This paper uses Pied Flycatcher as a study species. For the population of Pied Flycatchers they studied, 'pedigree information' was available. What exactly does this 'pedigree information' mean?
It means that they recorded family information for the traits that they were investigating in the paper, i.e., they had plumage characteristics for siblings or parent-offspring pairs. Look for this phrase in the paper: "phenotypic data usually available for one or two generations, mostly from parent-offspring pairs or siblings."