In order to assess possible effects of structures projecting into the airspace on flying birds, it is important to determine their flight altitudes with sufficient certainty. The same applies to the localization of birds in the area and, if necessary, the documentation of evasive movements. Particularly in environments with few structures, which lack objects of known height and distance as reference points, information on flight evelations and positions of flying birds based on estimates by observers is difficult. In such cases, a rangefinder (rangefinder binoculars with laser beam system) is a valuable tool to optimize data quality. In some cases, the use of rangefinders in projects to determine the effects of wind energy on flying birds is required by the permitting authorities.
Only high-quality devices are suitable for the reliable recording of birds, since flying birds are comparatively small and, moreover, are moving objects that often have to be registered at relatively large distances for the aforementioned purpose.

IfAÖ uses a type of device whose use has become established in ornithological surveys in recent years. The used rangefinder is, among other things, equipped with a battery-operated laser system and offers a 7-fold magnification.
For the suitability of a rangefinder for the detection of birds, a suitable interaction of quality and characteristics of the internal components including the laser beam, inclinometer, optics, compass as well as the interpretation of the measurement parameters by the device itself is fundamentally required.

The handling of the rangefinder is similar to that of binoculars, although the additional use of a tripod can facilitate data collection. Under optimal conditions, larger bird species can be measured up to a distance of approx. 3 km. If the geographical position and height of the device above ground or sea level are known, the use of the rangefinder can provide three-dimensional data on the flight paths of migrating birds, which can be stored automatically. Furthermore, the device can also be used for the pure measurement of flight altitudes or distances or for the calibration of estimated values.

Fields of application

  • research and construction projects in the on- and offshore area, where flight heights or trajectories of birds are to be determined
  • On request, we also lend out equipment and/or provide advice on the evaluation of the data

Technical Data

  • 42 mm binocular with 7x magnification, adjustable eye width, distance measurement from 5 m to 12,000 m with an accuracy of less than 5 m
  • Class 1 laser is used (DIN EN 60825-1: the accessible laser radiation is not dangerous or the laser is in a closed housing)
  • dimensions: 205 mm x 178 mm x 82 mm, weight: 1.7 kg
  • power supply with 6V lithium battery or external power source from 7VDC to 14VDC
  • RS-232 interface to PC or serial Garmin GPS of series 60/72/76


Dr. rer. nat.
Tobias Dittmann

T +49 381 252312-13
E dittmann(at)ifaoe.de