A murder and a mutant

I woke up the other day to see this:

A little closer:

Those aren’t leaves covering the trees – they’re crows! There must have been a few thousand of them (the picture only shows part of the flock, which extended to cover several other trees and rooftops). This is the third time this winter that I’ve seen a mega-roost in downtown Ottawa. Each time it has been on days that are much colder than usual. By noon, the flock had dispersed.

We had more bird encounters in Quebec last week where we saw a partial albino black-capped chickadee:

Here’s a black-capped chickadee with regular plumage, for comparison:

In domestic birds, partial albino (pied) mutations are recessive and fairly rare. It took about 100 years of cockatiel breeding before the pied mutation was established in the US, in 1951. I can’t find published numbers for chickadees, but bird banders counting mourning doves have recorded only 1 partial albino among 10,749 individuals. So this was probably a pretty rare bird! And here’s Ada, no longer impressed by a regular old chickadee:

Bird-inspired drones

This Christmas the strong winds decorated the trees with shiny new drones:

(photo by Rod Croskery)

Drones of the future are going to get a lot more maneuverable.

A group at Imperial College London has now built an aquatic diving drone with wings that can tuck in for protection during rapid plunges, inspired by the hunting behaviour of seabirds in the family Sulidae (gannets and boobies).

And a Swiss team has developed a drone with feather-like elements that allow the wing to fold into a range of configurations, analogous to the way birds can overlap their wing feathers. This allows the drone’s wings to be adjusted to suit the conditions – reducing wing area in strong winds, for example.

These advances should make it possible for drones to maneuver in a greater range of tough-to-access environments, just like birds.

Both studies are published in a new issue of Royal Society Interface Focus:

Siddall et al. Wind and water tunnel testing of a morphing aquatic micro air vehicle.

Di Luca et al. Bioinspired morphing wings for extended flight envelope and roll control of small drones.

How hummingbirds control flight

We have a new study out on how birds use visual cues in flight. Here is a summary:

Thanks to Charlie for helping to capture the video footage! The study is a collaboration with Tyee Fellows and Doug Altshuler at UBC.

For the experiments, we used eight high-speed black & white cameras to capture the entire length of the 5.5 metre-long flight tunnel (I only had space to show two in the Youtube video above). The cameras were part of an automated tracking system that tracked the birds’ motion, and determined the birds’ 3D flight paths from the different camera views. This works similar to the way multiple cameras are used to make 3D movies.

Hummingbirds were great subjects, not only because they are incredible fliers, but also because they are sugar fiends! They have to feed every 10-15 minutes throughout the day. This meant that we were able to design big experiments and test a wide range of visual conditions.

Here are two other clips that illustrate the data from the tracking system:

The best part about this project was that we started with a pilot study that seemed like a failure, at first. We tried to repeat what had been previously shown for other birds (based on a pioneering study of budgies), but we did not see the same results. At first, that can be pretty disappointing. But it also gives you the chance to think of new ideas, and then figure out ways to test them. I think this evolution from failed experiments to ones that work is the most exciting part of science! The catch is that it can take years to get there. I really started to appreciate this once I began working with birds in the lab.

Dakin, Fellows & Altshuer. 2016. Visual guidance of forward flight in hummingbirds reveals control based on image features instead of pattern velocity. PNAS, in press.

A bad year for birds

June 2013 was bad for tree swallows. At the Queen’s University Biological Station, over 90% of nests failed as a result of persistent cold, rainy weather.

This happened to be the same year we were conducting an experiment on the hormonal mechanisms of parental care in these birds. The bad weather made for a disastrous field season. Just a couple of weeks in, and we were turning up cold lifeless chicks in nearly every nest. The upside was that it led to some potential insights into the way stress hormones and tough weather conditions interact. My coauthors Jenny Ouyang and Ádám Lendvai were invited to write an excellent blog post about it here:

Terrible weather provides insight into a bird’s life

It was remarkable how closely the nest failure rates tracked the fluctuating air temperature. This could be caused by a couple of factors, with a major one being that tree swallows rely on flying insects to feed their young, and the ability of insects to fly depends on temperature. Persistent cold weather means that parent tree swallows cannot find enough food to support their offspring.

The corticosterone hormone implants made the treatment birds more susceptible to faster brood mortality, even during benign weather. It should be noted that the implants were deployed before the bad weather struck, and we would not have performed this experiment if we had known in advance that this would be such a tough year! Hopefully, though, the results provide some insight into the role of stress hormones as mediators of a sensitive period in the life history of these birds.

