Lead and Other Trace Elements in Danish Birds of Prey

Niels Kanstrup,Rune Dietz,Christian Sonne,Mariann Chriél,Thorsten Johannes Skovbjerg Balsby,Jens Søndergaard

doi:10.1007/s00244-019-00646-5

Niels Kanstrup, Rune Dietz + Show 4 more

Open Access

https://doi.org/10.1007/s00244-019-00646-5

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Abstract

Lead is a widely used and toxic heavy metal that poses a serious hazard to wildlife species and their ecosystems. Lead is used for production of hunting ammunition. Via gunshot or rifle projectiles, it spreads in ecosystems and may end up in predators and scavengers feeding on wounded or dead animals shot with lead-based ammunition. To assess to what degree Danish raptors are subject to lead contamination, we measured the content of lead in liver tissue from Danish birds of prey (n = 137). Additionally, the study included values for 54 other trace elements. In our analysis, emphasis was put on interpretation of lead levels. Levels of cadmium, mercury and selenium were also discussed, while data for the remaining elements were provided for reference purposes. Bismuth was included to assess if lead originated from bismuth gunshot used as an alternative to lead shot. Concentrations of lead, cadmium, mercury and selenium were generally below the levels in similar studies of birds of prey in other northern European countries and none exceeded known and generally accepted threshold values for adverse health effects. As for lead, this is possibly related to the phase out of lead shot for hunting since 1986. The study confirms results from other studies showing that bismuth shot contains traces of lead that is deposited with bismuth in the target animal.

Highlights

Lead has been used to produce ammunition for military and civilian purposes including hunting for more than 500 years
The molar ratio of selenium/mercury in white-tailed eagles in our study showed that selenium was in surplus, which in combination with the relatively low mercury levels observed indicated that these birds were not likely to be at risk of mercury intoxication
The examined birds of prey had concentrations of lead, cadmium, mercury, and selenium below the levels demonstrated in comparative studies of birds of prey in other countries and generally below levels considered to be at risk for the bird’s health, behaviour, reproduction and for sustaining a favourable conservation status

Summary

Introduction

Lead has been used to produce ammunition for military and civilian purposes including hunting for more than 500 years. It has been documented that predators and scavengers are exposed to lead fragments from rifle ammunition in offal from or carcasses of killed game animals (Kenntner et al 2001; Helander et al 2009; Krone et al 2009; Pain et al 2010; Nadjafzadeh et al 2013, Ecke et al 2017; Pain et al 2019). The risk of lead from gunshot and rifle projectiles to expose predators and scavengers through wounded game animals and from offal is poorly investigated in Denmark. The increasing population of deer, the increased opportunities for hunting and the local need for targeted population control combined with the current handling of offal from killed animals accentuate the need to investigate the risk related to leaded rifle ammunition

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