Conservation

BLACK HARRIERS MIGRATE EAST IN SUMMER

Posted on the 3rd April 2014

Black Harriers migrate east in summer
(Thanks to Rob Simmons for forwarding this material. - Ed.)

Now that the breeding season is well and truly over and all of our tagged birds have decided what their strategy will be for the hot summer and cooler autumn we can see a strong pattern emerging.
All of our birds bar one (karma in white below) have flown to the east…..
This has been a real voyage of discovery this year and thanks again to all of you who have helped with sponsorship (especially Golden Fleece Merino Stud, Birdlife South Africa and many individuals) and all of you who have reported birds to us and sent their appreciation of the work.
Now to use this to help conserve critical areas that the harriers need to survive…
Rob Simmons (for Sophie, Francois, and Bea)
Black Harrier Species Guardians - BirdLife South Africa
FitzPatrick Institute
UCT
Black Harrier migration confirmed
Black Harriers migrate east in summer
Now that the breeding season is well and truly over and all of our tagged birds have decided what their strategy will be for the hot summer and cooler autumn we can see a strong pattern emerging.
All of our birds bar one (karma in white below) have flown to the east.

A summary of all the movements of all tagged harriers from Western Cape (Calvinia, Van Rhynsdorp and West Coast NP) to the eastern Cape (Nov 2013 - March 2014)

 

 

 

 

 

 

 

 

 




 

 

 

 


Madiba (green) has made the longest journey and is still in the northern half of Lesotho. He has made two forays to Sterkfontein dam in the Free State grasslands. He is still in the Lesotho highalnds (2 April).

Kwezi (red), Cory (blue)  and Cade (pink) have all flown to the Eastern Cape grasslands via slightly different routes but all ended up within about 50 km of each other. Cade decided on 18 March to head further north and he is almost as far north as Madiba (30 March)

Vuvuzela (yellow) from Calvinia is in the southern Drakensberg near Barkly East. A close up of her haunts on 1-2 April reveals high mountains at 2300m asl. Interestingly Madiba followed the same path through here several weeks before (green line below). His track was less than 10 km from Vuvuzela's This suggests this area is a migration corridor for harriers. While not shown Moraea passed close by here in 2010 too.
 

Vuvuzela (originally from Calvinia) in high mountains >2300m asl in the southern Drakensberg 1-2 April 2014. The green line at back is the path of Madiba several weeks before .

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 




Alberta
Marlei and I went to try to find her just east of Stutterheim in the grasslands on our way back from the LAB conference in March.We were partially successful in that we found where she had roosted ( a lush grassy field with sheep grazing in it). We found one pellet at the base of a nearby fence but she was about 1.5 km away at the time we were there, on a grassy hillside with scattered trees. She was in the company of two white-backed Vultures and some Blesbok.
Moraea's previous track to Lesotho is shown in black to indicate that these birds are heading along the same route into the highlands of Lesotho.

Karma (in white) is the odd one out as she has stayed in the western Cape and in the Overberg in particular. She displayed a similar pattern last year and of course was paired with Madiba at their nest in Grasburg north of Nieuwoudtville. Why she stayed and the other tracked birds went east is unknown but we know that a lot of doves and pigeons visit the harvested fields in the Overberg to eat the grain and many rodent-eating Steppe Buzzards and Jackal Buzzards make a good living there too.

 

 

 

 

 

 

 

 

 

 

 



In summary our satellite tagged birds have shown us that the early results (from Lockie at right- who first revealed this journey in 2010) were not unusual. The birds move from the western Cape as the area dries out in summer and move into highland areas as the summer rains promote plant growth and increased prey productivity.
The really adventurous ones head into Lesotho at 3000m asl and probably hunt Ice Rats there.

Of interest here is that these movements were all predicted by Francois v d Merwe in his 1981 Ostrich paper that summarised everything we then knew about harriers!! He explained to us when we stayed with him recently that he used coloured pins stuck on a map to indicate the presence of birds in certain months. These data came from calling all the birders and ornithologists of the time and asking them for all their Black Harrier records. By assessing where birds were then he could see an eastward shift in the pins in summer and back again to the west in winter. So his predictions from 30 years ago are now vindicated - well done to him for his brilliant far-sightedness.


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