Read the study here:

Ouyang et al. 2015. Weathering the storm: parental effort and experimental manipulation of stress hormones predict brood survival

Feel the vibration

In between field work, I’ve been making a lot of videos lately – mostly for my students in the summer course in Ecology and the Environment. But my latest creation is entirely different: it’s for the upcoming American Ornithologists’ Union (read: bird nerd) conference.

It features slow-motion clips of peacocks vibrating their train feathers during their courtship displays. I used a special high-speed camera to film this behaviour at 210 frames per second – it was incredibly difficult to do, because the high-speed camera requires that you get really close, and males only perform the vibration when a female is nearby (and not a human one!). In the end, I was able to coax some hungry peahens practically into my lap by slowly doling out the treats. This allowed me to film males displaying at the females from just a couple of feet away.

From these videos, I estimated that peacocks vibrate their eyespot feathers at a rate of 25 Hz (i.e., the feathers move back and forth a whopping 25 times each second). That’s incredibly fast, but it’s hardly record breaking for birds. For instance, Teresa Feo and Chris Clark recently showed that hummingbirds vibrate their tail feathers at a rate of more than 80 Hz to produce a buzzy trill-like sound during their display dives. However, the hummingbirds do it passively, I believe.

Other birds are also making the news these days for their choreographic skills. Anastasia Dalziell and her coauthors at the Australian National University have shown that superb lyrebirds actually coordinate song and dance during their remarkable courtship displays.

Further Reading

  1. Feo and Clark. 2010. The Auk 127: 787-796.
  2. Dalziell et al. 2013. Current Biology. In press.

Nest in the city

One of the most incredible things about peafowl is how well these birds thrive in the suburbs. There were hundreds in Arcadia, CA, where I studied them, and every once in a while I hear about some other town where they’ve taken over – Orange County, Palos Verdes, Miami – they even disperse and occasionally pop up somewhere new (like here, or here). I’ve been told that in India (where the species is originally from), flocks also tend to settle down in villages. (And the name for a group of peafowl? A muster!) And peacocks are now on the cover of a book on urban birds1.

So what makes peafowl so much better at urban living than other, similar species?

It could be that they’re catholic about their diets, or that they’re tolerant of a broad range of environmental conditions2. Other research has suggested that, in mammals at least, successful invaders tend to have relatively large brains3 – possibly because a large brain confers the ability to respond flexibly to new situations. American crows fit this theory, as an urban success story with relatively large brains. But peafowl are some of the smallest brained birds out there, when you consider brain size relative to body size – and pigeons, starling and house sparrows aren’t particularly well-endowed, either. So what if it has more to do with how they use their brains to adapt?

A new study points to an intriguing benefit of city life for some birds, and it has me wondering about learning as a mode of urban adaptation. Apparently, some urban birds use cigarette butts to build their nests – and researchers have now shown that the cigarette butts actually improve the living conditions for young birds.

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Hipsters who hunt

An update on a previous post: my good friends Martin and Vanya are the official poster boys of a new movement.

Collecting oyster mushrooms north of Kingston. Photo by Charlie Croskery.

Read about it here, as told by Vanya’s sister-in-law, Emma Marris. It’s a great article. Charlie took the photos at the Croskery farm (more here). I helped with the shoot, including costume changes and strategic placement of my shadow to avoid lens flare. It was a lot of fun. The only problem is, hipster isn’t the right word for what these guys do. Not sure what would be.

Neanderthals were into birds

Well, into their feathers anyway. Thanks to a new study out this week, we now have paleontological proof that Neanderthals collected birds for more than just food. They probably used bird feathers for decoration – just like we do – suggesting that we aren’t the only hominid species to have developed an artistic culture1.

The research team – led by Clive Finlayson – used a combination of archaeological and paleontological evidence from several different sites where Neanderthals lived during the Paleolithic, ranging from Gibraltar in southern Spain to sites in the near East. For each site, the researchers tallied up the number of different bird species found in the fossil record at the same time and place as the Neanderthals, and they discovered that certain species were most frequent. The most common species were raptors (like vultures, kites and golden eagles) and corvids (like crows and choughs). Crucially, the researchers found that the remains of these particular species are far more abundant at the Neanderthal dwellings than they are at other paleontological sites – suggesting that the bird bones were there for a reason.

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Pitting science against media

Laysan albatross pair

Photo by Dick Daniels from Wikimedia Commons.

Odds are that the Laysan albatrosses in the photo above are a male and his female mate, but it’s worth checking their sex chromosomes to be sure. The reason? In this long-lived species, most of the adults are females, and two females often pair up to raise chicks (fertilized by other males of course). In some populations, up to a third of the nesting couples are female-female pairs1.

