Rusty Blackbirds in the Northern Forest Breeding Season

Rusty Blackbirds in the Northern Forest: Breeding Season Status and Habitat Associations at Local and Landscape Scales Stacy Mc. Nulty, SUNY ESF

Natural History Breeds in forested wetlands and bogs across North American boreal forest Winters in wooded wetlands and bottomlands in the southeastern U. S. Feeds on aquatic invertebrates Photos credits: D. Cote, S. Buckley, www. borealbirds. org

Rusty Blackbird Declined by approximately 90% since the 1970’s based on North American Breeding Bird Survey, Christmas Bird Count Difficult to study (remote, inaccessible habitats) Causes of decline still not clear

Rusty Blackbird Rangewide Decline Rusty Blackbirds recorded in the U. S. during Audubon’s Christmas Bird Count, 1959 -2004

Possible Causes for Decline Loss of winter habitat to conversion, fragmentation Climate change (water levels, phenological, other) Acidification of boreal wetlands, mercury contamination Habitat conversion in boreal forest (timber harvest, reservoir formation, energy development) “Ecological trap” – predation on breeding grounds, social factors Photos credits: S. Buckley, Garth Lenz, www. wildlifeforever. org

Objectives Identify predators of Rusty Blackbird nests Model nest survival as a function of habitat variables at multiple spatial scales Examine the relationship between cone cycles, predator populations and nest predation Model habitat selection at multiple spatial scales Inform future work on summer foraging ecology, behavior etc.

Study Areas

Nest Monitoring and Habitat Located and monitored nests in ME and NH in 2011 and 2012 Installed covert, passive infrared (PIR) cameras < 1 - 3 m from nests Measured vegetation in 5 -m radius plots around nests (post-nesting) Control plot 50 m from nest in random direction

Squirrel Surveys Broadcast surveys for squirrels at nests and in select mature stands Basal area measurements 90 m transects, passive/active broadcast squirrel calls with game caller

Landscape-Scale Habitat GIS: percent cover of forest and types within 500 -m radius of nests, distance to nearest road Data on stand area, species composition, etc. from landowners Wetland data from National Wetland Inventory (NWI) Database

Statistical Analyses Nest Habitat Selection • Nest-Patch-Scale (5 m): matched pairs logistic regression (MPLR), odds ratios • Landscape-Scale (500 m): logistic regression, odds ratios • Program R Nest Survival • Logistic exposure models, 27 exposure days • Two spatial scales: Nest Patch Scale (5 m) Landscape Scale (500 m) • Program MARK Comparison of Cone/Squirrel Abundance • Chi-square tests

Nest Habitat Selection • Located 72 nests in 2011 -2012 • NH = 43 • ME = 29 • 88% (n = 63) nests in harvested areas - wetlands and uplands 9 in unharvested areas wetlands only • Over 90% of nests within a few meters of an edge with an open habitat • Wetland • Skid road • Tree gap

Nest Habitat Selection Nest-patch-scale • Basal area at nests = small, dense, young conifers • Probability of selection increased by 65% with each 5 m 2/ha increase in small softwoods • Probability of selection decreased by 39% with each 10% increase in canopy cover

Nest Habitat Selection Landscape-scale • Probability of selection increased by 46% with each 10% increase in young softwood cover • Probability of selection increased with each 10% increase in wetland cover by site: • ME = 2. 46 times higher • NH = 5. 47 times higher

Nest Habitat Selection: Summary Different factors driving selection at different spatial scales, decoupled • Foraging requirements (wetlands) at landscape scale • Nest safety (dense conifers) at nest-patch scale Greater plasticity at landscape-level than nest patchlevel - as long as certain key features present, matrix appears of little importance Broad (regional) application of habitat management plans Habitat result of interacting disturbances, dynamic in space and time - need to look beyond “harvest history”

Cone Cycles

Predators and Cones Proportion of squirrel surveys with positive detections: ME Nests: ME Mature Stands: 2 = 6. 50, p = 0. 01 2 = 6. 75, p = 0. 009

Predators • Monitored 29 nests with cameras (21 in ME 2011/12, 8 in NH 2012) • 34, 446 photos • 8 predation events documented by 4 confirmed, 1 suspected species • Red squirrels most frequent predator, but only in 2012

Nest Survival – Nest Scale • • Overall survival: 53 + 9% (n = 65) Importance of total basal area No effect of timber harvesting Distance to road a factor in 2011, but not 2012

Nest Survival – Landscape-scale If there is an association between certain predators and roads, then it may be prudent to consider the potential effects of infrastructure associated with harvest operations, rather than focusing on stand treatments exclusively. Photo credits: S. Buckley

Conclusions Photo credits: S. Buckley, Richard Kent Decoupling of habitat selection at different spatial scales Red squirrels primary nest predators, but not every year Nest survival likely fluctuates with predator populations, mast cycles Nest survival not related to harvest per se – roads? Relationship between timber harvesting and Rusty Blackbird nesting ecology complex Productivity not chronically low, not driver of decline

Habitat and Species Conservation • Other habitat factors • Hydric soils • Beaver influence • “ Mappable” wetlands ? • • Ditches Vernal pools Seeps Puddles State status - RARE • VT – State Endangered • NH – Special Concern • ME – Special Concern • NY – High Priority SGCN

Management Recommendations Maintain stands of young (seedling/sapling) softwood, particularly around wetlands/hydric soils - can be small patches Retain snags as perches Sub-stand structure important

Current/Future Research Foraging ecology • • Aquatic invertebrate emergence phenology and diet Habitat characteristics Occupancy analysis of wetland foraging sites Detectability analysis and methodology testing Binational cooperation via IRBTWG • Habitat disturbance in core (boreal) breeding range Climate/hydrological change • Could Northeast US become a migratory stopover region?

Rusty Research Team Acknowledgments Shannon Buckley Lüpold Thomas Hodgman Jonathan Cohen Carol Foss Amanda Pachomski Luke Powell Patti Newell Wohner Ray Ary Henning Stebbins Stefan Lüpold Sean Flint Field technicians: Linnea D’Amico, Sara Prussing, Joe Roy, Devon Cote, Kelsey Schumacher, Amasa Fiske-White, and Thomas Ruland Landowners: Plum Creek, Wagner Forest Management, Northwoods Management, Prentiss and Carlisle, Appalachian Mountain Club, Umbagog National Wildlife Refuge Funding and Logistical Help: Edna Bailey Sussman Foundation, Garden Club of America, Maine Outdoor Heritage Fund, USFWS State Wildlife Grant Program, New Hampshire Audubon, SUNY ESF

References Greenberg, R. , and S. Droege. 1999. On the decline of the Rusty Blackbird and the use of ornithological literature to document long-term population trends. Conservation Biology 13: 553 -559. Greenberg, R. , and S. Matsuoka. 2010. Rusty Blackbird: Mysteries of a species in decline. Condor 112: 770 -777. Powell, L. , T. P. Hodgman, W. E. Glanz, J. D. Osenton, and C. M. Fisher. Nest-site selection and nest survival of the Rusty Blackbird: Does timber management adjacent to wetlands create ecological traps? Condor 112: 800 -809. Robertson, B. A. , and R. L. Hutto. 2006. A framework for understanding ecological traps and an evaluation of existing ecological evidence. Ecology 87: 1075 -1085.