It Feels Good When You Sing a Song (In Fall)

A repost of an original article published October 3, 2012.

Most male songbirds will sing when they see a pretty female during the breeding season. But some male songbirds sing even when it’s not the breeding season. Why do so many birds sing in fall at all?

Maybe singing feels good… But how do you ask a bird if it feels good to sing? European starlings are one of those bird species that sing both in spring (the breeding season) and in fall (not the breeding season). Lauren Riters, Cindi Kelm-Nelson, and Sharon Stevenson at the University of Wisconsin at Madison did a series of ingenious experiments to ask starlings if and when it feels good to sing.

A European starling sings his fall-blues away. Photo by Linda Tanner at Wikimedia.

Psychologists have long used a paradigm called conditioned place preference (CPP) to evaluate whether an animal finds something rewarding or pleasurable. CPP is based on the idea that if an animal experiences something meaningless while at the same time experiencing something else that is rewarding, the animal will learn to associate these two things with each other in a phenomenon called conditioning. For example, a puppy that has learned that every time it sits it gets a treat, will find itself sitting more often.

A researcher can also compare how rewarding different types of treats are. If we want to know if puppies like carrots or steak better, we can give one group of puppies a carrot every time they sit and another group of puppies a piece of steak every time they sit. If the group of puppies that are conditioned with steak spend more time sitting, we can conclude that steak is more rewarding to puppies than carrots are.

Lauren and Sharon used this principle to ask starlings if singing is rewarding. They put spring starlings in a cage with a nestbox and a female and let them sing away, while counting how many songs they sang in 30 minutes. Then they immediately put them in another cage that was decorated with yellow materials on one side and green materials on the other, but they restricted each bird to only one of the two colored sides. This is the conditioning phase in which the bird learns to associate the colored cage with the feeling they get from singing.

The next day, they put the starlings in the yellow and green cage without restrictions so they could choose what side they wanted to hang out in. If singing is rewarding, we would expect starlings that sang a lot to spend more time on the side with the color they were placed in the day before.



Do people that sing in the car spend more time in the car?
Photo by freedigitalphotos.net.

That didn’t happen. The spring starlings spent the same amount of time in the yellow or green side of the cage regardless of how much they sang the day before.

But when Lauren and Sharon did the same test with fall starlings singing without a female, there has a huge effect: Males that sang more spent much more time on the colored side of the cage they were placed in the day before. Singing, for a male starling, is apparently rewarding in fall, but not in spring.

This result actually makes a lot of sense. In spring, males sing to attract and court females, so they are rewarded by the feeling they get from the female’s response, not from the act of singing itself. But in fall, males are not attracting females. So why do they sing in fall? Because it feels good.

It looks like Sesame Street got it right with their 1970s song “It Feels Good When You Sing a Song”:

You can't go wrong
when you're singing a song
Sing it loud, sing it strong
It feels good when you sing a song

But why does singing feel good? At least some of the reason, it seems, is opioids. Not quite what Sesame Street had in mind, but hey.

Despite their reputation for being one of the world’s oldest drugs, many opioids are naturally occurring neuropeptides (brain chemicals). They are involved in pain relief and euphoria, commonly combined in the phenomenon of runner’s high. Could opioids be involved in the feel-good sensation created by singing? Maybe.

Cindi, Sharon and Lauren suspect that singing in fall causes male starlings to release opioids in their little brains, which makes singing more rewarding and makes them want to sing more. But how do we know how much opioid an animal has in its brain? Hmmm… Opioids cause analgesia (pain relief). Therefore, if singing a lot in fall releases more opioids, then birds that sing a lot in fall should be more pain-tolerant, right? The researchers let male starlings sing and counted how many songs they produced for 20 minutes. Then they dipped their foot in uncomfortably warm water and timed how long it took for the bird to pull its toes out. Fall males that sang more took longer to pull their feet out of the birdy foot-spa than did the males that sang less.

Interestingly, if you give starlings a drug to enhance opioids, they leave their feet in the foot-spa longer than if you give them a drug to block opioids. So it seems that singing in fall increases pain tolerance in the same way that opioids do, likely because the act of singing in fall causes the brain to release its own opioids. (Although it is also possible that birds that produce more opioids feel like singing more).

And what about singing in spring? When Cindi, Sharon and Lauren repeated the study with spring starlings, these birds did not get pain relief from singing. Again, they are probably rewarded by their interactions with females and not the act of singing.

So if you ever find yourself in pain, just

Sing
Sing a song
Make it simple
To last your whole life long
Don't worry that it's not good enough
For anyone else to hear
Sing
Sing a song
La la la la la la la la la la la
La la la la la la la

Want to know more? Check these out:

1. Riters LV, & Stevenson SA (2012). Reward and vocal production: song-associated place preference in songbirds. Physiology & Behavior, 106 (2), 87-94 PMID: 22285212

2. Kelm-Nelson, C.A., Stevenson, S.A., & Riters, L.V. (2012). Context-dependent links between song production 1 and opioid-mediated analgesia in male European starlings (Sturnus vulgaris) PLOS One, 7 (10)

3. Riters LV, Schroeder MB, Auger CJ, Eens M, Pinxten R, & Ball GF (2005). Evidence for opioid involvement in the regulation of song production in male European starlings (Sturnus vulgaris). Behavioral neuroscience, 119 (1), 245-55 PMID: 15727529

4. Kelm CA, Forbes-Lorman RM, Auger CJ, & Riters LV (2011). Mu-opioid receptor densities are depleted in regions implicated in agonistic and sexual behavior in male European starlings (Sturnus vulgaris) defending nest sites and courting females. Behavioural brain research, 219 (1), 15-22 PMID: 21147175

Birds, Vitamin E, and the Race Against Time: A Guest Post

A reposting of an original article by Alyssa DeRubeis

The long and tapered wings on this young
Peregrine Falcon means it was built for some
serious speed! Photo by Alyssa DeRubeis.

