History of the PBMS

The Predatory Bird Monitoring Scheme was started 50 years ago by the Nature Conservancy. During the 1960s there were serious concerns over the effects of organochlorine insecticides and organomercury fungicides on several birds and mammals. Early monitoring, accompanied by experimental and ecological studies, demonstrated the adverse effects of organochlorine insecticides (particularly dieldrin and DDT) on predatory bird populations in Britain. This work contributed to the scientific evidence that led to bans on agricultural use of these insecticides in Britain and elsewhere. The programme has measured levels of these compounds in predatory and fish-eating birds ever since.

The PBMS is the longest running scheme of its kind anywhere in the world, and therefore, our findings stimulate considerable interest in Britain and internationally.

PBMS Timeline

1962 Work starts at Monks Wood Experimental Station.
1966 Monitoring of polychlorinated biphenyls (PCBs) in predatory bird tissues and eggs begins.
1970 Monitoring of total mercury in predatory bird tissues and eggs begins.
1971 Monitoring of contaminants in gannet eggs begins.
1983 Monitoring of second generation anticoagulant rodenticides (SGARs) in barn owls begins.
2006 Monitoring of Deca-Brominated Diphenyl Ether (DBDE) in sparrowhawk begins.
2011 Monitoring of poly brominated diphenyl ether (PBDEs) in otter livers begins.
2012 PBMS report on flame retardants in otters.
2015 PBMS reports: anticoagulant rodenticides in sparrowhawks, mercury concentrations and stable isotope signatures in golden eagle eggs and perfluorinated compound (PFC) concentrations in gannet eggs.


Historical image of hatched eggs

Work starts at Monks Wood Experimental Station investigating the role of organochlorine insecticides and organomercury fungicides in the decline of several bird and mammal species

Historical image of Harold Wilson visiting the PBMS in the 1960s

The PBMS expanded its monitoring range of compounds to reflect contemporary conservation and regulatory concerns. Monitoring of the assimilation of industrial polychlorinated biphenyls (PCBs) began in 1966 after these contaminants were identified as pollutants that were potentially toxic to birds. In terms of long-term trends, there has been a decline in congener sum PCB contamination in the eggs of most of the species that have been monitored, except for coastal nesting golden eagles. In contrast, there has been no significant decline over time in PCB concentrations in sparrowhawk livers.

Historical image of PBMS monitoring

Mercury (Hg) derived from past agricultural and past and current industrial sources has been monitored since about 1970.Evidence for changes over time in mercury concentrations in predatory birds or their eggs is inconsistent across the species monitored. Where a decline has been detected, it has occurred before approximately 1990 and remained largely unchanged since then.
1971Pair of gannetsMonitoring of contaminants in gannet eggs begins. Eggs are collected biennially from two colonies, Bass Rock in the Firth of Forth and Ailsa Craig in the Irish Sea, and from other sites when available. There has been a statistically significant decline in PCB congener sum concentrations in gannet eggs during the monitoring period of 1969-2009
1983Image of a red kite soaring in the skySince 1983, investigations have been made into the exposure to and effects of the second generation of anticoagulant rodenticides (SGARs) on barn owls and more recently kestrels and red kites have been added to the species monitored. Data on long-term trends have been adjusted to account for changes over time in sensitivity of analytical methods. This has meant that very low residues (<0.025μg/g wet weight), which are now easily detectable, are not included in the time trend analysis. The proportion of owls with detectable SGAR residues was found to be two-fold higher in England than in either Scotland or Wales. Overall, the proportion of barn owls with detectable liver concentrations of one or more SGAR has increased significantly over the course of monitoring.
2006Image of a bird of preyMonitoring of Deca-Brominated Diphenyl Ether (DBDE) in sparrowhawk begins. DBDE can be released by many different processes into the environment (E.g. emissions during manufacture). Increased concentrations can be found in air, water, soil, food, sediment, sludge, and dust. It is not fully understood whether DBDE is degraded in the environment to other harmful chemicals.
2011Image of an otter entering the waterMonitoring of poly brominated diphenyl ether (PBDEs) in otter livers begins. This work allows the PBMS to measure levels of flame retardants in a predatory species that largely feed within the aquatic environment. PBDEs have been used in many products (building materials, electronics, furnishings, motor vehicles, airoplanes, plastics, polyurethane foams, textiles). They are similar in structure to the PCBs and other polyhalogenated compounds. There is growing concern that PBDEs have an environmental long life and may bioaccumulate in fatty (and other) tissues.
2012Image of the front page of a PBMS reportThe PBMS  published a report on concentration of flame retardants in otters from England & Wales. This is the first report on the findings of a collaborative study between the PBMS and the Cardiff University Otter Project (CUOP) in which the concentrations of Polybrominated Diphenyl Ethers (PBDEs) were determined in the livers of 30 Eurasian otters (Lutra lutra) found dead in 2010. The principle aim of this work was to determine the current concentrations of PBDEs accumulated by otters and whether there was any evidence of regional differences in sum PBDE concentrations.

How can you help?

If you find a dead bird of prey telephone us (01524 595830) or email (pbms@ceh.ac.uk) and see the How to send us a dead bird page.