Intercontinental migration of an Eurasian Hobby (Falcosubbuteo) tracked by means of a 5g satellite transmitter
K. D. Fiuczynski, P. W. Howey, C. Meyburg & B.-U. Meyburg
wwgbp@aol.com, www.Raptor-Research.deIntroduction
The Eurasian Hobby is a small falcon. It breeds
across Europe and Asia and is a long-distancemigrant. European birds winter in Africa. More than
5,700 Hobbies have been ringed in 10 European
countries, but so far there have been only two ring
recoveries south of the Sahara desert. Satellite
tracking using the Argos system is now an accepted
technique for long distance migration studies ofbirds. It is generally accepted that any device weburden a bird with should weigh no more than 3% of
the bird’s weight if we are not to affect its behavior.

MethodThe prototype of the smallest satellite transmitter(PTT) produced so far weighing just 5 g was fitted forthe first time to an adult female Hobby (weight 265 g)
on 9 August 2008 in Germany near Berlin andsuccessfully recorded the annual migration route.
The Hobby had raised two offspring and was trappednear its eyrie using the dho-ghaza-method. This new
type of solar-powered PTT was still in the trial phaseand is still working (in August 2009).

Results
This smallest and lightest satellite transmitter
produced to date delivered astoundingly highnumbers of good Argos Doppler fixes (LC:2 andLC:3).
After leaving on migration in the second week ofAugust, and a short rest period on the island of Elba
off the west coast of Italy from 6 to 13 September,the bird flew at first in a southerly direction towards
North Africa. The falcon held this course more or lessuntil reaching its main wintering area in Southern
Angola on 17 October. The migration to southern
Angola took 49 days including some days on theisland of Elba and one day (8 October) in Cameroon
when the falcon was not moving. On average thefalcon migrated 174 km per day including the days
when it did not migrate.

Female Hobby with the prototype of asatellite transmitter weighing only 5 g.
Photo: B.-U. Meyburg, 9 August 2008.

Interesting data was obtained on thewinter habitat used, the home range
size in winter and migration speed whencrossing ecological barriers (e.g. theSahara).

Crossing of the Sahara desert inautumn 2008
Outwardmigrationroute in2008 up tothesouthernmost point in
Zimbabwe
not showing
local
movements
duringwintering inAngola

The West African equatorial rain forest
proved to be one such significant ecologicalbarrier. Migration was noticeably rapid herewith distances of up to some 580 km flown
per day - also partly at night. In order toreach the northern perimeter of the area thebird flew an additional 260 km after sunset
on 14 April, and arrived at its night roostclear of the rain forest as late as midnight.
On one part of the route, 57 km in length, itflew at an average speed of 34.2 km/h.
Autumn and spring migration routes whilecrossing the rain forest belt in West Africa.

Over two months after arriving in southern Angola it
migrated further in a south-easterly direction andarrived in Zimbabwe on 29 December. On 1 January
2009 it reached the southernmost point of its
migration between the cities of Bulawayo and Hararein central Zimbabwe. The distance migrated from thebreeding site, not including regional movement, wasup to this point over 10,000 km.
The Hobby did not linger for long in Zimbabwe andretreated almost immediately to its wintering area inAngola. The bird arrived back at its old breeding site
in Brandenburg in May.

But even in its wintering area the small falcon
showed an eagerness for travel, as witnessedby the recording of 543 different fixes. Of thebarely 25 weeks spent in the south the bird
never spent as long as a week in the sameplace up to six weeks preceeding return
migration. In the wintering period from 16October 2008 to 7 April 2009, the bird covered atotal distance of at least 9,025 km. This
calculation is based on the distance between the76 precise night roost fixes, which amounted tosomewhat less than the half of all overnight
roosting places. Within Angola the fixes during
the night, usually recorded at an interval of 48
hours, were sometimes more than 300 km apart.
This means that the actual distance covered by
the bird during wintering was probably
significantly greater.

Kernel analysis of
the winter homerange of theEurasian Hobby inAngola andNamibia

The bird spent 50 % of its time in the AngolanMiombo woodlands, a habitat made up ofalternating moist, large-leaved savannah and5 -10 m high woods interspersed withgrassland, at an altitude mainly between 1,000
and 1,500 m ASL.
While wintering the falcon spent another 37 %of its time in the Zambezi Baikiaea woodlands,a mosaic of dry deciduous forest, thicket, andsecondary grassland. A large part of the bird’s
diet probably consisted of energy-rich termites,
which are particularly common in the area
visited during the rainy season.
The bird spent 86% of the time in southern
Angola and the rest of the wintering period in
Namibia, Zambia, Botswana and Zimbabwe.
In July and August 2009 eight more adult
Hobbies were marked with even smaller
satellite tags (size: 9.3 x 30 x 16.4 mm ).

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