30 November 2009

Pre-conditioned flash lamps in place

As for the replacement from old to new flash lamps in the PIV laser, we now had a third batch of lamps to install. Replacing these lamps is a risky business for various reasons, not only the need of climbing the tunnel but also the actual replacing these delicate (easy to break) filaments. And when the fourth (final) lamp was to be inserted - i broke! A word signaling a problem was heard from the tunnel top and it was immediately clear that something had gone wrong. Immediately checking with Litron people, however gave some hope in that it might work with one of the non-conditioned lamps in tandem with a pre-conditioned one. Some more work and then a final test - it worked. So, now we have a laser with a complete set of flash lamps. We now only have to align the thing to optimize the set-up for maximum power output.

07 November 2009

PIV laser gets new flash lamps

As the laser has lately given only about 25 mJ per pulse when set to maximum power, we figured it is perhaps time to change the flash lamps. In our Litron laser there are 4 lamps to replace, and on Friday afternoon we had everything in place, i.e. the lamps, new o-rings, appropriate laser manual and isopropyl alcohol to clean the new lamps. It took some time, and even if the manual explicitly said "do not lose" about 4 particular 3M bolts that was exactly what happened to one of them. It fell to the floor, two bounces was heard and then it was gone, probably it fell to the basement. The lost bolt must have moved a horizontal distance of at least 1 m, while subsequent experiments with a similar bolt showed an average horizontal displacement from the position of first floor contact of about 15 cm! However, we found new stainless steel 3M bolts and could proceed as planned. Also cooling water was renewed and before that we had changed to new filters. So, no we will hopefully get back the strong and clear light sheet that make stereo PIV such a nice method.

14 October 2009

New Lab meeting procedures

As we have agreed we will try a new strategy regarding our lab meetings, by having one meeting every week, starting at 09:00 Monday. The place will be the seminar room "Argumentet". In this way we can keep ourselves more informed and it should facilitate co-ordination of wind tunnel activities during the rest of the week. So, this new system will begin next Monday, 19 October, and I have also selected a paper for us to read until then. The paper is "Flapping wing flight can save aerodynamic power compared to steady flight" by Umberto Pesavento and Jane Wang. It appears in Physical Review Letters, which is the tabloid equal for physical sciences.

06 October 2009

New Lab Publication in J Exp Biol

In a new paper, published in J Exp Biol 212: 3365-3376 (2009), Christoffer Johansson and Anders Hedenström report on wake properties of blackcaps (Sylvia atricapilla) studied on the Lund University wind tunnel. They use a high speed stereo-3D PIV system to get information from the entire wake behind the flying bird. It was found that the wake geometry was slightly more complicated that previously thought about passerine birds. This is mainly due to that the PIV system used is capable of detecting more subtle features of the wake, than with previous 2D visualization. Another twist is that one bird accidentally molted its tail, but flying without a tail did not cause any dramatic changes as to the bird's wake. The function of the tail, whether it is a lift generating surface or if it works as a splitter plate that reduces the drag, remains unclear. New experiments will hopefully teach us more about what birds have tails for.

22 September 2009

New Publication from Oxford Group

In a new paper published in Science last week the Oxford group of animal flight, headed by Adrian Thomas, shows how important it is for a locust to have appropriate camber and wing twist to maintain the high performance achieved by insect wings. The way they do it is by using a CFD (computational Fluid Dynamics) model, and in a stepwise manner remove the camber and twist exhibited by the real locust. Before trusting the model output, the CFD model was validated against real data using smoke flow visualization and PIV measurements obtained from locusts tethered in the wind tunnel. In accompanying podcast Adrian explain certain problems they had in modeling the upstroke of the hind wings, so go an listen also for that.

15 September 2009

Final symposium tally

Abstract submission has closed for SICB's 2010 meeting, where we (Isabelle Bisson, Martin Wikelski, and I) will be holding our Integrative Migration Biology symposium. The way SICB organizes the meetings, the 13 symposium speakers (including Anders, Susanne and myself) are set, but people can apply to give a presentation in a coordinated session. The official numbers are in, and our symposium attracted more coordinated session speakers (24) than any other symposium this year! I can't wait to meet and talk with everyone who's coming; it sounds like there will be some great presentations.

You can still register for the meeting if you haven't already; it should be a lot of fun--and there are plenty of biomechanics talks for those of you who are less interested in migration than I am!

