Population data of the Heron Colonies in the Reedbed of Lake Kolon from a Non- Disturbance high altitude Aerial Photogrammetry based Survey

Abstract

Abstract Indicator species can provide warning signals for upcoming changes or shifts to an ecosystem such as climate change. Heron colonies as indicators are also suitable for monitoring changes in our environment, the effectiveness of habitat restoration or the effects of impacts. That’s why the importance of population survey is increasing. We have tested a high-altitude survey method of a breeding heron colony in Lake Kolon pilot area that allows accurate bird counting without disturbing the birds. Previously, the survey of large body-sized heron colonies was only statistically well analysed for nest counts. Surveying breeding colonies using 0.5 cm field resolution orthophotos taken with calibrated cameras carried on aircraft flying at over 240 km/h from 700 m above the ground provides much more accurate information. Individuals can be detected on at least 14 orthophotos and additional oblique images, and the resolution and geometric accuracy of approximately 20 cm increases the reliability of identification and reduces the risk of multiple counts. The primary aim of the surveys is to provide data of the heron colonies in 2018 and 2019 in Lake Kolon, and to do so in a way that the examination does not cause disturbance to the birds.