Rare Fall Wood Warblers in Santa Cruz County, California, 1992-2007

Prepared by David L. Suddjian
Santa Cruz Bird Club Bird Records Keeper
Updated December 2007

Here is a summary of records of 28 “rare fall warblers” recorded in Santa Cruz County, CA during 1992 – 2007, including a few species that are perhaps better termed uncommon instead of rare (Table 1). Species are listed from most to least frequently reported, based on the recent 10-year average. “Vagrant” species include all except the “western” species: Black-throated Gray, Nashville, Hermit and MacGillivray’s warblers and Yellow-breasted Chat. The seasonal span used for this summary was the North American Birds fall reporting period of August 1 – November 30. Note that straggling migrants of some species regularly occur into December, but such records were not included here, and a few August records of western species (e.g., Black-throated Gray and Hermit) were included that might pertain to local post-breeding dispersants rather than long distance migrants.

Commonly-occurring species left off this list are Orange-crowned, Yellow, Yellow-rumped, Townsend’s and Wilson’s warblers and Common Yellowthroat. Other vagrant warblers recorded in Santa Cruz County only in other seasons are Kentucky and Mourning warblers, and Painted Redstart.

Fall of 2007. The variety and (especially) abundance of rare wood warblers in Fall 2007 was below the average of the recent 10 year period (Table 1, Figures 1 and 2). Fewer individuals were reported in the county than in any fall since 1997. None of the more numerous species was found in above average numbers, with only the rare Virginia’s Warbler significantly exceeding its average (and setting a new record). Among western species, Hermit and Nashville warblers were well below their average. Vagrant species that were notably sparse included Palm Warbler, American Redstart, Blackpoll Warbler and Black-and-white Warbler. The only American Restart reported was actually a bird that stayed to attempt to winter. The rarest finds, averaging less than 0.5 individuals per year, were one Yellow-breasted Chat and three Virginia’s Warblers. Vagrant species that averaged over 0.5 per year that were missed this season were Black-throated Blue, Magnolia, Northern Parula, Prothonotary and Hooded.

Table 1.  Number of rare wood warblers reported in Santa Cruz County each fall from 1992 to 2007.

Figure 1. The number of species of rare wood warblers found in
Santa Cruz County each fall has varied little from 1992 - 2007,
except for a strong showing in 1999-2001.

Figure 2. Number of individuals of rare wood warbler species found in
fall in Santa Cruz County in 1992-2007.

Figure 3. Palm Warblers contributed prominently to the number of
individual vagrant warblers in about half the years considered here.