By Anais Tritto
Study on the vocalization of the Javan green magpie (Cissa thalassina thalassina)
The Javan Green magpie is a critically endangered species which is quite unknown. Few are known on its biology as this species is now difficult to find on the wild. This species shows no sexual dimorphism and a deep study of the different calls of the male and the female could be a way to determine sex. The study currently performed at Cikananga Wildlife Rescue Centre tries to determine the whole vocal repertoire of the Javan Green magpie to highlight sexual differences and also to understand the meaning of each call (territory call, alarm/distress call…). It is worth noting that the vocalizations of magpie species are quite complex, with lots of different vocalizations that some of them were learnt by imitation.
This study is still in progress and, currently, 15 different calls were recorded for the female and 19 different calls for the male. 6 calls are shared by both sexes while 9 calls from the female and 13 calls from the male are different and can consequently be used as sex determination. This study being not finished yet and recording being still performed; these results could vary in the time. Nevertheless, we can now conclude that vocalization could be used for sex determination in the Javan green magpie.
Moreover, some meaning of the vocalizations can be presented even if, currently, lots of them remain without clear significances. 7 calls (4 from the female, 3 from the male) can be considered as alarm or distress call. Indeed, all of them are quite loud and can be used to repeal potential intruders. They were all recorded when a disturbance was made in the environment such as keeper coming, unusual bird calls or motorcycle sound. One male call could be territorial as it was always recorded during the early morning (when birds usually start to reaffirm their territory) and answered by another male in an adjacent building. Finally, two calls (1 from the male, 1 from the female) were recorded when the keeper arrives in the building to feed them and could be interpreted as “food anticipation”.
This study is still progressing and a record of each call as long as a picture of the sound waves would be added to this report pretty soon.
Vocal interactions between pairs of Sumatran laughing thrushes (Garrulax bicolor)
This vocalization study tries to determine the frequency of calls made by pairs of Sumatran laughing thrushes at Cikananga Wildlife Rescue Centre. As this species is quite sensitive and seems to be territorial, it is worth knowing if several pairs housed in the same building can have deleterious effect on their welfare and on the breeding success. In the centre, two buildings house one pair of this species, two other buildings house two pairs and one building houses three pairs and two single males. After recording and analysing the frequency of calls in each building (the female call, the male calls and when they are duetting), we can conclude that the calls seem to be linked with the number of pairs housed in a building but mainly with the life history of each pairs. Firstly, if a pair is recently created, the number of duet is higher in frequency to create pair-bond and warn potential rivals of their mate status. Secondly, the number of vocalizations can be linked with a recent settlement inside a building. Male calls are frequent for a pair that just arrived in a building. These calls are loud and directed to outsiders to affirm the male territory and its position as mate. But these calls decrease along the days until a reasonable level which can be linked with an adaptation of the pair to the new environment and neighbours. Finally, the breeding condition has the opposite impact on the number of vocalizations as pairs which are sitting on the nest or rearing chicks will be quiet to avoid predators to discover the nest and thus, compromise the breeding success.
Nevertheless, three pairs of Sumatran laughing thrushes and two single males housed in the same building is too much because of the short distance between them and the fact that, in this case, the single males are in view of one of the pair and could be seen as potential rivals. The pair is, indeed, duetting more often than the other pairs and it could be interpreted as mate-guarding. The male is also performing lots of territorial calls. By moving this pair or created visual isolation (for instance, covering a part of the wire mesh with a curtain), the frequency of vocalizations could be reduced and the breeding condition for this pair would thus improve. Visual isolation was performed in the other buildings and the number of vocalization is at a reasonable level.
To conclude, housing several pairs of Sumatran laughing thrushes in the same building can be done without disturbance if the formation of the pair is old enough to show strong pair-bond and if visual isolation is promoted by increasing the distance between them or adding visual barriers.
I am a young French conservation biologist and ethologist. I did a Master degree in France in Animal Behaviour (University of Paris) and another Master degree in England in Zoo Conservation Biology (University of Plymouth). All my studies where bird-orientated because of this passion I have for them since my childhood. I am specialized in laughing thrushes and I did most of my research projects on these species. After being a bird keeper for a while in a French zoo, I did several researches on Blue-crowned laughing thrushes (Dryonastes courtoisi) where I studied all the husbandry aspects of this species in captivity (from aviary design, implementation of the new diet during the breeding season, hand-rearing to the impact of a particular disease on the mortality of chicks). I am currently doing a project at Cikananga Wildlife Rescue Centre (Java, Indonesia), founded by ZGAP, where I am analysing the vocalizations of different birds: the Sumatran laughing thrush (Garrulax bicolor), the Rufous-fronted laughing thrush (Garrulax rufifrons), the Straw-headed bulbul (Pycnonotus zeylanicus) and the Javan Green magpie (Cissa thalassina thalassina).