August is usually a quiet month for both birds and birders and August 2007 was no exception. This does not mean that there was no bird activity but that it was not obvious. Fall migration was well under way and towards the end of the month large numbers of birds were flying south through Boulder County every night. These can be identified by their flight calls but are rarely noticed. Visual signs were the large influx of hummingbirds throughout the county, the movement of mountain breeding birds, such as Chipping Sparrow and Wilson’s Warbler, on to the plains and the arrival of shorebirds in local ponds.

The most unusual bird of the month was undoubtedly a Ruby-throated Hummingbird that lingered for three days at a feeder in Niwot. This is probably a first record for the county as previous records from 1984 have the notation “dubious” alongside the entry. Calliope Hummingbirds were reported all over the county and were the commonest hummingbird species on the plains. We heard several comments referring to “baby hummingbirds” presumably by people who noticed the small size of the birds but did not realize that they were looking at a different species. A Black-chinned Hummingbird was also reported at the same feeder in Niwot.

Warblers were also on the move with the most unusual sighting being a Prothonotary Warbler, a species last seen in 2002.  Townsend’s Warblers were reported in several locations in the mountains; this is a warbler that is typically seen in fall migration. A  Tennessee Warbler was also a good find. Several species of the shorebirds commonly referred to as “peeps” were reported for the first time this year: Semipalmated Sandpiper, Western Sandpiper, Baird’s Sandpiper and Pectoral Sandpiper. Of these Pectoral Sandpiper is the most unusual in Boulder County.

Ash-throated Flycatcher was one of the less usual flycatchers to be reported. Loggerhead Shrike is always a bird that is hard to predict where to be found, but we would normally expect this species to have been seen long before August. Another bird that is normally reported during spring migration but was missed until now is Clay-colored Sparrow.

Several birds that were surely present in the county were not reported. Into this category fall Western Grebe, American Coot and White-throated Swift. Altogether 151 bird species were seen in August, a fairly average total for the month. We appear to have had fewer contributors to the inventory than normal.

September usually sees the height of the fall migration with the second largest (after May) monthly total number of bird species. However, this year’s  total of 164 bird species for September tied with that of June. It is very comparable with last year’s total of 166 species but a long way off the record 178 species seen in September 2000. Several birds that were missed during spring migration were seen this month such as Nashville Warbler and Black-and-White Warbler. In fact warbler migration was strong with particularly large numbers of Wilson’s Warblers being reported. In fact on the plains Wilson’s Warblers seemed to be more prevalent than even the usually more common Yellow-rumped Warblers. Orange-crowned Warblers were seen in far greater numbers than in the spring. One of the most unusual birds of the month was a male Mourning Warbler reported in Lafayette; this is only the second report of this species for the wildlife inventory with the previous being in 1982. As well as some late sightings of our breeding warblers, such as a single Virginia’s Warbler and two Common Yellowthroats, there was a Chestnut-sided Warbler found on the tundra. Altogether thirteen species of warbler were reported. Vireos were also well reported with a Bell’s Vireo at Pella Crossing being a most unusual sighting. This is the third report of this species for the wildlife inventory with the last sighting in May 2000. Cassin’s Vireo was reported for the first time this year; this seems to be a species that is most commonly seen in fall migration. Several Red-eyed Vireos were also reported, but Warbling Vireos appeared to have already left the county.

Shorebird migration was also strong with Short-billed Dowitcher being seen for the first time since 2004 and Red Phalarope for the first time since 2005. Stilt Sandpipers were seen in two locations. A Long-tailed Jaeger seen on Boulder Reservoir only stayed long enough to be seen by a few observers; this was a new record for Boulder County although one was seen at Union Reservoir in October 1993. There was an influx of Sabine’s Gulls into the county in the middle of the month with as many as nine birds being seen at Boulder Reservoir. Common Tern was reported in three different locations.

The fine weather in September meant that many birds still had young. Unfledged Barn Swallows that were reported still in the nest was surely a very late breeding record for this species. There appeared to be an influx of resident mountain birds out in the plains; Red Crossbills were seen out in Louisville and Lafayette and Clark’s Nutcrackers were seen in Dowdy Draw. Possibly these birds were also migrating. We seemed to have more reports of rare species that could not be confirmed this month than usual. Into this category would fall a Reddish Egret, a Wood Thrush and a Canada Lynx. Of course, we do not include such sightings in the wildlife inventory but it is always tantalizing to wonder whether these species were really what was suggested. TOP

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Mammals, Reptiles and Amphibians

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Contributors to the August 2007 Inventory:
Linda Andes-Georges, Alex & Gillian Brown, Raymond E. Davis, John Dunn, Ted Floyd, Steve Frye, Paula Hansley, Steve Jones, Chishun Kwong, Gene and Lynn Monroe, Sharon Norfleet, George Oetzel, Laura Osborn, Peter Plage, Ira Sanders, Bill Schmoker, Scott Severs, John Vanderpoel, David J. Waltman, Wild Bird Center.

Contributors to the September 2007 Inventory:
Linda Andes-Georges, Alan Bell, Alex & Gillian Brown, Cathy Comstock, Carol Cushman, Todd Deininger, Ted Floyd, Mike Freiberg, Steve Frye, Peter Gent, Brian Gibbons, Paula Hansley, Thomas Heinrich, Steve Jones, Bill Kaempfer, D.W. King, Steve Larson, Gene and Lynn Monroe, Christian Nunes, Laura Osborn, Nathan Pieplow, Pam Piombino, Peter Plage, Suzi Plooster, Bill Schmoker, Walter Szeliga, Oakleigh Thorne, John Tumasonis, John Vanderpoel, Wild Bird Center. TOP