They’re not alone – plenty of other organisms engage in same-sex courtship, copulation and even long-term pairing. And it’s often for a good reason. Take the deep sea squid Octopoteuthis deletron. Researchers from the Monterey Bay Aquarium recently took to the deep in submarines to study their sex lives. They observed sperm packets attached to the bodies of both male and female squid, suggesting that males inseminate every other squid they can, “indiscriminately and swiftly” – a good strategy in a dark habitat where it may be hard to tell who you’re looking at2.

The media response was predictable, calling the squid bisexual, sex-starved, same-sex swingers. Promiscuous? Maybe. Indiscriminate? Yes. But pervy? I’m not so sure.

It’s an issue that Andrew Barron and Mark Brown commented on recently in the journal Nature3. Sensationalized coverage of research, especially when it makes great leaps to compare animal behaviour to human sex, can do real damage – to science and to society as well, by dredging up tired stereotypes about sex.

That was Barron and Brown’s main point, and I certainly agree. But their article got me far more worked up than the sex-starved squid.

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Very superstitious

The Shark Worlds came to Kingston last month – not a fish thing, but rather the world championships for the Shark class of sailboat. My friend Martin was competing (his boat name? Cloaca. Martin is a biologist who takes taxonomic accuracy seriously).

As he was recounting some of his adventures, he mentioned that he had done quite well in the preliminary practice race. Memories flooded back from my former life as a sailor: “Did you finish it? Never finish the practice race!”


I explained that it was bad luck, especially if you win the practice race. Better to duck the finish line instead of crossing it. Our friend Chris, another evolutionary biologist, dismissed my advice. What did luck have to do with it? We’re rational scientists, right?

I struggled to explain it. “It’s like wearing the conference T-shirt during the conference.” It marks you as new and vulnerable. And if you do well, it does nothing for your mental game. Why set yourself up to have something to lose before the event even begins?

Chris was not convinced, and I’ve been thinking about it ever since – especially since today is a near-miss Friday the 13th. Can someone be rational and superstitious at the same time?

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Peacocking on Parliament Hill

Here’s my poster from the Evolution conference in Ottawa:

Evolution poster

The colours are a bit off in this shrunken version, but you can download a larger PDF version here. The poster covers some of my work on the lesser-known green peacock (a close relative of the familiar blue variety). Green and blue peafowl have markedly different body colours, and in the green species, the females are as colourful as the males. Interestingly, the two species have eyespot feathers that are nearly identical. Why are their eyespots so similar? I think it’s because these feathers are crucial for courtship, and females of the two species have similar taste.

One of the main results I’ve found is that despite appearances, there are subtle differences in the eyespot colours of the two species. These differences, while slight, might be readily apparent to birds since they have excellent colour vision. I think the differences are the result of adaptation to different light conditions. Blue peacocks live in India, and prefer bright, open habitat like riverbeds and agricultural fields. Green peacocks live in darker forested areas of Southeast Asia, and their eyespots may be slightly brighter and greener to take advantage of dim forest light.

It was my first Evolution conference, and I hope I can get to another. The talks were fantastic. Author David Quammen summed things up nicely in his public lecture: “Science is people.” This theme carried through the meeting, from Rosie Redfield’s tale of the pitfalls of falling in love with your hypothesis to a rally where scientists young and old marched together on Parliament Hill (see my pictures here). How often does that happen?

Life imitates [filmmaking] art

Congratulations to Myra Burrell – her peacockumentary has been short-listed for the Animal Behavior Society’s film festival!

Myra, a veteran of the natural history film program at the University of Otago in New Zealand, traveled to California with me in 2010. She helped with peacock field work, capturing more females than anyone thought possible. Somehow, in the meantime, she made a movie about the birds. It’s a short film that gives you an idea about what happens on a peacock lek, from the hen’s point of view.

It’s quite an honour to be among the 6 films selected for festival screening, since they must get on the order of ~100 applicants. If Myra wins, it would be oddly fitting: a wildlife film straight out of a park that moonlights as a real Hollywood set.

You can watch “Hen’s Quest” here.

The best parts? I love the music and Myra’s cinematography. I contributed writing (including the title!) and did the artwork; Brian McGirr turned my map drawing into a fantastic animation. Good luck, Myra!

How I learned to respect the peahen

Written for the Los Angeles Arboretum.

Meep meep? More like “Honk honk!”

