Studying the incubation behaviour of the Sichuan partridge
Chester Zoo’s science director, Simon Dowell is co-author of a paper on incubation behaviour in the Sichuan partridge published recently in the Journal of Ornithology. Chester Zoo has supported the conservation of the endangered Sichuan partridge through funding the protection of its broadleaf forest habitat in the Laojunshan nature reserve in China since 2002.
During that time, forest rangers in the reserve had noticed that the female partridges were spending an unusually long time away from their nests during the incubation period, leading to fears of egg chilling and poor productivity. This seemed to be linked to disturbance where birds were nesting along heavily used forest trails.
This reserve is thought to hold at least 10% of the world population of this species, and so we were concerned that increased disturbance might reduce breeding success. With the help of research funding from the National Natural Science Foundation of China, our partners in China decided to use the latest technology to take a closer look at what was happening.
Researchers used temperature data loggers placed inside an artificial egg in each nest to record the egg temperature during incubation. In addition, infrared cameras were placed a metre away from nests to monitor the behaviour of the female. The results were intriguing.
Sichuan partridge. Photo credit: Dai Bo
Sichuan partridge eggs experienced an average of 4.2 hours per day below 26oC which is the ‘Physiological Zero Temperature’, below which the embryo cannot develop. This is considerably more than that recorded for most bird species and would normally lead to death of the embryo. Despite this, hatching success was 88.4%, which is very close to the average hatchability rate for birds in general (89.1%). When investigated further we noticed a difference between nests close to busy forest trails and those in quieter areas of the forest; with the hens nesting in more disturbed areas spending longer off their nests than those in quieter areas. To compensate, the incubation period for nests in areas of high disturbance was about five days longer than the period for nests in undisturbed areas, but hatching success was not reduced.
It is possible that nests located close to forest trails gain some advantage through disturbance along trails reducing predation. At the very least, this research has demonstrated the resilience of the Sichuan partridge to disturbance along forest trails and shown that increased visitor numbers to the reserve will not necessarily lead to reduced breeding success of the key species that the reserve is there to protect. This is important information that will contribute to and inform the management of visitors in the reserve.
You can read the full paper here: Unusual incubation behaviour and embryonic tolerance of hypothermia in the Sichuan partridge (Arborophila rufipectus) Fu, Y., Bo, D., Wen, L., Chen, B., Dowell, S.D. and Zhang, Z. 2017. Unusual incubation behaviour and embryonic tolerance of hypothermia in the Sichuan Partridge (Arborophila rufipectus). Journal of Ornithology 158(1)