New Lab intern: Roel Vleugels

During the autumn 2009 Roel Vleugels, a student of aeronautical engineering at Delft University, is visiting our lab as part of his master program. Roel is going to adapt our aerodynamic balance for precise measurements of aerodynamic forces on different wings, such as flat plates and the Eppler 387. He will also make measurements on the drag of a swift look-alike model bird body. We welcome Roel to the group and hopes he gets a great time while here!

01 September 2009

New Fridge for the Wind tunnel

A new fridge was delivered today, 1 September 2009, to be used for storing animal food for wind tunnel birds and bats. The fridge has a constant temperature facility, meaning it has a fan that mixes the air inside the fridge. The old fridge was broken since many years and in the interim a constant temperature box has been used, which accommodates fridge-like temperatures but is otherwise not large enough. The recent problems with the large generic cold rooms in the Ecology building, with measurable water depth on floor and mold infestations, made this acquisition a necessary step in order to be able to keep high quality mealworms, crickets, honey, and nectar plus at optimal conditions. The picture shows happy Florian Muijres and Melissa Bowlin during the installation procedure of the new fridge.

Aerodynamic wake behind a flying bat

Here is a nice instructive video of the aerodynamic wake behind a flying bat. The bat species is Glossophaga soricina, and it has a forward flight speed of 4 m/s.

In the movie you see the flying bat from behind. The right side of the movie shows the right half of the bat body and its right wing, while the left side of the movie shows the wake generated by the flapping left wing. This wake is calculated using our DPIV system. The colors in it are vorticity strength while the black arrows are the in-plane air velocity vectors.

The movie is slowed down 10 times and it is looped 5 times.

27 August 2009

Lift in hovering hummingbirds

A new paper published in Proceedings R Soc B (still as FirstCite) explores the lift generating mechanism in hummingbirds. The study is made by the team Warrick, Tobalske and Powers, i.e. the same group that published a paper on hummingbird wakes in Nature in 2005. This is their follow up, now looking closer to the wing with their PIV cameras. The leading edge vorticity is not as prominent in hummingbirds as found previously for hawkmoths and bats (in Lund), but is more varying and with a mean contribution to lift of 16%. I think that everybody expected a big fat LEV in hummingbirds, being classified as honorary insects by some, and so this study shows an unexpected result. It is always a challenge to explain the unexpected, but we are facing some interesting phenomena here and we should soon be able to compare these results with that of avian hovering, such as in pied flycatchers.

The paper can be found here:

25 August 2009

New lab publication!

Once upon a time, a group of us sat down at a MIGRATE) meeting and decided to write something about how technology could impact migration research. Now, an undisclosed* amount of time later, the manuscript, titled "Integrating concepts and technologies to advance the study of bird migration," has finally been pre-printed in Frontiers in Ecology and the Environment, which is similar to TREE.

You can find our review here.


*an embarrassingly long time

21 August 2009

Call for abstracts/symposium announcement - Integrative Migration Biology. Deadline 11 September.

Hi Animal Flight Lab!

I know not all of you work on migration, but I thought I would post this here anyway.

We are sending out a call for abstracts to present in a session complementing our symposium, Integrative Migration Biology, which will be held at the 2010 Society for Integrative and Comparative Biology (SICB) meeting, Jan. 3-7, in Seattle, WA. We would especially like to extend this invitation to students and post-docs, but welcome abstracts from all researchers currently studying animal migration. As a student or post-doc, this would give you a wonderful opportunity to interact with some of the top researchers in the field of animal migration. We welcome submissions for both contributed papers and posters, and encourage students to apply for SICB’s Charlotte Mangum Student Support Program. Please check out the SICB meeting page at for more information.

Billions of animals migrate each year, and they can have enormous effects on the communities and ecosystems they inhabit. We wish to bring together researchers from all over the world who are attempting to integrate ecology, evolution, behavior, physiology, and theory in order to understand the phenomenon of migration. In order to migrate, organisms themselves must integrate many aspects of behavior, physiology, genetics, and morphology. Migration is therefore an excellent system in which to study adaptation and the interplay between various ecological and evolutionary levels of analysis. Traditionally, however, researchers have tended to focus on one narrow aspect of migratory behavior to the exclusion of all else. More recently, biologists have begun to examine multiple aspects of migration in order to better understand this important life history strategy. The primary goal of this symposium is to bring these researchers together with students and post-docs who are just staring their research programs in order to foster discussion and collaboration and further the development of integrative migration biology research.

