The BDI did a bird ringing demonstration at Vondeling Wine Farm. We were invited to show how bird ringing works to the Onderstepoort Veterinary Class of 1984. These were people who had qualified as vets in the Faculty of Veterinary Science at the University of Pretoria 40 years ago; some had retired, some were still working as vets, and some had moved into other fields. Some of the vets tried to recognize us as old colleagues from student days; for several of them it was the first time they had joined a class reunion!
Ringing at one of the many farm dams at Vondeling. The ringing station was just behind the car, and the mist nets were located along the far end of the wall of the dam, were there are reedbeds both in the dam and below the wall. The slopes of the Paardeberg still bear evidence of the enormous fire that burnt through this area in the final days of 2023.Photograph: Karis Daniel
Spend a few moments looking at the fine structure of the head of this African Reed Warbler. Photograph: Karis Daniel
The longest tail feathers of this Greater Striped Swallow are not the same length. This is called “fluctuating asymmetry”, and is a criterion used to select mates. “If you can’t get your tail feathers of identical length, then your genes are not up to scratch and I am reluctant to share mine with yours.”Photograph: Jean Ramsay
This is an opportunity to study the subtle differences in bill shape between a male Cape Weaver (left) and a male Southern Masked Weaver (right). Both are used for weaving! The differences in eye-colour and head-pattern are not subtle!Photographs: Dembo Jatta
This photo shows how the white V on the back of the Fiscal Flycatcher is implemented! One of the privileges of being a bird ringer is seeing birds close up. The nine outer wing feathers are called the primaries. The next group of feathers, closer to the body, are called the secondaries. They are shaped slightly differently. Because we are in the spring breeding season, all these feathers are intact; none are growing. As a general rule, birds try to separate the energetically demanding activities of breeding and moult. The nine primary feathers would have been replaced, from the inside outwards, over a period of several months, after last year’s breeding season. So the inner primaries, closer to the body, are a few months older than the outer primaries. Look carefully, and see that the tips of the inner primaries are slightly more worn than the tips of the outer primaries. Photograph: Dembo Jatta.
One of the Cape Weavers we mistnetted at Vondeling was a retrap which had initially been ringed on a nearby farm, Sonop, on 2 December last year. Of all the species we ring at an assortment of localities, it is the Cape Weaver that seems to be the most mobile. The distances are mostly relatively short, but it seems surprising how few birds of all the other species are retrapped at any place other than the site of ringing.
We handled a total of 83 birds, of 12 species. Unusually, all 12 species were passerines! Only the Cape Weaver, on 54, reached double figures. As a result of regular ringing at Vondeling over the past few years, the total number of retraps was 26. With a couple more years of data like this, we can start estimating survival rates!
It’s spring, and there are lots of beautiful flowers. Even more so, after the fire. But spring also brings showers. So, from a bird ringing perspective, the weather was not in our favour, with wind and rain.
Overall, in spite of the weather, we assessed that the bird ringing demonstration at Vondeling Wine Farm to have been a short but worthwhile trip to a ringing site where we hope to get a lot more data!
Previous ringing events, including those at Vondeling, are listed here. Each has a report similar to this! Future BDI events, including bird ringing courses, are described here.
Table 2. Ringing totals for Vondeling Wine Farm: 17 to 19 September 2024
Prof Les Underhill was Director of the Animal Demography Unit (ADU) at the University of Cape Town from its start in 1991 until he retired. Although citizen science in biology is Les’s passion, his academic background is in mathematical statistics. He was awarded his PhD in abstract multivariate analyses in 1973 at UCT and what he likes to say about his PhD is that he solved a problem that no one has ever had. He soon grasped that this was not the field to which he wanted to devote his life, so he retrained himself as an applied statistician, solving real-world problems. View all posts by Les Underhill →
