Ecological and demographic drivers of kin-directed cooperation in a social bird: Insights from a long-term study

The evolution of sociality is one of the major evolutionary transitions in the history of life and a key step in this transition is the occurrence of kin associations. Yet, the question of what demographic processes and environmental factors generate kin-structured populations and drive kin-directed cooperation remains open.
In this review, we synthesize 30 years of studies of the long-tailed tit Aegithalos caudatus, which has a kin-selected cooperative breeding system with redirected help: failed breeders may help to raise offspring of conspecifics, typically relatives, breeding nearby. We describe the use of ecological, demographic, genetic and behavioural approaches to reveal: (a) how kin-structured populations (here ‘kin neighbourhoods’) arise; (b) why the prevalence of cooperation varies among populations and individuals; and (c) how variation in dispersal and opportunities for cooperation influence individual fitness.
The kin neighbourhoods of long-tailed tits arise from three pro..., This data originates from the long-term monitoring of a wild population of long-tailed tit in the Rivelin Valley (UK). Most individuals were captured and colour-ringed, and every breeding attempt was closely monitored since 1994, allowing detailed data on local dispersal and recruitment rates across breeding seasons. We refer the reader to the publication for the method on actual data collection in the field. In short, the identity of each breeder was possible, at the vincinity of their nest, thanks to the unique colour ring combination their bare on their legs. Nestlings were also ringed with unique combinations of colour-rings. That allowed us to detect local recruits and estimate the proportion of fledglings that recruited locally, for each year (first table), and the dispersal distance they performed (distance between their natal nest in year Y and their first ever breeding nest in year Y+1).  
 , , # Ecological and demographic drivers of kin-directed cooperation in a social bird: Insights from a long-term study

[https://doi.org/10.5061/dryad.hhmgqnks3](https://doi.org/10.5061/dryad.hhmgqnks3)

## Description of the data and file structure

This data originates from the long-term monitoring of a wild population of long-tailed tit in the Rivelin Valley (UK). Most individuals were captured and colour-ringed, and every breeding attempt was closely monitored since 1994, allowing detailed data on local dispersal and recruitment rates across breeding seasons.

These two specific types of data (dispersal distance and recruitment rate) contribute to the knowledge of the species biology and we used and present them in our Review on the drivers of cooperation in the long-term studied population of long-tailed tits.

### Files and variables

#### File: Morinay\_et\_al\_2025\_JAE\_recruitment\_rate.csv

**Description:** Annual recruitment rate of locally ringed nestlings

##### Variables

* Y...