This symposium and the complementary session(s) are designed to provide a venue for researchers from around the globe to discuss the past, present, and future of migration research. The list of symposium speakers and preliminary titles include:

1. Melissa Bowlin (Lund University), Isabelle-Anne Bisson (Princeton University), & Martin Wikelski (Max Planck Institute for Ornithology). "Integrative migration biology: Past, present, and an exciting future."

2. Marilyn Ramenofsky (University of California Davis). "Endocrine and metabolic parameters coincide with daily fueling and flight cycles of captive migrants."

3. Anders Hedenström (Lund University). "Testing migration theory: the utility of inegrative approaches using field experiments and wind tunnels."

4. Chris Guglielmo (University of Western Ontario). TBA

5. Susanne Åkesson (Lund University). "Endogenous migration programs, migratory fattening and orientation in passerine birds."

6. Kasper Thorup (University of Copenhagen). "Understanding the migratory orientation program in birds: extending laboratory studies to studying free-flying migrants in a natural setting."

7. Tom Kunz (Boston University). TBA

8. Nir Sapir (The Hebrew University of Jerusalem). "The effect of weather on migrating bee-eaters studied by radio-telemetry and numeric atmospheric model."

9. Judy Shamoun-Baranes (Amsterdam University). "Integrating measurements and models to study the influence of weather on migration."

10. Peter Marra (Migratory Bird Center, Smithsonian Institution). "Seasonal interactions and carry-over effects – understanding migration in the context of the annual cycle."

11. David Wilcove (Princeton University). TBA

Additional information will be posted on our symposium website, which we will put up here: once we have finalized some additional details. If you have questions about the symposium or the meeting, please contact us at melissabowlin at gmail dot com or ibisson at princeton dot edu.

Funding for this symposium was provided by MIGRATE, an NSF-funded Research Coordination Network, and SICB.

Note: in order to ensure that your talk or poster will be placed in the correct session, be sure to put our symposium, Integrative Migration Biology, into the field following the statement, "I would like to be in a session complementing a regular symposium" on the abstract submission form on SICB’s meeting webpage.

We hope to see you in Seattle!

12 July 2009

Breaking news

Hi all,

Here is my follow-up to melissa's post:

Yes, Lieke and i got a son today! His name is:

Max Muijres

Isnt he georgeous. The detailed specs about him can be found in image 2.


Ps. The pics are not the best quality, but that's the first proof of
the fact that your priorities change when you get a kid (as one
advisor of mine clearly explained to me ;)

A little birdie just told me...

...that we have a new arrival at the flight lab named Max Muijres! Congratulations Florian and Lieke!

(Sorry, I have no pictures...yet!)

05 July 2009

...more from SEB

Since I'm finally back from Glasgow and back online I also wanted to add some information from the SEB conference. So first, I wanted to say that also Per gave an excellent talk but it was a pity that he wasn't in the Biomechanics session! But maybe he did a good thing in getting some genetics people interested in swifts...

On Tuesday I went to the radio workshop with Alun Lewis, who had worked for the BBC a long time and gave us many interesting and useful tips how to perform in a radio interview. Since the rest of the world has a hard time understanding scientists and has no chance of gaining knowledge if we don't try really hard to get out of our science language. I was interviewed on how we can be like superheroes :) It was a great workshop!

Unfortunately I can't tell you anything about the last day, because I wasn't at the conference any more, but instead I made a trip to Loch Ness and the Highlands, which I enjoyed a lot! Here is a small impression of what I saw that day:

01 July 2009

Day 3

Before I get to day 3, I just want to add a bit to what Per posted yesterday. On Monday I bounced back and forth between the biomechanics session (which he's already given a great overview of) and the evolution of evolution session. One great talk was by Bill Sellars, who had created a computer model where you could put in skeletons and add tendons and muscles and then use a genetic algorithm to make things walk. He started out with humans, and after a few generations showed us the 'best' model, which really couldn't walk very well--I couldn't help thinking of the old Monty Python skit about the Ministry of Silly Walks! But then he moved on to hadrosaurs, and showed that given their skeletons and morphology, they were probably more likely to be quadrapedal than bipedal, though it might depend on speed.

