Thursday 10 January 2013

The winter movements of a pair of Swifts

It is New Year and our swifts are very very far away. It’s the middle of winter here in the north and of course mid-summer in Southern Africa. Swifts are usually faithful to both nest site and partner, but do they stay together outside the short northern breeding season? Here’s one couple's answer.

Contributed by Lyndon Kearsley

These are maps of one of my geolocator pairs showing movements in December 2011 and January 2012. They nested in a nest box above a busy school playground in Hechtel, Limburg Province, Belgium. The coloured dots are smoothed average 24 hour locations, but remember that swifts keep flying so the accuracy is not great and the light level data weather dependent. Hopefully they are doing well and quite likely in the same regions at the moment. In 2012 they both received new geolocators and with luck we’ll know if they are equally faithful to their preferred wintering grounds come summer.

Click map to enlarge
December 2011
The female is the red track and she spent September, October and November above the Republic of Congo (Congo Brazzaville) and Gabon, leaving there on 6th December to head directly ESE to the lower Zambezi river area in East Africa. This region between Lake Malawi and the Zambezi Delta is an important wetland area with flood plains and coastal mangrove. Two large dam projects higher up-river in Zambia have reduced the impact of the summer rains but it is still a draw for west European Swifts.

The male in blue left west Congo much earlier and was, by this time, already in the south and spent the first half of the month in south east Botswana before heading into South Africa (RSA), close to the Kruger National Park, for Christmas.

As you can see they did not spend their winter together.

Click map to enlarge
January 2012
The lady goes “fly-about”. First up to the SE Tanzanian coast on 5th January where a second Belgian female breeder happened to be wintering, so an interesting area to keep an eye on. Then she flew inland towards the Lower Zambesi National Park in Zambia around 12th January, and finally south towards the Mozambique capital Maputo on 26th January returning to central Mozambique at month’s end.

The male stayed in South Africa (RSA) between Johannesburg and Swaziland in the coastal highlands and remained restricted to a fairly small area in comparison to the female.

In early February they gradually moved north, getting into position for the dash north in early May back to Belgium.

More about that later.

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