Travis J. Schepker1, Elisabeth Webb2, Ted LaGrange3 Missouri Cooperative Fish and Wildlife Research Unit1

US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit2

Nebraska Game and Parks Commission3

Evaluating the Relationship between Food Availability and Landscape Structure in Determining Dabbling Duck Habitat Use during Spring Migration

Source: Baldassarre and Bolen 2006

Wintering - Hunting Pressure - Pair-Bonding - Survival

Spring Migration ???

Fall Migration - Hunting Pressure - Pair-Bonding

Breeding - Nesting - Brood Rearing - Molting

Photo: Allen Wilson Photo: USFWS/Pat Hagan Photo: Johan Fredriksson Photo: Ryan Askern

Source: Dahl 1990

Percentage of Wetlands Acreage Lost, 1780s – 1980s

- Ohio: 90% - Indiana: 87% - Iowa: 89% - Missouri: 87% - Illinois: 85%

Breeding Habitat

Migratory Habitat

Winter Habitat

• Waterfowl migration can occur on a transcontinental scale • Replenish lipid and protein reserves

• Migratory body condition and breeding success (Devries et al. 2008)

• Initiated nesting sooner • Egg production • Better nesting propensity

Photos by: Ryan Askren

Seed

Den

sity

Summer Fall Winter Spring

Deterioration

Source: Reinecke et al. 1989, Greer et al. 2007, Hagy and Kaminski 2012, Drahota 2012

Foraging Threshold

Fall Seed Demand

Spring Seed Demand

1. Quantify local habitat parameters thought to be important to dabbling ducks during the spring.

2. Quantify inundated wetland area in surrounding landscape.

3. Model habitat selection for dabbling ducks at spring migratory wetlands that incorporates interactions between local and landscape variables.

Source: Webb et al. 2010, Straub et al. 2012, Drahota and Riechart 2015 Source: Fredrickson and Reid 1989, Fairbairn and Dinsmore 2001, Webb et al. 2010

Geographical Bottleneck

•4 million dabbling ducks

•50% mid-continent mallard population

• 30% northern pintail population

Population Goal (2030)

•~7 million dabbling ducks

Source: Gersib et al. 1992, RWBJV 2012

Ephemeral Playa Wetlands

Public Wetlands (48%) • United States Fish and Wildlife Service • Nebraska Game and Parks Commission

• 2014 n = 12 Public • 2015 n = 12 Public

Private Wetlands (52%) • Wetlands Reserve Program (WRP) • Agriculture

• 2014 n = 6 Private • 2015 n = 15 Private

Seed Sampling Techniques • Transect across longest distance of wetland • 10 – 20 soil cores at random locations along transect • Record water depth, vegetative dispersion, and wetland area • Pre-Migration and Post Migration

Seed Sampling Transect

Source: Hagy and Kaminski 2012, Drahota and Riechart 2015

Invertebrate Sampling Techniques • Collected invertebrate samples bi-monthly • 6 – 10 benthic core samples collected per event • 6 – 10 nektonic net samples collected per event • Record water depth, vegetative dispersion, and wetland area

3m

3m

3m

3m

3m

3m

Macroinvertebrate Sampling

Source: Tapp and Webb 2015

Net Sample

Core Sample

Source: Link et al. 2011, RWBJV 2015

Monitoring Inundated Area in Surrounding Landscape

• Problems: 1. “Ephemeral” wetlands 2. Access

• Solutions: 1. High resolution aerial imagery 2. Landsat8 satellite imagery

• Inexpensive • Readily available • Reoccurring (16 days)

Photo Credited To: USGS

Response Variable: Dabbling Duck Density

• Weekly point count surveys • Multiple vantage point

• Perimeter walks with handheld GPS

• Landsat imagery

𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 𝐷𝐷𝐷𝐷𝐷𝐷𝐷 = # 𝐷𝐷𝑏𝑏𝐷

𝑊𝐷𝐷𝐷𝐷𝐷𝑏 𝐴𝑏𝐷𝐷 (ℎ𝐷)

