A Century of Breeding Birds in NebraskaPapers in Ornithology
Date of this Version6-1-2000
AbstractWith the imminent publication of the Nebraska Breeding Bird Atlas and the turning of a new millennium, it is perhaps an appropriate time to survey the state of breeding birds in Nebraska. Wayne Mollhoff’s summary of the N.O.U.’s Nebraska Breeding Birds Aliasing Project (Mollhoff, 2000) provides important databases for the latter part of the past century, and the historic overview by James Ducey (1988) offers a useful basis for judging the breeding avifauna of Nebraska from about the beginning of the century. The Biological Resources Division of the U. S. Geological Survey’s (WSGS-BRD) annual Breeding Bird Survey data currently extends back more than three decades and continues to accumulate new information. And R. S. Sharpe, W. R. Silcock, and J. G. Jorgensen will publish in early 2001 their authoritative book, The Birds of Nebraska. Ducey (1988) plotted individual county breeding records for records for three time periods, namely pre-1920, 1921-1960, and from 1961 until the late 1980s. His data summary thus overlaps with the Nebraska Ornithologists’ Union’s period of data collection for the Breeding Bird Atlas, which extended from 1984 to 1988. We have counted and tallied all of the counties for which one or more breeding record existed within each of Ducey’s three time periods. These totals thus probably often represent a smaller overall number than would the total number of breeding records per county, which were usually not indicated. Mollhoff (2000) classified the available N.O.U. records into four categories of increasing confidence for breeding; but for our tallying purposes, we used and summed only the three highest probability categories. The Breeding Bird Survey data are based on standardized survey routes of 24.5 miles, with periodic stops for visual and auditory sampling of birds. These data are later analyzed both as to relative species abundance and for statistically significant trends in population density over multi-year time periods to 1993 (Price et al., 1995). The most recent BBS data (through 1998) are available from internet sources, but these do not provide relative abundance data for Nebraska as a whole. The only state-based summary data thus available are for long-term population trend estimates, and the summed sample sizes (total routes in which the species was encountered) provided for two data subsets (1966-79, and 1980-98) seem to offer the best general index to relative statewide abundance. In a very few cases there were more data points indicated for the entire time period than for the summed subsets; in such cases the larger numbers were used. These numbers are shown in the table, as well as positive or negative trend estimates for estimates based on larger sample sizes (usually those of ten or more data points). Those trends that are significant at the 99 percent confidence level are indicated by asterisks. A summary of all three of these data sources is presented in Table 1. They suggest that the number of species now breeding in Nebraska is approximately 200, which agrees closely with an earlier summary (Johnsgard, 1979). Several species that were listed by Ducey clearly now no longer breed in Nebraska; such records were either erroneous, represent species that have since become extirpated or extinct, or are extralimital records of species now breeding only some considerable distance from Nebraska’s borders. We have suggested the likely basis for the records of these species, which are listed in parentheses. Several species (dark’s Grebe, Pileated Woodpecker, Eurasian Collared-dove, Yellow-throated Warbler, Henslow’s Sparrow) have certainly bred in Nebraska recently, but were not documented in any of these listings; and the Sage Thrasher is also a very likely if rare Nebraska Panhandle breeder that still needs documentation.
Citation InformationJackie Canterbury and Paul A. Johnsgard. "A Century of Breeding Birds in Nebraska" (2000)
Available at: http://works.bepress.com/paul_johnsgard/347/