Lead burden in mute swans from Denmark

During the severe winter of 1978-79, large numbers of mute swans died in coastal areas in Denmark; of these 2111 were collected for autopsy. The area of origin and the sex of the 2111 swans, 184 of which were ringed, are given in Table I and Fig. 1. At autopsy (Table II) most of the swans were recorded as having died from starvation. Lead pellets were found in only 0.7% of the gizzards (Table III) probably because most ingested pellets had been eroded away before the swans died. The results of analysis of 76 swans selected at autopsy and of the 184 ringed swans show that lead poisoned swans are not always recognized at autopsy (Table III and IV). Ten per cent of the ringed swans carried more than 7 mg lead per kg liver wet weight (Ww) and 34% more than 3 mg/kg (Ww) (Table IV), while an elevated lead content (greater than 30 mg/kg dry weight) was found in the sternum of 40% of the swans (Fig. 2). The load of lead in the liver was higher in the few swans from the western part of Jutland than in swans from the main sampling areas, while in the sternum it was relatively lower in swans from the southern part of the country (Lolland, Falster) (Table V). No difference in lead content was found between males and females. The lead content in the liver was not correlated with age, while a positive correlation was found between age and the lead content in the sternum (Table VI).(ABSTRACT TRUNCATED AT 250 WORDS)