One important challenge for Sandhill Crane conservation is the collection of regular, accurate counts of birds roosting in flooded areas at night. Estimates of roost site numbers are an important way to track population size over time and detect any changes in site selection that may be a function of management or changes in site conditions. Traditional methods for estimating roosting crane numbers are morning and evening counts of cranes as they arrive at or depart their roosting sites. The accuracy of these counts however is often hampered by poor visibility in foggy and/or low light conditions, variations between observers, difficulties in accurately estimating the number of birds when many are flying to or away from the site, and difficulties in pinpointing specific locations where birds are roosting. Use of small unmanned aerial systems (sUAS) equipped with infrared cameras provide a promising alternative for developing more accurate estimates of roosting population numbers efficiently and more frequently, as well as a method of mapping specific roosting locations relative to habitat features. sUAS could also assist in surveying new areas for roosting cranes, as even though these birds are often traditional, they are known to colonize new areas if habitat conditions are suitable. This paper presents a case study on how to get approval from the Federal Aviation Administration (FAA) for night flight missions, how to decide the mission parameters and timing, as well as initial post-processing workflows. From 11 night missions performed, we also will share in this paper our findings and lessons learned.
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