Tuesday, April 17, 2018

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.


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

Tuesday, April 10, 2018

How To Get Into An Animal Behavior Graduate Program: An Outline

Do you dream about a career of studying animals?
Image by freedigitalphotos.net.
A repost of an original article from March 13, 2013.

**NOTE: Although this advice is written for those interested in applying to graduate programs in animal behavior, it applies to most programs in the sciences.**

So you want to go to grad school to study animal behavior… Well join the club! It is a competitive world out there and this is an increasingly competitive field. But if every fiber of your being knows this is the path for you, then there is a way for you to follow that path. With hard work, dedication and persistence, you can join the ranks of today's animal biologists to pursue a career of trekking to wild places to study animals in their native habitats, testing questions about the physiology of behavior in a lab, or exploring the genetics of behavioral adaptation.

This is an outline of advice on how to get into a graduate program in animal behavior. More details on the individual steps will follow, so leave a comment below or e-mail me if you have any particular questions you would like me to address or if you have any advice you would like to share.

  1. Get good grades, particularly in your science and math courses. And make sure you take all the science and math prerequisites for biology graduate programs.
  2. Prepare well for the GREs.
  3. Get research experience. This can come in many forms (such as volunteering in a lab, working as a field technician, or doing an independent project for credit), but as a general rule, the more involved you are in a project, the more it will impress those making acceptance decisions.
  4. Choose the labs you are interested in, not just the schools. As a graduate student, you will spend most of your time working with your advisor and the other members of your advisor’s lab. This means that the right fit is imperative. Figure out what researchers you may want to work with, then see if they are at a school you would like to attend.
  5. Be organized in your application process. There will be a lot of details to keep straight: due dates, recommendation letters, essays, communication with potential advisors… The more organized you are, the less likely you are to miss a deadline or make an embarrassing mistake.
  6. Write compelling essays. Most schools will ask you to write two short essays: a Statement of Purpose and a Personal History. This is your place to set yourself apart. They need to convey your experience with animal behavior research and passion for working with that particular advisor. They also need to be very well written, so expect to write multiple drafts.
  7. Be organized and prepared when you ask for your recommendation letters. The easier you make it for your references to write a thoughtful recommendation letter for you, the better the letters will be.
  8. Apply for funding. This isn’t essential: Most first-year graduate students do not have their own funding. But the ability of a school and a specific researcher to accept a graduate student depends on what funding is available to support them. If you have your own funding, it is more likely you will to be able to write your own ticket.
  9. Be prepared for each interview you are invited to.
  10. If at first you don’t succeed, try and try again. Although heartbraking at the time, it is very common in animal behavior graduate programs to not be accepted anywhere in your first year of applications. If you are rejected, it doesn’t necessarily mean you are not a good candidate. Often it means there is no funding available to support you in the labs you would like to join. Spend the year participating in research and applying for funding so you can reapply next year.
The submission of a successful application takes a lot of planning and preparation. Getting good grades is a continuous effort. Plus, the most successful applicants often have two or more years of research experience. Ideally, you are working on these two things at least by your sophomore year of college. But if you waited too long and you haven’t taken enough science or math prerequisites, your grades are not where they need to be, or you don’t have enough research experience, you can take some extra time after you graduate to take community college courses and volunteer or work in a lab. Persistence and dedication are key to following a challenging path.

Tuesday, April 3, 2018

Animal Mass Suicide and the Lemming Conspiracy

A repost of an original article from April 4, 2012.

Ticked off Norway lemming doesn't like gossip!
Photo from Wikimedia Commons by Frode Inge Helland 
We all know the story: Every few years, millions of lemmings, driven by a deep-seated urge, run and leap off a cliff only to be dashed on the rocks below and eventually drowned in the raging sea. Stupid lemmings. It’s a story with staying power: short, not-so-sweet, and to the rocky point.

But it is a LIE.

And who, you may ask, would tell us such a horrendous fabrication? Walt Disney! Well, technically not Walt Disney himself… Let me explain:

The Disney Studio first took interest in the lemming mass suicide story when, in 1955, they published an Uncle Scrooge adventure comic called “The Lemming with the Locket” illustrated by Carl Barks. In this story, Uncle Scrooge takes Huey, Dewey and Louie in search of a lemming that stole a locket containing the combination to his vault … but they have to catch the lemming before it leaps with all his buddies into the sea forever. Three years later, Disney further popularized this idea in the 1958 documentary White Wilderness, which won that year’s Academy Award for Best Documentary Feature. A scene in White Wilderness supposedly depicts a mass lemming migration in which the lemmings leap en masse into the Canadian Arctic Ocean in a futile attempt to cross it.

