Accurate Non-Disturbance Population Survey Method of Nesting Colonies in the Reedbed with Georeferenced Aerial Imagery

Abstract

High altitude aerial surveys have the potential to improve disturbance-free data collection in wildlife research, but previously, bird species were not recognizable in high-altitude orthophotos. This method of aerial surveying is effective and can be repeated frequently due to its low cost; it also has the additional advantage of being able to monitor the status of protected areas. In the case of waterbirds, due to the low vegetation coverage, aerial remote sensing is an exceptionally effective technique for surveying populations and detecting nests. Aerial surveys made at low altitudes can cause serious stress for birds. The method we developed and employed is unlikely to be detected by either ground-based or nesting birds but is far more reliable compared to the low-resolution imaging methods and to the evaluation of non-georeferenced photo series. The modern sensors and photogrammetric procedures enable the use of the present method worldwide; furthermore, the large-scale ortho image-derived information has become obtainable more frequently. Direct georeferencing makes the field geodetic survey unnecessary. Orthophotos with a 0.7 cm spatial resolution allow us to reliably identify even the individuals of smaller species, and by the use of oblique images, they can be tracked from two or four different directions.

Toward a High Spatial Resolution Aerial Monitoring Network for Nature Conservation—How Can Remote Sensing Help Protect Natural Areas?

“…The most effective tools that can help to study environmental processes on a large scale are numerous spatially distributed study sites, frequent image acquisition, quick evaluation of the results, and free flow of information [57]. Digital photogrammetry and multi-source satellite remote sensing create data at higher spatial, spectral, and temporal resolution than data collected at any other time on the ground [30][31][32]58]. The main technological components of our innovative workflows are aerial remote sensing by fixed-winged aircraft imagery, highprecision autopilot flight itineraries, digital photogrammetry technology, very high spatial and spectral resolution, orthophotos and additional oblique imagemaps and point clouds, high-rate image data acquisition, a direct georeferenced photogrammetric platform, highspeed automatic image preprocessing, field validation with local experts, and cooperation with research projects [28,32].…”

“…However, data collection is confronted with the controversial challenges of increasing spatial resolution, higher frequency of surveys, and ever-faster evaluation providing readily available information on increasingly large areas [20][21][22][23][24][25][26][27]. Our team is continuously experimenting with the latest technologies and workflows to find the most cost-effective, innovative solutions adapted to the different spatial resolutions demanded by nature conservation monitoring [28][29][30][31][32] which comply with legal requirements.…”