Methods: Birds were surveyed on 4 repeat visits to each stand from mid-May through early July, using a point count method at 1-6 points/stand. Distance to and species of each bird observed was recorded during 10 minute count periods. Physical habitat features (e.g., aspect and slope) and basal areas were recorded at each bird count point and net location. Basal areas of conifers, hardwoods, snags were recorded using 40 basal area factor (BAF) prisms in old-growth, 20 BAF in young stands. Four 5 m radius satellite plots were established at random distances (between 10m and 50m) in the 4 cardinal directions from bird count plot centers. In these satellite plots, the average upper and lower height of each of 3 main layers of vegetation (tree, shrub, and herb) and the sub-layers (numbered) within the main layers was estimated (ocularly for lower strata, clinometer used for upper strata). Cover of each woody plant species was estimated ocularly.
In 1995, birds were mist-netted in the forest shrub layer from 2 June to 18 August. In 1996, we operated 8 - 10 12-m ground nets two days in each stand, with a 2-3 week interval between sample days in three triads (9 stands) from 26 May to 16 July. In 1997 we operated 8 - 10 12-m ground nets on 2 days in 7 stands, and on 1 day in 2 stands, with a 2-3 week interval between sample days in three triads (9 stands) from 4 June to 30 July. In all 3 years captured birds were weighed, aged, and sexed. Fecal samples collected from captured birds were stored in alcohol pending diet analysis. In 1996 and 1997 birds were banded with federal bands.
Arthropods were collected from understory vegetation in 1996 and 1997 in the same stands where mist nets were operated. In each stand, we selected for sampling the 3 species of understory shrubs that appeared to be dominant. We collected 8 to 10 samples from each shrub species within 8 days of netting birds in each stand. One sample of a shrub was equal to 100 leaves (vine maple, ocean spray, and salmonberry), 50 leaves (salal and hazel), 5 fronds of bracken fern and 8 of sword fern, or 1 m2 branch (western hemlock). Arthropods were collected from shrubs by beating foliage within 2m of the ground onto a 1x1 m canvas beating sheet. The foliage sampled was clipped, dried, and weighed, and the arthropod specimens were preserved in alcohol. Some shrub samples spoiled prior to weighing, resulting in missing data. We averaged the weights of unspoiled samples of same species to derive an estimate of weights for missing measurements.
Arthropod Sampling In each stand, we selected for sampling the 3 species of understory shrubs that appeared to be dominant. We collected 8 to 10 samples from each shrub species within 8 days of netting birds in each stand. One sample of a shrub was approximately equal to 100 leaves of vine maple, ocean spray, and salmonberry, or 50 leaves of salal and hazel, or 5 fronds of bracken fern and 8 of sword fern, or 1 m^2 branch of western hemlock. Arthropods were collected from shrubs by beating foliage within 2 m of the ground. The foliage sampled was clipped, dried, and weighed, and the arthropod specimens were preserved in alcohol.
Habitat Sampling Cover was estimated by vegetation layer for each dominant shrub and tree species in 4 5-m radius plots centered on each bird count point and mist net location. Vegetation layers were subjectively determined by apparent natural discontinuities in the vertical profile of the foliage. To aid in these determinations, lower and upper height for each dominant shrub and tree species was estimated and recorded.