Joan Hagar, USGS-FRESC Judy Li and Janel Sobota, OSU Department of Fish & Wildlife  Designed to protect AQUATIC resources

 Riparian habitat is also important for some TERRESTRIAL wildlife species

 Function of headwater riparian areas as habitat for terrestrial species?  Higher abundance and diversity of reputed for riparian habitat

 Emergent aquatic may provide a “subsidy” to terrestrial consumers

 Higher capture rates of some species in Trask headwater riparian areas compared to uplands

 Do aquatic subsidies explain riparian association?  Deciduous vegetation supports more prey than

 Deciduous tends to flourish streamside, Conifers upslope

 Pattern less pronounced on high-gradient headwater streams

 Changes in distribution of arthropod prey in relation to stream size? Relate the distribution of birds along inter- riparian gradients in headwater forests to availability of prey • What are riparian- associated birds eating? — Aquatic vs terrestrial

• Does prey availability (Terrestrial and Aquatic) differ between Riparian and Upland habitats? 6 Sites:

2008 2009 GS1 GS1 PH3 PH3 PH2 GS3 PH4 UM3  Swainson’s Thrush, Pacific-slope Flycatcher, Wilson’s Warbler, and Pacific  Diet samples collected from birds captured in nets  ID fragments in fecal samples to Order; Aquatic vs Terrestrial Stream Streamside and Upland Emergence: Adult Aquatic Malaise: Adult Aquatic Insects and Terrestrial Insects (2x per week) (once per week) What are the birds eating? 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Pac-Slope Flycatcher 0.2 Wilson's Warbler 0.1 0.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 Swainson's Thrush 0.2 Pacific Wren 0.1 0.0  Beetles and Flies were popular fare  Aquatic emergents (EPT) rare  Fruit was important in Swainson’s thrush diet Gradients in arthropod prey availability 100 90 80 70 60 50 40 Riparian 30 20 Upland 10 0

*Others: Neuroptera, Psocoptera Biomass of Flying Insects (>2 mm)

1.2 RIPARIAN UPLAND 1.0

0.8

0.6

0.4 (Mean + S.E.) 0.2 Dry Mass (g)/Week

0.0 2008 2009 Flying Insects (>2 mm <25 mm) in Summer

250 2008 RIPARIAN 200 UPLAND

150

100

50

0 6/26 7/16 8/5 8/25 Flying Insects (>2 mm <25 mm) in Summer

250 2008 RIPARIAN 200 UPLAND 150

100

50

0 6/26 7/6 7/16 7/26 8/5 8/15 8/25 (Mean + S.E.) Individuals/day 250 2009

200

150

100

50

0 6/26 7/6 7/16 7/26 8/5 8/15 8/25

 Little evidence of aquatic emergent insects in bird diets  Aquatic insects represented small proportion of available prey biomass Terrestrial food resources most important to birds  More prey in riparian than upslope samples  Distinct riparian vegetation may influence prey abundance  Riparian vegetation contributes to aquatic and terrestrial food webs

 Understory may be helpful in defining management zones