It Takes a Village to Raise Aegithalos caudatus (long-tailed tits)

Long-tailed tits are adorable…they just are.

Now, before we are all driven to state of cute agression, let’s take a break and discover why this plucky little passerine is more than just a pretty face.

Long-tailed tits (Aegithalos caudatus) are a common fixture throughout Europe and Asia. They are small, measuring a mere 13–15 cm in length with 7–9 cm of that length devoted to their tail. During the non-breeding season, they can found in gregarious groups of around 20-30 individuals and spend their time noisily bouncing about woodland and parkland in search of arthropods.

Once breeding season rolls around, the groups splinter and eventually whittle down to monogamous breeding pairs. Both the male and female Aegithalos caudatus participate in nest-building. Their choice of material is very particular.

The nests of Aegithalos caudatus are built from four specific materials – lichen, feathers, spider egg cocoons, and moss. It has been reported that it can take around 6,000 individual pieces of material before the pair are satisfied with their construction.

The interior of the nest lined with over 2,000 feathers collected from the environment. Pairs have even been spotted plucking the bodies of dead birds during feather supply runs if the opportunity presents itself.

After the nest is constructed, egg laying begins. Aegithalos caudatus lay clutches of 8-15 eggs. After hatching, the young long-tailed tits require about 14-18 days in the nest before joining their parents outside.

A burgeoning nest full of hungry young birds isn’t their parents’ greatest problem, however. A very high predation rate means that only 17% of nests each season have success. That leaves a lot of former parent birds out of work, but there’s an upside.

When a pair of Aegithalos caudatus loses their nest, the pair typically splits and each bird joins the nesting efforts of their respective relatives. The result is improved success rates for the remaining nests which benefit from the added family help. These new familial units (composed of the parents, offspring, and relatives) will often go on to form the base of the gregarious flocks that begin to appear around wintertime.

It’s an approach to reproduction that ensures the evolutionary success of family lines despite high predation rates. If a family’s genes can’t move on to the next generation through a particular pair of birds, those genes still have a chance to persist through the offspring of that pair’s close relatives (especially with relatives lending a hand.)

So next time you see a group of Aegithalos caudatus twittering in the trees, remember that it took about 6,000 bits of lichen/moss/spider cocoons, roughly 2,000 feathers, and the bird equivalent of a village to get each one of them up there.

Further Reading

• Long-tailed Tits – Royal Society for the Protection of Birds
• Gaston, A. J. (1973) The ecology and behaviour of the Long-tailed Tit. Ibis, 115(3), pp.330-351.
• Hansell, Michael Henry (2007). Built by animals: the natural history of animal architecture. Oxford University Press. pp. 76, 77. ISBN 978-0-19-920556-1.
• Hatchwell, B. J., et al. (1999) Reproductive success and nest-site selection in a cooperative breeder: effect of experience and a direct benefit of helping. The Auk, 116(2), pp.355-363
• Mcgowan, Andrew, Ben J. Hatchwell, and Richard J. W. Woodburn (2003). “The Effect of Helping Behaviour on the Survival of Juvenile and Adult Long-tailed Tits Aegithalos Caudatus“.Journal of Animal Ecology 72 (3): 41–99.