Latest / Okay, But... Birds / Okay, but what happens when a bird gets sick?

Transcript

Okay, but what happens when a bird gets sick? · Okay, But... Birds

• 0:00
  Coming up on this episode of Okay, But Birds, do you see evidence of a man cold?
• 0:05
  Like, are the male crows bigger wimps when they're infected?
• 0:12
  I would love if that was like an evolutionarily conserved trait.
• 0:40
  Being sick sucks.
• 0:42
  It just does.
• 0:42
  Whether it's a cold or flu, COVID, food poisoning, or something worse.
• 0:46
  When your body's on the defense, you always feel lousy.
• 0:49
  And sometimes our immune defenses fail us.
• 0:52
  If you haven't noticed, I'm currently in the final stages of a lovely cold.
• 0:57
  The first time I got COVID, I was pretty lucky.
• 0:59
  I'd already been vaccinated, so my body was prepared to fight off the virus.
• 1:02
  My adaptive immune system was ready.
• 1:05
  Even still, I did not feel good at all.
• 1:08
  Sore throat, stuffed up nose, headaches.
• 1:10
  I temporarily lost my sense of smell, which was a crazy experience.
• 1:15
  I was tired.
• 1:15
  I didn't feel like doing much of anything, and I spent 10 days isolated from my partner.
• 1:20
  But I survived, unlike many people who got COVID before the vaccine was available, before any of us had any adaptive immunity to this novel virus.
• 1:29
  Adaptive immunity is an amazing thing, and we're not the only creatures that have it.
• 1:33
  Birds have an adaptive immune system too.
• 1:35
  Remember how we can vaccinate condors against bird flu?
• 1:38
  Which brings us to the topic of today's episode.
• 1:40
  Okay, but what happens when a bird gets sick?
• 1:43
  To explore this topic, we'll talk with Dr. Andrea Townsend, an associate professor of biology at Hamilton College.
• 1:49
  As a primer before we get into it, birds and mammals both rely on the same basic two-part immune system, innate defenses that respond immediately and adaptive defenses that learn and remember specific pathogens.
• 2:00
  But the details diverge in some interesting ways.
• 2:03
  Take B cells, a type of white blood cell, the cells that manufacture antibodies.
• 2:07
  We grow ours in bone marrow.
• 2:10
  Birds grow theirs in an organ we don't have at all, a small pouch near the back end of the gut called the bursa of Fabricius, which fittingly sounds like a pretty bad Roman gladiator.
• 2:19
  Our first responders to an infection are called neutrophils, white blood cells that swallow invaders whole.
• 2:24
  Birds send heterophylls instead.
• 2:26
  Same job, different mechanism.
• 2:28
  The antibody doing most of the heavy lifting in our blood is immunoglobulin G, while birds run on immunoglobulin Y, an older take on roughly the same idea.
• 2:37
  And birds don't have lymph nodes at all.
• 2:40
  We have hundreds of them, little filtration stations where immune cells meet the enemy and coordinate a response.
• 2:46
  Birds scatter that tissue in loose patches throughout the gut, spleen, and other organs instead.
• 2:51
  And remember how hot birds can be?
• 2:53
  In episode 33, we learned birds are little furnaces with body temperatures often 40 to 42 Celsius, or 104 to 108 Fahrenheit.
• 3:02
  It turns out an extra warm body may act as a built-in fever that discourages many pathogens before an active immune response even kicks in.
• 3:10
  The two lineages, mammals and birds, have been evolving these systems independently for roughly 300 million years since their last common ancestor.
• 3:18
  So, while the overall strategy looks familiar, the components underneath are often quite different.
• 3:23
  Now, on with the episode.
• 3:24
  Stay tuned.
• 3:31
  Welcome back to the podcast, everyone.
• 3:32
  I'm really excited to have Andrea with us today to talk all about what happens when birds get sick.
• 3:37
  So thanks for joining us, Andrea.
• 3:38
  Thanks for having me, Scott.
• 3:39
  Of course.
• 3:40
  I thought we could start off with a little bit of your origin story as it pertains to birds and sickness.
• 3:45
  So you're known around your campus as the crow lady, apparently, because they follow you around.
• 3:51
  How did you start studying crows?
• 3:54
  I became very interested in the phenomenon of cooperative breeding.
• 3:57
  So I know you guys have talked about that on the pod before.
• 4:00
  So it's when you have basically a family with a bunch of babysitters.
• 4:05
  So the adult kids stay home and help their parents raise their younger brothers and sisters.
• 4:10
  And I started seeing this phenomenon.
• 4:11
  It's actually a really rare phenomenon in birds.
• 4:14
  Something like, depending on how you define it, like 3% of bird species are cooperative.
