Tag / sexual selection

by Roslyn

Peacock physics

We have a new paper out!

Biomechanics of the peacock’s display: how feather structure and resonance influence multimodal signaling

In this study we describe the rapid feather vibrations that peacocks use during courtship. These vibrations – at a rate of about 26 Hz on average – represent a substantial mechanical and metabolic challenge for the birds, especially given that they are performed using a massive array of feathers with widely varying lengths.

IMG_3139

A peacock shows his stuff. His train feathers range from 10 cm to > 150 cm in length, and the whole thing weighs about 300 g. Photo by Roslyn Dakin.

We recorded high speed videos of peacocks displaying in the field. We also used lab experiments to test whether the peacocks move their feathers at resonance (which would be an efficient strategy), and to understand how the colourful eyespots can remain so steady during these vibrations. One surprising result was that the peacocks with the longest trains actually used slightly higher vibration frequencies overall – making their displays a greater challenge to perform. The next step is to understand how these feather motions influence the iridescent colour patterns as viewed by the peahens (the females), and ultimately, the hens’ choice of a mate.

Media coverage has been great – here are a few of my favourites:

…and Suzanne reports that her husband met a couple in the Netherlands who had just read about our study in that newspaper. Pretty gratifying to hear that!

The videos associated with the paper are available here.

by Roslyn

Life in LA

The Los Angeles Arboretum is one of the most beautiful places I have been. Where else can you see six species of hummingbird zooming from perch to flower, an Asian red-whiskered bulbul nesting beside a dancing peacock, with noisy flocks of parakeets commuting overhead? Even the introduced species (on this list, all but the hummingbirds) are beautiful.

So it was fitting right after I got back from LA to read the news that 30 new, never-before-seen species of flies were just discovered in the city. Read more about it here. And how did the discoverers identify these flies as unique? By the gnarly shapes and bristles of their genitalia. These traits can help define species in other groups too, like bats and primates.

Photo by Kelsey Bailey, LA Natural History Museum BioSCAN project.

by Roslyn

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.
by Roslyn

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?

by Roslyn

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.

Continue reading →

by Roslyn

Elections are like peacocks

Both are loud, and both cause colourful flashy things to pop up on lawns everywhere. And much like elections, the peacock’s train is a costly endeavour. The species might be better off in terms of survival and abundance if they could just do away with those feathers. In terms of sheer waste, they remind me of the Green party pamphlets in our apartment building entrance way. They were stuffed blindly into all of the available mailboxes – which happen to be for street level businesses on our downtown block, not residents. Nice.

Peacocks and elections are both supposed to experience strong positive feedback effects. In politics, momentum can lead to rapid climbs in popularity. Sexual selection can be similar: as Ronald A. Fisher pointed out, exaggerated male traits can potentially evolve through a process of positive feedback. If enough females prefer the particular male trait initially, and the next generation inherits both the female preference and the exaggerated male trait, it can kick-start a runaway process of sexual selection to extremes.

Despite claims to the contrary, we don’t actually know whether Fisher’s runaway process contributed to peacock evolution. But it may be reasonable to assume that it played at least some role: positive feedback should set up easily so long as mate choice is not very costly for females2.

Thinking about peacocks gave me an insight that may have cured my allergy to all things political, at least temporarily. Not that I don’t care about the election – I do – but I can’t get over my frustration at the kinds of things that count as good arguments in the political sphere. Here’s an example: I’d like to learn more about the Green party, but they seem to support a whole lot of pseudoscientific nonsense. Apparently their health care platform includes homeopathy and various other forms of alternative medical quackery. How can we be sure they won’t apply the same less-than-rational approach to the environment? If only there could be “one true party”, I thought after the leaders’ debate – a notion that, briefly, made me wonder whether I might be a closet fascist.

