Red-breasted Nuthatch
 
Red-breasted Nuthatch was recorded on 32 of 44 counts (73%; Figure 3). Its sporadic presence in the early years of the count was likely due in part to more limited coverage of the count circle. Small numbers of Red-breasted Nuthatches are resident in the count circle, mostly on Ben Lomond Mountain in forest areas containing knobcone pine and Douglas fir. During irruption years they are more widespread throughout the forested areas (especially areas with Douglas fir, knobcone pine and ponderosa pine) and also occur in planted Monterey pines in suburban and park settings along the coast (more rarely in cottonwood riparian forest).
 
 
Figure 3. Red-breasted Nuthatch on the Santa Cruz County CBC, 1957-2000.

 

Raw counts ranged from 0-111 birds. Irruptions (counts >150% of the standardized average, 0.08 per party hour) were recorded in eight years (18%): 1963, 1969, 1979, 1983, 1986, 1989, 1990 and 1996. Note that the 1996 count had rain all day, undoubtedly reducing the count of nuthatches. With better conditions it is expected that 1996 would have had an even higher tally. Counts >100% of average occurred in 11 years (25%), and counts <25% of average occurred in 19 years (43%). All the major irruption years recorded on the count have been followed by years of much lower abundance (Figure 3).
 

 

Numbers on the five neighboring counts were fairly well correlated during the 16 years examined, particularly during major invasion events and years of low regional abundance, but not all circles had high relative abundance in the same years (Figures 4 and 5). Monterey Peninsula (avg 0.15 per party hour) and Santa Cruz County (avg 0.12) had the most nuthatches, probably due to the greater extent of pine forest habitat in those circles. Nuthatches were much less numerous at Año Nuevo (avg. 0.05), Moss Landing (avg 0.03) and Palo Alto (avg. 0.01). The relatively low counts at Año Nuevo may be due to limited coverage of ridgeline habitats where the Douglas firs and knobcone pines favored by nuthatches are especially common.
 

Figure 4. Red-breasted Nuthatch on the five neighboring counts, 1983-84 to 1999-2000.
 

 
 
Year
Count Circle
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
Año Nuevo
n.d.
Palo Alto
Santa Cruz
Moss Landing
Monterey Peninsula
Legend
0-50%
51-100%
101-150%
>150%
 

Figure 5. Comparison of Red-breasted Nuthatch annual abundance among the neighboring counts as measured by % of each count’s average. (Note: for year, “83” = “winter 1983-1984”, “84” = “winter 1984-1985, etc.; n.d. = no data.)

Golden-crowned Kinglet
 

Golden-crowned Kinglet was recorded on 30 of 44 counts (68%; Figure 6). Kinglets were recorded on only 19% of counts from 1957-1992, but were found on 96% of counts from 1973-2000, probably due to improved coverage and birding knowledge. This species is easily overlooked unless one is able to discern its quiet, high-pitched calls. Small numbers of Golden-crowned Kinglets nest within the count circle and are likely resident. These are limited to certain areas of redwood forest with Douglas fir. In most winters they are found in those forests, even when regional kinglet abundance is low. During irruption years kinglets become much more numerous in those forests, and also occur in pine forest, suburban and park settings and deciduous riparian forest. They are generally present in the coastal lowland portions of the circle only during moderate to large invasions.
 
Figure 6. Golden-crowned Kinglet on the Santa Cruz County CBC, 1957-2000.

 

Raw counts ranged from 0-263 birds. Irruptions (counts >150% of the standardized average, 0.17 per party hour) were recorded in eight years (18%): 1958, 1976, 1981, 1990, 1995, 1996, 1998 and 2000. As described for the nuthatch, rainy conditions on the 1996 count likely inhibited detection of this species as well. Counts >100% of average occurred in 14 years (32%), and counts <25% of average occurred in 17 years (39%). Five of the irruption years were followed by years of moderate to high numbers (Figure 5).

Hermit Thrush
 

Hermit Thrush was recorded on all 44 counts (Figure 3). A migratory breeding subspecies is replaced in the fall and winter in the count circle by at least two migratory wintering subspecies. Although perhaps not a classic “irruptive” species in our region, winter numbers of Hermit Thrush do fluctuate widely and include years of notable abundance and others of relative paucity (Figure 3). During all winters Hermit Thrushes occur throughout varied forest and woodland habitats, also using manzanita scrub and other chaparral types. Berries of madrone, toyon (Heteromeles arbutifolia) and poison-oak (Toxicodenron diversilobum) are among the favored winter foods. Hermit Thrushes are most numerous where there is well-developed shrub or other understory cover. They are least numerous in the coastal portions of the circle, but may be fairly common in those areas during irruption years, especially in riparian corridors, parks and planted woodlots.
 
 
Figure 7. Hermit Thrush on the Santa Cruz County CBC, 1957-2000.
 
 

Raw counts ranged from 5-386 birds. Irruptions (counts >150% of the standardized average, 0.65 per party hour) were recorded in ten years (23%): 1960, 1961, 1968, 1981, 1987, 1989, 1990, 1992, 1994 and 1998. Counts >100% of average occurred in 17 years (39%), and counts < 25% of average occurred in 3 years (7%). Major irruption years have been variably followed by years of higher, similar or lower abundance (Figure 7).

Part III

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