• 4:18
  And most of them are in the tropics.
• 4:20
  But I wanted to study them on the Cornell University campus because that's where I was.
• 4:25
  And there was only one choice, which was the American crow.
• 4:28
  So that's the only cooperative breeder in New York State.
• 4:31
  Wow.
• 4:31
  And it just so happened that there was already a marked population, a long-term study population of American crows there.
• 4:39
  And it was established by Kevin McGowan and Ann Clark.
• 4:43
  And they kindly allowed me to join their research group.
• 4:47
  And so I got to be...
• 4:48
  Part of this long-term study of the American crow.
• 4:53
  I just can't go back to other birds because they're just so interesting.
• 4:57
  So they're not just kids staying home with their parents, although there's obviously some of that.
• 5:03
  So they can stay home for many years, like seven years.
• 5:06
  Some of them will stay home and help their parents.
• 5:08
  And then some of them will like go away and try to set up their own territory.
• 5:13
  And then they'll come back and they'll like have an injury or droopy wing or a cut.
• 5:18
  And their parents will just let them come back.
• 5:20
  You know, so it's like watching birds try to become independent, fail, and then come back home.
• 5:25
  Just like people.
• 5:26
  Yeah, just like people.
• 5:28
  And then sometimes there's uncles.
• 5:30
  And then sometimes there's just random birds that are not, you know, that just join a family group.
• 5:35
  But then not only that, but then they're...
• 5:38
  very variable in how they get along.
• 5:40
  Some family groups are really nice to each other, and they're peaceful, and they're playful.
• 5:46
  And then some family groups are just really dysfunctional.
• 5:51
  constantly fighting and there's just a lot of angst in the groups.
• 5:56
  So that got me really interested too.
• 5:58
  So it's just like a soap opera.
• 5:59
  And then when we talk about their mating system, they also have a very bizarre mating system.
• 6:04
  So all of these things, it's a constant discovery when you're watching these families.
• 6:10
  Yeah, for sure.
• 6:11
  So then how did that like interest in, I mean, crows are fascinating.
• 6:14
  We get a lot of questions about how can I become friends with a crow?
• 6:18
  Can you please talk more about crows and all of these things?
• 6:20
  So people love crows.
• 6:21
  I think that's a broad feeling and their social behavior is amazing.
• 6:25
  But then how did that turn into studying crow diseases specifically?
• 6:29
  Like what was that flip for you?
• 6:32
  So I started studying them in 2005, and that was right after there was an outbreak in Ithaca of West Nile virus.
• 6:40
  Right.
• 6:41
  So it's an emerging infectious disease.
• 6:44
  We brought it over, we think, from the Middle East in 1997 to New York City, and then it's moved across North America since then.
• 6:54
  And it has outbreak years, and then it disappears for a little while, but stays at really low levels.
• 7:01
  So basically, it's become endemic, we call it.
• 7:04
  So something that's constantly around low levels, but then has outbreaks periodically.
• 7:09
  They had had their first outbreak of West Nile virus in 2003, 2004,
• 7:17
  And more than half of the birds died, so of the marked birds.
• 7:21
  And West Nile is a vector disease, right?
• 7:23
  So it's vectored by mosquitoes?
• 7:25
  Yes.
• 7:26
  Okay, yeah.
• 7:27
  And certain bird species are highly susceptible to West Nile virus.
• 7:31
  So if an infected mosquito bites them and they become infected, then all of them die.
• 7:36
  So crows, well, at least as far as we know, all of them die, right?
• 7:40
  That was the initial studies.
• 7:42
  All of them were dying.
• 7:43
  They might have developed some resistance over time.
• 7:46
  That's an ongoing area of research.
• 7:49
  So crows are highly susceptible.
• 7:50
  All the corvids.
• 7:51
  So that's the jays, ravens.
• 7:55
  Also, a lot of raptors are highly susceptible.
• 7:57
  So hawks, eagles, owls, highly susceptible to West Nile.
• 8:02
  The epidemic had just occurred.
• 8:03
  So it was coming into this really sort of tragic, devastating time where half of the birds in the population, or more than half, had disappeared.
• 8:13
  And everything was just in shambles.
• 8:15
  So normally they're in these very stable, long-term social groups.
• 8:20
  And now everything had gotten disrupted.
• 8:22
  Because one kind of sad thing about West Nile is that it doesn't...
• 8:27
  Most diseases, most endemic diseases, and this is true in people, it's true in birds, they mostly affect the young because youngsters, young humans, young birds don't have an adaptive immune response yet.
• 8:39
  They haven't been exposed to stuff and then they can mount a response to it later.
• 8:45
  So just like baby humans get sick all the time, baby birds tend to be the ones that are getting sick and have high mortality from disease.
