Spatio-temporal variation in egg-laying dates of nestbox-breeding varied tits (Poecile varius) in response to spring pre-breeding period temperatures at long-term study sites in South Korea and Japan

ABSTRACT

Climate change can alter and disrupt the phenology and phenological interaction between organisms from various trophic levels in forest ecosystems. In temperate forests, the breeding phenology of birds is correlated to local microclimate, especially spring temperature to match the timing of food availability. Recent studies revealed that the temperature warming is more pronounced in high-elevation areas (elevation-dependent warming), while the breeding phenology shift of birds in this condition needs further investigation. We studied the annual change in the egg-laying dates of varied tits (Poecile varius) and a pre-breeding temperature index in three plots located along with the elevational gradient in South Korea and a low-elevation plot in Japan. We found strong support for disproportionate rates of changes in higher elevation for warming trends in pre-breeding period and advances in egg-laying dates over the last decade. Next, we compared three segments of 36-year data from Akazu Research Forest. The evidence from pre-breeding temperature during 36 years indicates that we could detect the change in thermal environment and breeding phenology with longer years of data, especially in lower elevation regions. This result shows the need for long-term research to understand the change in local temperatures and the ecology of forest birds. Our study presents evidence of elevation-dependent phenological advance in avian breeding activities and discusses the need for systematic long-term research on multiple taxa and climatic drivers in Asia.

KEYWORDS:

• Experimental forests
• elevation-dependent phenological shift
• long-term monitoring
• forest songbirds
• breeding phenology

Acknowledgments

We are grateful to Prof. Kamata Naoto in the University of Tokyo for providing help in developing this study in the initial stage, and suggesting the data source in Japan, collected by his colleagues; Yanase Kiriko, Mizutani Mizuki, Sato Takanori, Arakida Yoshitaka, Matsui Masaki, Takatoku Kae and Saiki Michio in Ecohydrology Research Institute, the University of Tokyo. We also acknowledge the members of the Laboratory of Wildlife Management and Ecology, Department of Forest Sciences in Seoul National University for assisting nestbox monitoring. The staff of Seoul National University Research Forest supported this study to great extent, especially Jongyeong Park and Giho Ha for their many years of efforts on nestbox survey in Mt. Jiri, that made this study possible, we are very thankful for their contribution for the data collection and support in the field logistics. Hankyu Kim was supported by Oregon State University while preparing this manuscript. We are very grateful to the editors Dr. Masahiro Takagi and Dr. Satoshi Ito and anonymous reviewers who reviewed and commented on our submitted manuscripts. Thanks to their keen review, we were able to improve this manuscript to a great extent.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by 'R&D Program for Forest Science Technology (Project No. 2014109C10-2020-AA01)' by Korea Forest Service (Korea Forestry Promotion Institute), LG Evergreen Foundation, and College of Agriculture and Life Sciences of Seoul National University.