This doubt came up again when I was reading an article in this week’s Nature about the effect of social media on research priorities. It focused on the controversial and totally unproven “liberation procedure” for MS – extremely popular in Canada but, oddly enough, nowhere else1. The article mentioned that Michael Ignatieff has stated his support for clinical trials of the treatment, despite the recommendation by a panel of CIHR experts that a clinical trial would be premature without further evidence from observational studies1. The authors of the Nature article – a group of doctors and medical researchers in Canada – ended up somewhere close to Ignatieff’s position nonetheless. They concluded that the benefits of a full-blown experimental trial might outweigh the costs if thousands of social media-influenced patients are travelling outside of the country to receive private treatment anyway, “exposing themselves to the risks and costs”1. In other words, popularity is an important – and rational – consideration when it comes to medical science.

I have two things to offer for election day. First, there is a good summary of where the major parties stand on science and research funding here. Some are a lot more rational than others.

On to the peacocks. Democratic elections, like sexually selected traits, are communal illusions. Money is another example. The more you accept them, the more you believe in them, the better they work.

References

  1. Chafe, R. et al. 2011. Nature 472: 410-411.
  2. Lande, R. 1981. PNAS 78: 3721-3725.
by Roslyn

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.

Continue reading →

by Roslyn

Groupthink

Which animal would use Facebook most, if it could?

My poll in class last week was a popular one – a fact that I couldn’t properly enjoy, since Charlie came up with it for me in a fit of brain-dead incapacity. Charlie’s Facebook question elicited chirps of excitement, compliments and even a few drawings on the response sheets. Here are the results, ranked by favour among the students:

  • Chimpanzees: So they have opposable thumbs, and can “use the spacebar” (is this actually important in Facebook?). A number of students gave bonobos special mention, since they would probably want to keep track of all their casual sexual relationships.
  • Dolphins: Highly intelligent, social, and they might also be interested in monitoring multiple sexual conquests. Dolphins and migratory whales could use Facebook to keep in touch while roaming widely over the oceans – the long-distance relationships of the animal kingdom. For some reason, students in different tutorial groups who chose dolphins were inspired to draw them for me as well. Coincidence?
  • Parrots and other birds: Especially in species that have high levels of extra-pair paternity, birds could use Facebook as a form of mate-guarding to keep tabs on their social partner1,2. There are other reasons to think that songbirds might easily make the transition to internet gossip. Female black-capped chickadees, for instance, eavesdrop on the outcome of song contests between rival males, and use this information when deciding on a mate3.
  • Eusocial animals: Like ants or naked mole rats (the only known eusocial mammal). A couple of students also mentioned highly social meerkats, since living in groups of 10-40 individuals would require them to keep track of a lot of social information.
  • Other yappy follower-types: hyenas, seals, lemmings, and Yorkshire terriers all got a mention.

Charlie and I discussed it over dinner at the Iron Duke. My first thought went to ants, for their extreme group lifestyle. The problem is that ants don’t really care about what other ants do or think about each other. Insect sociality is all about the greater good: worker ants toil away for the colony despite having no hope of reproducing on their own. Ok, so maybe the internet isn’t conducive to real reproduction either, but ants just don’t have the ego required. Plus, as one clever student pointed out, a colony of eusocial animals are all very close genetic relatives of one another – and she tends to block family members from Facebook.

Charlie mentioned peacocks for spending so much time on courtship and preening, but I rejected that one too.

Continue reading →

by Roslyn

Wherefore the mustache?

Ears, palms, toes, neck, and nose. In that order.

These are the grossest places for humans to have hair, according to Queen’s students. Ok, there were a few others that I didn’t mention. The upper lip, however, did not receive a single vote.

Last fall a number of men in the biology department grew competitive mustaches for “Movember” prostate cancer research fundraising. This required mass beard shaving on the first of November. Martin Mallet, known for his thick coat of fur, emphatic hand gestures and all-around intensity, suddenly transformed into a meek imposter. For the first time Martin had no probing questions for the speaker at the EEB seminar. I can’t help but wonder: if he did, would anyone have noticed?

