Temporal trends in classical and alternative flame retardants in bird eggs from Doñana Natural Space and surrounding areas (south-western Spain) between 1999 and 2013

•HFRs detected in bird eggs corresponding to two different time periods.•Decrease of the contribution of the components of Penta-BDE in birds from South Spain.•Ratio between HNs and PBDEs in each sample was higher in contemporary samples.•Presence of PBDEs is still higher than the presence of HNs.•Percentage contribution of α-HBCD increased between the two time periods.