Photos by: Ryan Askren

Photos by: Ryan Askren

Local Parameters • Forage (Inverts + Seed) • All Seed • Coarse Seed (>0.7mm) • Fine Seed (>0.3mm & > 0.7mm) • All Invertebrates • Benthic Invertebrates • Nektonic Invertebrates • Depth • Vegetation • Wetland Area

Repeated Measure: Week Random Effect: Site

Photo by: Jerod Foster

Landscape Parameters • Wetland area within 4.6km • Wetland area within 2.3km • Wetland units (>1ha) within 4.6km of

study site • Wetland units (>1ha) within 2.3km of

study site • Wetland density: wetland area/66.48

(4.6km) • Wetland density: wetland area/16.62

(2.3km)

Repeated Measure: Week Random Effect: Site

Photo by William Johnson

-1

-0.5

0

0.5

1

1.5

Par

amet

er E

stim

ate

2014 Model Average Parameter Estimates Dabbling Duck ~ Density

-1.5

-1

-0.5

0

0.5

1

1.5

Par

amet

er E

stim

ate

2015 Model Average Parameter Estimates Dabbling Duck ~ Density

0

50

100

150

0 10 20 30

y

g 2015 Waterfowl Response to Depth

Dab

blin

g D

uck

Den

sity

Depth (inches)

Food Resource Availability

• Coarse seed availability (2014 & 2015) • Invert and seed (2014) • Water depth (2014)

• Positive relationship • Availability and maneuverability

0

50

100

150

0 200 400 600

y

Dabbling Duck Response to Coarse Seed

Dab

blin

g D

uck

Den

sity

Seed Biomass kg/ha

Source: Fredrickson and Reid 1988 , Hagy and Kaminski 2015

Wetland Density within 2.3km of study site

• Positive relationship in 2014 • Observed in 3 models, significant in 1 model

• Negative relationship in 2015 • Observed in 2 models, significant in 2 models

2014 2015 Wetland Area: 2.3km 4.53 ha 23.61 ha

Wetland Area: 4.6km 21.89 ha 53.15 ha

Dabbling Density 104 birds/ha 33 birds/ha

Wetland Density within 2.3km of study site

• Positive relationship in 2014 • Observed in 3 models, significant in 1 model

• Negative relationship in 2015 • Observed in 2 models, significant in 2 models

Opportunity to Disperse

• Less competition at individual wetlands

• Avoid forage depletion

• Prevent overcrowding (disease)

• Efficient interaction with other wetland habitat

2014 2015 Wetland Area: 2.3km 4.53 ha 23.61 ha

Wetland Area: 4.6km 21.89 ha 53.152 ha

Dabbling Density 104 birds/ha 33 birds/ha

Photo by William Johnson

Population Goals • Current population in the RWB

~ 4 million dabbling ducks

• Desired population in the RWB ~ 7 million dabbling ducks

• Will food availability be a limiting factor?

• 50-250 kg/ha (???)

Source: Gersib et al. 1992, RWBJV 2012, Hagy and Kaminski 2012, Drahota and Reichart 2015

0

500

1000

1500

2000

2015 Wetland Seed Biomass

250

Public PRE Public POST WRP PRE WRP POST Agriculture Se

ed B

iom

ass

(kg/

ha)

