DOI: 10.5061/dryad.x95x69pjx
title: Why do parents produce small broods of offspring that have lower body mass, survival, and lifetime reproductive success? A case study in a long-lived bird

description: Numerous studies have examined the correlation between
 offspring quantity and quality, and many have found that
 the most common brood size is often smaller than broods with the highest
 offspring quality or production. However, the reasons why these small
 broods with lower offspring quality are produced, are still poorly
 explained. Using data spanning 29 years, we investigated the effects of
 brood size on nestlings’ body mass and the lifetime fitness for those
 offspring as adults (as proxies of offspring quality) in the Crested Ibis
 (Nipponia nippon). We also examined the temporal variation of brood size.
 We found that overall offspring quality increases with brood size and that
 individuals from broods of three had the highest quality, as quantified by
 larger body mass, higher adult survival, and lifetime reproductive
 success. Furthermore, brood size of an individual pair significantly
 varied across years, and the proportion of broods containing two offspring
 increased while broods of three decreased after 2000 when the population
 dispersed to low-quality habitat. These findings indicate that
 spatiotemporal variation in resources may impact variation in brood size
 and subsequent fitness consequences, and that small broods are more common
 in resource-poor years or low-quality habitats. In contrast, parents with
 access to high-quality resources produce larger broods of nestlings that
 achieve higher body mass and subsequently experience higher adult survival
 and lifetime fitness. This study highlights how variation in life history
 traits can be influenced by resource condition, and provides an insight
 into particular habitat that need conservation for Crested Ibis.
description: <strong>Offspring quality</strong>: Body mass of
 nestlings of crested ibis <strong>Survival
 rate</strong>: Marking-rediscover history of crested ibis 
 <strong>Lifetime reproductive
 performance</strong>:<strong> </strong>Age of first
 reproduction, breeding lifespan and lifetime reproductive
 success <strong>Reproductive performance in each
 year</strong>: The number of nestlings producing by parents in each
 year
description: # Why do parents produce small broods of offspring that have lower body
 mass, survival, and lifetime reproductive success? A case study in a
 long-lived bird
 [https://doi.org/10.5061/dryad.x95x69pjx](https://doi.org/10.5061/dryad.x95x69pjx) | **file name** | **variable name** | **discription** | | :------------------------------------------ | :-------------------------- | :------------------------------------------------------ | | **CI\_body\_mass** | id | bird ID | | **CI\_body\_mass** | [brood.no](http://brood.no) | the no of broods | | **CI\_body\_mass** | year | natal year | | **CI\_body\_mass** | bs | brood size | | **CI\_body\_mass** | sex | the sex of nestlings | | **CI\_body\_mass** | hatching.order | the hatching order of nestlings | | **CI\_body\_mass** | bodymass | the body mass of nestlings | | **CI\_survival\_rate** | id | bird ID | | **CI\_survival\_rate** | year | natal year | | **CI\_survival\_rate** | ch | rediscover (1) or not (0) | | **CI\_survival\_rate** | bs1 | broods of 1 nestling | | **CI\_survival\_rate** | bs2 | broods of 2 nestlings | | **CI\_survival\_rate** | bs3 | broods of 3 nestlings | | **CI\_lifetime\_reproductive\_performance** | year | natal year | | **CI\_lifetime\_reproductive\_performance** | bs | the natal brood size | | **CI\_lifetime\_reproductive\_performance** | first.age | the first age of reproduction of individuals | | **CI\_lifetime\_reproductive\_performance** | b.lifespan | the breeding lifespan of individuals | | **CI\_lifetime\_reproductive\_performance** | life.success | the lifetime reproductive success of individuals | | **CI\_lifetime\_reproductive\_performance** | failure.years | the number of times of breeding failure during lifetime | | **CI\_reproductive\_performance\_eachyear** | id | the ID of breeding bird | | **CI\_reproductive\_performance\_eachyear** | year | breeding year | | **CI\_reproductive\_performance\_eachyear** | bs  | brood size |