Arboretum regulars will no doubt recognize the call of a startled peahen, but you may not be aware of the clever ways they use it. Not that they try to boast or taunt the enemy, necessarily, but I’m starting to think that the birds at the Arboretum owe a lot to their version of the Road Runner’s call.

How do I know? Some background is in order here: I’m the tall blond woman who has been hanging around the Arboretum morning and night for the past few years, overdressed and hauling a camera, a pair of binoculars, some peanuts and, if I was lucky, a peacock. Working at the park each spring, I often wished I had more time to chat with visitors. But I was preoccupied, and the life of an ornithologist can sometimes feel like that of Wile E. Coyote on a bad day.

For the past four years, I’ve been chasing peafowl across the continent – from Arcadia in February to Winnipeg, Toronto and New York in May and June. Incidentally, the Bronx Zoo is the only place in North America that even comes close to the Arboretum in sheer number of peafowl. Three years into my PhD in biology, and I’ve spent literally hundreds of hours watching these birds.

You may be wondering what got me into this mess.

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Quirks, quarks and quantum sailboats

An old mystery from my days as a sailor resurfaced this week. Does air on one side of the sail somehow know what the air on the other side is doing? Sounds strange, but it happens to be a key part of explaining how boats, birds and airplanes work, and it stumps a whole lot of people who should probably know better – including most pilots.

I was reminded of this by Bob McDonald from CBC’s Quirks and Quarks radio show. He was in town to give a talk on “The Science of Everyday Life”. It was clear that this was going to be a show for kids, but I dragged Charlie along for two reasons. First, I was planning on presenting some of my peacock research at a family science festival on Saturday; I thought it might be useful to see a master of this sort of thing in action. Fandom came into it too – the Quirks show is one of a handful of radio programs that got me through my troglobite period of 8 hour days in the darkroom last summer.

I was pretty sure what we were in for – baking soda and vinegar magic for the edification of the grade school set – but I wasn’t prepared for how quickly McDonald would put me under his spell, too. Sitting there cold and hungry in the dingy auditorium, I had forgotten all about my surroundings by the time McDonald was whirling a mop around and keeping a kid trapped in his chair using only his thumb to demonstrate centre of gravity. And he was just getting started. Although the talk was too long at nearly 2 hours, it was worth the wait to see video of McDonald’s adventures in weightless flight at the end. His imaginative pitch for the space tourism industry was another highlight. I was hooked at his concept for a giant rotating space hotel. If we put a cylindrical swimming pool smack in the middle, the water would stick to the outer walls by centripetal forces. You could literally fly around in the air at the zero-gravity centre and dive down in any direction to the water below.

McDonald mentioned something in his explanation of how to make a better paper airplane that brought up an old problem for me.

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Furious about eyespots

I think I flubbed an interview this week. My supervisor Bob and I just published a paper that is getting some press, because it addresses a recent controversy about the peacock’s train1. Eager for the interview with Nature News, I wasn’t exactly prepared with good lines for the reporter to go on – and I wonder if that’s why he had to pump up our story as a “furious debate”2.

In truth, most of the “debate” played out in a flurry of news articles back in 2008. That was when Mariko Takahashi and her colleagues in Tokyo and Kanagawa published the fruits of their exhaustive 7-year study of the peafowl at the Izu Cactus Park in Shizuoka, Japan3. I’ve never met Takahashi, although I did meet her supervisor and one other player in this story at a conference back then, and all were quite friendly. But the title of Takahashi’s 2008 paper, “Peahens do not prefer peacocks with more elaborate trains” was a direct jab at an earlier one, “Peahens prefer peacocks with more elaborate trains”, by Marion Petrie in the UK4. Takahashi and her coauthors had the difficult task of proving a negative – and they did it pretty convincingly, with the aid of a much more extensive data set than anyone had gathered before with this species. The upshot? For a peacock in Japan, having a bigger train ornament doesn’t necessarily win you any favours with the ladies.

Bigger in terms of the number of eyespots visible in the ornament during courtship, that is; males have about 150 on average, each on the end of a single feather. The results of the Japanese study were in direct contradiction to Marion Petrie’s earlier work as well as some recent studies of peafowl in France suggesting that eyespot number is often correlated with male mating success4,5. What’s more, in the 1990s Petrie had confirmed the causal effect of eyespots by showing that you could alter a male’s fate just by removing about 20 of them6.

Peacock in flight

Taken at the Los Angeles Arboretum in 2009. Photo by Roslyn Dakin.

The Japanese team proposed a rather bold new hypothesis. Perhaps the cumbersome, ridiculous train ornament is obsolete – a relic of sexual selection past, no longer used by females in quite the same way as it was when it first evolved3.

