Heavy metals in eggshells of cattle egret (Bubulcus ibis) and little egret (Egretta garzetta) from the Punjab province, Pakistan

► Sites specific and species specific variations in heavy metals concentration. ► Metals were significantly higher among sites and between species. ► Mn, Pb and Cr were significantly higher in Shorkot. ► Mn, Ni, Pb, Cd, Cr, Cu and Li were higher in fish eating little egrets. ► Multivariate analyses identified the anthropogenic and natural sources of heavy metals.