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Headwater Riparian Habitat: Prime Real Estate For Birds

Headwater Riparian Habitat: Prime Real Estate For Birds. Joan Hagar, USGS-FRESC Judy Li and Janel Sobota , OSU Department of Fish & Wildlife. Riparian Reserves. Designed to protect AQUATIC resources Riparian habitat is also important for some TERRESTRIAL wildlife species

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Headwater Riparian Habitat: Prime Real Estate For Birds

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  1. Headwater Riparian Habitat: Prime Real Estate For Birds

    Joan Hagar, USGS-FRESC Judy Li and JanelSobota, OSU Department of Fish & Wildlife
  2. Riparian Reserves 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?
  3. Riparian-Upland Gradients: Birds and Insects Higher abundance and diversity of birds reputed for riparian habitat Emergent aquatic insects may provide a “subsidy” to terrestrial consumers Higher capture rates of some bird species in Trask headwater riparian areas compared to uplands Do aquatic subsidies explain riparian association?
  4. Riparian-Upland Gradients: Vegetation Deciduous vegetation supports more arthropod prey than conifers 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?
  5. Research Goal Relate the distribution of birds along inter-riparian gradients in headwater forests to availability of insect prey
  6. Research Questions What are riparian-associated birds eating? Aquatic vs terrestrial arthropods Does prey availability (Terrestrial and Aquatic) differ between Riparian and Upland habitats?
  7. Trask River Study Sites 6 Sites:
  8. Methods: What are riparian-associated birds eating? Swainson’s Thrush, Pacific-slope Flycatcher, Wilson’s Warbler, and Pacific Wren Diet samples collected from birds captured in nets ID fragments in fecal samples to Order; Aquatic vs Terrestrial
  9. Methods: Assessing Prey Availability for Birds Streamside and Upland Malaise: Adult Aquatic and Terrestrial Insects (once per week) Stream Emergence: Adult Aquatic Insects (2x per week)

  10. RESULTS:

    What are the birds eating?
  11. Diets of Pacific Slope Flycatcher (n=18) and Wilson’s Warbler (n=15)
  12. Diets of Swainson’s Thrush (n=73) and Pacific Wren (n=23)
  13. Bird Diet Highlights Beetles and Flies were popular fare Aquatic emergents (EPT) rare Fruit was important in Swainson’s thrush diet

  14. RESULTS:

    Gradients in arthropod prey availability
  15. Malaise trap Results:Flying Insects >2 mm <25 mm *Others:Neuroptera, Psocoptera
  16. Biomass of Flying Insects (>2 mm)
  17. Flying Insects (>2 mm <25 mm) in Summer 2008
  18. Flying Insects (>2 mm <25 mm) in Summer 2008 Individuals/day (Mean + S.E.)
  19. Conclusions
  20. No Evidence of Aquatic Subsidy 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
  21. Prey abundance varied from streamside to upland More prey in riparian than upslope samples Distinct riparian vegetation may influence prey abundance
  22. Conclusions Riparian vegetation contributes to aquatic and terrestrial food webs Understory may be helpful in defining management zones
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