Maybe you’ve been put under the false assumption that humans are cool. Don’t get me wrong; our bodies can do some pretty neat physiological stuff. But I’m gonna burst your bubble: humans are lame. Just think of how fast we can run compared to a Peregrine Falcon in a full stoop: 27 MPH versus 242 MPH.

Keep thinking about all the cool things birds can do. It doesn’t take us long to realize that our feathered friends are vastly more fascinating compared to humans. Now that you’re finally admitting defeat, I ask that you read on.

The most amazing avian physiological feat is the ability to travel long distances seasonally (a.k.a migrate). Between poor weather conditions, preventing fat loss, and staying alert, migration is not easy by any means. However, birds can cope with all of these things by assimilating and using antioxidants like vitamin E.

Here’s a classic bird migration scene: thousands of Tundra Swans, geese, and ducks congregate on the Mississippi River in Minnesota. Here, they rest and refuel before continuing their journey south. Photo by Alyssa DeRubeis.

Let’s talk a little bit about bird migration. It’s a two-way street, where a migratory bird will (usually) fly north as soon as possible to rear its young, and then fly south where it can stay warm and eat all sorts of goodies. During these two bouts of intense exercise, the birds produce free radicals, which are types of atoms, molecules, and ions that can harm DNA and other important stuff inside the body. This is where vitamin E comes in to save the day, because this vitamin, along with vitamin A and carotenoids, are antioxidants. They drive away bad things like free radicals from birds’ bodies; some scientists suggest that they may even reduce risks of cancer! In the case of migrating birds, antioxidants can make this migration headache a lot more bearable.

Well, that’s great. But where do these antioxidants come from? The short answer is avian nom-noms, but it’s one thing to eat something with an antioxidant in it. It’s quite another to actually be able to assimilate and use this antioxidant. Okay…so where do the birds get this ability from? It’s parentals!

Anders Møller from the University of Paris-Sud, along with his international team including Clotilde Biard (France), Filiz Karadas (Turkey), Diego Rubolini (Italy), Nicola Saino (Italy), and Peter Surai (Scotland), pointed out that there is little research looking at maternal effects on our feathered friends. Møller hypothesized that maternal effects (the direct effects a mother has on her offspring) play a critical role in migration: If mothers put a lot of antioxidants in their eggs, the chicks will be able to absorb antioxidants better later in life. This would give these birds a competitive edge because they will migrate in a healthier condition and arrive to breeding grounds earlier.

This male Barn Swallow on the left must’ve gotten back pretty early for him to have landed himself such a beautiful female. Thank you, Vitamin E! Photo by Alyssa DeRubeis.

In the early 2000s, Møller and his five colleagues collected 93 bird species’ eggs. The crew was able to analyze how the natural differences in antioxidant concentrations (put in by the mother) related to the birds’ spring arrival dates in 14 of them. They found that vitamin E concentration, but not vitamin A concentration, was a reliable predictor of earlier arrival dates.

This European posse took it a step further by injecting over 700 barn swallow eggs with either a large dose of vitamin E or a dose of corn oil (which contains a small amount of vitamin E). It was soon evident that the chicks with more vitamin E were bigger than chicks that received less vitamin E, thus already giving the big chicks a competitive edge over their less vitamin E-affiliated brethren. The researchers kept track of the eggs that hatched out as males in the following spring via frequent mist-netting sessions (a bird-capturing technique). Guess what? The fellas with higher vitamin E concentrations arrived earlier on average by ten days than those with lower concentrations!

Sweet. But what does it all mean? First off, vitamin E is crucial for migratory birds because it allows them to process antioxidants more efficiently. In fact, another study done by Møller, Filiz Karadas, and Johannes Emitzoe out of University of Paris-Sud suggested that birds killed by feral cats had less vitamin E than birds that died of other reasons. Furthermore, the early birds get the worm. Events such as insect hatches—vital for baby birds—now occur earlier in the spring as temperatures rise (read: climate change). Plus, if you’re a male arriving at the breeding grounds early, you get to pick the best spots to raise your offspring.

Wood-warblers, such as this Palm Warbler, must get back to their northerly breeding grounds in a timely fashion in order to hit the insect hatch for da babies. Photo by Alyssa DeRubeis.

Obviously, there’s an advantage to up the vitamin E intake and get a head start as a developing embryo. In an egg, most nutrients come from the yolk…which comes from the mother. The healthier the mother, the more vitamin E she will put in her eggs. And vitamin E isn’t produced internally; birds must consume it. While Møller’s paper on maternal effects states that vitamin E can be found widely in nature, a separate study found no apparent association between vitamin E and avian diet. Hmm. So then where DO birds get vitamin E from? Is it a limiting resource? Is there competition for it?

Clearly, we’ve got some questions and answers. As the field of “birdology,” advances, we will learn more and keep humans jealous of birds for years to come.


REFERENCES

1. Møller, A., Biard, C., Karadas, F., Rubolini, D., Saino, N., & Surai, P. (2011). Maternal effects and changing phenology of bird migration Climate Research, 49 (3), 201-210 DOI: 10.3354/cr01030

2. Møller AP, Erritzøe J, & Karadas F (2010). Levels of antioxidants in rural and urban birds and their consequences. Oecologia, 163 (1), 35-45 PMID: 20012100

3. Cohen, A., McGraw, K., & Robinson, W. (2009). Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species Oecologia, 161 (4), 673-683 DOI: 10.1007/s00442-009-1423-9

Vampires!

Photo by Alejandro Lunadei at Wikimedia.

A reposting of an original article from October 19, 2015

Vampire mythologies have been around for thousands of years, terrifying the young and old alike with stories of predatory bloodsuckers that feed on our life essences. You may not believe in vampires, but they are all around us. In fact, you may have some in the room with you right now! You just don’t notice them because they are not human, or even human-like.