I started to recognize Martin again when the hair on his upper lip attained visibility. Other men of Movember fared less well. It can’t be a good thing when the people who work in the same office as you don’t even notice your new, mustachioed face.

But what, if anything, is it for? My experience suggests that human facial hair serves as a male status signal. Is this why we evolved mustaches in the first place?

Inca Tern

Why do mustaches evolve? Inca tern, from Wikimedia Commons.

In class the other week we discussed Stephen Jay Gould and the trouble with adaptationism. Gould famously criticized the proliferation of sloppy adaptive reasoning in his 1979 paper “The Spandrels of San Marco and the Panglossian Paradigm“1. He took aim at scientists who apply adaptive “story-telling” to nearly anything – from the colour of our skin to the size of our noses – in an unverifiable, unfalsifiable way.

It can be easy to jump on the adaptationist bandwagon, since these stories are often quite plausible. This may have been especially true when “Spandrels” was written, due to the rise of some revolutionary ideas about how to apply evolutionary biology to the study of social behaviour. There was plenty of new research to be done. Of course, many of the people doing this research disagreed with Gould’s characterization2. At its worst, adaptationist thinking might lead to some bad science, especially when it comes to human behaviour (where confounds are especially hard to control). But speculation is a necessary part of the scientific method, and adaptive reasoning can be a good place to start.

It is worth noting that Gould’s paper has been enormously influential. “Spandrels” has been cited well over 3500 times. I’m still waiting on citation number 3 for my Master’s research.

And yet, the response of the research community to the “Spandrels” critique has largely been, “That’s well said, but let’s get back to our field work.”2 In that spirit, consider the mustache. Can we speculate about it in a reasonable way, avoiding the big adaptationist pitfalls?

First of all, is this question worth asking?

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by Roslyn

Masters of illusion

It can be easy to see intelligence in the animals we spend a lot of time with. Everyone has their pet example, one of the most common being dogs who can anticipate the precise time of their owners’ return. But what does this really say about the mental life of dogs? Some birds are capable of even more impressive mental stunts – only they often go unnoticed in the wild. Two recent field studies in Africa and Australia provide a nice illustration. The results challenge our notion of limited animal intelligence, but as we will see, the way we interpret them might say more about our own minds than it does about the birds.

Fork-tailed drongos are masters of deception. These small, glossy black birds from southern Africa are known for their ability to mimic the calls of other bird species – much like the mockingbirds found throughout the US and parts of southern Canada. Most of the time, drongos forage alone hunting insects, but occasionally they get other animals to do the hard work for them. Drongos will follow groups of meerkats and pied-babblers – mammals and birds known for their highly social lifestyles – and steal their food, a process known as kleptoparasitism. It might not be a complete loss for the victims, either. Drongo thieves give plenty of alarm calls along the way, and these may help the meerkat and babbler groups avoid predation1.

Perhaps not surprising for an accomplished mimic, the fork-tailed drongo has a diverse alarm call repertoire that includes its own unique warning “chink” as well as the calls of several other bird species. On the savannahs of the Kalahari Desert, birdwatchers noticed that drongos often seem to use these mimicked calls during kleptoparasitism, swooping in to steal food from pied-babblers immediately after sounding a false alarm1. For Tom Flower at the University of Cambridge, this was fascinating anecdotal evidence, so he set out to test whether these alarm calls are used by the drongos in a deceptive way2.

The first thing Flower needed to do was eliminate the possibility that the drongo false alarms are coincidental. If the drongos are truly deceptive, the calls should only occur when the birds are attempting to steal food. Flower also had to establish that the drongos sound the same, regardless of whether they are using their alarm calls in an honest or deceptive context. Finally, he had to show that the meerkats and babblers respond similarly in both cases.

Fork-tailed drongo

Fork-tailed drongo.