• 8:55
  Mm-hmm.
• 8:56
  And by the time they get past that first year, they've got a much stronger immune response.
• 9:02
  You don't see the same diseases in an old crow.
• 9:05
  Anyway, West Nile virus comes in.
• 9:07
  It's a brand new pathogen.
• 9:09
  And there's no resistance in the population.
• 9:12
  It's kind of like COVID in humans where adults are susceptible to it because it's not something we had been exposed to when young.
• 9:19
  Mm-hmm.
• 9:20
  Weston virus is the same way.
• 9:22
  There was no resistance in the population.
• 9:24
  The old birds were just as likely.
• 9:26
  The old birds that should have had a long life full of potential, they were dying at equal rates to the young birds.
• 9:36
  So, yeah, that's something that you see with emerging infectious diseases often.
• 9:40
  You'll see...
• 9:43
  higher mortality than you'd expect in older age classes.
• 9:46
  Yeah, we see that in bird flu as well, that it's taking out kind of just everyone.
• 9:50
  There is some immunity evolving, but it is killing kind of indiscriminately compared to an endemic virus or disease that would take out the young first.
• 9:59
  Yeah.
• 10:00
  Yeah.
• 10:00
  And in crows, you just talked about the complexity of their social behavior and all of this.
• 10:05
  And so if you're losing adults, that's got to be particularly bad for the stability of the whole population, really.
• 10:12
  Yeah.
• 10:12
  Yeah, the stability of the family group and the stability of the population, perhaps.
• 10:16
  But definitely the family group.
• 10:18
  So, you know, you're losing the mom, you're losing the dad, you're losing a helpful brother and sister.
• 10:22
  You're changing everything.
• 10:24
  And life is hard for a young bird.
• 10:27
  So I'd say the vast majority of them die that first year, whether it's from predators or disease.
• 10:34
  But then once you get to be like one, you should have a nice long life.
• 10:39
  You know, crows can live 20 years.
• 10:40
  Wow.
• 10:41
  I think the oldest known crow is 19 years.
• 10:43
  I just asked Kevin McCowan.
• 10:44
  Oh, nice.
• 10:45
  That's the oldest known wild crow.
• 10:47
  Yes.
• 10:48
  Wow.
• 10:48
  In captivity, I think the oldest known crow is like 60.
• 10:52
  That's amazing.
• 10:53
  So I came into this long-term population.
• 10:55
  Birds were dying.
• 10:56
  My initial plan was to look at their genetic, the genetic mating system of American crows.
• 11:01
  So like most birds...
• 11:03
  They're socially monogamous, but I thought maybe something interesting is going on.
• 11:06
  Maybe they're cheating on each other.
• 11:08
  How did that affect cooperation within a group if they're cheating?
• 11:12
  And so that was my initial plan, but then they're all dying of West Nile.
• 11:16
  So my ideas and my research shifted to, okay, how does disease affect mating strategies?
• 11:23
  And my thought was that they would do something smart.
• 11:26
  Like maybe they went in times of disease, maybe they would choose like even better mates.
• 11:31
  Maybe they would choose these high condition mates, or maybe they would cheat a lot and hope that some of their kids were surviving because they just happened to get some resistance gene.
• 11:41
  Yeah.
• 11:41
  So that was what I had predicted.
• 11:43
  But what it turned out was very shocking, which was that crows tend to inbreed a lot.
• 11:50
  Okay.
• 11:51
  Yeah.
• 11:52
  Interesting, because they have pretty large populations.
• 11:54
  And you might expect, I would probably have made the same predictions as you, that they would outbreed to diversify the population.
• 12:01
  How close are brother-sister pairs and that sort of thing?
• 12:04
  Yeah.
• 12:04
  So a lot of uncle-niece social pairings.
• 12:07
  Okay.
• 12:07
  Okay.
• 12:08
  So those are the social mom and dad.
• 12:11
  But then there's also, so you have these adult sons within family groups.
• 12:16
  There were extra pair matings between moms and their adult sons.
• 12:20
  Okay, interesting.
• 12:22
  So we call that incest, first order pairings, you know.
• 12:26
  And...
• 12:27
  you might be kind of like having a disgust response.
• 12:30
  And that is totally evolutionarily adaptive and appropriate because, and it's one of the few rules that most animals obey.
• 12:40
  Like we avoid inbreeding and there's really good reasons for that.
• 12:44
  And especially when it comes to disease, because, you know,
• 12:48
  When you mate with...
• 12:49
  There's lots of good reasons.
• 12:51
  You could express deleterious alleles, but I won't talk about that one.
• 12:53
  But another good reason to avoid inbreeding when there's lots of disease around is if you mate with someone who's unrelated to you, your babies are going to be more genetically diverse, and therefore they're going to recognize more pathogens.
