10 March 2008
Issue # 1
Dear hadeda enthusiasts
This is the first of our new-look, web-based newsletters which we will be using in all future postings. The file will either be displayed in the body of the email or will come as an attachment. If it comes as an attachment, by double-clicking it, it will open in your default browser (Microsoft Internet Explorer, Opera, Firefox) but you will need to be connected to the internet in order to view any images.
1. Ringing and resighting update
With your help, our database on hadedas in the Cape Town/ Paarl/ Sommerset West/ Stellenbosch area is steadily growing. We have now ringed 98 nestlings, which, as most of you know, involves plenty of tree climbing! Many of these birds were resighted repeatedly after fledging, and we have collected 133 resighting records so far. Seven of our ringed hadedas have been found dead.
|| Hadeda "DJ" photographed by Jessie Blackshaw in Tokai Forest on 7 November 2008. This bird was one of three chicks colour-ringed at a nest in Tokai forest on 14 August 2007. Only one of the other birds "DF" has been re-sighted.
| Hadeda "FX" photographed by Juliet Canales. This bird was picked up as a chick in Camps Bay (after falling out of the nest) and given to Juliet who raised it in her back garden. We ringed the bird on 29 October 2007 and the bird was released soon after that. It was often seen in the company of adults and returned to Juliet's garden on a regular basis.|
| Doug and Res busy ringing Hadedas "IF" and "IH" at Peter and Sharon Bridger's home in Bel Ombre Road, Bergvliet on 25 March 2008. This is the third lot of chicks ringed at this nest. Photograph taken by Peter Bridger.|
These data already allowed us to calculate survival rates, even though we still need a bit more data to be confident about the results. However, it looks like rather many young hadedas die soon after fledging. Our preliminary estimates suggest that as many as 1 in 4 fledglings die within a month of fledging and as few as 1 in 10 youngsters survive to their first birthday. Even though these calculations correct for the fact that not all surviving ringed hadedas could possibly have been detected, we think that these values are probably a bit low. For one, we still donít know much about movement of young hadedas, and it is possible that many birds moved outside our study area. We are hoping to get more resightings, especially as there should be quite a few ringed hadedas around by now. With more data, our results will become more reliable.
2. Hadeda survey - April 2008
One missing piece in the puzzle is adult survival, for which we have no data yet. We are planning to ring adult hadedas, and are currently testing a few methods for capturing them. One method involves walk-in traps, which we initially need to leave open and baited for a while until the hadedas get used to them. If anyone knows of a safe place where we could set up traps and leave them for a while, please let us know.
Although it seems that many young birds die within the first year of leaving the nest, hadedas seem to be doing well around Cape Town. We conducted a survey in November last year, and estimated that there are about 3000-4000 hadedas in the area spanning Simonstown, Cape Town, north to Milnerton, and east to Goodwood. We are planning another survey in April this year. Please let us know if you are interested in participating.
The success of the hadedas then seems mostly related to their spectacular breeding success. Even though some of the monitored nests failed completely, others produced up to 9 fledglings within just over a year. On average, the nests we know of produced just over 2 fledglings during that time.
Finally, thank you for your support and interest. We are looking forward to hearing about your latest hadeda observations. Resightings of birds that 'hang around' in your garden or near the nest site can be reported to us on a monthly basis. There are still a few active nests around at the moment but with the peak breeding season approaching (June-November), nest building, egg laying and chick rearing is sure to increase. We are keen to reach 100 ringed nestlings as soon as possible.
Res Altwegg (Tel. 021 650 4549) and Doug Harebottle (Tel. 021 650 2330)