Common Nighthawksand

the Effects of Land Use and Climate Change

Gretchen N. Newberry

Nighthawks in

Midwest

↓ Row Crop

↑Grasslands

? Pastures

U.S.

58% ↓ since 1960s

Canada

80% ↓ since 1960s

↑in Boreal Forests?

New England

Now largely absent

North American Breeding Bird Survey 1966-2003 (Sauer et al., 2008)

Photo: ND Parks and Recreation Department

Photo: Robert Mortensen Photo: Rick & Nora Bowers

Photo: Jeff Pippen

Dixon et al.2012

1892

1950s

2006

• Loss of Grassland

habitat during

biofuel boom

• Continuing loss in

heterogeneity in

agricultural

landscapes

Wright and Wimberly 2013

Wright and Wimberly 2013

Willmer, Stone and Johnston 2005

• Is rooftop

nesting habitat

suitable?

• Urban areas

“heat island”

(Bonan 2002)

Kenward et al2014

Operative temperature (Te) Microclimate 2017:

• North Sioux City Flat, Gravel Rooftop

• Broken Kettle Prairie (Loess Hills), Iowa

0

20

40

60

80

6/6 6/7 6/8 6/9 6/10 6/11 6/12 6/13 6/14 6/15 6/16 6/17 6/18 6/19 6/20 6/21

Grassland Temp °C (Te) Gravel Roof Temp °C (Te)

Climate Change: Past• Yankton NOAA station data

May-August:

Humidity and Cloud Cover

• These trends reflected

in Sioux City, Sioux

Falls data

P<0.001, r2 =0.722, Coef=-0.091

P<0.001, r2 =0.22, Coef=0.224

Climate Change: Future

• Expect Great Plains annual mean temperatures to increase 3.6°C - 6.1°C by 2102 (Ojima and Lackett 2002)

• Expect Increase in mean summer temperatures 6.3°C, dew points 1.1°C at Sioux City urban areas by 2100 (Kenward et al. 2014).

• IPCC 2013: ↑ Maximum Temps

Ojima and Lackett 2002

Research Objectives:

• Local distribution, the effect

of land use change (Chapter 1)

• Nesting success, chick condition (i.e., corticosterone),

thermal microclimate for urban rooftop nest sites

(Chapters 2 and 4)

• Chick evaporative cooling responses to heat exposure,

ambient temperature levels that induce thermoregulatory

responses (Chapter 3)

Chapter 1: Land cover and nighthawk habitat associations

• Two study areas:

➢Eastern: Flat, gravel rooftops and dominated by row crops

➢Western Study Region: More pasture, hay and grassland; no gravel rooftops

• Land Cover Analysis

➢Landsat data

(Cropland, Forest,

Water, Grassland,

Urban)

➢Satellite Imagery

(Flat gravel

rooftops)

Mean percent (±SE) land cover

surrounding points where

birds were present in the two

study regions. Significant

between-region differences

are denoted by A (for P <

0.05) for two-tailed two-

sample Welch’s t-tests.

Points Where

Birds present

Gravel

Rooftops

(Eastern

Study

Region

Habitat)

Eggs & iButton

Operative

Temperature

Sphere

Camera

Chapters 2-4:

• Microclimate with iButton

thermometer, operative

temperature moved every nest

check

• Microclimate wind with handheld

anemometer at nest check

• Camera for abandonment dates

Chapter 2: Rooftop Chick Stress

Hormones and Climate

• Measured blood corticosterone

(stress hormone) levels

• Collected blood <3 minutes of capture

=baseline

• Collected blood after being placed in a

cloth bag in the shade for 30

min=response to stress

Photo: Hunter Smith

Chapter 2: Rooftop Chick Stress Hormones and Climate

Swanson, D. L.

Chapter 2: Rooftop Chick Stress Hormones and Climate

Swanson, D. L.

Chapter 2: Rooftop Chick Stress Hormones and Climate

• Max. weather station

temp for previous day

for high CORTB

group>low CORTB

group

Chapter 3: Temperature Threshold That Induces Heat

Stress in Rooftop Chicks

• Observed chick gular flutter starting at 42.4 ± 3.4 (SE) °C

Expected Heat Tolerance:

-----low ------------------medium-high -----------------high---------

Actual Heat Tolerance:

---medium-high -----------medium-high-----------------high---------

•Cost : No water available

to replace evaporative

water loss

•9.1% loss of body mass.

•Temperatures > 42.4 °C

gular flutter threshold for

37.2% of breeding season

Chapter 4: Rooftop Nesting Success and Temperature

• Low survival rates for eggs and chicks – 9%

• Compared to my temperature data

*

Comparison of means (±SE) between successful and failed nests

during the pre-hatching period for nest success covariates.

Egg Period

• Only maximum iButton

temperature had a

significant and negative

relationship

• iButton measures

temperature between the

eggs or chicks at a low

profile in the gravel

• Adult

thermoregulation

critical

• Especially if

continually disturbed

Committee

Mark Brigham

Mark Dixon

Meghann Jarchow

Ken Renner

Dave Swanson

Equipment

Mark Dixon

Bob Garner

Jake Kerby

Joe Madison

Jerry Warmbold

Blair Wolf

Bernie Wone

Field Assistance

Will Culver III

Ming Liu

Ryan Munes

Funding

Bioblitz Papercrafts patrons

Prairie Biotic Research, Inc.

South Dakota Game, Fish and Parks Wildlife Diversity Grants

South Dakota Ornithologists’ Union

USD Biology

USD Graduate School

Rooftop Access

Kevin O’Kelley & Hunter Smith

USD Art & Science Deans Matt Moen & Kurt Hackemer

Other Property Managers

Statistics & Other Advice

Mark Brigham & CONIflab

Victoria Danzeisen

Mark Dixon

Erica Mize

Brett Sandercock

Mike Watt

Erliang Zeng

Thanks!