• 13:05
  But if you mate with kin...
• 13:08
  your babies are going to be less genetically diverse.
• 13:10
  They won't recognize as many pathogens.
• 13:13
  So this was the opposite of what I expected to find, which is really high levels of mother-son.
• 13:20
  There's a lot of uncle-niece and some mother-son.
• 13:24
  And this has been true in now, I've studied three populations and it's happening in all three of them.
• 13:29
  So-
• 13:29
  Really?
• 13:29
  So it's not just like an Ithaca specific thing?
• 13:32
  Not just an Ithaca thing, no.
• 13:33
  Interesting.
• 13:34
  So crows are just kind of prone to inbreeding regardless of population size.
• 13:37
  No matter what we look at, we find accumulating costs of inbreeding.
• 13:41
  So they tend to be in poor condition.
• 13:43
  They don't live as long and they tend to die with signs of disease.
• 13:47
  And it's not just West Nile.
• 13:49
  One of the most common things we see is avian pox.
• 13:52
  which is basically like smallpox in humans.
• 13:55
  It's the bird version of it.
• 13:56
  So it's not transmissible to humans, thank God, because it's really gross.
• 14:00
  Have you guys talked about avian pox before?
• 14:02
  We have not talked about avian pox, no.
• 14:05
  It's really sad.
• 14:06
  They get these lesions that can be on their face.
• 14:08
  It can make them blind.
• 14:09
  If they get them around their beaks, they can't swallow anymore.
• 14:13
  So it's deadly sort of by a physical process.
• 14:16
  Yeah.
• 14:17
  And sometimes they can recover.
• 14:19
  Then you'll see it on their feet.
• 14:21
  Sometimes they can recover.
• 14:22
  If it's just on their feet, they can recover sometimes from that.
• 14:24
  But if it gets on their face, usually they don't.
• 14:27
  It's to be a crow.
• 14:29
  And the inbred crows, have you seen that they're more susceptible to pox as well?
• 14:33
  Oh, yeah.
• 14:33
  Just like across the board, yeah.
• 14:34
  Yeah.
• 14:35
  Yeah.
• 14:35
  So...
• 14:36
  Sometimes when you know that a brood was produced mother-son, it's just a matter of time.
• 14:42
  You just start watching that brood and then you'll start seeing the pox lesions, you know, even in the nest.
• 14:47
  Yeah.
• 14:47
  Even while they're still in the nest.
• 14:49
  Oh, wow.
• 14:49
  So there's like really immediate costs.
• 14:51
  Yeah.
• 14:52
  Wow.
• 14:58
  My lab is mainly studying or focused on campylobacter right now.
• 15:01
  And so campylobacter is a disease.
• 15:03
  It's a pathogen.
• 15:04
  It's a bacterial pathogen.
• 15:05
  It has a fecal-oral transmission route.
• 15:08
  Like, I don't know if you are following the cyclospora.
• 15:12
  It's nothing like cyclospora because cyclospora is a different, it's a protist.
• 15:17
  And campylobacter is a bacteria.
• 15:19
  But they both come from poop that gets into a mouth.
• 15:22
  Yeah, exactly.
• 15:23
  They've got a poop-to-mouth transmission route.
• 15:26
  Yeah.
• 15:27
  So, and birds are considered a reservoir for it.
• 15:31
  So it's really common in birds.
• 15:34
  And it's thought to be commensal in chickens.
• 15:38
  So it causes no harm, but it causes a lot of harm in crows.
• 15:43
  So we found it's not like immediately lethal.
• 15:45
  And that's why I study it.
• 15:47
  So it causes, they're in poor condition.
• 15:50
  They're anorexic.
• 15:51
  So they've got very little interest in eating at all.
• 15:54
  Okay.
• 15:55
  Yeah, and they don't live as long.
• 15:58
  Okay.
• 15:58
  So over a 12-month period, they've got a lower survival probability.
• 16:02
  And Campylobacter then, is it native?
• 16:05
  Like, is it a native disease to North America?
• 16:09
  That is such a good question.
• 16:10
  Or did it come from chickens?
• 16:11
  Yeah.
• 16:12
  So we looked at the genomics of Campylobacter.
• 16:16
  Okay.
• 16:17
  And crows carry two different strains.
• 16:20
  One is crow only, their very own strain of Campylobacter.
• 16:24
  Oh.
• 16:24
  Okay.
• 16:25
  So first of all, I should say about 60% of crows are carrying this in the population.
• 16:29
  Oh, wow.
• 16:29
  So it's like hugely, yeah.
• 16:30
  So many of them are carrying this.
• 16:32
  Gives you lots of individuals you can study.
• 16:34
  So great choice from a research perspective.
