On Monday March 20th, we estimated 378,000 +/- 40,500 Sandhill Cranes around the Platte River between Chapman to Overton, NE, which appears to be a 17% decrease in numbers from last week. This is slightly surprising as we were expecting an increase from last week. However, there are many plausible reasons to lead us to believe we may have had a lower than average detection rate this week. The large numbers of Snow Geese that stayed in the area later than normal most likely depleted waste corn in the fields closer to the river causing the Sandhill Cranes to forage in an area wider than our survey detection area. The river has also been experiencing lower flows recently, leaving the riverbed dry and more accessible to predators. As a result the cranes could be more alert and more easily startled. Subsequently partners along the river have seen many mass liftoffs from the river recently, indicating this could be partially why we saw lower numbers on the river early in the morning despite the predicted increase in crane numbers. We have also heard, as of early this week, that there are still Greater Sandhill Cranes in Texas which could indicate that peak is still to come. Greater Sandhill Cranes on average migrate earlier than Lesser Sandhill Cranes so Greater Sandhill Cranes still in Texas indicate the possibility that there are many more cranes to migrate through.
