| Autor: |
Rimmer, Christopher C., Faccio, Steven D., Lloyd-Evans, Tervor L., Hagan III, John M. |
| Zdroj: |
Studies in Avian Biology; 2004, Issue 29, p123-134, 12p, 2 Charts, 4 Graphs |
| Abstrakt: |
We compared population trends from spring and fall migration capture data from two constant-effort banding stations in New England: one coastal (Manomet Center for Conservation Sciences, hereafter "Manomet") and one inland (Vermont Institute of Natural Science, "VINS"). Data were examined for two time periods, 1981-1992 and 1986-1992. Twelve-year population trends were compared to regional Breeding Bird Survey (BBS) data for the same period. The two migration data sets showed little congruence. Of 22 species examined, Manomet data showed significant declines in 11 during one or both seasons, whereas seven species increased significantly at VINS. The number of significant trends at both sites increased between a 7-year and a 12-year sample. Among six species that were strictly transient at the two sites, rive showed the same 12-year trend in fall. In general, Manomet tracked BBS data from the Northern Spruce-Hardwood region reasonably well, while VINS more closely tracked BBS trends from Northern New England. Neither site correlated well with BBS trends from Quebec. VINS captured significantly higher proportions of adult birds than did Manomet in 81% of species examined. However, the two sites tracked trends in age ratios largely independently. Several factors appeared to account for the weak congruence between sites, and we discuss the limitations in comparing these two data sets. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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