Open Day for bird ringing at Grotto Bay Private Nature Reserve : 12 September 2026

The BDI arranged an Open Day for bird ringing in partnership with the Grotto Bay Private Nature Reserve on 12 September 2026. If you missed this one you have a second opportunity on Saturday 3 October.

The Rock Kestrel above is looking at you with its BDI!

Cape Weaver. Adult male. Grotto Bay Bird Ringing September 2026
Photo: Daniel Venter

Given that 47 of the 63 birds we handled were Cape Weavers, it is not inappropriate that the species features in first bird photos on this blog. This is a male in breeding plumage. In this photo, the BDI is the colour of a marie biscuit.

Cape Weaver females : Grotto Bay Bird Ringing September 2026
Photo: Thalia Sparke

… and this Cape Weaver’s BDI is dark chocolate brown, almost black. It is probably a female.

One of the Cape Weavers (CV78923) had been ringed during our visit on 27 May 2023, and was retrapped on 29 November 2025, and again on this visit. Another (CA41878) was ringed during on 31 August 2024 and retrapped on this visit.

Cape Bulbul : Grotto Bay Bird Ringing September 2026
Photo: Thalia Spark

This is a Cape Bulbul. The BDI is set near the back of the eye-ring, which is elliptical. Last year in November, we caught a hybrid between Cape Bulbul and African Red-eyed Bulbul here at Grotto Bay. There are photos of the hybrid near the bottom of the blog from that visit. African Red-eyed Bulbuls have a circular eye ring with the eye in the centre.

Cape White-eye : Grotto Bay Bird Ringing September 2026
Photo: Thalia Spark

In contrast to the white eye-ring of the Cape Bulbul made of skin, the white eye-ring of the Cape White-eye is made of feathers.

Chestnut-vented Warbler : Grotto Bay Bird Ringing September 2026
Photo: Thalia Spark

Cape Robin-chat

SpeciesNumber
Bar-throated Apalis1
Cape Bulbul1
Cape Robin-chat1
Cape Sparrow2
Cape Weaver47
Cape White-eye1
Chestnut-vented Warbler1
Southern Double-collared Sunbird1
Southern Masked Weaver4
White-backed Mousebird1
Yellow Bishop3
Totals: Species 11Birds 63

The White-backed Mousebird (4B02908) was a retrap. Ringed on 27 May 2023, retrapped on 31 August 2024 and then again on this trip.

The weather …

The weather was not particularly kind. Far less wind than the forecast predicted, but it did drizzle a bit on and off. Like this Rock Kestrel, we were grateful to have shelter to creep into. For us it was the Grotto Bay Conservation Centre. For the kestrel it was this nest box …

Rock kestrel in nest box
Photo: Muneeba Lamera

Both BDIs peeping out!

Rock Kestrel at nest box
Photo: Muneeba Lamera

… and the sky was as grey as these photos suggest …

Rock Kestrel
Photo: Muneeba Lamera

Fortunately, actual rain held off, and the little bit of drizzle did not interfere much with ringing activities. We had even planned a fall back programme of fairly impromptu talks in the Conservation Centre; we were happy we did not have to activate Plan B.

Next time …

The next Open Day for bird ringing is planned for Saturday, 3 October 2026. Do join us: ringers, trainees, Grotto Bay residents, and birders in general are all welcome. For all upcoming events, see here.

Previous visits

Three of the BDI’s previous visits here have blogs like this one: May 2023 (41 birds of 15 species), August 2024 (62 birds of 19 species) and November 2025 (76 birds of 27 species). For blogs about past events, see here. The retraps highlighted above were all ringed on these visits.

Thank you

Thank you to the Grotto Bay Private Nature Reserve for sharing this beautiful place with us, and especially to Roy Lawrence and Michelle van Acker for their in person support.

Les Underhill
Les Underhill
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.

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