The Hadeda Hotline
News and updates from the Hadeda Ringing Project
9 November 2011
Dear hadeda enthusiasts,
The hadeda project has recently published work on the demography of hadedas in an international scientific journal. This is the third publication in scientific journals from the project, and this paper was based on the first chapter of Greg's MSc thesis. It's the first paper to ever document any hadeda demographics. This type of work is important in filling gaps in knowledge because wading birds (the group to which hadedas belong) are very understudied and globally, not much is known about their demographics. We found that 27 out of every 100 nestlings make it through their first year of life, and after that, 75 out of every 100 make it through the subsequent years. This demographic analyses relied on the valuable resightings that you have reported over the duration of this project. Without your help in reporting ringed birds we would not have been able to complete such a study. So we say a big thank you from this side, and show you exactly how we use your data! Please email us if you'd like a copy of the paper.
The core breeding season for this year has finished for hadedas. Unfortunately, we didn't have the capacity to ring as many nestlings as we would have liked. Nonetheless, we did venture out in the wind and rain this winter to ring a few nestlings. Our total of ringed birds now stands at a credible 242 birds over 5 years. So, if you do see a group of hadedas within Cape Town, there is a very good chance that one will be ringed, so please be on the lookout. Given that the average nest produces 2.09 nestlings of ringing age per brood, and about 40 birds were ringed on the ground or by other qualified ringers, we estimate that we've had to climb about 96 trees in getting to our current total!
We are now beginning to receive important resightings which represent milestones for the project: we have had two more reports of birds that we had ringed as nestlings now breeding in Cape Town (after "FD" was reported to us last year). One bird is "IJ", who was ringed in Kenilworth in March 2008, and was seen with its offspring on numerous occasions in Rondebosch in October 2011. Another bird, "CV" had recently started incubating, when the nest was unfortunately attacked by a gymnogene. "CV" and mate then abandoned the nest. Nonetheless, it's great that we are receiving resightings of birds breeding and has given us a good understanding of their generation time. It's also fantastic that these resightings are in Cape Town, because as this species is expanding its range so quickly, one might expect birds to disperse from Cape Town in order to breed.
We reported in an earlier newsletter that Dr. Desire Dalton, based in Pretoria, had begun genetic work on the hadeda project. She has sexed all of our nestling blood samples so far. Analysing the gender data shows that there is a female biased sex ratio of nestlings (1.4 females born for every 1 male), but this is not statistically significant. We have since acquired a large number of blood samples and will be sending them to Desire soon for sexing. It would be interesting to note if there is a statistically significant bias in sex ratio in hadedas. It has been recently shown for birds that the incubating individual is able to adjust the sex ratio of their offspring, depending on environmental and individuals. We wonder if this is the case with hadedas, and if it has helped them to expand their range as well as they have.
Dr. Dalton is also participating in a DNA barcoding project, which attempts to barcode all South African vertebrate species (birds, mammals, reptiles and amphibians), in collaboration with SANBI and the African Centre for DNA Barcoding (ACDB). DNA barcoding is used to identify an organism at species-level by examining its genetic code, and is useful in controlling food quality, traceability of raw and processed products derived from trade species, and in providing valuable information in conservation biology and wildlife management. This project forms part of a larger initiative, the International Barcode of Life (IBOL) - the largest biodiversity genomics project ever undertaken. The goal of this initiative is to create a digital identification system for all species - a quick way of identifying organisms in nature simply by comparing a DNA barcode to an online reference library linked to relevant information for each species. Hadedas have now been added to this database.
That is a brief update on what has been happening in the hadeda project lately. We now have a greater capacity to ring nestlings, and we are trying to ring as many nestlings as we can before the end of the breeding season, so we ask to to please keep an eye out for any hadeda breeding activity, or, any other interesting sightings