USFWS Biologist Shilo Comeau reports to TTSS from Martin, South Dakota:

High Plains Trumpeter Swan FlockDuring the 2009 survey, biologists counted a record-high 523 swans in the High Plains Flock (HPF). This is an increase of 22% from the 2008 estimate (Fig. 2), and was primarily the result of a higher number of cygnets and breeding pairs observed (Table 1). The number of breeding pairs increased, and correspondingly so did the number of broods and average brood size. However, the number of non-breeding pairs remained relatively stable (71 to 72). The 2009 results are above the 20-year average for total birds (298 ± 21), white birds (213 ±1), and cygnets (86 ±6). The Flock continues to experience a positive growth rate of 4.8% annually from 1990 to 2009 (Fig. 3). The overall production of cygnets increased this year and the index of production rate (i.e., cygnets/white birds) was (0.49) compared to the long-term average (0.44). The specific results for each category are listed in Table 1.

The number of swans counted this year is the highest on record for the HPF and this was attributed to an increase in breeding pairs and cygnet production. All the production parameters for this flock increased, including the number of breeding pairs and average brood size. This increase in production could be attributed to the coinciding factors of a large number of white birds becoming reproductively active and an improvement in habitat quality.

The full report can be found at


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