...Except that at one point, the genetic algorithm found a bipedal gait that was better than normal bipedalism or quadrapedalism: hopping like a kangaroo! As he said, GAs are great for exploring parameter space, and for generating hypotheses we wouldn't have even considered (though he doesn't think that hadrosaurs actually hopped due to strain on the skeleton).

Yesterday's highlight for me was a talk by Steve Cook on conservation physiology as a discipline using his research on the Fraser River sockeye salmon as a case study. He argued that because physiologists can link cause and effect (when water temperatures are warm, parasites grow faster, and those parasites kill the fish), whereas demographers and more 'traditional' conservationists can only get correlations (when water temperatures are warm, fish die). It got me to thinking--is there any way that we, as biomechanicists/people who study animal movement, can inform management decisions? (Actually, I saw a great talk at SICB a few years ago looking at the performance of hatchery-bred fish vs. wild-caught fish which showed that hatchery-bred fish are quite useless when it comes to escaping predators.) Is there anything like that we could do with birds or bats? I don't know how it is in Sweden, but in the US you're much more likely to get funding if you can bend your research conservation-wards.

Yesterday was also the dinner and dance, which was a lot of fun. Today there's very little biomechanics, but lots of physiological energetics...so that's where I'll probably be!

30 June 2009

Second day of SEB Glasgow

Short report from the second day:

This day I spent almost entierly in the Biomechanics sessions. There were several interesting talks about stability in walking and running on both humans and other animals. Furthermore this day was the one with the "flight-session", in which Rhea and Melissa had their talks. Rhea had a very nice talk about the comparison between the two bats species beeing studied in Lund. It was an exellent talk showing very nicely comparisons between both kinematics and aerodynamics, with some nice movies on SDPIV results and the beautiful iso-surfaces. Melissa held her fascinating talk about the effect of moult gaps on kinematics and aerodynamics of the flycathcers. This talk was also very good and showed very clearly the impact of the moult gap on both kinematics and aerodynamics. Good work both of you! My talk was not in the Biomechanics session, but in the General Biology session. I talked about flight speeds in swifts during three different seasons and behaviours; spring migration, autumn migration and summer roosting.

Furthermore, in the biomechanics session, there were a couple of talks about butterfly and hawkmoth flight, with some application to MAV design. Very impressive work. Anna Carruthers talked about here Steppe Eagle and the function of the leading edge flap and some CFD analysis on high angles of attack during landing. Bret Tobalske had a nice talk about muscle activity and metabolic rate in hummingbird including power curve estimate. Excellent.

After the sessions we all took a walk through the city center all the way to the Cathedral. This was an impressive building, as many others are in this city. We all returned to our hotels satisfied and tired from a full day of impressions.


28 June 2009

Greetings from Glasgow!

As Day 1 of the conference draws to a close, I thought I would post a quick update. I spent most of the day in the Evolution of Evolution: What would you tell Darwin? symposium in honor of Darwin's 200th birthday, though I caught a few biomechanics talks in the afternoon. In between talks and the welcome wine trail event, Per, Rhea and I walked through the city, trying to find a building you can see from my hotel room window that I jokingly dubbed the Fairy Tale Castle. We found it--and found out that it was actually the main university building, which you can see pictured to the right (sorry for the quality--I have a cheap camera). I'm quite jealous of the students at Glasgow University!

This is what the entrance looked like. Sadly, it was behind a locked gate--it's apparently not open on Sundays.

Highlights of the day:
  • Seeing Rosemary and Peter Grant again and getting an update on the finches through their symposium talks: the effects of La Nina droughts on G. fortis have been completely reversed on Daphne Major due to the establishment of a population of G. magnirostris!
  • Seeing Bret Tobalske again; he talks tomorrow in the same session Rhea and I are talking in.
  • A talk on the evolution of whales by Michael Berenbrink about how to physiologically solve the problem of holding your breath for hours at a time. It turns out that whales--and other diving mammals and even birds--increase the solubility of myoglobin in their muscle tissue by evolving myoglobin with a higher net positive charge. In other words, mutations to amino acids that decrease the net charge of the protein appear to be favored in diving animals. This then allows them to keep more myoglobin in their muscle, which can hold onto large amounts of oxygen during long dives. Very neat!

