Stopover Habitat Decisions in a Vanishing Landscape
Transcription
Stopover Habitat Decisions in a Vanishing Landscape
Caitlyn Gillespie and Joseph J. Fontaine Nebraska Cooperative Fish and Wildlife Research Unit University of Nebraska-Lincoln Rainwater Basin Joint Venture Informational Seminar February 10, 2015 Migration: a common life history strategy Photo: J.J. Fontaine Stopover habitat is essential Migrants must frequently make habitat decisions in unfamiliar environments Tree phenology Migratory species have evolved strategies to cope with environmental uncertainty For example, birds time arrival to coincide with regional and seasonal peaks in food abundance # Migratory birds http://nationalzoo.si.edu/ McGrath et al 2009 http://nationalzoo.si.edu/ Migrants are known to make habitat decisions based local food resources, which are often annually and regionally predictable Proportional use by migrants Migratory species have evolved strategies to cope with environmental uncertainty Tree species McGrath et al 2009 Shorebird stopover habitat is unpredictable Ephemeral wetland habitat is annually and regionally variable Skagen and Knopf 1994 Map: University of Delaware, College of Earth, Ocean, and Environment Photos: C. Gillespie, J.J. Fontaine Not all wetlands are created equal Photos: J.J. Fontaine, C. Gillespie Shorebird stopover is highly correlated with local resource phenology Stutzman and Fontaine In Press-- Studies in Avian Biology Photo: J.J. Fontaine Landscapes are changing Land-use change alters wetland availability, distribution, and function Photos: K. Hayes, C. Gillespie Climate change also disrupts wetland availability and phenology Art: R. Rohde Photos: K. Hayes, J. Dupuie, C. Gillespie What are the consequences? Shorebirds can adjust their stopover decisions in response to natural variation in wetland conditions and abundance Does behavioral plasticity allow individuals to cope effectively with anthropogenic disturbance across the landscape? Photos: C. Gillespie How does anthropogenic change influence stopover decisions of migratory shorebirds? Photo: C. Gillespie Calidris shorebirds • Arctic-nesting sandpipers • Long-distance migrants Photo: C. Gillespie Rainwater Basin • Important stopover site for many migratory species, including Calidris shorebirds • Fewer than 10% of historical wetlands remain Cultivated Crops Wetland Basins Nebraska NLCD 2011, RWBJV 2012 Photo: C. Gillespie What are the local wetland attributes predicting Calidris shorebird habitat use in a highly altered landscape? Photos: J.J. Fontaine Shorebird Surveys, Spring 2013 and 2014 Photos: C. Gillespie, J. Dupuie, C. Jordan, E. Rodriguez, N. Staton, R. Stutzman Occupancy Birds respond predictably to local habitat attributes Percent Mud χ2 (1)=9.54, p<0.01 Photo: C. Gillespie Colwell and Oring 1988, Davis and Smith 1998, Skagen and Knopf 1994, Stutzman 2012 Probability of Calidris occupancy Birds find wetlands with food Invertebrate Abundance Photo: C. Gillespie, C. Jordan χ2 (1)=5.59, p<0.05 Birds time arrival with peak food abundance 180 2013 160 Total Abundance Total Abundance 140 Total Abundance 2014 2013 120 100 80 60 40 20 0 2014 600 2014 500 JulDay vs AllPeeps JulDay vs Invert Migrants Invertebrates 400 300 200 Migrants Invertebrates 100 0 80 100 120 140 160 Julian Day Julian Day Photo: C. Gillespie Flock Size …but food abundance does not predict bird abundance at wetlands Invertebrate Abundance χ2 (1)=7.21, p<0.01 Photo: C. Gillespie, R. Stutzman Foraging habitat can disappear quickly Photo: G. Jukkala, C. Gillespie Art: C. Gillespie Occupancy Shorebirds still need shore Percent Mud How does the availability of suitable habitat change over time? Photo: C. Gillespie Habitat changes seasonally May 2 Percent Mud April 23 May 12 Julian Day, 2013 May 21 Mud: χ2 (1)= 30.69, p<0.001; Green: χ2 (1)=382.58, p<0.001; Short: χ2 (1)=22.22, p<0.001 Photos: C. Gillespie, N. Staton, E. Rodriguez Wetland availability often declines seasonally Wetland Area 