This was taken up with gusto by the news media. Check out the headlines: “Peacock feathers: That’s so last year”, “Have peacock tails lost their sexual allure?”, “Peacock feathers fail to impress the ladies”. Amusingly, this last article was also published with the title, “Female peacocks not impressed by male feathers” by Discovery News7-10. Males could probably be forgiven for striking out with those elusive female peacocks, since they don’t actually exist.

Headlines aside, Takahashi’s interpretation is somewhat of a concern. Here’s why: creationists picked up on this story too11.

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Another reason for eggs

Roman soldiers used them for protein1. In Mexico, men steal them from endangered sea turtles for their supposed effects on virility2. Bird eggs and roe, the ripe ovaries of fish, have a rich balance of proteins, fats and minerals – nutritionally, almost everything a predator needs. The whole point of these things is to feed something for an extended period of time. It’s no wonder eggs are so delicious.

The applications go beyond adding energy to our diets and structure to baked foods. Laying hens also contribute to medicine. Fertilized chicken eggs are used to grow viruses for mass production of vaccines. In 2007, scientists figured out how to genetically engineer hens to incorporate certain cancer-fighting proteins right into their egg whites, in a more efficient way to manufacture drugs that has been dubbed “pharming3.

This morning, enthusiasts have yet another reason to celebrate, since a new study suggests that bird eggs might hold even more promise for medical research.

It has to do with migration, but not the kind you’re used to hearing about with birds. Cellular migration refers to the movement of cells within an organism during growth or embryonic development. For a long time, biologists studying this behaviour focused on the movement of single cells in isolation. In the last decade, however, the focus shifted to cells moving in a large, cohesive group. This collective migration is a fundamental part of gastrulation and neural crest development – two of the necessary steps for turning a blob of cells into a fully formed embryo during development (watch a time lapse video of this process in zebrafish).

Collective cell movement, or epithelial migration, occurs on a grand scale during bird embryo development. Every fertilized egg contains a tiny blastula, the hollow ball of cells that will eventually become a fetus. Early on, the cells of outer blastoderm layer of the ball start to expand across the vitelline membrane that surrounds the egg yolk, in a process known as epiboly. Eventually, the expanding sheet of cells envelops the entire yolk – a requirement for the yolk sustain the embryo during its transformation from a ball of cells into a viable chick.

Bird embryo and yolk

A chicken embryo grows while attached to its yolk, because of epiboly. Modified from drawing by D.G. Mackean.

This around-the-yolk migration happens rapidly, within days. From the perspective of a single cell, it’s a feat that bioengineer Evan Zamir likens to “an ant walking across the earth”4. And we still don’t know exactly how birds do it, with their humongous yolks; so far, most research on epithelial migration has involved other organisms.

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A case of mistaken celebrity

They all look the same to us. Celebrities, that is. And by us, I mean academics.

The proof starts with peacocks. Last fall, I was working on some measurements I took of the crest ornament in these birds. Peafowl have this funky little fan of feathers on top of their heads, and though it’s not that small in the grand scheme of fancy bird plumage ornaments, the peacock’s five centimetre crest looks a bit ridiculous next to the metre-and-a-half long train.

Why bother having a crest when you also have a big train? And why do females wear crests too? In this species, the crest appears to be the only plumage ornament shared by both sexes. Here are some of my pictures from the field, taken on the cusp of the breeding season:

Crest ornaments of male and female peafowl

Crests of (a) male and (b-c) female peafowl. Scale bars are 10 cm. Photos by Roslyn Dakin.

Over the years, I’ve measured the crests of close to 150 birds. These data lend some support to the idea that the crest is a signal of health in both males and females, although it might work in slightly different ways for the two sexes1. As you can see from the picture above, there is a lot of variation in how the crests look – and it’s mostly on the female side of the equation. Almost all adult males have tidy looking crests like the one shown in (a), but females often have crests with a lot of new feathers growing in (c). It turns out that males in better condition tend to have fuller, wider crests. The healthiest females, on the other hand, have crests that look most like those of males, with all feathers grown out to the top level (b).

The extreme variability among females leads to an additional hypothesis, and it’s one that I can’t rule out at this time. Perhaps the crest is a signal of individual identity that the birds use to sort out who’s who in their social groups – just as faces do for us. A clue that this could potentially work for peahens is that my field assistants and I can do it. Once you spend enough time hanging around with these birds, you find yourself recognizing certain females that haven’t been captured yet (and that therefore lack identifying leg bands). Your first clue? Usually a unique pattern of crest feathers.

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