Vampires feed on the blood of their victims in order to sustain their own lives. This phenomenon, called hematophagy, is more common than typically occurs to us at first. Just take mosquitoes and ticks as examples. Once we’ve opened our minds to the idea of bloodthirsty arthropods, we quickly think of many more: bedbugs, sandflies, blackflies, tsetse flies, assassin bugs, lice, mites, and fleas. In fact, nearly 14,000 arthropod species are hematophages. We can expand our thoughts now to worms (like leeches), fish (such as lampreys and candirús), some mammals (vampire bats), and even some birds (vampire finches, oxpeckers, and hood mockingbirds). We’ve been surrounded by vampires our whole lives, we just never sat up to take notice!

Hematophagous animals are not as scary as mythical vampires, in part because they don’t suck their victims dry – they just take a small blood meal to sustain their tiny bodies. Hematophagy is not, in itself, lethal. However, the process of exposing and taking the blood of many individuals transmits many deadly diseases, like malaria, rabies, dengue fever, West Nile virus, bubonic plague, encephalitis, and typhus.

Because blood feeders do not kill their meals, feeding can be even more dangerous for them than for traditional predators. As a result, many hematophagous animals have developed a similar toolkit. Many have mouthparts that are specialized to work as a needle or a razor and biochemicals in their saliva that work as anticoagulants and pain killers. Their primary skill, however, is their stealth: they can sneak up on you, eat their meal, and be home for bed before you even notice the itch.

Although a few species, like assassin bugs and vampire bats, are obligatory hematophages (only eat blood), most hematophages eat other foods as well. Somehow, Dracula is not quite so intimidating when you imagine him drinking his morning fruit juice, like many mosquitoes do.

Why drink blood in the first place? Blood is a body tissue like any other, and it contains a lot of protein and a variety of sugars, fats and minerals, just like meat. However, blood is mostly water, which means that a blood meal contains less protein and calories than the same weight of meat. Because you need to consume so much more to get enough protein and calories out of a meal, large animals and animals that generate their own body heat can't usually rely on blood meals alone. So much for human-like vampires that only live off the blood of their victims.

A deadly vampire spreading malaria. Photo by the CDC available at Wikimedia.

So true vampires are everywhere, but they are small, take small blood meals, don't generally kill their hosts, and often use blood to supplement their other meals. Not so scary any more, are they? ...Although, about 3.2 billion people (about half the world's population) are at risk of contracting the deadly disease, malaria, from these bloodsuckers... so maybe you aren't scared enough. Bwaa-haha!

Caught in My Web: Mind-Altering Substances

Image by Luc Viatour at Wikimedia Commons

Drunken birds have gone viral this week! For this edition of Caught in My Web, we wonder if animals alter their mental states like people do.

1. Drunk Minnesotan birds are flying into windows! At least that is what the viral story says. But the truth may be a bit more measured. As the Police Chief of Gilbert, Minnesota says, “It sounds like every bird in our town is hammered, and that’s not the case.” Read the real story here.

2. But do wild animals really drink alcohol? Not in the way that we do, maybe, but many consume overly fermented fruits. Some have developed a tolerance to the high alcohol content, others, not so much. Just ask this poor drunk moose that got herself stuck in a tree after eating too many fermented apples.

3. But it’s not just fermented fruits that get animals drunk. Some fish can make their own alcohol to help them survive a long winter under the ice.

4. What about the effects of other mind-altering substances on animals? Ever wonder what kind of web a spider would make on different drugs? In 1948, a zoologist at the University of Tubingen in Germany by the name of H.M. Peters did.

5. Octopuses are normally very solitary creatures… that is, unless they are given ecstasy. Apparently, even octopuses seek social interactions when they take the common party drug.

Birds, Vitamin E, and the Race Against Time: A Guest Post

A repost of an original article by Alyssa DeRubeis on February 6, 2013

The long and tapered wings on this young
Peregrine Falcon means it was built for some
serious speed! Photo by Alyssa DeRubeis.

Maybe you’ve been put under the false assumption that humans are cool. Don’t get me wrong; our bodies can do some pretty neat physiological stuff. But I’m gonna burst your bubble: humans are lame. Just think of how fast we can run compared to a Peregrine Falcon in a full stoop: 27 MPH versus 242 MPH.

Keep thinking about all the cool things birds can do. It doesn’t take us long to realize that our feathered friends are vastly more fascinating compared to humans. Now that you’re finally admitting defeat, I ask that you read on.

The most amazing avian physiological feat is the ability to travel long distances seasonally (a.k.a migrate). Between poor weather conditions, preventing fat loss, and staying alert, migration is not easy by any means. However, birds can cope with all of these things by assimilating and using antioxidants like vitamin E.

Here’s a classic bird migration scene: thousands of Tundra Swans, geese, and ducks congregate on the Mississippi River in Minnesota. Here, they rest and refuel before continuing their journey south. Photo by Alyssa DeRubeis.

Let’s talk a little bit about bird migration. It’s a two-way street, where a migratory bird will (usually) fly north as soon as possible to rear its young, and then fly south where it can stay warm and eat all sorts of goodies. During these two bouts of intense exercise, the birds produce free radicals, which are types of atoms, molecules, and ions that can harm DNA and other important stuff inside the body. This is where vitamin E comes in to save the day, because this vitamin, along with vitamin A and carotenoids, are antioxidants. They drive away bad things like free radicals from birds’ bodies; some scientists suggest that they may even reduce risks of cancer! In the case of migrating birds, antioxidants can make this migration headache a lot more bearable.

Well, that’s great. But where do these antioxidants come from? The short answer is avian nom-noms, but it’s one thing to eat something with an antioxidant in it. It’s quite another to actually be able to assimilate and use this antioxidant. Okay…so where do the birds get this ability from? It’s parentals!