2013 Julian Day, 2013 χ2 (1)= 393489, p<0.001 Photo: E. Rodriguez Wetland landscapes also respond quickly to weather events May 8 Photos: K. Hayes, C. Gillespie May 18 Late spring thunderstorms can increase wetland availability seasonally Wetland Area 2014 χ2 (1)= 409630, p<0.001 Julian Day, 2014 Photo: K. Hayes Percent Mud Heavy rainfall changes habitat availability both within and among wetlands Julian Day, 2014 χ2 (1)= 6.53, p<0.05 Photo: C. Gillespie What are the consequences of unpredictable habitat for migratory stopover? Photos: C. Hause, G. Jukkala Art: C. Gillespie Habitat availability changes annually Even in wet years, habitat within the Rainwater Basin is limited Nebraska RWBJV 2012 Photo: C. Gillespie All Water in the Rainwater Basin, Spring 2013 Nebraska Photo: C. Gillespie Flooded acres on WMA/WPAs in March What role does landscape-scale habitat availability play in stopover decisions? 3500 Distribution of water on landscape has relevance for shorebirds 3000 2500 2000 1500 1000 500 0 RWBJV 2014 Photo: C. Gillespie 2013 2014 Water availability was much higher in 2014 Skagen and Knopf 1994, Farmer and Parent 1997, Albanese and Davis 2013 What are the consequences of limited habitat on migratory stopover? 1400 Calidris shorebirds in the Rainwater Basin 1200 #Birds 1000 800 600 Spring 2014 400 200 0 27-Mar Spring 2013 6-Apr 16-Apr 26-Apr Date 6-May 16-May 26-May 5-Jun Photo: C. Gillespie # Birds per Used Wetland Individual wetlands in dry years have fewer birds, despite habitat scarcity 2013 χ2 (1)= 796.76 p<0.0001 2014 Birds appear to respond to landscape dynamics and alter stopover decisions Photo: C. Gillespie Prairie Pothole Region How do birds respond to landscape differences within years? Photos: Google Rainwater Basin # Birds per Used Wetland Bird abundance was also higher in the PPR in 2014 Spring 2013 χ2 (1)= 1679.4 p<0.001 Spring 2014 Photo: C. Gillespie Landscapes have relevance across years 2000 1800 2013 1600 1400 1200 1000 800 600 400 #Birds 200 0 2000 1800 2014 Calidris shorebirds in two landscapes 1600 1400 1200 1000 Rainwater Basin 800 600 Prairie Pothole Region 400 200 0 2-Mar 22-Mar 11-Apr 1-May Date 21-May 10-Jun 30-Jun #Birds per Used Wetland Wetlands in landscapes with more habitat support more birds Rainwater Basin Region: χ2 (1)=9.56, p<0.01; Percent Mud: χ2 (1)= 5.33, p<0.05; Year: χ2 (1)= 295.82, p<0.001 Prairie Pothole Region Photo: C. Gillespie How do species in dynamic systems cope with anthropogenic change? Shorebirds may respond to increasing change by skipping historically beneficial stopover sites Photo: C. Gillespie How do we manage for migratory species while considering the full scale at which birds make stopover decisions? Photo: J.J. Fontaine Shorebirds respond to landscape habitat availability, not just local wetland conditions Delivering water to isolated wetlands may support a few birds, but may be insufficient to support a population Phenology of late-spring habitat may be highly subject to the structure and function of wetlands in response to local temperature and precipitation Wetlands do not necessarily dry out at the same rate Photo: C. Gillespie Wetlands may support more migrants if management focuses on maintaining habitat at a landscape scale Photo: C. Gillespie Landscapes are vital for the support of migratory populations in dynamic systems Habitat conservation efforts must consider landscape context to best mitigate the effects of escalating change Photos: J. Dupuie, C. Gillespie Acknowledgements Fontaine lab (past and present): TJ Fontaine, Lucia Corral, Kent Fricke, Chris Jorgensen, Jessica Laskowski, Mandy Lipinski, Dustin Martin, Lindsey Messinger, Ryan Stutzman, Lyndsie Wszola Committee members: Gwen Bachman and LaReesa Wolfenbarger Funding sources: USGS Climate Change and Wildlife Science Center, Rainwater Basin Joint Venture, Great Plains LCC, Nebraska Game and Parks Housing: Crane Trust, USFWS UNL and Coop Unit Grad Students and Staff, Technicians, Private Landowners