The statistical analyses by the folks at the BBS do not believe that Wood Ducks actually have declined in Tennessee in recent decades. For species that are spotty and/or erratic their models will tend towards a more conservative estimate of the changes. They also don't pick up any decline in Black-throated Green Warblers, though their data only run through 2009 and the sudden drastic drop in raw BBS counts was for 2010. Still this is a bird found by a small number of observers on a small number of routes in Tennessee, so it is harder to detect changes than for more widespread species.
As for Bobwhites -- they are very spotty. On my own BBS routes this year, one had a high count, two had low counts, one missed entirely. On the three survey routes I reran in Lewis County after having first run them 5 years ago, all Bobwhite counts were up. But on my own farm (also in Lewis County), they are missing this year for the first time since we moved here in 2002. This is often the way population trends happen -- spotty and inconsistent from place to place, only the large-scale average showing the overall trend. For all its weaknesses, this is the real strength of the BBS, having had the same places sampled using the same protocol every year, several thousand individual point counts across the state each year.
Bill Pulliam Hohenwald TN
On Oct 12, 2011, at 10:16 PM, Roger Applegate wrote:Just a thought but in many areas of the US where river otters have remained abundant, wood ducks have also remained abundant.Roger D. Applegate Small Game Coordinator Tennessee Wildlife Resources Agency Ellington Agricultural Center PO Box 40747 Nashville, TN 37204 PH: 615/781-6616 FAX: 615/781-6654 Email: roger.applegate@xxxxxxxxxxx UPS Address: 440 Hogan Road Nashville, TN 37220 FedEx Address: 5107 Edmonson Pike Nashville, TN 37211 >>> David Vogt 10/12/11 7:13 PM >>>First, thanks to Bill for putting these graphs together. Very helpful to see the TN data reflected in graph form. I'd like to speculate on causes for the apparent declines indicated for Black- throated Greeen Warblers and for Wood Ducks. The obvious explanation for the Black-throated Green Warbler decline is the precipitous die-off of the hemlocks in east Tn due to the Hemlock Wooly Adelgids.As for Wood Duck numbers: I've noticed pretty a drastic decline of Wood Duck numbers on the lake at Fall Creek Falls State Park in the last 4 years. This decline coincides with the appearance of river otters on the lake. I wonder if river otters are taking a toll on ducklings which would account for the numbers reflected on BBS routes. It looks as if the decline in TN WODU numbers pretty closely follow the dates of TN Wildlife Resourses Agencies project to reintroduce river otters to the state.Again, these are only theories and, I do not mean to suggest that river otter should not have been reintroduced but thought I'd suggest this explanation.Thanks again to Bill for his efforts, David Vogt, Park Naturalist Fall Creek Falls State Park
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