The population of Trumpeter Swans continues to increase among the sandhills and the high plains region.
The High Plains Flock in 2012 showed an increase to 664 swans, compared to 573 in 2011. The increase of 93 was attributed to "an increase in the number of white birds in groups," according to a report issued by Lacreek National Wildlife Refuge.
White birds are more readily observed during the aerial surveys, according to biologists. The increase "could be credited to a relatively high number of cygnets produced in 2009 and 2010."
Despite an increase in the number of swans counted, the "number of successful breeding pairs declined," as did the average brood size, according to the report.
There was a decrease in the number of cygnets, or young swans. In 2012, 120 cygnets were observed, compared to 161 in 2011, 174 in 2010 and 171 in 2009. In 2008, there were 115 cygnets observed, according to the report, authored by Shilo Comeau, Fish and Wildlife Service, and Mark Vrtiska, Nebraska Game and Parks Commission.
During the 2012 survey, the "majority of wetlands in the survey area appeared to contain less water and subaquatic food resources than the previous four years," they said.
It was hot and dry during the breeding season. Precipitation levels were below normal, according to numerous indicators. Drought conditions meant a lesser extent of suitable water habitat for swans and other wetland-dependant species.
Management objectives for this species are based upon particular parameters. Drought has an obvious influence, as it alters the extent of available habitat.
The Trumpeter Swan's current status is now dramatically different in comparison to the occurrence of these magnificent birds fifty years ago. In the early 1960s, a reintroduction program was initiated to bring them back into a region where they were known to occur historically.
The High Plains Flock includes the sandhills, western South Dakota, and the extreme northeast corner of Wyoming, with the latter area not surveyed in 2012.
The annual fall survey was conducted September 4-6, 2012 during an "aerial cruise survey" using a Cessna 182 airplane, and is done to "determine production and distribution" of the High Plains flock.