• 16:36
  Yeah.
• 16:36
  Yeah.
• 16:38
  Yeah, there was a reason we picked it.
• 16:41
  So most of them, well, I'd say maybe 70% of them are carrying this crow-only strain.
• 16:45
  But about 30% of the ones that are infected are carrying the human strain.
• 16:49
  So ones that are carried by humans, goats, livestock, chickens.
• 16:56
  I guess that's not human.
• 16:57
  But we're all sharing a strain and crows are getting that.
• 17:00
  So that's probably new to crows.
• 17:03
  That might be like spillover.
• 17:05
  from us to crows.
• 17:07
  And one thing that'd be really cool to know is, okay, maybe they're adapted to their own crow specific one, but maybe it's this new one that's making them sick.
• 17:18
  So you're saying with Campylobacter, they have little interest in eating.
• 17:21
  They might have higher mortality on the longer term.
• 17:24
  But what are some of the other signs that a crow is trying to fight off a Campylobacter infection?
• 17:31
  One thing we've been studying is cognitive effects.
• 17:35
  So crows are smart.
• 17:37
  So that led to a study of variation among individuals.
• 17:41
  So why are some crows performing well on tasks and some performing less well?
• 17:46
  And it turns out that diseases seem to have a really strong effect on how they do on these cognitive tasks.
• 17:52
  Oh, cool.
• 17:52
  Yeah.
• 17:53
  Yeah.
• 17:54
  And there's actually not much information from wild animals about how disease affects their cognitive abilities.
• 17:59
  So this has been really fun.
• 18:01
  Yeah.
• 18:01
  So what we do is we bring crows into the aviary, wild crows, and we have them for about three weeks.
• 18:07
  And we analyze them.
• 18:09
  So about half of them are carrying Campylobacter just naturally.
• 18:12
  And you just figure that out from like a fecal test?
• 18:15
  Yeah.
• 18:16
  It's really easy.
• 18:16
  It's like a COVID cassette test.
• 18:18
  Oh, nice.
• 18:19
  So it's super fast.
• 18:20
  Put some poop in there.
• 18:21
  Yeah.
• 18:23
  And so then we give them a battery of tests.
• 18:26
  So we give them problem-solving tests where they have to pull up a string with their beak and step on it and pull a few times until they get the food.
• 18:34
  There's other ones where they have to pull a couple of levers to get food.
• 18:38
  There's memory tests, so associative learning.
• 18:40
  Can they memorize a color with a food?
• 18:43
  Mm-hmm.
• 18:44
  And then there's spatial memory.
• 18:45
  So can they, if you hide stuff, can they remember where it's been hidden?
• 18:49
  What we found is that crows, sick crows, crows infected with Campylobacter, don't do well on these tests.
• 18:56
  Yeah.
• 18:56
  Yeah.
• 18:57
  They...
• 18:58
  They're less likely to try.
• 19:00
  Oh, so they just have lower motivation?
• 19:02
  I mean, I hear that.
• 19:04
  Like, how do you, when I have a cold or flu, I'm not super motivated to do anything at all.
• 19:09
  So that's interesting.
• 19:10
  Totally, yeah.
• 19:12
  So they're like, I don't wanna.
• 19:14
  And then, of course, they're not food motivated as much.
• 19:16
  We know that because we give them endless food.
• 19:19
  We measured how much they ate.
• 19:20
  And the sick ones, first of all, weren't when they were just given like a big bowl of food, they ate less.
• 19:25
  Mm-hmm.
• 19:26
  And then, of course, they're not going to try as hard on these cognitive tests with a food reward.
• 19:32
  But so some of them don't even try.
• 19:34
  And when they try, they might try a few times.
• 19:36
  They're like, ugh, you know, and then they'll give up.
• 19:40
  So that's one issue.
• 19:42
  And then, but in some cases, that can't explain it.
• 19:45
  Like...
• 19:47
  Spatial memory.
• 19:48
  They're not so good at remembering where food is hidden.
• 19:51
  And they're trying to find it.
• 19:53
  They're just going to the wrong bowls.
• 19:54
  So just not trying doesn't explain it all.
• 19:58
  They are not performing as well.
• 20:01
  Yeah.
• 20:02
  Different pathogens will affect our cognitive abilities in different ways.
• 20:06
  So there's some, like West Nile virus, that can cause neurological damage.
• 20:12
  Or COVID in humans causes...
• 20:14
  neurological damage.
• 20:15
  It causes neuroinflammation.
• 20:16
  And that's legitimately causing damage to the brain.
• 20:21
  And that's why some of us experience brain fog.
• 20:24
  Campylobacter is not like West Nile virus or COVID that causes neuroinflammation.
• 20:30
  It's a gut pathogen.
