While a number of studies have extensively investigated flame retardant (FR) contamination in aquatic ecosystems from the Laurentian Great Lakes basin, there remains a dearth of information for terrestrial ecosystems. In the current study, American kestrels (Falco sparverius) (AMKE) and European starlings (Sturnus vulgaris) (EUST) that are terrestrial ecosystem consumers, and from the southern Lake Ontario regions, were investigated as potential terrestrial bio-monitoring species. Egg homogenates were screened for sixteen PBDE congeners and nineteen non-PBDE FRs of established or emerging environmental importance. PBDE congeners dominated the FR burdens in eggs of AMKE and EUST, with total concentrations ranging from 3.4 to 39.8 (median: 13.5) and 1.5 to 117 (median: 4.9) ng g−1 wet weight (ww), respectively. Although the production and application of the Firemaster FF-1 (a commercial hexabromobiphenyl PBB mixture) has been discontinued for over four decades, its major component, 2,2′,4,4′,5,5′-hexabromobiphenyl (BB-153), was still frequently detected in AMKE and EUST eggs. Two isomers of the chlorinated FR Dechlorane plus (DP) were mostly detected in eggs collected from Niagara-on-the-Lake in the western portion of Lake Ontario, approximately 15 km from the only North American DP manufacturing site, clearly reflecting point source influences. FR comparisons in eggs from AMKE, EUST and Great Lakes herring gulls revealed species-specific contamination burdens and PBDE congener profiles, likely due to influences from trophic levels and PBDE congener-specific bioaccumulation and biomagnification capacities in terrestrial versus aquatic food chains. Insectivorous birds (e.g. great tit) and relatives of AMKE have also been used as bio-monitoring tools in European and Asian regions, allowing investigation of spatial distribution patterns on a more international scale. AMKE and EUST have also been used as model species for laboratory evaluation of FR toxic effects in birds. Therefore, AMKE and EUST are deemed valuable bio-monitoring species for investigating FR contamination in terrestrial ecosystems.