Anders Møller from the University of Paris-Sud, along with his international team including Clotilde Biard (France), Filiz Karadas (Turkey), Diego Rubolini (Italy), Nicola Saino (Italy), and Peter Surai (Scotland), pointed out that there is little research looking at maternal effects on our feathered friends. Møller hypothesized that maternal effects (the direct effects a mother has on her offspring) play a critical role in migration: If mothers put a lot of antioxidants in their eggs, the chicks will be able to absorb antioxidants better later in life. This would give these birds a competitive edge because they will migrate in a healthier condition and arrive to breeding grounds earlier.

This male Barn Swallow on the left must’ve gotten back pretty early for him to have landed himself such a beautiful female. Thank you, Vitamin E! Photo by Alyssa DeRubeis.

In the early 2000s, Møller and his five colleagues collected 93 bird species’ eggs. The crew was able to analyze how the natural differences in antioxidant concentrations (put in by the mother) related to the birds’ spring arrival dates in 14 of them. They found that vitamin E concentration, but not vitamin A concentration, was a reliable predictor of earlier arrival dates.

This European posse took it a step further by injecting over 700 barn swallow eggs with either a large dose of vitamin E or a dose of corn oil (which contains a small amount of vitamin E). It was soon evident that the chicks with more vitamin E were bigger than chicks that received less vitamin E, thus already giving the big chicks a competitive edge over their less vitamin E-affiliated brethren. The researchers kept track of the eggs that hatched out as males in the following spring via frequent mist-netting sessions (a bird-capturing technique). Guess what? The fellas with higher vitamin E concentrations arrived earlier on average by ten days than those with lower concentrations!

Sweet. But what does it all mean? First off, vitamin E is crucial for migratory birds because it allows them to process antioxidants more efficiently. In fact, another study done by Møller, Filiz Karadas, and Johannes Emitzoe out of University of Paris-Sud suggested that birds killed by feral cats had less vitamin E than birds that died of other reasons. Furthermore, the early birds get the worm. Events such as insect hatches—vital for baby birds—now occur earlier in the spring as temperatures rise (read: climate change). Plus, if you’re a male arriving at the breeding grounds early, you get to pick the best spots to raise your offspring.

Wood-warblers, such as this Palm Warbler, must get back to their northerly breeding grounds in a timely fashion in order to hit the insect hatch for da babies. Photo by Alyssa DeRubeis.

Obviously, there’s an advantage to up the vitamin E intake and get a head start as a developing embryo. In an egg, most nutrients come from the yolk…which comes from the mother. The healthier the mother, the more vitamin E she will put in her eggs. And vitamin E isn’t produced internally; birds must consume it. While Møller’s paper on maternal effects states that vitamin E can be found widely in nature, a separate study found no apparent association between vitamin E and avian diet. Hmm. So then where DO birds get vitamin E from? Is it a limiting resource? Is there competition for it?

Clearly, we’ve got some questions and answers. As the field of “birdology,” advances, we will learn more and keep humans jealous of birds for years to come.

REFERENCES

1. Møller, A., Biard, C., Karadas, F., Rubolini, D., Saino, N., & Surai, P. (2011). Maternal effects and changing phenology of bird migration Climate Research, 49 (3), 201-210 DOI: 10.3354/cr01030

2. Møller AP, Erritzøe J, & Karadas F (2010). Levels of antioxidants in rural and urban birds and their consequences. Oecologia, 163 (1), 35-45 PMID: 20012100

3. Cohen, A., McGraw, K., & Robinson, W. (2009). Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species Oecologia, 161 (4), 673-683 DOI: 10.1007/s00442-009-1423-9

Can a Horde of Idiots be a Genius?

A modified reposting of an article from April, 2012.

Let’s face it: The typical individual is not that bright. Just check out these human specimens:

Yet somehow, if you get enough numbskulls together, the group can make some pretty intelligent decisions. We’ve seen this in a wide variety of organisms facing a number of different challenges.

In a brilliant series of studies, Jean-Louis Deneubourg, a professor at the Free University of Brussels, and his colleagues tested the abilities of Argentine ants (a common dark-brown ant species) to collectively solve foraging problems. In one of these studies, the ants were provided with a bridge that connected the nest to a food source. This bridge split and fused in two places (like eyeglass frames), but at each split one branch was shorter than the other, resulting in a single shortest-path and multiple longer paths. After a few minutes, explorers crossed the bridge (by a meandering path) and discovered the food. This recruited foragers, each of which chose randomly between the short and the long branch at each split. Then suddenly, the foragers all started to prefer the shortest route. How did they do that?

This figure from the Goss et al 1989 paper in Naturwissemschaften shows (a) the design of a single module, (b) ants scattered on the bridge after 4 minutes (I promise they’re there), and (c) ants mostly on the shortest path after 8 minutes

You can think of it this way: a single individual often tries to make decisions based on the uncertain information available to it. But if you have a group of individuals, they will likely each have information that differs somewhat from the information of others in the group. If they each make a decision based on their own information alone, they will likely result in a number of poor decisions and a few good ones. But if they can each base their decisions on the accumulation of all of the information of the group, they stand a much better chance of making a good decision. The more information accumulated, the more likely they are to make the best possible decision.

In the case of the Argentine ant, the accumulated information takes the form of pheromone trails. Argentine ants lay pheromone trails both when leaving the nest and when returning to the nest. Ants that are lucky enough to take a shorter foraging route return to the nest sooner, increasing the pheromone concentration of the route each way. In this way, shorter routes develop more concentrated pheromone trails faster, which attract more ants, which further increase pheromone concentration of the shortest routes. In this way, an ant colony can make an intelligent decision (take the shortest foraging route) without any individual doing anything more intelligent than following a simple rule (follow the strongest pheromone signal).