• 20:32
  So how is it affecting the brain?
• 20:35
  And you guys might have heard of the gut-brain axis.
• 20:38
  So when your stomach hurts, that communicates to the brain and changes your behavior.
• 20:44
  So that's the idea.
• 20:46
  So in this case, it might be triggering changes in motivation or willingness to devote energy towards cognitive tasks, that kind of thing.
• 20:56
  So different diseases, different pathogens are going to affect...
• 21:01
  your cognitive performance by different mechanisms.
• 21:04
  But here is one potential example of a foodborne pathogen, a fecal-oral pathogen doing it to a bird.
• 21:11
  No, that's fascinating.
• 21:12
  Is your work on campylobacteria where you've seen like the social distancing thing?
• 21:16
  Oh, social distancing.
• 21:18
  So that was another thing that I expected to happen.
• 21:22
  Okay.
• 21:22
  That...
• 21:23
  That crows being so smart would, during times of high disease pressure, would start social distancing.
• 21:31
  So, you know, avoiding infected conspecifics or overall become less social.
• 21:37
  And I was listening to your episode with Nicola Hill, and she was talking about how she saw some evidence that turns, I think it was.
• 21:45
  Yeah, common turns would kind of evict a really sick individual that had bird flu.
• 21:50
  Yeah.
• 21:50
  Yeah, but where I'm going with this is I've seen no evidence for that in crows.
• 21:54
  They do not seem to avoid sick family members or sick birds in general.
• 22:00
  And that's interesting.
• 22:02
  I mean, I don't know if you know about this about crows, but they're also famous because of funerals, this funeral behavior where when a bird dies, they will actually, in some cases, congregate around it, sometimes for days.
• 22:14
  And that can be really problematic in times of disease stress.
• 22:18
  Totally.
• 22:19
  Yeah.
• 22:19
  Sometimes those are, you know, places where you can pick up pathogens.
• 22:23
  So one problem with my initial hypothesis with West Nile virus, which was that they should start avoiding each other, is that West Nile virus is transmitted by mosquitoes.
• 22:31
  And so it's actually worse.
• 22:33
  So imagine that you're trying to avoid West Nile virus.
• 22:36
  It's worse for you to go off by yourself.
• 22:38
  Right.
• 22:39
  And you're the one target.
• 22:40
  Yeah, all the mosquitoes are going to bite you.
• 22:42
  What you should do is get in a big crowd and go in the middle.
• 22:47
  So there's actually evidence for this in birds.
• 22:49
  If you're in a big roost, you're less likely to be the one to get bit than if you're off by yourself.
• 22:56
  So that prediction that they should become less social during West Nile virus was actually flawed to begin with.
• 23:02
  Thinking just back to like, okay, so you have these sick crows.
• 23:05
  They're not that motivated to do your memory tasks or your problem-solving tasks.
• 23:11
  When a crow is sick, are there behaviors that it undertakes to try to cope with the disease it's experiencing?
• 23:18
  What other coping strategies do wild birds have when they're experiencing infection, if that infection doesn't just kill them right away?
• 23:25
  Yeah, well, there's a classic suite of behaviors we call sickness behaviors, and it's really conserved across the animal kingdom.
• 23:33
  So humans do it, dogs do it, bees do it, birds do it.
• 23:37
  So at least for certain pathogens, when they get infected, they will exhibit all the things that you might do when you're sick.
• 23:45
  So they're less active.
• 23:47
  They tend to curl up in a ball.
• 23:49
  With a bird, they might fluff up their feathers.
• 23:51
  Okay.
• 23:52
  Their...
• 23:53
  unmotivated to eat and drink and have sex and be social.
• 23:57
  And what else might they be?
• 24:00
  Unmade.
• 24:01
  Solve problems, apparently.
• 24:02
  Yeah.
• 24:03
  Do your annoying test.
• 24:04
  I can't imagine if someone plucked me out of my house when I was like in the middle of a flu and just like, solve this, read this.
• 24:11
  I'd be like, leave me the f*** alone.
• 24:13
  When you have like an awful stomach ache, diarrhea, you know, come on, solve my problem.
• 24:18
  Yeah.
• 24:21
  Do you see evidence of a man cold?
• 24:23
  Like, are the male crows bigger wimps when they're infected?
• 24:30
  I would love if that was like an evolutionarily conserved trait.
• 24:35
  That is awesome.
• 24:36
  You know, and I'm totally seeing a paper.
• 24:39
  No, I have not.
• 24:41
  You know, and we totally could because we've never separated.
• 24:44
  You would think this would be an obvious thing to do.
• 24:46
  We've never separated out by sex if they're willing to participate, for example, or in these tests when they're sick and not sick.
• 24:54
  So such an obvious next step.
