There is no record of the number of people who attended the Open Day for bird ringing at Grotto Bay, but it was probably roughly 40, both residents and visitors.But we do know that 76 birds of 27 species were handled. There were eight retraps, so the number of birds ringed was 68! The list is near the bottom of this report. This was our third Open Day to the Grotto Bay Private Nature Reserve, and reports on the two previous visits are here (27 May 2023) and here (31 August last year).
Fortunately, in spite of dire and persistent predictions to the contrary, the wind was missing in action. Mist nets hanging like curtains in one of the firebreaks at Grotto Bay.
The wind clearly did not read the forecast that it was supposed to be doing 27 to 30 km per hour in the critical period 05h00 to 08h00, with gusts of 38 to 45 km per hour. It failed to get up and stayed in bed. And for that we were grateful.
The veranda of the Grotto Bay Conservation Centre is a marvellous resource for bird ringing, and for explaining bird ringing.
The Conservation Centre at Grotto Bay is a few hundred metres farther inland from the village itself. Just in front of it is a small wetland. This is the view from the veranda. It was a high-quality day, both weatherwise and action-wise!
Extracting a bird safely and gently from a mist net takes real skill. This white-irised bird is a Layard’s Warbler.
We caught birds at a steady pace, but were never overwhelmed.
The wonderful thing about bird ringing is the opportunity to see birds up close.
This is a young Bokmakierie
Head of Karoo Prinia.
Head of a juvenile Long-billed Crombec.
Adult male Southern Masked Weaver being ringed. The leg is held firmly but gently at the “knee” during this operation, so that it can’t move.
The weaver took advantage of a moment’s lapse in concentration of the ringer! The beak is strong – it weaves nests – and although it can deliver a good pinch, it does not draw blood.
The marie biscuit-coloured eye indicates that this is an adult male Cape Weaver.
Measuring the “total-head length” of a juvenile Yellow Canary with dial calipers. The reading is 25.6 mm. The 20 comes from the yellow part of the calipers. The dial makes one revolution in 10 mm. It is at 5.6 mm. So 20 + 5.6 is 25.6 mm.
There is nothing quite like bird ringing to help develop connectedness to nature.
Daniel is using the gadget which helps us decide on the appropriate ring size for the Malachite Sunbird he has in the ringer’s grip. There will be stories to tell at school on Monday morning.
The fieldguide is open at the Cape Weaver page. This is a remarkable way to learn the identification features of a bird!
Hybrid bulbul?
The morning was invaluable from the social science perspective, in achieving its Open Day objectives! From the natural science perspective, we helped expand the SAFRING database. But the stand-out and intriguing piece of natural science was a bulbul which is possibly (maybe even probably) a hybrid between a Cape Bulbul and an African Red-eyed Bulbul.
Both of these birds had brood patches, and both were adults. The bulbul on the left is Cape Bulbul. We suspect the bird on the right is a hybrid between a Cape Bulbul and an African Red-eyed Bulbul. In the Cape Bulbul, the white cere around the eye is an ellipse, and the eye is at the back end of the ellipse. In this bird, the short axis is 65% of the length of the long axis. For the bird on the right, the short axis is 88% of the length of the long axis, and the eye is almost in the centre of the cere. In African Red-eyed Bulbuls, illustrated below, the cere is bright red, and circular. The colour of the cere of the suspected hybrid is a bit of a mess, a kind of pink intermediate between white and red. The fact that the cere of the bird on the right is more circular than the norm for a Cape Bulbul also adds fuel to the idea that it is a hybrid.
This is an African Red-eyed Bulbul. Chief differences with Cape Bulbul are the circular red cere, the darker head, and the whiter belly.
The suspected hybrid, on the right, has a slightly whiter belly than the Cape Bulbul on the left. Ringers have picked up other examples of suspected hybrids recently. In the northern part of the Western Cape, in the Olifants River valley as far south Citrusdal, most of the bulbuls are now African Red-eyed. There are even records of African Red-eyed Bulbul at Stanford and even at Cape Agulhas; see this paper in Biodiversity Observations.
Here is the list of the 27 species at Grotto Bay, and the number of birds of each species handled.
| Common name | Count |
| Laughing Dove | 3 |
| Speckled Mousebird | 1 |
| Cape Penduline Tit | 2 |
| Cape Bulbul | 9 |
| Cape Robin-chat | 6 |
| Karoo Scrub Robin | 3 |
| Long-billed Crombec | 3 |
| Bar-throated Apalis | 8 |
| Chestnut-vented Warbler | 1 |
| Layard’s Tit-babbler | 1 |
| Bokmakierie | 2 |
| Malachite Sunbird | 4 |
| Southern Double-collared Sunbird | 2 |
| Cape Sparrow | 3 |
| Cape Weaver | 12 |
| Southern Masked Weaver | 3 |
| Southern Red Bishop | 1 |
| Yellow Bishop | 2 |
| Yellow Canary | 2 |
| Cape Bunting | 1 |
| Cape White-eye | 1 |
| Totals : 27 Species | 76 |
Past and future
There is a list of all past BDI ringing events that have reports here. The next ringing event is also an Open Day. It is in Saturday 20 December, with ringing on the western side of Zandvlei, followed by a bring and brunch at Marina da Gama, on the eastern side. Details here. Information about future ringing plans are here.
Thank you
First and foremost, all the visitors want to thank the Grotto Bay Private Nature Reserve for the warm welcome, and the generous hospitality. The muffins, the shortbread, the quiches, …, …, … were amazing and greatly appreciated. Especial thanks to Roy Lawrence, Michelle van Acker, Suzette Vorster, and also to Loutjie Steenberg, who made the original arrangements, but in the end suffered FOMO in being unable to attend. Many of the photographs in this blog are Suzette’s – thank you.