Home is where the heart is. Photo of a bee swarm by Tom Seeley

Honeybee colonies also solve complicated tasks with the use of communication. Tom Seeley at Cornell University and his colleagues have investigated the honeybee group decision-making process of finding a new home. When a colony outgrows their hive, hundreds of scouts will go in search of a suitable new home, preferably one that is high off the ground with a south-facing entrance and room to grow. If a scout finds such a place, she returns to the colony and performs a waggle dance, a dance in which her body position and movements encode the directions to her site and her dancing vigor relates to how awesome she thinks the site is. 

Some scouts that see her dance may be persuaded to follow her directions and check out the site for themselves, and if impressed, may return to the hive and perform waggle dances too. Or they may follow another scout’s directions to a different site or even strike out on their own. Eventually, the majority of the scouts are all dancing the same vigorous dance. But interestingly, few scouts ever visit more than one site. Better sites simply receive more vigorous “dance-votes” and then attract more scouts to do the same. Like ants in search of a foraging path, the intensity of the collective signal drives the group towards the best decision. Once a quorum is reached, the honeybees fly off together to their new home.

But groups can develop better solutions than individuals even without communication. Gaia Dell’Ariccia at the University of Zurich in Switzerland and her colleagues explored homing pigeon navigation by placing GPS trackers on the backs of pigeons and releasing them from a familiar location either alone or in a group of six. Because they were all trained to fly home from this site, they all found their way home regardless of whether they were alone or in a group. But as a flock, the pigeons left sooner, rested less, flew faster, and took a more direct route than did the same birds when making the trip alone. By averaging the directional tendencies of everyone in the group, they were able to mutually correct the errors of each individual and follow the straightest path.

In each of these examples, each individual has limited and uncertain information, but each individual has information that may be slightly different than their neighbors’. By combining this diverse information and making a collective decision, hordes of idiots can make genius decisions.


Want to know more? Check these out:

1. Couzin, I. (2009). Collective cognition in animal groups Trends in Cognitive Sciences, 13 (1), 36-43 DOI: 10.1016/j.tics.2008.10.002

2. Goss, S., Aron, S., Deneubourg, J., & Pasteels, J. (1989). Self-organized shortcuts in the Argentine ant Naturwissenschaften, 76 (12), 579-581 DOI: 10.1007/BF00462870

3. Dussutour, A., Nicolis, S., Deneubourg, J., & Fourcassié, V. (2006). Collective decisions in ants when foraging under crowded conditions Behavioral Ecology and Sociobiology, 61 (1), 17-30 DOI: 10.1007/s00265-006-0233-x

4. List C, Elsholtz C, & Seeley TD (2009). Independence and interdependence in collective decision making: an agent-based model of nest-site choice by honeybee swarms. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 364 (1518), 755-62 PMID: 19073474

5. Dell'Ariccia, G., Dell'Omo, G., Wolfer, D., & Lipp, H. (2008). Flock flying improves pigeons' homing: GPS track analysis of individual flyers versus small groups Animal Behaviour, 76 (4), 1165-1172 DOI: 10.1016/j.anbehav.2008.05.022

6. Honeybee Democracy by Thomas Seeley

7. The Smart Swarm by Peter Miller

Mosquitoes Don’t Like Parasites Either (A Guest Post)

By Maranda Cardiel

A photograph of Culex pipiens, the species of mosquito that the researchers used
in their experiment. Source: David Barillet-Portal at Wikimedia Commons.

Everybody hates mosquitoes. They are annoying, persistent, and make us itch like crazy. Sometimes there are so many of them that we are afraid to go outside unless we want to risk getting covered in spots and scratching ourselves all over for the next week. And if that wasn’t enough, they can also carry dangerous diseases with the potential to kill us. However, just like us, mosquitoes don’t like to be bugged by parasites that can make them sick either. Research shows that they may even avoid interacting with hosts that might pass along parasites to them.

A group of researchers - Fabrice Lalubin, Pierre Bize, Juan van Rooyen, and Philippe Christe from the University of Lausanne in Switzerland and Olivier Glaizot from the Lausanne Museum of Zoology – wanted to see if mosquitoes would show a preference for feasting upon birds that were infected with malaria (a blood parasite) or uninfected birds. Mosquitoes find animals to snack on by sensing odors and carbon dioxide in the air that animals give off, along with using their senses of vision, hearing, and touch. In order to figure out if mosquitoes use these senses to specifically choose their unlucky victims, the researchers did an experiment with mosquitoes, malaria, and great tits (a type of bird with a funny name).

For their experiment, the researchers collected mosquito eggs that they hatched and raised in a lab. Only female mosquitoes suck blood, so only female mosquitoes were used in the experiment. The mosquitoes had never been exposed to birds before and were starved of sugar for one day to make sure that they would be hungry. The researchers also caught wild adult great tits, and they took small blood samples from each bird to test for malaria before and after the experiment.

Next it was time to see if the mosquitoes would find some birds to be more appealing than others. A special Y-shaped wind tunnel allowed the mosquitoes to choose between the odors of two birds: one that was infected with the malaria parasite and one that was not. But don’t worry, the mosquitoes could not directly contact the birds. The researchers set up the lab so that it was completely dark to mimic the natural settings of when mosquitoes feed in the wild. This also meant that the mosquitoes were blind and could only choose a bird based on the chemicals in the air. Randomly-chosen pairs of birds and new mosquitoes were used for each round of the test.

A cartoon depicting the experiment setup. A hungry female mosquito hones in on the odors
of a healthy great tit and a great tit infected with malaria parasites. Source: Maranda Cardiel

The results of the study showed that the mosquitoes had a strong preference for birds that were not infected with the malaria parasite. This was true even when the researchers took into account the body sizes and sexes of the birds. Previous studies with different kinds of birds, mosquitoes, and malaria or malaria-like parasites have found similar results. The researchers think that this may be because the malaria parasite somehow causes changes in the chemical processes in the birds’ bodies that the mosquitoes can pick up on.

