These active, nervous little birds always seemed to come in small flocks, almost never alone. Their behavior and appearance are reminiscent of the Bushtit of Western North America and the two are classified in the same family, the Aegithalidae. Their breeding ecology has been studied extensively and includes helpers at the nest, usually failed breeders helping successful male kin raise their young. These birds are part of an eastern subspecies group showing dark head bands similar to some European populations, but widely separated from them. The nominate race with all white head occurs across northern Eurasia including Hokkaido. Canon PowerShot SX60.
References:
Harrap, S. (2019). Long-tailed Tit (Aegithalos caudatus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/59741 on 16 April 2019).
B. J. Hatchwell, D. J. Ross, M. K. Fowlie, A. McGowan (2001) Kin discrimination in cooperatively breeding long–tailed tits 268 Proceedings of the Royal Society of London. Series B: Biological Sciences. https://doi.org/10.1098/rspb.2001.1598
Stuart P Sharp, Michelle Simeoni, Ben J Hatchwell (2008) Dispersal of sibling coalitions promotes helping among immigrants in a cooperatively breeding bird. 275. Proceedings of the Royal Society B: Biological Sciences http://doi.org/10.1098/rspb.2008.0398