Various external attachment techniques have been developed that indirectly attach biologgers and transmitters to birds via a neck collar, backpack, harness or leg band. Neck collars and backpacks generally have excellent transmitter retention (often for the life of the bird). Various harness designs are available that provide better fits to particular species because poorly fitting harnesses may cause abrasions or impede wing movement. In addition, the design of a biologger housing, attached to the harness via a base plate, must often be adapted to specific species and the requirements set by the applied sensors, i.a. in terms of size and antenna positions. However, size and shape of sensor hoursing can have a significant impact on the drag coefficient. Here, a streamlined shape, proper dimensions, and a reduced frontal area may reduce drag. In an experimental wind tunnel setup, Obrecht et al. (1988) found that adding a rounded fairing to the front end and a pointed fairing behind helped reduce the drag of the transmitter by about one-third compared to a rectangular box. Recently, Mizrahy-Rewald et al. (2023) reported on how the shape of biologger housings can have a considerable effect on heart rate and VeDBA of Northern Bald Ibises - both parameters have been used as proxies for energy expenditure.
Please contact us to discuss your needs in sensor housings for avian harnesses. For adaptation to available sensors and harnesses, a detailed 3D-model or a hands-on test are strongly advisable. See this recent blog post on how biologging sensor housings have been used in research by Mizrahy-Rewald et al. (2023).
Images for illustration purposes only, design subject to change without notice