• 24:57
  The data are there.
• 24:59
  Put insects in that analysis.
• 25:00
  So yeah, I'll let you know the next time I see.
• 25:03
  I would love to know.
• 25:03
  I mean, there probably isn't because, yeah, whatever.
• 25:07
  It feels made up in humans anyways, but something funny to check out.
• 25:11
  Yeah.
• 25:12
  But if there is a man cold in crows, that would be interesting.
• 25:15
  There's some evidence that testosterone can suppress an immune response.
• 25:21
  And so whether that leads to birds just not exhibiting the same sickness behaviors or being more likely to, depending on the time of year, that would be an interesting question.
• 25:34
  Oh yeah.
• 25:34
  That would be super cool since
• 25:36
  The circulating hormones are really, like they really ramp up before the breeding season.
• 25:42
  Yeah.
• 25:43
  Yeah.
• 25:44
  There's some evidence that in the breeding season, some birds will hide if they're sick.
• 25:48
  They will not exhibit sickness behaviors.
• 25:51
  The idea being that too much is at stake.
• 25:54
  Is there an equivalent of like typically flus and colds are more common in the fall and winter in humans?
• 26:02
  Is there similar evidence of that seasonal variation in birds?
• 26:05
  I guess with West Nile, you have to have the vector in order to have the disease.
• 26:10
  So they must be more infectious than the summer.
• 26:12
  But what about like Campylobacter or...
• 26:14
  Yeah, well, those are interesting questions.
• 26:17
  And it will vary with the pathogen.
• 26:20
  So things like H5N1, it's starting to ramp up.
• 26:24
  So avian influenza is, I've seen it starting in August, and then it...
• 26:31
  increases through the winter months.
• 26:33
  So through February or now maybe through January, I've seen it.
• 26:37
  So basically increasing through January and I haven't seen it.
• 26:41
  There wasn't H5N1 in my population, at least last year, but it has been here in the previous two years.
• 26:49
  Oh, interesting.
• 26:50
  So it was there for a couple of years in your crows and then gone for a year.
• 26:53
  Last year, no cases.
• 26:55
  Wow.
• 26:55
  Yeah.
• 26:56
  Fingers crossed.
• 26:57
  And for West Nile virus, it will track mosquito numbers.
• 27:01
  So those tend to start in, you start seeing it in birds in July and peak in August and then drop off.
• 27:11
  Things like Campylobacter, so interesting.
• 27:13
  So it seems to be always around, like whenever I test them, maybe lower in the summer, more in the winter.
• 27:20
  But I think that's largely social behavior.
• 27:22
  So I don't know if y'all have seen the roosts.
• 27:24
  I have.
• 27:25
  They're amazing.
• 27:26
  They're amazing.
• 27:27
  Yeah.
• 27:28
  But there's a lot of poop happening at those roosts.
• 27:32
  And they're not just pooping on the ground.
• 27:34
  They're also pooping on each other.
• 27:36
  And then they do this adorable thing where they preen each other.
• 27:40
  It's called allopreening.
• 27:43
  And they're preening themselves.
• 27:44
  So you can imagine that this is a great time to be picking up fecal-oral pathogens.
• 27:49
  And so we tend to see higher prevalence of campylobacter foodborne pathogens midwinter when there's a lot of birds around.
• 28:00
  So you've described a snowball effect where stressed environments make animals sick and then sickness impairs the ability the animals have to deal with the stress that we're causing, whether that's urbanization, forest clearing, or whatever.
• 28:16
  So with things like avian flu and other diseases reshaping ecosystems, we try to point out that there is hope as regularly as we can, although there are a lot of challenges facing birds.
• 28:26
  So any hope would be great to hear too.
• 28:30
  Yeah, this is a tough one.
• 28:33
  Well, West Nile virus has been around for a while and it's here to stay.
• 28:38
  So it's endemic now, just like COVID is here to stay.
• 28:42
  It's endemic.
• 28:43
  But just like COVID, West Nile virus had an outbreak that was pretty devastating, killed a lot of birds.
• 28:50
  But then what tends to happen, at least with COVID and West Nile virus, is it goes away or it goes to really low levels for a
• 29:01
  And this is true for all birds that are affected by, say, West Nile virus.
• 29:05
  Their populations recover to some extent.
• 29:08
  And so there's time for the populations to recover.
• 29:12
  There's still a lot of crows out there.
• 29:15
  So these things aren't constant pressures.
• 29:19
  And so it's pretty rare when pathogens themselves...
• 29:25
  drive a species to extinction.
• 29:27
  It's happened, especially like in islands.
• 29:29
  Yeah.
• 29:31
  Islands and right now with H5N1 and seabirds, although there will probably still be a recovery there, but it's hard to know.
