On January the 10th, the Schlammwiss-Team comprising Jim, Dave, Cédric, Nicole and Niklas visited another bird-ringing team in Bonn, Germany.
The local team around the ornithologists Esther Koch, Victor Corman and Sönke Twietmeyer as well as many other helping hands met at a roosting place near the river Rhine to ring rose-ringed parakeets (Psittacula krameri). Esther Koch has already examined the influence of the rose-ringed parakeets on cave breeders in Bonn in her diploma thesis.
With a current population size of approximately 1.300 individuals in Bonn, she found that the parakeets do not pose a significant threat to native cave breeders.
The parakeet’s native range is India and Africa but the wild populations in Bonn, and also those in Cologne and Brussels, are descendants from individuals which succeeded in escaping from private keepers and zoos.
In order to learn more about this bright green colored bird concerning age, sex and their life history in cities of temperate zones, the team of experts decided to continue the study on the rose-ringed parakeet. They are usually being captured with standard mist-nets for song birds. For parakeets, these nets are more effective than nets with wider meshes because this way the parakeets lie loosely in the pockets and can be removed easily by experienced bird-ringers. The disadvantage is, that many of those caught turn around in the net pocket and escape.
The whole team which included more than 20 bird ringers, scientists and helpers placed two nets near a group of plane trees not far away from the river Rhine. Plane trees are the favourite roosting trees of that species. As soon as the night fell, swarms of starlings, carrion crows and jackdaws settled down on the branches of the surrounding trees. Shortly afterwards, small groups of parakeets gathered on trees along the banks of the Rhine and places nearby. As it got darker, more parakeets flew in. Typical for their behavior before roosting time, groups of parakeets rush almost on ground level at high speed towards the trees and then rising again onto the branches where they loudly inform their conspecifics of their presence.
That is the moment in which the parakeets were caught. The team split up into small groups to remove the birds from the nets to ring and examine them. Others stayed hidden but close enough to the nets to observe further fly-ins. Regarding the strong force of their beak that even allows them to crack nuts, we took care of ringing them with rings made out of steel. Simple aluminium would rapidly fall victim to the beak’s destructive force. It became clear very soon that is impossible to ring parakeets without using protective handgloves. Indeed, their strong beak can cause painfull injuries. Additionally, it is hard to put the ring on the bird’s leg because it is just a tiny bit longer than the ring itself. After the ringing, the wing length and the length of the middle pair of tail feathers were measured. That method showed that males have longer tail feathers than females. Then the weight of the birds was taken and their wing was spread on a black background to take a photo. Lots of wing photos will allow to see differences in feather characteristics for age determination.
To really find out whether a non-male couloured bird is a female or a juvenile, the scientists took a cloacal swab of each bird for a molecular examination in a laboratory. Moreover, that same sample gives information about the bird’s health. The exact age of a rose-ringed parakeet cannot be determined by pure vision. We know however that adult males only get a rose coloured ring around their neck during their third calendar year.
Concerning age determination, there is another unusual characteristic whose occurrence depends on the season of catching and the past weather conditions. Partially, the rose-ringed parakeets showed signs of frost bite on the underside of their feet. Claws and toes can fall of in case of long term frost periods. Knowing that, a young parakeet hatched the year before, it can be distinguished from adults by the good condition of its feet on. If the toes are still on in January, the winter weather has been rather soft in that year.
Although the weather was windy and dark clouds and short rain showers accompanied the ringing action in the late afternoon, the team had great luck with at least six rose-ringed parakeets that made a little stop-over before they went into their roosting trees.
For the Schlammwiss team this was the first contact with this species. An exceptional experience for all of us – and probably not the last.
THANKS for the impressing insights into the handling and ringing of rose-ringed parakeets to Sönke Twietmeyer and the whole team in Bonn.
Autor: Nicole Thien