Seed dispersal dynamics and the decline of Hawaii`s fruit
Transcription
Seed dispersal dynamics and the decline of Hawaii`s fruit
Seed dispersal dynamics and the decline of Hawaii’s fruit-eating birds L. Pejchar1, S. Culliney1, M. Kaushik1, S. Bombaci1, L. Crampton2, R. Switzer3, V. Ruiz-Gutierrez1 1Colorado State University, 2Kauai Forest Bird Recovery Project, 3Keauhou Bird Conservation Center Photo: ZSSD How are birds important for seed dispersal? Distance dispersal Directed dispersal Photo: ZSSD Fertilizing effects Germination benefits 50% of Hawaii’s native plants rely on seed dispersal by birds 50% of Hawaii’s native plants rely on seed dispersal by birds The Alala, Omao and Puaiohi are Hawaii’s only extant native frugivores Drivers of Decline and Extinction Predation Habitat loss and degradation Competition and disease Captive population, future release? Photo: ZSSD Susan Culliney-ZSSD Questions 1. What seed dispersal services are lost…and restored, by the extinction and recovery of Alala? 2. Does the decline of Puaiohi in the presence of exotic birds alter seed dispersal dynamics? 3. Are bird reintroductions restoring ecological processes in New Zealand’s mainland sanctuaries? Questions 1. What seed dispersal services are lost…and restored, by the extinction and recovery of Alala? 2. Does the decline of Puaiohi in the presence of exotic birds alter seed dispersal dynamics? 3. Are bird reintroductions restoring ecological processes in New Zealand’s mainland sanctuaries? ´Alalā Corvus hawaiiensis Native - extinct in wild Ōma´o Myadestes obscurus Native – narrow range Leothrix Leiothrix lutea Exotic - widespread Japanese White-eye Zosterops japonicus Exotic - widespread ´Alalā Corvus hawaiiensis Native - extinct in wild Ōma´o Myadestes obscurus Native – narrow range Leothrix Leiothrix lutea Exotic - widespread Japanese White-eye Zosterops japonicus Exotic - widespread Keauhou Bird Conservation Center (Volcano, HI) Susan Culliney: ZSSD Susan Culliney: ZSSD Susan Culliney: ZSSD Plants Included in Study Methods: Dispersal Behavior 1) Gave each ´Alalā suite of berries, observed (Bird level) Susan Culliney: ZSSD Eat Susan Culliney: ZSSD Carry Susan Culliney: ZSSD Cache 2) Fate of seeds discovered next day (Flock level) Susan Culliney: ZSSD % seeds digested % seeds plucked/moved Results: Dispersal Behavior (EAT) 1.0 Old Alala (>3 yr) Young Alala (0-3 yr) 0.6 0.4 0.2 Plant Species N= 6 12-19 12-18 10-29 10-23 10-27 15-24 3 12-18 12-25 Loulu green Loulu black Halapepe Hoawa Ohe mauka Pilo Kolea Naio Pukiawe Olapa Kawau Mamaki Ohelo 0.0 Oha kepau Probability of eating 0.8 t=? p=? 3-25 6-13 4-12 3-9 ´Alalā flock consumed all plants in the study, a form of seed dispersal Results: Dispersal Behavior (CARRY) Flock carrying behavior 1.0 0.8 t=? p=? 0.6 0.4 0.2 Loulu green Loulu black Halapepe Hoawa Ohe mauka Pilo Kolea Naio Pukiawe Olapa Kawau Mamaki Ohelo 0.0 Oha kepau Probability of observed carrying Old Alala (>3 yr) Young Alala (0-3 yr) Plant Species N= 6 12-19 12-18 10-29 10-23 10-27 15-24 3 12-18 12-25 3-25 6-13 4-12 ´Alalā flock carried all plants, a form of seed dispersal 3-9 Halapepe Loulu black Loulu green Pilo Kolea Naio 0.8 Pukiawe 0.6 Olapa 3.9 Kawau 2.9 Mamaki Hoawa % times cached Ohelo 1.2 2.2 0.7 1.1 0.5 0.2 1.2 3.6 2.4 1.5 Oha kepau Ohe mauka Results: Dispersal Behavior (CACHE) ´Alalā flock cached all plants, a form of seed dispersal Methods: Germination Benefits Compared germination success among four treatments: Whole Cleaned Fecal Pellet Susan Culliney: ZSSD Results: Germination Success (%) Oha kepau Ohelo a 60 40 20 b cl fec Clean 60 40 b 20 b fec Clean 20 b 10 Mean % Germination 30 pell wh Pellet Whole t=3.24, p=0.0604, n=5 wh Whole t= 7.87, p=0.0411, n=3 Hoawa 80 a a 60 40 b 20 a 80 60 a a 40 b 20 0 0 0 fec Fecal 100 a a Clean Fecal cl Clean Pilo a fec 10 Whole 100 cl b 20 t= 7.24, p=0.0087, n=5 Olapa 50 ab ab 30 wh Fecal t= 16.52, p=0.0014, n=5 40 40 0 cl Whole a 50 0 wh Fecal Mean % Germination a Mean % Germination a 80 0 Mean % Germination Mamaki 60 80 Mean % Germination Mean % Germination 100 cl fec Clean Fecal pell wh Pellet Whole t= 10.78, p=0.0010, n=5 cl fec Clean Fecal pell wh Pellet Whole t= 5.41, p=0.0171, n=5 For most plant species ´Alalā digestion increased germination success probably by removing fruit pulp from seeds Hoawa (Pittosporum hosmeri) % Germination Mean % Germination 100 a 80 60 a a 40 b 20 0 cl fec Clean Fecal pell wh Pellet Whole t= 5.41, p=0.0171 Summary ´Alalā: • Dispersed seeds of all plants • Dispersed seeds via multiple mechanisms • Increased germination success for some species : ZSSD Culliney et al. 2012 Ecological Applications Summary ´Alalā: • Dispersed seeds of all plants • Dispersed seeds via multiple mechanisms • Increased germination success for some species 1. Feed Alala native fruit prior to release : ZSSD 2. Select/restore reintroduction sites with popular fruiting plant species 3. Alala may be critically important for some large-fruited species…yet another reason to invest in recovery efforts Culliney et al. 2012 Ecological Applications Questions 1. What seed dispersal services are lost…and restored, by the extinction and recovery of Alala? 2. Does the decline of Puaiohi in the presence of exotic birds alter seed dispersal dynamics? 3. Are bird reintroductions restoring ecological processes in New Zealand’s mainland sanctuaries? How does the decline of Kauai’s last native frugivore impact seed dispersal dynamics? Are introduced birds filling the gap? Kawaikoi Mohihi Kawaikoi Mohihi Exotic frugivores 37.15 birds/ha 43.22 birds/ha Puaiohi 1-2 territories 17-19 territories s 1. Does seed rain differ in the absence of Puaiohi? 2. How similar is the diet of Puaiohi and Japanese White-eye? % of samples with seeds Composition of seeds in fecal samples 80 70 60 50 40 30 20 10 0 Japanese Series1 White-eye n = 33 Puaiohi Series2 n = 66 % of samples with seeds Composition of seeds in fecal samples 80 70 60 50 40 30 20 10 0 Japanese Series1 White-eye n = 33 Puaiohi Series2 n = 66 Questions 1. What seed dispersal services are lost…and restored, by the extinction and recovery of Alala? 2. Does the decline of Puaiohi in the presence of exotic birds alter seed dispersal dynamics? 3. Are bird reintroductions restoring ecological processes in New Zealand’s mainland sanctuaries? Research Questions 1. How does bird density and diversity in and out of sanctuaries affect the rate and pattern of seed dispersal? 2. What is the relationship between sanctuary size, bird diversity and seed dispersal dynamics? 3. Do sanctuaries have “spillover effects”, thus altering seed dispersal dynamics beyond the fence? Conclusion • ´Alalā disperse a wide variety of native plants, and enhance germination for many • In the absence of Puaiohi, we predict a shift towards smallerseeded & exotic plants • New Zealand’s mainland islands and the ecological consequences of bird reintroductions…stay posted! Acknowledgements Keauhou Bird Conservation Center & The Zoological Society of San Diego Alan Lieberman, Richard Switzer, Jeremy Hodges, Robby Kohley, Blake Jones, Sarah Bebus, Rachel Kingsley, Lynne Neibar, Pete Bibeault, Lisa Komarczek, Jen Holler, Kyle Parsons, Kara Kneubuhler, Angie Sewell, Rebecca Espinoza, & numerous interns. Funding Sources CSU Warner College of Natural Resources Hawaii Division of Forestry and Wildlife CSU Office of International Programs National Science Foundation Fulbright Foundation Sigma XI Field Assistants Jen Holler, Kyle Parsons, Jeremy Hodges, Kasha Malling and the staff of KFBRP Image Sources ZSSD, Jack Jeffrey, Patrick Ching, Google Image Search, Susan Culliney, Monica Kaushik, KFBRP, Sara Bombaci Plant Collection Jon Price, Rhonda Loh, Sierra McDaniels, Peter Van Dyke, Linda Pratt, Thane Pratt, Jack Jeffrey Thank you! Liba Pejchar Dept. of Fish, Wildlife and Conservation Biology Colorado State University [email protected] http://warnercnr.colostate.edu/~liba/ Lab twitter: @TheLibaLab