Ecological Impacts of Introduced Game Birds in Hawaiian Forests
Samuel B. Case (1), Jinelle H. Sperry (2), and Corey E. Tarwater (1)
- Majority of native Hawaiian plants are bird-dispersed, but nearly all native frugivorous birds are extinct
- Extinct forest avifauna includes passerines, corvids, ibis, rails, and large-bodied flightless geese. Geese and corvids were large-bodied birds that were likely important seed dispersers
- Introduced frugivores might functionally replace extinct ones, but if they depredate native seeds or consume and disperse non-native seeds, their cumulative impact on the ecosystem may be negative
- Two game bird species, the Kalij Pheasant (Lophura leucomelanos) and Erckel’s Francolin (Pternistis erckelii), were introduced to Oʻahu in the last century and now occupy a large range of forested habitat
- Both species consume fruit, but their roles in seed dispersal remain largely unknown
-Identified seeds in fecal samples
-56.2% of sorted fecal samples contained depredated seeds (n = 32)
-Gizzard of a necropsied francolin contained lava rock, whole seeds, worn seeds, and seed fragments
-Currently testing germination with captive birds
- Compared to other introduced frugivores, game birds had a larger body mass and gape width, suggesting that they may consume more seeds and larger seeds, but they may depredate more seeds
Comparative Morphology of Introduced Frugivorous Birds
- Compared to other introduced frugivores, game birds had a larger body mass and gape width, suggesting that they may consume more seeds and larger seeds, but they may depredate more seeds
-Deployed game cameras on fruiting plants, collected fecal samples, observed foraging, necropsied specimen
-Game birds consume both native and non-native fruits, including three federally-listed endangered species
- How does game bird morphology compare with other introduced frugivore avifauna?
- What is the diet composition and foraging behavior of game birds?
- How does the game bird gut passage affect seed germination?
- How do game birds move (and deposit seeds) across the landscape?
- GPS/UHF Telemetry, six individuals tagged since May 2018
Movement Ecology
- GPS/UHF Telemetry, six individuals tagged since May 2018
- Game birds are important seed dispersers (or depredators) in Hawaiian forests
- Low foraging of game birds and the morphological ability to consume larger seeds may substitute foraging by extinct large-bodied frugivores (geese and corvids)
- Currently examining dispersal distance and gut passage effects on seeds
- Whether overall impact is positive or negative is under investigation
We thank out outstranding team of scientists at the Hawaii VINE Project, as well as our partners, Hawaii Division of Forestery and Wildlife, Oahu Army Natural Resource Program, and Waimea Valley. The research was funded by the Strategic Environmental Research and Development Program and U.S. Army Corp of Engineers
