CR 54:95-112 (2012)  -  DOI: https://doi.org/10.3354/cr01099

ABSTRACT: The impact of climate change on the bird communities of Asia is poorly understood. Since the 1950s, the Japanese Meteorology Agency has recorded first arrival (i.e. first sighting) and first singing for a selection of resident (Alauda arvensis, Cettia diphone, and Lanius bucephalus) and migratory species (Hirundo rustica and Cuculus canorus) in more than 300 bird populations. First records (i.e. first sighting or singing) show a delay of 5.4 d since the end of the 1970s. Nevertheless, there is a marked heterogeneity in the temporal trends among populations in each species. Most populations of A. arvensis, C. diphone and H. rustica show a negative relationship with local temperature (i.e. first records were earlier in warmer years) and this sensitivity to temperatures has increased in recent decades. Exploration of the possible causes of variability in phenological trends among populations demonstrated that greater delays were observed in those populations subjected to smaller increases in local temperature and a greater increase in human population (a surrogate for the conservation status of bird populations). Therefore, declining bird populations are the most probable cause of the observed delay in the phenology of first individuals. Migratory species were affected by climate in their wintering and passage areas. Overall, first sightings of H. rustica were earlier, while the onset of singing by C. canorus was delayed in response to warmer temperatures in southeastern Asia. However, there was a noteworthy variability among populations, with no discernable regionalization or spatial organization. This suggests that there is no clear connectivity between breeding and wintering populations.

KEY WORDS: Arrival date · Heat island effect · Long-term study · Migratory birds · Phenology · Singing onset · Temperature · Warming