In 1982, the fifth estate, a television news magazine by the CBC (that’s the Canadian Broadcasting Corporation), broadcast a documentary about animal cruelty in Hollywood. They revealed that the now infamous White Wilderness lemming scene was filmed on a constructed set at the Bow River in Canmore, Alberta, nowhere near the Arctic Ocean. Lemmings are not native to the area where they filmed, so they imported them from Churchill after being purchased from Inuit children for 25 cents each. To give the illusion of a mass migration, they installed a rotating turntable and filmed the few lemmings they had from multiple angles over and over again. As it turns out, the lemming species filmed (collared lemmings) are not even known to migrate (unlike some Norwegian lemmings). Worst of all, the lemmings did not voluntarily leap into the water, but were pushed by the turntable and the film crew. Oh, Uncle Walt! How could you?!

Norway lemmings really do migrate en masse, but they don't commit mass suicide.
Drawing titled Lemmings in Migration, in Popular Science Monthly Volume 11, 1877.
As far as we know, there are no species that purposely hurl themselves off cliffs to die en masse for migration. But, strangely enough, North Pacific salmon do purposely hurl themselves up cliffs to die en masse for migration. And what, you may ask, is worth such a sacrifice? Sex, of course!

Migrating sockeye salmon thinking about sex.
Photo from Wikimedia Commons by Joe Mabel.

The six common North Pacific salmon species are all anadromous (meaning that they are born in fresh water, spend most of their lives in the sea and return to fresh water to breed) and semelparous (meaning they only have a single reproductive event before they die). After years at sea, salmon swim sometimes thousands of miles to get to the mouth of the very same stream in which they were born. Exactly how they do this is still a mystery. Once they enter their stream, they stop eating and their stomach even begins to disintegrate to leave room for the developing eggs or sperm. Their bodies change in other ways as well, both for reproduction and to help them adapt to fresh water. They then swim upstream, sometimes thousands of miles more, and sometimes having to leap over multiple waterfalls, using up their precious energy reserves. Only the most athletic individuals even survive the journey. Once they reach the breeding grounds, the males immediately start to fight each other over breeding territories. The females arrive and begin to dig a shallow nest (called a redd) in which she releases a few thousand eggs, which are then fertilized by the male. They then move on, and if they have energy and gametes left, repeat the process with other mates, until they are completely spent. If the females have any energy left after laying all their eggs, they spend it guarding their nests. Having spent the last of their energy, they die and are washed up onto the banks of the stream.

Now that’s parental commitment! So the next time your parents start laying on the guilt about everything they’ve given up for you, share this nugget with them and remind them it could be worse…

Want to know more? Check these out:

1. Learn more about semelparity here

2. Learn more about salmon reproduction at Marine Science

3. And learn even more about salmon reproduction with this awesome post by science blogger and Aquatic and Fishery Sciences graduate student, Iris. Her current blog posts can be found here.

4. Ramsden E, & Wilson D (2010). The nature of suicide: science and the self-destructive animal. Endeavour, 34 (1), 21-4 PMID: 20144484

Tuesday, March 27, 2018

Those Aren’t Chocolate, Easter Bunny!

A repost of an original article from March 27, 2013.

The Easter Bunny has a dirty secret. When he’s not hopping around in his pristinely white fur hiding beautifully colored eggs and decorated baskets full of treats…he’s eating his own poo. Gross!

Never trust a rabbit. Photo by the Mosman Library at Wikimedia.

But don’t judge him before you understand him. It’s not that he chooses to eat poop, but that he has to for his own health. In fact, all rabbits do.

Rabbits are herbivores, which means that they only eat plant material. Plant material is very difficult to digest, although it may not seem like it (I mean, we eat plants all the time with no problem, right?). But when it comes to digestion, it’s not what you put in your mouth and swallow that matters, but what your body can break down.

This process of breaking down food depends on digestive enzymes, a group of chemicals that break down food. Each type of digestive enzyme is specific for breaking down a particular type of food chemical. Plant material is so hard to digest because it is largely composed of cellulose, a sugar that we vertebrates don’t have an enzyme for.

Herbivorous animals that lack this enzyme have developed an alternative strategy to get the nutrients they need out of these plants – They have microbes that live in their guts and ferment the plant material. Many of these microbes, which include bacteria, protists, yeast and fungi, produce the enzyme needed to break down cellulose. But these microbes are slow-acting (which means herbivores with longer guts get more nutrients), and they are sensitive (which means herbivores with special microbe gut chambers get more nutrients).