• 29:37
  And with H5N1, just making it...
• 29:40
  When we released the episode, it wasn't in Australia or New Zealand yet, and now it is.
• 29:44
  And so it'll be interesting to see, especially if bird populations are already small,
• 29:49
  because we've driven them to small sizes for all the other reasons, you know, introduced predators, loss of habitat, then we need to be concerned.
• 29:58
  But yeah, with some of our more widespread species, there is time evolution happens and diseases evolve on both sides, right?
• 30:04
  Like the birds can evolve resistance and the diseases typically will evolve towards being less virulent or less deadly.
• 30:13
  But yeah, so there is- It varies, but yes.
• 30:14
  Yeah, it varies.
• 30:15
  There's the idea that they don't want to kill all their hosts.
• 30:17
  Yeah.
• 30:17
  Yeah, otherwise you can't transmit super well.
• 30:20
  Yeah.
• 30:21
  Yeah, yeah.
• 30:22
  Yeah.
• 30:23
  We've reached the part of the show we call That's BS or That's Bird Stuff, where we give our guests an opportunity to debunk a myth that ruffles their feathers.
• 30:30
  So Andrea, what do you want to call BS on?
• 30:33
  Okay, so this might be more sour grapes than a myth.
• 30:39
  But I'm frequently asked if crows bring me gifts.
• 30:43
  And this is a very irritating question to me.
• 30:46
  Because the answer is no.
• 30:47
  The answer is no.
• 30:51
  Now, and I have a lot of crow friends.
• 30:53
  Yeah.
• 30:54
  Yeah, everywhere I go, I have crows.
• 30:56
  Because I'm throwing them peanuts.
• 30:57
  Right, okay.
• 30:58
  Let's be honest.
• 30:58
  Let's be honest.
• 30:59
  Let's call a spade a spade.
• 31:00
  Yeah.
• 31:01
  But yeah, so they're just wherever I go.
• 31:04
  So down the street, on campus, in my car, on my bike, it doesn't matter.
• 31:08
  There's just crows following me, which is, you know, it's so fulfilling.
• 31:12
  And I also have crows in an aviary who I consider friends.
• 31:18
  And I have yet to receive a gift.
• 31:20
  Oh, man.
• 31:21
  Yeah, I know.
• 31:22
  So I'm jealous.
• 31:24
  But I also have, I'm skeptical that this occurs.
• 31:29
  And it's probably because I'm Dales.
• 31:30
  But in the aviary, sometimes crows will be carrying around.
• 31:35
  They carry around toys sometimes, like a piece of bark mulch.
• 31:38
  And when I come in, they might put it down because they want to hang out with me.
• 31:42
  Is that a gift?
• 31:44
  If you want it to be, maybe if you need it to be.
• 31:47
  Is this bark mulch for me?
• 31:51
  There's still hope.
• 31:52
  You, you know, someday.
• 31:54
  I still have time.
• 31:54
  Yeah, we can have you back on.
• 31:56
  Once you receive your gift, we can do a whole episode about how you feel.
• 31:59
  And I'll apologize.
• 32:01
  Awesome.
• 32:02
  Well, thanks so much for joining us on the podcast today.
• 32:03
  It's been really fun to chat all about what happens when birds get sick.
• 32:07
  So appreciate you taking the time.
• 32:09
  Thanks, Scott.
• 32:13
  Birds are dinosaurs, and around here we like our snacks, so we end each episode with a dinosaur nugget.
• 32:18
  Today's nugget is, brain fog isn't just a human thing.
• 32:21
  About 60% of Andres crows are carrying a gut bacteria called Campylobacter, and it doesn't kill them outright.
• 32:27
  It just makes them worse at being crows.
• 32:29
  Infected birds quit on puzzles they should be able to solve, and they forget where they stashed their food, going back to the wrong bowls again and again.
• 32:36
  The infection never touches the brain.
• 32:38
  It sits in the gut and talks to the brain through the gut-brain axis, the same worrying that makes you want to lie down when your stomach hurts.
• 32:45
  So a bird whose whole survival strategy is being clever picks up a stomach bug, and the first thing it loses is its cleverness.
• 32:51
  That's a wrap on this week's episode.
• 32:53
  Okay, but what happens when a bird gets sick?
• 32:55
  If you're thankful I powered through a cold to bring you this episode, you can pay me back by leaving a rating or a review and following the show wherever you're listening.
• 33:02
  Think of it as chicken soup, but for a podcast.
• 33:05
  Now, if you'll excuse me, I'm going to go exhibit some sickness behaviors and lay down.
• 33:09
  We'll catch you next time.
• 33:10
  Byeee.
• 33:15
  Okay, But... Birds is hosted by Scott Taylor with production and creative by Zach Karl.