, which is really good for fruit growers. However, they also eat the fruits. So that's bad for fruit growers. And then you might also think about their Falcons that deter the rodents, but then the same birds can also carry the pathogen, and then we're interested in conservation. So thinking about all of these good and bad things of birds do, and trying to figure out how we can manage farms to try to promote the good and deter the bad. So we're really interested in understanding how the broader land use context, for example, what your neighbors are doing, interact with what you're doing to try to have birds that are more beneficial and less harmful.

Phil Tocco:

That's, that's great. That's, you know, and we hear it bandied about a lot. I think what's neat is the fact that this fits in your your research in your in what you're trying to, to work on, really is in a broader context, what's happening across a lot of different disciplines. I know with our new water rule coming in, they're talking about doing a risk analysis and really thinking about the the total risk that that a water system poses to the crop. So you're not just looking at hazards, but you're looking at how those hazards interact, to form an overall risk profile. And it sounds like that's what you're doing but with birds, so it's really neat. It's refreshing.

Olivia Smith:

Thank you!

Phil Tocco:

A lot of what I do is education around produce safety specifically to farmers. And so, you know, one of the things that we're going to try and keep doing is bringing some of the research that's in process or beginning and really pushing it forward so that the growers get a chance to see what's coming. And I think that's why, when I read your paper it was like, this is exactly what we need to be talking about. The qualitative risk analysis of everything is really something that across the board we're seeing,

Olivia Smith:

Yeah, while you're kind of talking about the next wave of stuff I was thinking maybe you'd be interested in what we're doing in Michigan?

Phil Tocco:

Absolutely. What are you up to in Michigan?

Olivia Smith:

Yeah, so we have a project in the Traverse City area, working in Cherry orchards. And our question was, on the one hand, how likely are birds to contaminate fruit? So thinking about the probability of the cherries having feces on them? And then of those, how many have pathogens, and then we were interested in if growers could install nest boxes for American Kestrels that are predatory Falcons? And then if they install these nest boxes, could that improve food safety? And the thinking is that prior work at MSU by Catherine Lindell's lab has shown that these predatory Falcons can reduce bird abundances in the orchards. And so there are fewer birds, there should be fewer feces. And so we've done one year of data collection, and it seems from the first year that Kestrels might be a good way to improve food safety. But we also we tested 153 fecal samples for Campylobacter and only one of them was positive. So, the birds up there probably aren't a huge issue.

Phil Tocco:

Well, I'm curious to how that would interact with the way they're harvested. Now, did you do this in tart cherries or sweet cherries?

Olivia Smith:

We were specifically focusing on sweet cherries. As I'm sure that you know, the blocks are typically directly adjacent. So the Kestrels are, you know, moving back and forth. But we were focusing on the sweet cherries because previously Katherine had seen more bird activity in sweet cherries.

Phil Tocco:

Well, the reason I ask is not so much because they're one right next to the other, but because typically they're harvested very differently. Some sweet cherry trees are hand picked, in which case, you have a really high selectivity for for things where there's no poop on I mean, they're they're really selective the, the, the harvesters are very selective about what they pick. And they don't pick poopy produce. That's our big mantra is don't pick poopy produce. Whereas tart cherries and even some sweet cherries are shaken. And then they're put in to basically a big cherry tanks are basically a big tank of water and they dump them in. So you can you can imagine if you have just one cherry that's got poop on it, all of a sudden you have an entire cherry tank with poop in it. See what I'm saying?

Olivia Smith:

Yeah, the people that we worked with the summer all use the machines to harvest we didn't see anyone hand picking where we were. So yeah, that's an interesting, we haven't looked in our work at kind of the likelihood of post farm processing, like once it gets to the processing plant, it could definitely have very different dynamics,

Phil Tocco:

Right. And I mean, to my mind, if you're dealing with a cherry shaker, and let's say you have even a very small percentage of of Campylobacter ridden fruit, that fruit is going to have food contact surfaces all along the way that it touches. So it doesn't take a ton of poop in order to cause some pretty significant, you know, downstream negative impacts. So, again, we need to know how much is happening in the field first, and then once we do we can figure out you know, obviously, whether or not that stuff actually moves, or if it contaminates food contact surfaces and whatnot.

Olivia Smith:

Yeah, that's pretty interesting future work, and then kind of thinking along the lines of maybe how long these bacteria will survive. We have a new grant with the collaborators at UC Davis, where we're gonna be inoculating bird feces with e coli, and then seeing how long it's viable on lettuce. So we have some projects in place kind of looking at these next steps beyond what, you know, right now, we're kind of looking at the, the first part of the pathogen contamination equation of how many birds have it, how likely is it to be on the produce and then now we're, we're starting to move more into the survival aspect.

Phil Tocco:

Sweet. Yeah, I mean, that's, that's interesting because to my mind, the next step when you when you talk about that, you know, in when it's in a matrix like when it's in a, i n the matrix of feces, sometimes it could potentially be protected against some of the things that we think deactivate those those bacteria or kill those bacteria. And in some cases, it may actually be in in competition with stuff that's in, in the poop. So you never I guess you never know until you test it.

Olivia Smith:

Yeah, we've been wanting to do a project for a while looking at how the microbial diversity in the feces influences survival, but we haven't gotten to it. So maybe if any researchers listen to this, that would be really interesting to do.

Phil Tocco:

Okay, sounds like sounds like you have literally a careers where the research ahead of you that it's like, okay, I can do this now. Yeah. Well, thank you so much for talking with me today.

Olivia Smith:

Yeah, thanks for having me.

Alison Work:

Links to anything referenced in this episode are provided in our show notes, which can be accessed on the website at canr.msu.edu/agrifood_safety. Thank you to everyone for listening, and don't forget to tune in next month for another episode of our produce bites podcast.