Continue reading →

by Roslyn

Deep archives: Irreducible beauty

Peacocks and audience at the Toronto Zoo

Were peacocks designed with this kind of audience in mind?

A while back I was searching for images of peacock feathers on Google, and I stumbled upon this article. It’s a piece by Stuart Burgess, an engineer who is head of the Department of Mechanical Engineering at Bristol University, and apparently also quite an opinionated creationist.

Burgess’ idea is that the peacock’s train feathers “contain an extremely high level of optimum design”, so much so that they provide evidence against Darwinian evolution. He thinks that the aesthetic features of the peacock are so complex, so contingent upon each other, that no step-by-step process of evolutionary change could have produced them. He’s right that these ornaments are highly complex, and that selection for this kind of extreme aesthetic feature presents a bit of a puzzle for evolutionary biology. To claim that the extraordinary complexity must be “irreducible”, however, is a big assumption.

The article provides a lot of amusing examples of twisted logic along the way. For example, one of the features that Burgess finds irreducibly beautiful is the fact that the peacock’s train forms a fan-like shape. This is because “the axis of every feather can be projected back to an approximately common geometrical center” – indeed, the body of the bird that grew them!

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by Roslyn

Deep archives: Sex “pests” get more practice

Juvenile male peafowl practice their displays

Having finished my field work this year, I thought I’d keep up with this blog by writing about interesting things that other people have seen animals do.

To start: this BBC science news report on the discovery of a “sex pest” seal that attempted to mate with a penguin, brought to my attention by Rob Ewart (the original paper can be found here but you will need a subscription to the journal to read the whole thing).

Apart from the entertainment factor – the abstract to the scientific paper concludes, “we report a case of interspecific sexual harassment bridging the rank of vertebrate class” – there are a few interesting issues here. The first being, why on earth would the seal do this? The authors provide a few possible answers. Apparently these fur seals sometimes eat king penguins, so perhaps by some strange mis-wiring, predatory arousal translated into sexual arousal in this case. Alternatively, the seal may have been too young to find a real mate, desperation leading it astray. Or, intriguingly, the young seal could have been play mating, a form of practice for the real thing later on.

The second issue: why on earth would a scientific journal publish something like this? Is it really that unusual for hormonally-charged animals to make the occasional mistake? This year alone I witnessed a peacock give chase to a human female (with the characteristic “hoot” of excitement that accompanies all mating attempts), and I’ve seen several peacocks attempt the same with guinea fowl and squirrels. All of these events happened with males that were displaying intently but that hadn’t had any peahen visitors in quite some time. Is this paper really such a novel finding, or are the authors just as desperate as the seal?

On reflection, it’s probably important to document these unusual behaviours somewhere, since it would be an interesting outcome if they turned out not to be mistakes after all. Young peacocks, for example, will frequently display their undeveloped train feathers to each other (pictured above). This male-male display may seem futile, but I wouldn’t be surprised if the kind of dancing skill required later in life demands some practice. Similarly, in Costa Rica I remember hearing juvenile long-tailed manakins displaying long after the real mating season had ended, no doubt honing their skills for next year. There is even some evidence that the reason male manakins pair up for their co-ordinated display dances, even though only the dominant member of the pair will get to mate, is for the practice.

The full citation for the seal paper:

De Bruyn PJN et al. 2008 Journal of Ethology 26:295-297.

And two on long-tailed manakin displays:

Trainer et al. 2002 Behavioral Ecology 13: 65-69.

Trainer and McDonald 1995 Behavioral Ecology and Sociobiology 37:249-254.

by Roslyn

Deep archives: Lek perspective

Scene from a lek at the Bronx Zoo

Males display in the “Wild Asia” exhibit at the Bronx Zoo, which can only be seen by riding the zoo monorail. The structure behind the birds is the monorail track.

