ML615443925
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Media notes
Almost as good as being at the Merced NWR!
Observation details
Between approximately 10:50 and 11:30 a.m., I saw and heard four waves of migrating Sandhill Cranes All waves approached from the south. It is all but certain that they set out from the Merced NWR. Wave #1 consisted of two elliptical swarms riding thermals. I guessed that there were at least 500x cranes in the upper swarm and 100x in the lower swarm. The two swarms eventually merged. They continued upwards on a slow helical trajectory with superimposed northward drift. The cranes broke out of the helix before they reached me. They passed almost directly overhead in a ragged V-formation. The attached photo and recording pertain to this wave at closest approach. Wave #2 consisted of ~70x cranes in V-formation. This wave also passed directly overhead. Wave #3 consisted of ~100x cranes in V-formation. These were a little to the east of where I was standing but still close. Wave #4 consisted of ~200x cranes. Their flight path was at least half a mile west of where I was standing. All four waves continued on a N or NNW heading. I ran into John Fulton at the end of this visit. I mentioned that I never see flocks of migrating cranes early in the morning. I usually see them late morning or early afternoon. John said this is probably because they are waiting for thermals to develop. That makes sense. Can cranes tell if there are thermals whlle they are standing on the ground? Or do they make short test flights to see if conditions are right? I wonder what instinct or logic the cranes use to form the individual migration waves. If a family of 3 or 4 took off from the Merced NWR, intending to migrate, and no other cranes followed, they wouldn't go it alone. They would turn back and land. Are there "group leaders" who decide when it is time for their pre-defined "groups" to migrate? Or is it quasi-random?
Technical information
- Recorder
- Microphone
- Accessories
- Original file size
- 3.27 MB