Bite force transducers
We use a variety of force transducers to measure bite performance in vertebrates (Aguirre et al., 2002; Herrel et al., 1999, 2002). Piezo-electric transducers are ideal for these kinds of measurements as they are rugged and pre-calibrated. For small animals we use a Kistler type 9203 force transducer (+/- 500N). For larger animals we use a Kistler type 9311B force transducer (+/- 5000N). Transducers are hooked up with a high-impedance cable to a hand-held Kistler type 5995 charge amplifier with hold function. The small size and robust nature of this set-up allows us to take it into the most remote field locations. Transducers are mounted in a custom-made holder with adjustable bite plates. The new design by our lab's own inventor of crazy things, Jan Scholliers, allows us to rapidly and accurately adjust the bite plates so the set-up can be used for a wide range of animals. Click on the following link to learn more about the set-up: force transducers
Portable race track
Again a unique design by our inventor of crazy things ! The design is based on Keyence photo cells and is programmed by Comet Belgium. Both the emitor and receiver are positioned on moveable aluminum bars. The distance bewteen emitor and receiver can be changed according to the size of the animals. The lightweight aluminum frame fits into a box that can be "easily" transported (it even fits a six-seater plane ...we've tried it). The electronics and cells are transported in a small robust case and can be easily hooked up to the frame. The frame is 2 meters long, free-standing and can be tilted to study climbing performance (Vanhooydonck et al., 2001). The legs can be used to extend the frame to 4 four meters to study high-speed sprinting or sprint performance in larger lizards.
High speed field camera
To quantify movements of animals in the field we use a Redlake motion meter high-speed camera with a Canon TV zoom lens (8-48; 1:1.0). Movies can be recorded at speeds of up to 500fps at full resolution (292x220 pixels) and at 1000fps at half the resolution. We use a Sony video walkman to transfer the video to tape. The motion meter runs of a Hawk-Woods speedcharge battery belt that can be easily be worn around the waist (although it is rather heavy when running through the bush in some tropical location). We use a manfrotto monopod when filming in field conditions as it allows rapid set-up of the camera and provides the stability needed to film animals in close-up. The biggest disadvantage of the system as I have experienced it is the lack of a digital video out. Thus digitally recorded images have to be D-A transformed and then converted back to digital format for analysis.
Portable force plate
Our newest addition is a field-portable Kistler 'squirrel' force plate (120 x 200 x 35 mm) which is used to measure jumping performance of lizards in the field. The first field test was in spring 2005 when we (Bieke Vanhooydonck, Katleen Huyghe, Chloe Marien, Jay Meyers, Duncan Irschick and Anthony Herrel) went to the Dominican Republic (Barahona peninsula) and measured jumping performance of 10 different species of Anolis lizards. After some initial problems with drift on the channels, we got some very nice results. These data will be combined with data on sprints speed and bite force to investigate sexual dimorphism and the role of dewlap in conspecific signalling.
Indispensable in any field study is a pair of sturdy electronic calipers. The new Mitutoyo 'Absolute Coolant Proof Caliper' is water and dust proof and thus ideal for field conditions.
- Aguirre, L.F., A. Herrel, R. Van Damme and E. Matthysen (2002) Ecomorphological analysis of trophic niche partitioning in a tropical savanna bat community. Proc. R. Soc. Lond. B. 269: 1271-1278.
- Herrel, A., L. Spithoven, R. Van Damme and F. De Vree (1999) Sexual dimorphism of head size in Gallotia galloti; testing the niche divergence hypothesis by functional analyses. Funct. Ecol. 13(3): 289-297.
- Herrel, A., J.C. O'Reilly and A.M. Richmond (2002) Evolution of bite performance in turtles. J. Evol. Biol. 15: 1083-1094.
- Vanhooydonck, B. and R. Van Damme (2001) Evolutionary trade-offs in locomotor capacities in lacertid lizards: are splendid sprinters clumsy climbers ? J. Evol. Biol. 14: 46-54.
Funded by a Research Grant of the Fund for Scientific Research - Flanders (Belgium)(F.W.O. - Vlaanderen) to Bieke Vanhooydonck.
Keyence sensors, vision & measurement.
Comet Belgium(site under construction, but has contact info).
Mitutoyo precision measurements.