Rabbits have a special gut chamber called a cecum (or caecum) that houses many of their gut microbes. The cecum is so important to rabbit digestion, it’s even bigger than their stomach! When a rabbit eats something, the food is broken down by chewing, swallowed, and passed on to the stomach (follow along with the diagram below). The stomach stores and sterilizes the food while breaking down some of the nutrients before it passes the food on to the small intestine. The small intestine absorbs the nutrients it can before the remaining food gets sorted at a fork in this digestive road. The fibrous food parts move on to the colon, where it is converted into little hard turd-balls. The non-fibrous parts go to the cecum, where the microbes living there work their magic, breaking down the remaining food into absorbable nutrients.

This diagram of the rabbit digestive system was posted by Sunshineconnelly at Wikimedia. Trace through it as we talk about where each digestive step happens.

The trouble is, this food has already passed the part of the digestive tract that absorbs most of these nutrients: the small intestine. Now, it has nowhere to go but out. So the cecum pushes these remaining nutrients into the colon, which turns them into cecotropes (or caecotrophes): mucus-covered, nutrient-rich, moist turds shaped like a bunch of grapes (and according to the Easter Bunny, just as delicious). And the only way rabbits can get the nutrients (and remaining microbes) out of these little nuggets is to send them through the digestive tract all over again by eating them. So that is what they do.

Eating poo sounds gross and unusual, but it is actually fairly common in the animal kingdom. So common, in fact, that there is a term for it: coprophagia. Hamsters and capybaras have similar digestive tracts to rabbits and eat their own poo for the same reasons. Other animals, like elephants, hippos, pandas, and koalas, are born without the necessary microbes to digest the food available, so the babies obtain these microbes by eating their mothers’ poo. And many coprophagous insects, like flies and dung-beetles, subsist on diets composed of the poo of large animals.

So don’t hate on the Easter Bunny for his repulsive ways. He can’t help what he is. Just appreciate him for all the chocolate eggs he brings you every Easter. Wait… Those are chocolate eggs he brought you, right?

Tuesday, March 20, 2018

Physicists Determined That Cats Are a Liquid

Marc-Antoine Fardin, a physicist at Paris Diderot University, was inspired by a post at boredpanda.com called “15 Proofs That Cats Are Liquids” and set out to use the tools of his trade to determine if this is, in fact, true.

Figure from "On the Rheology of Cats": (a) A cat appears as a solid material with a
consistent shape rotating and bouncing, like Silly Putty on short time scales.
(b) At longer time scales, a cat flows and fills an empty wine glass.
(c-d) For older cats, we can also introduce a characteristic time of expansion and
distinguish between liquid (c) and gaseous (d) feline states.

Rheology is the branch of physics that studies the flow of matter. Matter can come in three forms: solid, liquid and gas. Under pressure or stress, solid matter deforms whereas liquid and gas matter flows. Liquid matter is incompressible, whereas gas matter is compressible. Thus, liquids are substances that conform to the shape of their containers (i.e. are fluid) and have constant volume (i.e. are incompressible).

Flow is the process of conforming to the shape of containers and has a set duration for different substances. In rheology, this duration is called the relaxation time. The ability to determine if a substance is a liquid depends then on whether you observe it for longer than its relaxation time. Based on the evidence provided in images, Marc-Antoine determined that cats can, in fact, conform to the shapes of their containers if given enough time. Therefore, cats are liquid.

But this leaves us with additional questions about how cats flow. For one thing, some fluids are more viscous (thicker) at some times and less viscous (runnier) at others. This property is called thixotropy. Do cats exhibit thixotropy? In other words, does the relaxation time of a cat depend on its age? And do they flow with vortices or with laminar flow? A substance flowing with vortices would spin around the container and start to climb of the walls of the container. A substance flowing in a laminar way would calmly follow the outline of their container. Cats may be a fluid that can do both.

Figure from "On the Rheology of Cats": (a) A cat spontaneously rotates in a cylindrical jar.
(b) Normal forces and Weissenberg effect in a young sample of Felis catus.

Clearly, more work needs to be done on this very important question. If you have a cat, you can explore this question with some photographic evidence of your own.

Want to know more? Check this out:

Fardin, M.A. (2014). On the Rheology of Cats. Rheology Bulletin, 83(2):16-17.