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.