I’ve had some success on this trip after all. The weather was perfect for my model experiments yesterday (sunny, warm, not too much wind), and although I wasn’t able to fit in quite as many trials as I was hoping for, the ones that I was able to accomplish worked perfectly. Of 16 successful trials (i.e. ones where the male danced for the model), 6 ended in a copulation attempt. In California, 3 of 22 trials ended in such an attempt. This apparent geographical difference in Penelope’s popularity is a bit of a mystery (it could be because a number of my California trials were at the end of the breeding season, when males were somewhat less motivated and harder to trick). Nevertheless, it’s safe to say that overall she was a hit.

One reason I didn’t get as many trials as I could have was that the Bronx peacocks were the most skittish ones I’ve encountered so far. When I stepped into the nyala enclosure at 7 am yesterday, I had about 2 hours to collect as much data as I could (as many as 20 five-minute trials, I figured). But it took a long time for the males to get used to me being in there. I spent the first hour waiting quietly (and nervously) for one of them to make a move, while they did the same – watching me carefully and no doubt waiting for me to leave. This stand-off shouldn’t be too surprising, though, since the Bronx Zoo birds have enough space to live their entire lives away from people.

This morning, I moved across the Bronx River to work in “Wild Asia”, and the birds there were even more difficult. Happily, though, I was able to get a video of a male reacting positively to Penelope, which will be excellent for illustrating exactly how she worked.

I also made a trip to the “World of Birds” exhibit. They have some pretty amazing animals there – here is a picture of another lek-breeding bird, the lesser bird of paradise:

Juvenile male lesser bird of paradise

Continue reading →

by Roslyn

Deep archives: New York on foot

I’m back at the Bronx Zoo now, with the model peahen, attempting some more behavioural experiments. My first day was both good and bad. I had no trouble finding my accommodations on the zoo grounds last night – I’m staying in the “Bat Cave”, so named because of the bats.

(Not really – the apartment is called the Bat Cave because it’s on the ground floor of the building pictured below, which also houses the families of three zoo staff members that live permanently on site…)

Accommodations for humans at the Bronx Zoo

If the fact that several staff members live on site doesn’t give you a sense of how well-equipped this zoo is, perhaps the contents of my apartment will. I have my own kitchen, washer and dryer for laundry, animal-themed blankets on the bed, and if bored I can read anything from The Iliad to Seabiscuit:

Reading selection in the Bat Cave

Books in the Bat Cave: no one can complain about the selection.

The zoo even has it’s own NYPD patrol.

In the future, all police will drive golf carts.

I managed to head out this morning at 6 am, beating the peafowl by at least an hour (since, for birds, they tend to roost until fairly late in the morning). It didn’t take long to find the main lek; males were roosting conspicuously in most of the surrounding trees. It was a spectacular one – at least 10 males displaying in view of one another, with another 5-6 quite close by. At first glance, this would seem ideal. I had an excellent view of a large number of birds. However, all of the display territories were nested within mammal enclosures that I couldn’t access. The birds were just out of my reach, and I needed males in accessible areas so that I could set Penelope up nearby.

I spent the rest of the day on foot, continuing to explore the peafowl haunts with Penelope in tow (I walked at least 15 km today all told – this zoo is huge!). People were startled, fascinated and amused by Penelope, and many of them tried to talk to me about her. Normally this would have been slightly annoying, but today it helped me stay positive despite the other frustrations. By afternoon, I had managed to get a few good peacock videos and permission to work in one of the mammal enclosures for tomorrow. I’ll be in and out with Penelope before the nyala (an African antelope) are released into the enclosure for the day, and again at the end of the day after they’re put inside for the night.

by Roslyn

Deep archives: A working strategy

I am very excited to report that Penelope has finally lived up to her name!

