An assessment of annual mortality rates in adult-sized migrant houbara bustards (Chlamydotis [undulata] macqueenii)

Between the years 1994 and 2000, we assessed the mortality rate of adult-sized, migrant Asian houbara bustards (Chlamydotis [undulata] macqueenii) via banding and satellite tracking programmes. The birds were captured either on their breeding grounds in Kazakhstan (Taukum desert and Buzachi peninsula) and in China (Jungar basin) or on their wintering grounds in Pakistan (Cholistan desert) and in the United Arab Emirates (Baynunah area). For the banding programme, 104 houbara bustards were marked and statistical analysis was performed on the number of transmitters and rings returned by falconers. This allowed us to calculate a 0.045 (SD 0.061) annual mortality rate attributable to hunting activities. The tracking programme analysed the fate of 41 houbara bustards equipped with satellite transmitters (PTTs). Overall, the satellite-tracked birds were followed for 10,965 days and had travelled all over the distribution range of the species in Asia. The causes of mortality were assessed from the interpretation of the ARGOS data relayed by the sensors embarked on the PTTs. The annual mortality rate was derived from the calculation of the average finite daily survival rate using the Trent & Rongstad (1974) method. With this method, the overall annual mortality rate in adult-sized houbara bustards migrating through Asia was 0.283 (95% lcl 0.186-95%ucl 0.404). The hunting and poaching pressure could explain 73.5% of the observed mortality. The mortality rate during winter, when the houbara is under severe hunting pressure, was 11.2 times higher than during the breeding season. Houbara appear to be especially at risk in Pakistan, Afghanistan and Iran. A VORTEX simulation showed that under current hunting and poaching pressures, the probability of extinction of the houbara population modelled can be anticipated at 50 years with a 94% probability. The maximum sustainable yield was estimated at 7.2% of the adult-sized population whereas as much as 20.8% is currently taken. This work stresses the need for conservationists and Arab falconers to take appropriate concerted measures as soon as possible.