Lead (Pb) and Mercury (Hg) concentrations in predatory bird livers 2012: a Predatory Bird Monitoring Scheme (PBMS) report

Walker, L.A.; Chaplow, J.S.; Lawlor, A.J.; Pereira, M.G.; Potter, E.D.; Sainsbury, A.W.; Shore, R.F.. 2014 Lead (Pb) and Mercury (Hg) concentrations in predatory bird livers 2012: a Predatory Bird Monitoring Scheme (PBMS) report. Lancaster, NERC/Centre for Ecology & Hydrology, 17pp. (CEH Project no. C04288)

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The Predatory Bird Monitoring Scheme (PBMS; is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability contaminant monitoring and surveillance work. By monitoring sentinel avian predators, the PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. The present study summarizes the results of monitoring to quantify the scale of exposure to [and associated risk from] two toxic metals, lead (Pb) and mercury (Hg) in predatory birds. A major concern over Pb is that birds of prey may be exposed to Pb shot and ammunition fragments when they prey on or scavenge game animals. The aim of the current Pb monitoring was to quantify the extent of exposure [assessed from liver residues] in four predatory bird species, the barn owl (Tyto alba), common buzzard (Buteo buteo), red kite (Mivus milvus) and sparrowhawk (Accipiter nisus). The red kite and buzzard are scavengers and, as such, are particularly at risk from consumption of ammunition and shot in unretrieved game. In contrast, barn owls and sparrowhawks predominantly take prey [live small mammals and passerine birds, respectively] that are unlikely or less likely to have been shot. Pb levels in barn owls and sparrowhawks may therefore give an indication of “background” Pb contamination in birds of prey against which to judge any elevated levels in red kites and buzzards. Mercury is a neurotoxin and there has been global concern over its impact of humans and wildlife. It has been predicted that global Hg emissions may rise because of increased coal-fired power generation, but, in 2013, the United Nations Environment Programme (UNEP) agreed The Minamata Convention on Mercury, a global treaty to protect human health and the environment from the adverse effects of mercury. An overarching aim of the convention is to control the anthropogenic releases of Hg to the environment. Therefore, long-term trends in environmental Hg concentrations are uncertain. One means of assessing this is to monitor exposure of sentinel wildlife species. We report Hg residues in birds of prey with the aim of providing baseline data against which to assess future change in Hg environmental concentrations and associated wildlife exposure. We did this in two ways: (i) by examining liver Hg concentrations in those species that we analysed for Pb, thereby providing a current measure of accumulation in different species, and (ii) by combining new liver Hg data for sparrowhawk with those obtained in previous years to determine current trends in exposure and assess key factors that may influence accumulation in this sentinel species. Median liver Pb concentrations in the four species studied were between 0.03 and 0.6 µg/g dry wt., lower than levels associated with clinical and sub-clinical adverse effects in Falconiformes. Barn owls and sparrowhawks generally had lower Pb concentration than those measured in buzzards and red kites. Female sparrowhawks had higher liver Pb concentrations than males, but there were no differences between males and females for the other species. Median liver total Hg concentrations ranged between 0.22 and 1.3 µg/g dry wt. in the four species studied and all birds had residues below those suggested to be potentially indicative of mortality or effects on reproduction. Red kites had lower Hg residues than sparrowhawks and buzzards and barn owls had lower residues than sparrowhawks. In sparrowhawks, Hg residues were higher in adults than juveniles and in starved than non-starved birds. Between 1990 and 2012, there was no significant temporal change in liver total Hg concentrations in sparrowhawks and 9.4% of female sparrowhawks had liver Hg concentrations greater than those potentially associated with effects on reproduction.

Item Type: Publication - Report
Programmes: CEH Topics & Objectives 2009 - 2012 > Biogeochemistry > BGC Topic 1 - Monitoring and Interpretation of Biogeochemical and Climate Changes > BGC - 1.1 - Monitor concentrations, fluxes, physico-chemical forms of current and emerging pollutants ...
UKCEH and CEH Sections/Science Areas: Shore
Funders/Sponsors: NERC/Centre for Ecology & Hydrology, Natural England, Campaign for Responsible Rodenticide Use, Royal Society for the Protection of Birds, Defra, Scottish Environment Protection Agency, Scottish Natural Heritage
Additional Keywords: PBMS, Predatory Bird Monitoring Scheme, annual report, environmental contamination, monitoring, lead, Pb, mercury, Hg, Great Britain, sparrowhawk, redkite, barn owl, buzzard, birds of prey,
NORA Subject Terms: Ecology and Environment
Related URLs:
Date made live: 13 May 2014 09:15 +0 (UTC)

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