2014 2015 Wetland Area: 2.3km 4.53 ha 23.61 ha

Wetland Area: 4.6km 21.89 ha 53.15 ha

Dabbling Density 104 birds/ha 33 birds/ha

Questions

Blue Highlight: Actual Perimeter

Shaded Region: Area Projected from Landsat

Eckhardt WPA

• Delineated: 03/26/2014 • Imagery: 03/25/2014

Projected Area: 19.322 Actual Area: 20.846 Percent Difference: 7%

Week Site Perim_Date Sat_Date File Site_Actual Site_Projected 46kmComp 46kmUnits 46kmDen 23kmComp 2.3kmUnits 23kmDen Week 1 Eckhardt 2/25/2014 2/21/2014 Landsat 15.5 15.6 94.0 5 1.4 0.0 0 0 Week 2 Eckhardt NA NA Avg Rate (1,3) NA 20.3 109.1 5.0 1.6 0.0 0.0 0.0 Week 3 Eckhardt NA 3/9/2014 Landsat NA 25.0 124.2 5 1.9 0.0 0 0 Week 4 Eckhardt NA 3/15/2014 RWBJV NA 23.9 111.8 5.0 1.7 0.0 0.0 0.0 Week 5 Eckhardt 3/26/2014 3/25/2014 Landsat 20.8 19.3 93.1 5.0 1.4 0.0 0 0 Week 6 Eckhardt NA NA Avg Rate (5,8) NA 17.4 65.8 4.5 1.0 0.0 0.0 0.0 Week 7 Eckhardt NA NA Avg Rate (6,8) NA 14.0 52.1 4.3 0.8 0.0 0.0 0.0 Week 8 Eckhardt 4/16/2014 4/17/2014 Google 14.3 13.6 38.4 4.0 0.6 0.0 0 0 Week 9 Eckhardt NA NA Week8 NA 13.2 37.3 4 0.6 0 0 0

Appendix II: Example of validation assessment at Eckhardt Marsh WPA (Week 5). Eckhardt marsh perimeter was walked on 3/26/2014 to determine the geographical area in hectares (Site_Actual). Landsat Imagery was recorded on 3/25/2014 and processed in ArcMap to determine the geographical area in hectares (Site_Projected). There was a 7% (1.5ha) discrepancy between the two dates. There was imagery available for 5 of the 8 study weeks for the site. Weeks with no imagery available were extrapolated from rates of change during the preceding 2 weeks. Surrounding landscape configuration (wetland area, number of units, and density surrounding site) is described below table, and corresponds with imagery obtained for 2014 analysis.

46kmComp (ha of wetland area within 4.6km of site), 4.6kmUnits (number of wetlands > 1ha in area with in 4.6km of site), 46kmDen (wetland density within 4.6km of site) 23kmComp (ha of wetland area within 2.3km of site), 23kmUnits (number of wetlands > 1ha in area with in 2.3km of site), 23kmDen (wetland density within 2.3km of site).

2014 (AICc Δ 4)

Model 1 Adj R2 = 0.47

Model 2 Adj R2 = 0.47

Model 3 Adj R2 = 0.46

Model 4 Adj R2 = 0.46

Model 5 Adj R2 = 0.44

Model 6 Adj R2 = 0.45

Area + Vegetation - - Depth + + + + + + Invert + Seed + + + 2.3km Density + + + Coarse Seeds + + + Invert Benthic - Invert Nektonic -

Green indicates significant relationship with dabbling duck density

2015 (AICc Δ 4)

Model 1 Rsq Adj = 0.50

Model 2 Rsq Adj = 0.49

Model 3 Rsq Adj = 0.50

Model 4 Rsq Adj = 0.49

Model 5 Rsq Adj = 0.48

Model 6 Rsq Adj = 0.49

Area - - - - Vegetation - - - - - Depth + + + + + Invert Benthic - Invert Nektonic - Coarse Seed + + + + + + 2.3km Density - - 4.6km Density -

* Implies significant effect on corresponding model Green implies significant relationship with dabbling duck density

Previous Modeling at the Local Level

• Vegetative dispersion: Hemi-Marsh

• Wetland area

• Water depth: 5 – 25cm

• Seed and invertebrate availability

Webb et al. 2010, Straub et al. 2012, Drahota and Riechart 2015

Photo by: Jerod Foster

Modeling Beyond the Local Level

• Wetland complex

• Upland landscape • Cropland • Native Vegetation

Photo by: William C Johnson

Source: Fredrickson and Reid 1989, Fairbairn and Dinsmore 2001, Webb et al. 2010

2014 (AICc Δ 4)

Model 1 Adj R2 = 0.47

Model 2 Adj R2 = 0.47

Model 3 Adj R2 = 0.46

Model 4 Adj R2 = 0.46

Model 5 Adj R2 = 0.44

Model 6 Adj R2 = 0.45

Area + Vegetation - - Depth + + + + + + Invert + Seed + + + 2.3km Density + + + Coarse Seeds + + + Invert Benthic - Invert Nektonic -

Green indicates significant interaction with dabbling duck density