26 June 2009

Flight lab at SEB

During next week the annual scientific meeting of the Society for Experimental Biology is taking place in Glasgow, Scotland. This is a major arena for animal flight related work, and the Lund Animal Flight Lab is represented by three members - all giving oral presentations about their work. Melissa Bowlin is talking about "the aerodynamics of moult gaps", Per Henningsson is presenting work on "flight speeds in swifts" (partly based on his recent Proc R Soc B paper), and Rhea von Busse is talking about "Bat kinematics and aerodynamics". I am sure all these talks will be of great interest to the lucky audience. If possible, we will be able to read daily bulletins from the SEB conference composed by Melissa, Per and Rhea on this blog. Looking forward to getting updated about the research front of our field.

24 June 2009

New Journal Impact Factors

Each year ISA publishes what is called "impact factors" for scientific journals (see Table below). The impact factor (IF) basically measures how often papers are cited that have been published in that journal during the last two years. The impact factor may not be a good guide about the importance of a paper, but I think we do, consciously or unconsciously, select where we publish our papers partly based on a journals IF. Just for fun, I assembled some of the new IFs for our favourite journals, and some others for control. The Journal of Avian Biology still comes out as top of the heap in the category ornithology, but the Auk is very close and has been so for quite some years now. Nature and Science are still around 30, Proc Roy Soc B has 4.25, JEB has 2.98, while J R Soc Interface has 3.62. The engineering journals are always much lower than the biology ones, with Exp Fluids at 1.85. At the medium level we find PloS Biology (12.68) and PNAS (9.38), which perhaps soon should get the honor of publishing some wind tunnel stuff.


Impact Factor

Phil Trans R Soc


Proc R Soc B


J Exp Biol


J R Soc Interface




Funct Ecol










Exp Fluids


J Avian Biol




Wilson Bull








PLoS Biology


16 June 2009

Scaling of moult

In a New paper published in the open access journal PLoS Biology, Siewert Rowher and co-workers investigate how the duration of moult scales with body size. They find that moult takes progressively longer to complete as the bird gets larger, and argue that moult is a significant player in the evolution of body size in birds. At a size above approximately 3 kg an annual complete moult is no longer possible according to Rowher et al's analysis, and we get phenomena such as sabbaticals form breeding and 'staffelmauser'. A mechanistic explanation for the the observed scaling is also presented. The paper is also commented by Nature.

15 June 2009

Diving Anna's hummingbirds

Courtship dives of Anna's hummingbird offer insights into flight performance limits, by Christopher James Clark, Berkley.

In this new paper the dice speeds of displaying hummingbirds was found to be 27.3 m/s, representing 385 body lengths per second. It is claimed to be the highest size-specific dives measured this far, and it should represent a body drag coefficient of less than 0.3. This resembles me of a paper on diving birds recorded by radar in Spain, as they reached southern Spain after the crossing of Sahara in spring. In that study, Felix and I recorded terminal velocities in barn swallows at about 50 m/s, i.e. nearly double that in the hummingbird. However, due to the more than twice longer body length in the swallows they will not quite reach the 385 body lengths per second as the hummingbird. What is interesting here is that the hummingbird appears to reach 27 m/s with flapping wings, and hence some significant profile drag in addition to the drag of the body. As we are currently concerned with drag of bodies and various random additions, this paper may be quite relevant.

03 June 2009

Felix Liechti is visiting

Felix Liechti, head of the Swiss radar research group is visiting this week, and he is arriving already on Thursday evening, but leaves on Monday morning. This means that we have Friday for work on the light logger experiments, or rather for starting working on it. I hope as many as possible will be here Friday, when we will also be able to talk to Felix about research in his group. 

27 May 2009

Next lab meeting will be on Friday at 10:00, Argumentet, where we will discuss our wish list for the CAnMove technological innovation lab. What can they do for us, and what do we want them to do. Yesterday Arne and Johan presented themselves at the CAnMove seminar, and my impression was that potentially they can be very useful to us. I will meet with them next week as part of their "inventory" to present what we decide on.

26 May 2009

Dear All Animal Flight Lab members!

To facilitate communication among us I have created this blog, and invited you all as writers. You only have to get a google account (which I am sure you already have), and  then you can post whatever could be of interest. I was thinking of highlighting new research papers, from ourselves or others, information about meetings and anything else of relevance. Hope you find this a useful way of communicating.