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Worlds Best Migrant

The Barn Swallow, or as it was previously known the European Swallow, is a widespread and common summer visitor to Southern Africa. It is often regarded as the announcer of spring/summer in both the northern and southern hemispheres; it is also one of most well known migrants in the world, which in a way makes it one of the most studied birds in the world, so why do we still study them, the answer to this is simple – they are an amazing little bird.

 

Most of the work is done in their breeding grounds in Europe, and generally only ringing is done in Southern Africa. I started doing ringing at Mt. Moreland where the roost hosts 3 million birds during the Southern African summer of 2006, primarily to try and find out more about the movements of these birds before the new King Shaka International Airport opened in 2010, however once you start you just get more and more involved and things can progress at an alarming rate which is what happened in the 2010 season with a roost at Umzumbe on the KZN South Coast which hosts 1.5 million swallows. Recently I have also been studying the recapture data of the Barn Swallows from the SAFRING database. This has shown some very interesting movements of the birds in Southern Africa. It seems to confirm some suspicions that we have had regarding the roosting sites north of Cape Town.

 

The analysis of the data was time consuming and entailed sifting through in excess of 900 records. The first step was to calculate the time elapsed from ringing to recapturing this allowed me to separate out a couple of hundred records of birds that were recaptured during the same season at the same site, Although it sounds irrelevant it at least shows that they remain at the same site throughout the season, if not remaining at that site they at least keep using that site throughout the season. I was also able to establish the oldest bird on the system which happened to be a swallow ringed in Durban at the Kwa Mashu Sewrage works on 11th December 1966 it was recaptured in Durban North on the 4th December 1975, 3280 days (over 8yrs) later with the distance between the two ringing sites being 8km’s. This bird has however covered around 160 000 km’s on migration alone (2 journeys a year of about 10 000km’s per journey). I was also able to obtain migration times for the birds with the quickest time being 27 days from ringing to recapturing, the bird was ringed in the Hawaan Forest area of Umhlanga rocks on 12th April 1970 and recaptured in Whitely Bay, England on the 9th May 1970 with a straight line distance between the two points of 9915km’s. The second quickest was a bird ringed in Johannesburg and recaptured in Leninsk, Russia 34 days later with a distance of 10 548km’s. We must also remember that the birds never left on migration the day they were ringed and in all likelihood were not recaptured on the day they arrived. The northward migration is always quicker than the southerly migration, the reason for this is a natural instinct I refer to as “The need to Breed”. On the southerly migration there is no need to arrive here as quick as possible and reclaim your nesting site and partner.

 

My next step was to calculate the distance traveled for all the birds also showing some very interesting data, with birds being recaptured the day after being ringed a distance of 54km’s from the ringing site, this was for quite a few birds giving a good indication of the daily feeding range of the birds. I was also able to see the greatest distance on a single migration was a bird ringed in Zeekoevlei, Cape Town and was recaptured near Krasnozerskoye, Russia with a distance traveled of 11384km’s.

 

After all of this I looked at the birds ringed within Southern Africa at the start of the Swallow season and recaptured later in the same season, showing that some of the birds ringed in the northern roosts in the region finished up at the southern roosts, giving a clear indication that the swallows use the large roosts on their migration south. This alone could be a worrying factor as any disturbance or damage to these roosts could cause problems for the southern birds on their migration, a point that is very relevant with the opening of the King Shaka Airport near Durban. The runway of which finishes 2.6km’s away from the reed beds at Mt. Moreland. In defence of the airport a bird strike radar has been installed and if used correctly should prevent any bird strikes from happening.