Barn Swallow migration patterns on the move

A new paper in the top Royal Society journal, "Proceedings of the Royal Society B," looks in detail at how the timing of migration in three regions of South Africa is changing with the climate.

Swallows, delicate birds which breed in Europe and migrate to Africa for the northern winter, have been the subject of lyrical folklore in many cultures of South Africa, as well as the nickname for Europeans who spend the cold northern months in southern Africa.

Barn Swallows respond to climate change

Barn Swallows (Hirundo rustica) breeding in Europe have shown well-documented responses to climate change there, mainly by arriving earlier after their African migration, to coincide with the earlier springs that are a feature of climate change. Yet it has not been known what's happening on their non-breeding grounds in Africa, where swallows undergo critical life-cycle events such as moult and refueling after breeding. Do swallows leave their African non-breeding grounds earlier, fly faster, or perhaps not fly as far south as they did previously?

New study shows that Barn Swallows leave SA earlier

The new study in Proceedings uses a novel source of data from two innovative citizen-science projects, the Southern African Bird Atlas Projects 1 (1987-1991) and 2 (2007-present), to show that Barn Swallows certainly do leave earlier from those parts of their South African non-breeding grounds where they used to stay longest. They did not advance their departure, however, from areas in which they stay for shorter periods, which could mean that they are constrained from doing so.

Dr Res Altwegg, population ecologist at the South African National Biodiversity Institute (SANBI) and lead author of the paper, says "Shifts in arrival of migratory birds at their breeding grounds are among the most noticeable effects of climate change, but almost nothing has been known about the phenology (timing of life history events) on non-breeding grounds." By contrast to a wide array of strong studies in the northern hemisphere on climate change impacts on birds and other biodiversity, little has been known until now of how climate change is affecting vulnerable species in Africa.

Other coauthors of the paper include Kristin Broms, a student from the University of Washington, Dr Birgit Erni of the Animal Demography Unit (ADU) and Department of Statistical Sciences at the University of Cape Town (UCT), with which Res Altwegg is also associated, Dr Phoebe Barnard and Dr Guy Midgley of SANBI, and Professor Les Underhill, director of the ADU.

Bird of the Year

The Barn Swallow is the 2011 "Bird of the Year" for the major South African conservation NGO, BirdLife South Africa, which has been promoting this species in a climate change context all year.

Media enquiries

Dr Res Altwegg, res.altwegg@gmail.com

Issued by BirdLife South Africa (BLSA) and the South African National Biodiversity Institute (SANBI)

Comments

Submitted by website manager at 20/05/2014 - 14:05

Barn swallows do migrate in loose flocks, although I do not think we generally know whether the individuals in a flock remain together for long during a migration. They certainly congregate at migrant roosts, and fly off together in the mornings.

Submitted by Hugo Knoetze (hugo.knoetze@telkomsa.net) at 04/04/2014 - 9:10

I were at Lanseria airport Wednesday last week (2014/03/26) and while waiting for my flight observed many of the Barn swallows in and out of their nests just outside the departure hall doors. Now my question-do certain area located swallows leave on the same time and then regroup somewhere in the air and fly north? Why I am asking-a few years ago I were at Tshipize in the bush veld and observed thousands upon thousands on swallows migrating northwards- I were in the pool and observed them for more than three hours on end?

Submitted by Yusuf at 22/03/2014 - 11:03

I am one of the lucky few who live right next to a swallow nesting place. I have been a keen observer of the Swallows for many years. And this year, its the largest flock I've ever seen. For those living in and around Gauteng and want to observe the event of our lovely friends preparing to migrate to Britain can do so by coming to Lenasia, Nirvana Drive West. The best times are mornings at sunrise and evenings at sunset. My cell 0845102450.

Submitted by website manager at 24/01/2014 - 15:06

Mitchell, Please contact Res Altwegg directly. Email provided above.

Submitted by Mitchell at 24/01/2014 - 1:25

I need a migration rout map

Submitted by Adrian at 07/11/2012 - 8:23

Certainly, this year North of Mount Moreland there are decreased numbers in the air. One wonders just what the mortality rate has been between migration to and from Europe this year.

Submitted by Res Altwegg at 10/05/2012 - 8:29

Most barn swallows have departed from South Africa by now (see http://sabap2.adu.org.za/spp_summary.php?Spp=493). However, it is quite possible to still see a few late birds. There are a number of other swallow species around PE that may at first glance look similar to the barn swallows but migrate later (e.g. the two species of striped swallows) or to a lesser extent (e.g. pearl-breasted swallow). So another explanation could be that you saw a different species.

Submitted by Johan Nortier at 05/05/2012 - 17:39

We live in PE and assume that the swaalows we see here are barn swallows- is that correct? Secondly, we have observed swallows here this morning still, is that not late for them to be around? Regards

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