| Abstract: | Currently the operational analysis of Breeding Bird Survey (BBS) data by the National Biological Service accounts for observer differences in estimating the trend for each route but within-observer differences are not modeled. We tested for the existence of a form of within-observer differences in skill level: a change in ability to count birds of a given species after an observer‘s first year on a given route. An increase in ability could positively bias the trend estimate. Removal of an observer‘s first year of observation on each route for the period 1966-91 resulted in lower average unweighted trend estimates for 415 of 459 species (90%). These reductions were statistically significant for 213 species (46%). The average reduction in trend was 1.8 percent change per yr (SD = 5.4 percent change per yr). In route-regression analysis, route data are weighted by a measure of precision. Removing first-year observer counts reduced the weighted trend estimate for 275 of 416 species (66%), but differences were generally small. |
| Genre: | Article |
| ProdID: | 5223223 |
| Citation Author: | Kendall, W.L.; Peterjohn, B.G.; Sauer, J.R. |
| Citation Contributing Office: | Patuxent Wildlife Research Center |
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| Citation End Page: | 829 |
| Citation Issue: | 4 |
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| Citation Language: | English |
| Citation Larger Work Title: | Auk |
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| Citation Number Of Pages: | 7 |
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| Citation Phsyical Description: | 823-829 |
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| Citation Search Results Text: | First-time observer effects in the North American Breeding Bird Survey; 1996; Article; Journal; Auk; Kendall, W.L.; Peterjohn, B.G.; Sauer, J.R. |
| Citation Start Page: | 823 |
| Citation Volume: | 113 |
| Citation Year: | 1996 |
| Type: | citation/reference |
| Text: | First-time observer effects in the North American Breeding Bird Survey; 1996; Article; Journal; Auk; Kendall, W.L.; Peterjohn, B.G.; Sauer, J.R. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DOCUMENT): | http://elibrary.unm.edu/sora/Auk/v113n04/p0823-p0829.pdf |
| Date Other: | Wed, 16 Jun 2010 12:17 -0500 |
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