Infection with malaria might change what the birds smell like to the mosquitoes or how much carbon dioxide the birds give off. There is also evidence that birds who are more susceptible to malaria infections have a different odor than birds with stronger immune systems. But why should mosquitoes be picky and choose to bite healthy birds? They certainly don’t seem like they care whose blood they suck when they are swarming around us!

Previous research has shown that mosquitoes infected with malaria parasites have problems developing their eggs and can have trouble sucking up blood from their victims. Female mosquitoes use blood to nourish their eggs, so if they don’t drink as much blood, they will not be able to lay as many eggs. This means that female mosquitoes carrying malaria parasites are less likely to produce as many healthy offspring. Thus, it makes sense for female mosquitoes to want to avoid feeding on birds that are infected with malaria.

This probably has not changed your thoughts about mosquitoes. They are still a nuisance that we all squish - or at least attempt to squish - upon sight. It might be ironic, but mosquitoes don’t like to have parasites bothering them either. Even though we hate them, maybe now you can find some solace in mosquitoes finding you attractive. It might be a sign that you are actually healthier than your peers.


Source:

Lalubin, F., Bize, P., van Rooyen, J., Christe, P., & Glaizot, O. (2012). Potential evidence of parasite avoidance in an avian malarial vector Animal Behaviour, 84 (3), 539-545 DOI: 10.1016/j.anbehav.2012.06.004

Do Not Google These Animals

This is not my week to be mature, so we’re going to point and laugh at animals with funny names.

Great Tits

Image by Ken Billington at Wikimedia Commons.

The great tit (Parus major) is a common songbird throughout Eurasia. There is actually a whole family of tits, which also includes the less-fortunately named ashy tit (Melaniparus cinerascens), and the strip-clubbing cousin, the stripe-breasted tit (Melaniparus fasciiventer). “Tit” also means small, which is likely the origin of using it to describe a small bird that doesn’t even have nipples.

Brown Boobies

Image by Muriel Gottrop at Wikimedia Commons.

Brown boobies (Sula leucogaster) are large seabirds that commonly breed on the islands in the Gulf of Mexico and the Caribbean Sea. Like the tit family, there is also a booby family, including the more commonly known blue-footed booby (Sula nebouxii). Boobies were named using the Spanish word bobo, which means “stupid” or “clown-like”, due to their clumsiness on land and lack of fear of humans.

Slippery Dick

Image by Brian Gratwicke at Wikimedia Commons.

The slippery dick (Halichoeres bivittatus) is a small fish in the wrasse family that lives in reefs in the tropical western Atlantic Ocean. The name of this unfortunate species apparently predates the present use of the term. "Slippery dick" was mentioned as early as 1859 in John Jones’ The Naturalist in Bermuda as the name fishermen commonly used for this wrasse species. It apparently is difficult to hold onto and easily slips through your fingers. “Dick”, at the time, was the common nickname for Richard and was commonly used to refer to any “fellow”. It was not used to refer to a body part until the late 1800s, and this latter use of the term is attributed to British army slang.

Vampires!

Photo by Alejandro Lunadei at Wikimedia.

Vampire mythologies have been around for thousands of years, terrifying the young and old alike with stories of predatory bloodsuckers that feed on our life essences. You may not believe in vampires, but they are all around us. In fact, you may have some in the room with you right now! You just don’t notice them because they are not human, or even human-like.

Vampires feed on the blood of their victims in order to sustain their own lives. This phenomenon, called hematophagy, is more common than typically occurs to us at first. Just take mosquitoes and ticks as examples. Once we’ve opened our minds to the idea of bloodthirsty arthropods, we quickly think of many more: bedbugs, sandflies, blackflies, tsetse flies, assassin bugs, lice, mites, and fleas. In fact, nearly 14,000 arthropod species are hematophages. We can expand our thoughts now to worms (like leeches), fish (such as lampreys and candirús), some mammals (vampire bats), and even some birds (vampire finches, oxpeckers, and hood mockingbirds). We’ve been surrounded by vampires our whole lives, we just never sat up to take notice!

Hematophagous animals are not as scary as mythical vampires, in part because they don’t suck their victims dry – they just take a small blood meal to sustain their tiny bodies. Hematophagy is not, in itself, lethal. However, the process of exposing and taking the blood of many individuals transmits many deadly diseases, like malaria, rabies, dengue fever, West Nile virus, bubonic plague, encephalitis, and typhus.

Because blood feeders do not kill their meals, feeding can be even more dangerous for them than for traditional predators. As a result, many hematophagous animals have developed a similar toolkit. Many have mouthparts that are specialized to work as a needle or a razor and biochemicals in their saliva that work as anticoagulants and pain killers. Their primary skill, however, is their stealth: they can sneak up on you, eat their meal, and be home for bed before you even notice the itch.

Although a few species, like assassin bugs and vampire bats, are obligatory hematophages (only eat blood), most hematophages eat other foods as well. Somehow, Dracula is not quite so intimidating when you imagine him drinking his morning fruit juice, like many mosquitoes do.

Why drink blood in the first place? Blood is a body tissue like any other, and it contains a lot of protein and a variety of sugars, fats and minerals, just like meat. However, blood is mostly water, which means that a blood meal contains less protein and calories than the same weight of meat. Because you need to consume so much more to get enough protein and calories out of a meal, large animals and animals that generate their own body heat can't usually rely on blood meals alone. So much for human-like vampires that only live off the blood of their victims.

A deadly vampire spreading malaria. Photo by the CDC available at Wikimedia.

