Nesting biology and population dynamics of Jankowski's Bunting Emberiza jankowskii in Western Jilin, China

Jankowski's Bunting Emberiza jankotoskii is endemic to China, Russia and Northern Korea, and was listed as a 'Vulnerable' species. The population in Dagang Forestry of western Jilin is one of the small remaining discrete breeding populations in the species' range. Very little information on the nesting biology and population dynamics has previously been published. We studied the nesting biology from 1999 to 2002 and population dynamics of the bunting from 1999 to 2006 (except 2003). A total of 74 nesting attempts were monitored. Jankowski's Bunting breeding season began in late April and usually ended in late July. Both sexes participated in nest-building, feeding young and defending the nest. Mean full clutch size for three years combined was 5.26 +/- 0.76 eggs, and ranged from four to seven. Clutch size decreased with nest-initiation date. Mean hatching rate was 41.2%. Overall probability of Mayfield nest success to fledging was low for the three years, averaging 0.218 +/- 0.007. The factors leading to low nest success include nest parasitization, nest predation, human activities and nest abandonment. Low survival of Jankowski's Bunting nests may be a factor in declining populations and the slow recovery of populations because of low recruitment at the population and the individual level. The population of Jankowski's Bunting in the Dagang Forestry grassland was small and declined dramatically from 1999 to 2006. The main threat is habitat loss and fragmentation due to agriculture, tree planting and housing following human colonization of the region. The habitat has been reduced in extent by c.70% since the 1960s. In addition, grazing by domestic livestock dramatically destroyed their preferred vegetation. Furthermore, the restriction to several small, discrete sites makes the bunting inherently vulnerable to catastrophic and stochastic events that can eliminate subpopulations. Jankowski's bunting is one of the most threatened species in China and faces an unpredictable future. Maintaining the structure and general composition of remaining Jankowski's Bunting nesting habitat is important to ensure continued presence of this species in western Jilin and worldwide.