This data consists of one text file that explains the data labels, and two csv files. One csv file was used to compute the consistency of neophobia, control, and feeding rate measures and their impact on jackdaw fitness, the other was used to analyse the factors influencing blood CORT hormone levels. Neophobia scores, measures of reproductive success, and offspring stress hormone levels were collected from a wild population of breeding jackdaws (Corvus monedula) in Madingley, Cambridgshire, UK in 2013. Neophobia was assessed at nest boxes based on birds’ latencies to return to their nest when a novel object was present. Reproductive success was determined by counting the number and body condition of chicks per nest. A measure of baseline and stress-induced corticosterone (CORT) was taken for each chick within a subset of nests. The csv files contain data used for the analyses supporting the related research article (Wild jackdaws’ reproductive success and their offspring’s stress hormones are connected to provisioning rate and brood size, not to parental neophobia). Please see the main article for further discussion relating to the results generated from this data.