The Darvill Bird Sanctuary in Pietermaritzburg is home to South Africa’s longest-running bird ringing project which recently celebrated 30 years of monthly bird ringing. This project has seen over 30 000 birds, representing 200 species, ringed and their vital data recorded. Some of these ringed birds have been found as far afield as Latvia and Corsica.
The project was initiated in 1982 by Dr David Johnson of the former Natal Parks Board to track the movement of migrant and local birds. In 2003, Brown inherited the project and ran it until he moved on the Nature’s Valley Trust in Plettenberg Bay, recording valuable data that plays an essential role in ornithological research. All the collected information is stored in the South African Bird Ringing Unit (SAFRING)’s data base which operates out of the Animal Demography Unit at the University of Cape Town.
The Darvill Bird Sanctuary, which forms part of the Pietermaritzburg sewage works, is an ideal site for capturing birds. Due to its high nutrient content, it represents a haven for high densities of birds, especially seed-eating, reed-dwelling and water birds. Also, by using the same site, the recovery or re-catch rate is significantly increased – the national recovery rate is less than one percent as opposed to the re-trap rate at Darvill which is approximately 25 percent. Brown said that he has re-trapped birds that were initially ringed 11 years earlier.
Every month this team of up to 35 volunteers, including around eight qualified bird ringers, gather at the crack of dawn at the Darvill Bird Sanctuary. Their first task is to strategically position fine nets and traps to catch the birds. As the birds are caught, they are expertly extracted and placed in cotton bags which are hung in a safe and shady place. The qualified ringers, seated at a table under cover, carefully remove the birds from the bags and identify, weigh, and measure them, recording the data. Aluminum or stainless steel rings are then placed on their legs and they are released. An average of 150 birds are captured and ringed during any one session which normally lasts between six and seven hours. Although the process is a fairly invasive one, the birds are not hurt in any way.
According to Brown, ‘Ringing is an essential research tool for the modern day ornithologist.’ Apart from migration, the data is used to study longevity, patterns of breeding and moulting and differences between species and sexes.