This small and fluffy bird is called the long-tailed tit, named aptly as its tail is often larger than its body. This species has a cooperative breeding system where birds (who are not the parents) help care for the chicks of their relatives. This involves an evolutionary trade-off, since individuals invest work into tending for chicks that are not their own direct offspring, but they can still improve their own fitness by promoting their genetic lineage!

Art by Lei Zhong

[Edited by Isabelle McDonald]

References:

MacColl, A. D. C., & Hatchwell, B. J. (2003). Sharing of caring: nestling provisioning behaviour of long-tailed tit, Aegithalos caudatus, parents and helpers. Animal Behaviour, 66(5), 955–964. https://doi.org/10.1006/anbe.2003.2268