So true vampires are everywhere, but they are small, take small blood meals, don't generally kill their hosts, and often use blood to supplement their other meals. Not so scary any more, are they? ...Although, about 3.2 billion people (about half the world's population) are at risk of contracting the deadly disease, malaria, from these bloodsuckers... so maybe you aren't scared enough. Bwaa-haha!

Song Battles With Other Species Can Change Your Tune

Many animals defend territories from members of their own species for mating, breeding, and finding food and they often use species-specific vocalizations to do this. Defending a territory can be risky and costly in both energy and time, so even territorial animals generally don’t waste this effort on other species that do not share their same food and breeding needs. But what do you do if you live around another very similar species that has the same needs that you do? Can two species learn to speak each other’s languages to live in territorial harmony?


A common nightingale.
Photo by Frebeck at Wikimedia Commons.

A thrush nightingale.
Photo by Locaguapa at Wikimedia Commons.

Today at Accumulating Glitches, I tell the story of two species of nightingales and how they are learning to sing each other's songs to defend their territories! Check out the article here.

The Biology of Nagging

A female pied flycatcher can't feed herself sufficiently
while she incubates her eggs and newly-hatched
chicks. Photo by Alejandro Cantarero.

I have been blessed with the fortune of not just having two healthy and happy babies, but being able to spend much of the spring and summer nurturing them and watching them develop and grow. But it has not been all roses: their smiles beam through the fog of my sleep deprivation and exhaustion. Their tears are met with my own. Our clothes are stained in a rainbow of bodily fluids. Now I am back at work trying to remember how my life used to be and how to meet my obligations to countless people, all while trying to keep up with the ever-changing needs of my daughters. Luckily, I am not alone. The girls have a rotating schedule with their grandparents one day, with their dad another, at daycare for a few days, and with me on weekends and evenings. But as the expectations on me grow heavier, I find myself pushing my husband harder to do more with the girls and around the house. Now it seems like every time I open my mouth, I am accused of “being a nag” and “for no reason” no less. The truth is, nagging has a deep biologically-based reason and may even be critical to species survival.

We are not the only species that nags, although in other species these vocalizations are often called “begging signals”. Begging signals are commonly heard in bird species in which the female does most or all of the egg and chick incubation. Because these females cannot sufficiently feed themselves while ensuring the survival of their brood, their male partners need to spend extra time foraging for the females in addition to foraging for the chicks and themselves. There is an inherent conflict between how mated males would prefer to spend their time (feeding themselves, maintaining their dominance status, and flirting with females) and how their female partners want them to spend their time (providing as much as possible for the family). The male response to this conflict is often to see how little he can get away with contributing while he sneaks off to spend his time as he wishes. The female response is to produce loud, juvenile vocalizations and gestures until he brings food to the nest. Is this really necessary though? Maybe she is just being manipulative to try to get him to do more than he really needs to.

Alejandro Cantarero, Jimena López-Arrabé, Antonio Palma, and Juan Moreno from the National Museum of Natural Sciences in Madrid, Spain and Alberto Redondo from the University of Córdoba in Spain set out to test whether the begging signals made by female pied flycatchers were an honest signal of need or were just obnoxious melodrama. They predicted that if the females’ begging calls were an honest reflection of how much help they needed, then begging calls would increase as energy needs increase.

The researchers studied 71 pied flycatcher nests in a forest in central Spain. Behaviors were observed by nest-mounted video cameras five days after the females finished laying their clutches of eggs. Two days later, each female was caught and measured, fitted with an identifying leg band, and had her wings clipped. About half of these females had their primary feathers clipped at the base to impair their ability to fly (these females are called the “handicapped” group). The other half had their primary feathers clipped at the tip so that their ability to fly would not be affected (these are the “control” females). When the females were released, they all returned to their nests. Their behaviors were measured again three days later.

Females in the handicapped group lost weight and begged significantly more after their wings were clipped, whereas the control females did not. This suggests that females are adjusting their begging rates to accurately reflect their needs. Furthermore, male partners of the handicapped females fed their partners more after the wing-clipping, whereas the male partners of the control females did not. This shows that the males are responding to either their partners’ increased begging or increased need or both. Revealingly, the amount that females begged was positively correlated with the amount that the males fed them, even when the researchers statistically controlled for whether their wings were clipped or not. This means that males were feeding females more because they begged more (and not simply because they needed more, which was also true).

This nagging female gets exactly what she needs.
Video by Alejandro Cantarero.

So, at least among pied flycatchers, females don’t “nag for no reason”, but because they genuinely need the help to keep their bodies and families healthy and safe. And males respond to the calls for help by increasing their contributions. But the graph that shows that males feed females more because they beg more also reveals that males would not help enough if females did not beg enough. Nagging is an adaptive strategy that females must engage in to meet the needs of the family.

Is someone nagging you too much? If we are like our pied flycatcher friends, than if you meet that person’s needs, the nagging should stop.

Want to know more? Check this out:

Cantarero, A., López-Arrabé, J., Palma, A., Redondo, A., & Moreno, J. (2014). Males respond to female begging signals of need: a handicapping experiment in the pied flycatcher, Ficedula hypoleuca Animal Behaviour, 94, 167-173 DOI: 10.1016/j.anbehav.2014.05.002

Some City Birds Are Changing Their Tune



European starlings are one of the many bird species changing their songs
 in urban environments. Image by 4028mdk09 at Wikimedia Commons.

The human world population has climbed to over 7.1 billion people and for the first time ever, more than half of us live in an urban area. Urban areas are spreading and more animals are either getting pushed out or are becoming urbanized in the process. Birds are among the many species we are used to seeing and hearing in our cities, but how exactly are they and their songs being affected by urban spread?

This week at Accumulating Glitches I tell the story of how urbanization is changing our avian soundscape. Check it out here.

