NEBRASKAland Magazine is dedicated to outstanding photography and informative writing with an engaging mix of articles and photos highlighting Nebraska’s outdoor activities, parklands, wildlife, history and people.
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58 Nebraskaland • June 2020 went more east than south. Some also bypassed the wintering area closest to their breeding marshes. Swan Nesting In conjunction with the movement study, we began assessing how well trumpeter swans were reproducing in the Sandhills in 2016 and 2017. Aerial surveys helped us find a number of nesting pairs, and observations by Game and Parks staff, U.S. Fish and Wildlife Service staff at the Valentine National Refuge, and tips from local landowners and other interested parties helped us find more. Once a nest was found, Heather Johnson, who led the field work on this part of the study, used a kayak to visit and study the nest. Eggs were numbered and floated – a technique to age the stage of incubation – as quickly as possible to allow the female back on the nest. After the anticipated hatch date, or when the pair was observed with cygnets, Johnson returned to the nest to determine how many eggs had actually hatched. Pairs and cygnets were observed until late summer, just prior to when they were able to fly, to determine how many cygnets survived. The study found that 92 percent of the nests we monitored were successful, hatching at least one egg, and that a little more than 70 percent of the eggs laid hatched. Both of these numbers match the high end of success rates found in studies from other parts of North America. However, where we found the biggest discrepancy between trumpeter swans in the Sandhills and other populations was in cygnet survival. Only about 40 percent of cygnets survived to flight stage, compared to 70 to 85 percent elsewhere. The biggest difference was that in lakes with largemouth bass and northern pike, cygnet survival was much lower than in lakes without those aquatic predators. Despite cygnet survival rates being lower than in other populations, the swan population continues to grow in the Nebraska Sandhills. The Future The Sandhills is a unique place in North America and, indeed, the world. One aspect of its uniqueness is that it is relatively undisturbed compared to other habitats. But that may change. Swans need water throughout their life cycle, and water demand will only increase in the future, a fact that already has some looking at ways to move water from the Sandhills elsewhere. Climate change could also affect water in the region. Other threats to swans include the development of wind and other energy sources, and the corresponding transmission lines may alter where swans can or want to go. One thing is certain, though. The beauty and calm splendor of trumpeter swans in this unique region will remain. As a biologist, one reward is the observations that few others get to have. We had the fortune to watch a cygnet take its first swim with its father, while the mother stayed behind to continue to incubate the remaining unhatched eggs. The cob waited patiently as the cygnet carefully, yet clumsily, made its way Heather Johnson measures eggs in the nest at Cottonwood Lake SRA. Her work on the study earned her the nickname "The Swan Lady" among Sandhills residents she worked with.