Bird use of Delaware wetlands during fall migration based on weather radar observations

Jeffrey J. Buler1, Tim D. Schreckengost1, Jaclyn Smolinsky1, James McLaren1, Deanna K. Dawson2, Eric L. Walters3

1 Dept. of Entomology and Wildlife Ecology

2 Patuxent Wildlife Research Center

3 Dept. of Biological Sciences

WSR-88D Weather Surveillance Radar – 1988 Doppler

(a.k.a. NEXRAD)

Initiation of nocturnal migration

Onset of migration

From Diehl and Larkin 2005

Reflectivity (Z or cm2/km3) (relative bird density)

Radial Velocity (m/s)

Sample volume Tilt = 0.5°

360° rotation

WSR-88D operation and data products

Temporal sampling rate 5 – 10 minutes

Volume scan

Low High

Bird layer

Range from radar (km)

2 – Height distribution of birds (Where are the birds?)

Height distribution of birds

Prop

ortio

n of

bird

s det

ecte

d

1.0

0.8

0.6

0.4

0.2

0.0

1 – Beam propagation (Where is the beam?)

Adjustment for range bias

0 5 10

Buler & Diehl. 2009. IEEE Trans. Geosci. Remote Sens.

Exlcude data if <10% of

distribution sampled

Buler & Dawson (2014)

Autumn (2008 & 2009)

Pooled Autumns 2008 – 2014 (n = 91 days)

Pooled Autumns 2008 – 2014 (n = 91 days)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

Forest Forestedwetland

Developed Agriculture Marsh

Mea

n bi

rd d

ensit

y (c

m2

/hec

tare

) Bird density among habitat types

9,841 5,310 1,920 38,036 4,428

Annual trend (cm2/ha per year)

Trend in migrant use from 2008 - 2014

Annual trend (cm2/ha per year)

Trend in migrant use from 2008 - 2014

2014 2008 2012

Prim

Annual trend (cm2/ha per year)

Declining bird use on Prime Hook NWR

LANDSAT SWIR Band

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

2008 2009 2010 2011 2012 2013 2014

Stan

dard

ized

bird

den

sity

Irene 8/28/11

Sandy 10/31/12

Areas of declining bird use at Prime Hook NWR

Photo: Michael Menefee

Wintering waterfowl feeding flight

“Raw” waterfowl exodus 1/1/2016

Reflectivity (dbZ)

Change in bird density over 13 year period (1995 – 2007)

Change in wetness index over years

Steep decrease

Steep increase

No change

From Buler et al. (2012) Sacramento Valley of California

∆ wetness

RegressionCoefficient (Std Dev)

< -2

-2 - -1

-1 - 1

1 - 2

> 2

∆ bird density

5 km From Buler et al. (2012)

Acknowledgements

• Barry Truitt, The Nature Conservancy

Undergraduate students Matt Levendosky

Janine Antalffy Lauren Cruz Laura Young