And to learn more, check this out:

Slabbekoorn, H. (2013). Songs of the city: noise-dependent spectral plasticity in the acoustic phenotype of urban birds Animal Behaviour (85), 1089-1099 DOI: 10.1016/j.anbehav.2013.01.021

Birds, Vitamin E, and the Race Against Time: A Guest Post

By Alyssa DeRubeis

The long and tapered wings on this young
Peregrine Falcon means it was built for some
serious speed! Photo by Alyssa DeRubeis.

Maybe you’ve been put under the false assumption that humans are cool. Don’t get me wrong; our bodies can do some pretty neat physiological stuff. But I’m gonna burst your bubble: humans are lame. Just think of how fast we can run compared to a Peregrine Falcon in a full stoop: 27 MPH versus 242 MPH.

Keep thinking about all the cool things birds can do. It doesn’t take us long to realize that our feathered friends are vastly more fascinating compared to humans. Now that you’re finally admitting defeat, I ask that you read on.

The most amazing avian physiological feat is the ability to travel long distances seasonally (a.k.a migrate). Between poor weather conditions, preventing fat loss, and staying alert, migration is not easy by any means. However, birds can cope with all of these things by assimilating and using antioxidants like vitamin E.

Here’s a classic bird migration scene: thousands of Tundra Swans, geese, and ducks congregate on the Mississippi River in Minnesota. Here, they rest and refuel before continuing their journey south. Photo by Alyssa DeRubeis.

Let’s talk a little bit about bird migration. It’s a two-way street, where a migratory bird will (usually) fly north as soon as possible to rear its young, and then fly south where it can stay warm and eat all sorts of goodies. During these two bouts of intense exercise, the birds produce free radicals, which are types of atoms, molecules, and ions that can harm DNA and other important stuff inside the body. This is where vitamin E comes in to save the day, because this vitamin, along with vitamin A and carotenoids, are antioxidants. They drive away bad things like free radicals from birds’ bodies; some scientists suggest that they may even reduce risks of cancer! In the case of migrating birds, antioxidants can make this migration headache a lot more bearable.

Well, that’s great. But where do these antioxidants come from? The short answer is avian nom-noms, but it’s one thing to eat something with an antioxidant in it. It’s quite another to actually be able to assimilate and use this antioxidant. Okay…so where do the birds get this ability from? It’s parentals!

Anders Møller from the University of Paris-Sud, along with his international team including Clotilde Biard (France), Filiz Karadas (Turkey), Diego Rubolini (Italy), Nicola Saino (Italy), and Peter Surai (Scotland), pointed out that there is little research looking at maternal effects on our feathered friends. Møller hypothesized that maternal effects (the direct effects a mother has on her offspring) play a critical role in migration: If mothers put a lot of antioxidants in their eggs, the chicks will be able to absorb antioxidants better later in life. This would give these birds a competitive edge because they will migrate in a healthier condition and arrive to breeding grounds earlier.

This male Barn Swallow on the left must’ve gotten back pretty early for him to have landed himself such a beautiful female. Thank you, Vitamin E! Photo by Alyssa DeRubeis.

In the early 2000s, Møller and his five colleagues collected 93 bird species’ eggs. The crew was able to analyze how the natural differences in antioxidant concentrations (put in by the mother) related to the birds’ spring arrival dates in 14 of them. They found that vitamin E concentration, but not vitamin A concentration, was a reliable predictor of earlier arrival dates.

This European posse took it a step further by injecting over 700 barn swallow eggs with either a large dose of vitamin E or a dose of corn oil (which contains a small amount of vitamin E). It was soon evident that the chicks with more vitamin E were bigger than chicks that received less vitamin E, thus already giving the big chicks a competitive edge over their less vitamin E-affiliated brethren. The researchers kept track of the eggs that hatched out as males in the following spring via frequent mist-netting sessions (a bird-capturing technique). Guess what? The fellas with higher vitamin E concentrations arrived earlier on average by ten days than those with lower concentrations!

Sweet. But what does it all mean? First off, vitamin E is crucial for migratory birds because it allows them to process antioxidants more efficiently. In fact, another study done by Møller, Filiz Karadas, and Johannes Emitzoe out of University of Paris-Sud suggested that birds killed by feral cats had less vitamin E than birds that died of other reasons. Furthermore, the early birds get the worm. Events such as insect hatches—vital for baby birds—now occur earlier in the spring as temperatures rise (read: climate change). Plus, if you’re a male arriving at the breeding grounds early, you get to pick the best spots to raise your offspring.

Wood-warblers, such as this Palm Warbler, must get back to their northerly breeding grounds in a timely fashion in order to hit the insect hatch for da babies. Photo by Alyssa DeRubeis.

Obviously, there’s an advantage to up the vitamin E intake and get a head start as a developing embryo. In an egg, most nutrients come from the yolk…which comes from the mother. The healthier the mother, the more vitamin E she will put in her eggs. And vitamin E isn’t produced internally; birds must consume it. While Møller’s paper on maternal effects states that vitamin E can be found widely in nature, a separate study found no apparent association between vitamin E and avian diet. Hmm. So then where DO birds get vitamin E from? Is it a limiting resource? Is there competition for it?

Clearly, we’ve got some questions and answers. As the field of “birdology,” advances, we will learn more and keep humans jealous of birds for years to come.

REFERENCES

1. Møller, A., Biard, C., Karadas, F., Rubolini, D., Saino, N., & Surai, P. (2011). Maternal effects and changing phenology of bird migration Climate Research, 49 (3), 201-210 DOI: 10.3354/cr01030

2. Møller AP, Erritzøe J, & Karadas F (2010). Levels of antioxidants in rural and urban birds and their consequences. Oecologia, 163 (1), 35-45 PMID: 20012100

3. Cohen, A., McGraw, K., & Robinson, W. (2009). Serum antioxidant levels in wild birds vary in relation to diet, season, life history strategy, and species Oecologia, 161 (4), 673-683 DOI: 10.1007/s00442-009-1423-9