Quantifying Bird and Insect Movements

using Operational Weather Radars

Adriaan Dokter1,2, Hidde Leijnse3, Felix Liechti4, Hans Beekhuis3,

Laurent Delobbe5, Pierre Tabary6, Iwan Holleman3

1Netherlands Institute of Ecology (NIOO-KNAW)

2University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics 3Royal Netherlands Meteorological Institute

4Suisse Ornithological Institute 5Royal Meteorological Institute Belgium

6Météo France

Bird migration on weather radar Example 17 October 2008

Redwing

Turdus iliacus

reflectivity factor radial velocity

Bird migration on weather radar Example 17 October 2008

50 km

reflectivity factor radial velocity

Bird migration on weather radar Example 17 October 2008

50 km

Bird migration

Precipitation

= Wideumont radar

Spatially smooth

Spatially variable

Target identification

1) Radial velocity analysis (VVP)

Automated processing

Precipitation

(cold front passage)

Bird migration:

Stddev threshold 2 m/s

Ground speed

Flight direction

2) precipitation masking

Automated processing

Weather radar reflectivity

)(2

1)(

2

2

4

5

RZm

mR

birdbirdR )(

500 m

R

V

Reflectivity (back-scatter cross-section/unit volume)

related to density bird and cross section bird:

wavelength (5.3 cm), m index of refraction water, Z the reflectivity factor in [mm6/m3]

Calculate from the reflectivity factor Z: V the radar cell volume

Weather radar algorithm output

Heig

ht [k

m]

night

twilight

Bird density altitude profile

Height-integrated bird density

day

Superfledermaus

Weatherradar

Wideumont

Weather radar validation

Dokter et al., J. R. Soc. Interface 8 54, 30, 2011

Comparison bird radar - weather radar (full migration season)

Weather radar

Bird radar

Songbird wingbeat pattern

Forest type (LANDSAT data)

Stop-over areas (from radar reflectivity data)

Diehl & Larkin 2005

Gauthreaux & Belser 2005 Ruth et al. 2008

Aim 1) extracting spatial information

Aim 2) Designing a similar operational

algorithm for insects

Radar echos

in summer

25/26 jun 2009

Common Swift Apus apus

Swift wing beat pattern Measured by KNMI weather radar

0 5 10

1 2 3

Time [s]

0 5 10 15 20 25 30

Frequency [Hz]

Am

plit

ude

Echo s

trength

(ra

dar

cro

ss s

ection)

8 Hz: Swift wing beat frequency

Distance: 21.6 km, altitude: 2.1 km

Time [s]

Insect & swift echoes

Dokter et al. 2013 Twilight ascents by common swifts, Apus apus, at dawn and dusk: acquisition of orientation cues?

Anim. Beh. 85, 545

Target identification: Dual polarization radar Detect horizontally and vertically polarized radiation independently

Image NOAA

Reflectivity factor Correlation coefficient HV

Bird migration & precipitation simultaneously:

Conclusions

• Weather radar can determine reliable bird density altitude profiles automatically – method is easily portable.

• A prototype insect profiling algorithm based on the bird profiling algorithm would be fairly easy to design (for situations without precipitation).

• Diurnal insect movements at mid-latitudes much more

pronounced in weather radar than nocturnal movements, and more easily distinguished from birds

• Cases with spatial overlap insects/birds remain problematic (with and without dual-pol).

Thank you

29 Oct 2008: migration Netherlands → United Kingdom