Here she is right before being courted by male no. 30:

Setting up the model peahen for a displaying male

(Photo credit: Rob Ewart)

The secret to her success? You have to present her to males that are already (preemptively) inspired to display their tails. When you present her to a male that is resting on his territory, he just watches her curiously out of the corner of his eye while making himself look busy feeding and/or preening. But sometimes males will have their tails up when there aren’t any real females in the immediate area (either because they expect females to arrive very soon, or because some females have just left the area, or possibly because these males simply have the energy for it and nothing else is more pressing at the moment). Penelope’s best strategy is to target these males: when you initially approach them, they are slowly turning in circles as they keep a look out for their next female target. When you put Penelope in front of them, they enter into a pattern of dancing that is quite clearly directed towards the stuffed bird.

During one of the trials with male no. 30 (shortly after the picture above was taken), the peacock backed up alongside the model, shivered his train at her for an infinitesimal amount of time, and mounted her almost immediately for a mating attempt. Although initially shocked (and delighted) we soon remembered that we had to intervene, and certainly won’t let it happen again.

Update: Penelope was mounted two more times in California (bringing her total to three different males). I am with her now at the Bronx Zoo in New York City for some further experiments, and am determined to start writing here regularly again!

by Roslyn

Deep archives: An instance of spite?

I have seen my first peafowl egg. Laid in the sink of the men’s bathroom, some of the Arboretum staff found it and brought it to me, unsure of what to do with it. The peafowl are overpopulated here and the staff are encouraged to find (and destroy) eggs. I ended up giving this one to Rob’s relatives from Palmdale in the hopes that they could hatch it (they keep chickens and have an incubator).

Perhaps in line with the fact that laying season is upon us, we’ve seen a few quite heated episodes involving the peahens in the last few days. Specifically, I’ve seen a couple instances of females being aggressive towards other females right in front of displaying (and preferred) males. Although this behaviour has been described before, it’s quite a paradoxical thing from the evolutionary point of view since female-female aggression over a presumably unlimited resource (mates) would be entirely spiteful.

I had seen the females in Winnipeg aggressively displaying their tails to each other in front of certain males a few times, but a recent episode here in Los Angeles has clarified the situation. This was, unmistakably, a female trying to prevent other females from mating with one of our top males. Here’s how it unfolded…

Male no. 30 was displaying his tail, with three females in the area: two sitting nearby in a little garden, preening away, and the third seeming to mirror the male while she aggressively displayed towards the preening females.

Peahen-peahen aggression

This went on for several minutes. Eventually, one of the preeners got up and left, and a few seconds later the aggressor lowered her tail and started walking away. Almost immediately, the second preener hopped down from her perch and accepted male 30’s advances right away. This brought the aggressive female literally running back to the scene, but it was too late for her to prevent the copulation. Luckily we managed to photograph the whole thing.

Peafowl copulation

Not sure what to make of it yet, but interestingly yesterday I saw more female-female aggression in front of another one of our favoured males. Our good intentions to work this morning were foiled by some light rain (peacocks don’t do anything when their trains are wet), but hopefully I’ll see some more of this action soon.

by Roslyn

Deep archives: Further notes from the field: deliberation, surprise and a misguided attempt

A few more things worth mentioning:

The other day we saw a female following a very interesting (and rather human-like) pattern while shopping around for a mate. She was visiting a particular male, and she’d watch him for a few moments (not always directly; it’s a good idea for females to seem as though they aren’t interested even when the are). She would start walking away and he would continue displaying; she’d make it about ten metres, stop, and then decide to go back. I watched this repeat about 4 or 5 times before she finally decided to accept that particular male. There weren’t any other males in the area that she would have been comparing on these forays, but it seemed pretty clear that something was going on in that pea-brain of hers. This is the first time I’ve noticed a female doing anything like this (at least in such an obvious way), but it’s possible that they could often make one or two of these little trips before making a decision.

Yesterday I saw one of the stickered males mate for the first time! It was one of the males with the decidedly less-conspicuous black stickers. I think this might actually be a good thing, since it means the females are at least considering the stickered males as potential mates.

And finally, I watched a peacock attempt (and manage) to mount one of the helmeted guineafowl that race around the park grounds. Hope for Penelope grows.