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Home > Migration blog > The migration of the Lesser Spotted Eagles

The migration of the Lesser Spotted Eagles

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In 2010, in the LIFE project „Conservation of Aquila Pomarina in Romania” the members of the Milvus Group Association mounted satellite transmitters on six eagles (three juveniles and three adults): Adel, Béni, Jakab, Arthur, Benjámin and Cingár.

Due to the satellite transmitters we were able to find out when each bird set off for the migration (Table 1). In 2010, the migration start period covered a relatively wide time span: 6-22 September. The chicks were more in a hurry and left for the journey 2-10 days before their parents.

Eagles

Adél

Béni

Jakab

Arthur

Benjámin

Cingár

Date of departure (2010)

6.09

12.09

22.09

17.09

14.09

12.09

Table 1: The migration departure dates of the 6 eagles monitored by the LIFE project

The data provided by the satellite transmitters show us that currently the birds started their journey home from the wintering areas in south-eastern Africa. Arthur is in the Democratic Republic of Congo, Benjámin in Zambia and Cingár remained in South Africa. Béni, the only juvenile whose transmitter is still operational, is in South Africa.

Curious facts about eagles’ migration

Migration of adults

More conservative, the adults generally took the same route of migration known from the specialised literature. The classical migratory route of the lesser spotted eagle covers the Balkans, passes over Asia Minor (Turkey) then crosses the Suez channel to Africa, following the Eastern coast of the continent (Figure 1).

Figure 1 The migratory routes of the adult birds on 7 January 2010 (Arthur – blue, Benjámin – orange, Cingár – black)

Migration of juveniles

Unlike the adults, the juveniles each took his own migratory route (figure 2).

 

Figure 2 The migratory routes of chicks until 7 January 2011 (Adél – black, Béni – green, Jakab – red)

adel
adel adel
Adél, the unlucky one, did not manage to find her way to cross from Asia Minor to Africa over the Suez Gulf. It seems that Adel (Figure 3) had serious orientation issues – she avoided the Bosphorous Strait to Asia through the West and passed over the Dardanelles Strait and made a pretty large detour through western Turkey. Once she even went out on an offshore island in the Aegean Sea. It seems that the Sinai Peninsula is a trap for “disoriented” eagles. Experienced birds pass in Africa through the north of the peninsula where they do not have to fly over the sea but only over the Suez channel. Birds which do not use this route and adventure more to the south must pass over the Suez Gulf, an obstacle which they can only overcome under favourable winds. The landscape is not good for feeding (as it is mostly desert) and each day which passes by without the bird being able to cross over the gulf decreases its chances of survival. After several unsuccessful attempts to find the route to Africa, Adel headed towards the water treatment station from the town of Sharm-el-Sheik, in Egypt. The bird died on 15 October 2010 most likely because of the repeated consumption of residual water.

Jakab-photo by ...
Jakab-photo by Kósa Ferenc Jakab-photo by Kósa Ferenc
Jakab, the bold one, after having almost followed in Adel’s steps, trapped in the trap of the Sinai Peninsula, had a bit of luck and followed his own route. From the Suez Gulf the chick took the migratory route of the steppe eagles (Aquila nippalensis) along the eastern coast of the Red Sea, through the Arabian Peninsula and then into Ethiopia over the Bab-el-Mandeb Strait. Jakab (figure 4) spent the winter in Ethiopia without migrating to the south of Africa where the other lesser spotted eagles went.

After having successfully crossed the Suez channel, instead of going south, Béni, the explorer, suddenly turned west heading towards the Sahara desert. Although few were those who gave him chances to cross the Saharan inferno, in a relatively short time he managed to overcome this obstacle.

Beni (figure 5) is also the holder of several records: the biggest speed (92 km/h), the largest distance covered in a single day (511,7 km) and the most kilometres covered in the migration (13869,17 km until 06.01.2011).

 

 

 

The satellite transmitters

Small but efficient devices (they only weight 45 grams), the satellite transmitters give us important information about the birds’ area of movement and their use of the species habitat. The news received from these devices are not always good. For instance, with their help we found out that Adel died in the Sinai Peninsula. Jakab’s transmitter only sent data until 20 December 2010 which may be explained in two ways: either the transmitter broke down or the bird died. The data received from the satellite transmitters give us the flying speed and altitude and also the distances covered by the 6 eagles.

 

Flying speeds

Because the transmitters register the birds’ flying speeds, we could determine the average and the maximum flying speed of the eagles (table 2). The average flying speed during the autumn migration (2010) ranged between 20-50 km/h.

 

Eagles

Béni

Cingár

Benjámin

Arthur

Adél

Jakab

Maximum flying speeds

92 km/h

85 km/h

82 km/h

82 km/h

73 km/h

72 km/h

Table 2. The maximum flying speeds reached by the six eagles monitored in the LIFE project

Altitudes reached

Besides the flying speeds, the transmitters mounted by the LIFE project also register the flying altitudes (table 3). The average flying altitude ranged between 867-1031 m and the maximum altitude reached was of 2041 m.

 

Eagles

Adél

Béni

Jakab

Arthur

Benjamin

Cingár

Maximum altitude

1975 m

1969 m

1990 m

2041 m

1950 m

2007 m

 

Average altitude

867 m

1078 m

943 m

1119 m

1031 m

1159 m

 

Table 3. The flying altitudes of the lesser spotted eagle monitored in the LIFE project (2010)

Distances covered

Most lesser spotted eagles cover over 10,000 km in migration to the wintering areas from south-eastern Africa (table 4). In average, the daily distances covered by the 6 eagles were of 200 km/day. The maximum, daily distance was covered by Beni who on 26.10.2010 flew 511.7 km.

 

Eagles

Adél

Béni

Jakab

Arthur

Benjamin

Cingár

Distance covered (km)

4894,10

13869,17

7963,10

12735,48

10469,16

11893,51

Until:

 

2010.10.12 7:00 a.m.

2011.01.06

1:00 p.m.

2010.12.20 12:00 p.m.

2011.01.07 1:00 p.m.

2011.01.06 1:00 p.m.

2011.01.06 4:00 p.m.

Table 4. Distances covered by the lesser spotted eagles monitored by the LIFE project (2010)

The monitoring of the eagles equipped with satellite transmitters will continue for as long as the birds are in Africa but also later on their way back to Romania.

The information provided above is based on the data provided by Mr. Kósa Ferenc, expert in satellite data analysis and interpretation for the LIFE project.

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