Lead (Pb) concentrations in predatory bird livers 2010 and 2011: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability contaminant monitoring and surveillance work on avian predators. By monitoring sentinel vertebrate species, the PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Lead (Pb) is a highly toxic metal that acts as a non-specific poison affecting all body systems and has no known biological requirement. Sources of Pb in the environment include lead mining, the refining and smelting of lead and other metals, the manufacture and use of alkyl lead fuel additives, and the use of lead ammunition. The present study is the first two years of a PBMS monitoring programme to quantify the scale of exposure to [and associated risk from] Pb in predatory birds. The aim is to quantify the extent of exposure to lead [as assessed from liver residues] in two predatory bird species, the red kite (Mivus milvus) and the sparrowhawk (Accipiter nisus). The red kite is a scavenger and, as such, is particularly at risk from consumption of Pb ammunition in unretrieved game. Sparrowhawks prey predominantly upon live passerine birds that are unlikely to be shot in the UK; likely sources of exposure are diffuse Pb contamination although some individuals may also be exposed to Pb particles ingested by their prey. We also examined the liver Pb isotope ratios in to explore whether they can be used to ascribe likely sources of any Pb detected in the birds. Red kites had significantly higher Pb concentration than those measured in sparrowhawks but the majority of sparrowhawks and all the red kites had liver Pb concentrations below those thought to cause clinical and sub-clinical adverse effects in Falconiforme species. There was overlap in the liver Pb isotope ratios of red kites and sparrowhawks yet there was evidence of separation between the two species. There was also evidence of overlap with the isotope signature for coal and for Pb shot but the isotope signatures in the bird livers were distinct from that of petrol Pb. The Pb isotope pattern observed in the red kites and sparrowhawks in the current study may reflect the fact that liver Pb concentrations were low in the small sample of birds that were analysed and may have been a result of exposure to low-level, diffuse contamination.birds. Red kites had significantly higher Pb concentration than those measured in sparrowhawks but the majority of sparrowhawks and all the red kites had liver Pb concentrations below those thought to cause clinical and sub-clinical adverse effects in Falconiforme species. There was overlap in the liver Pb isotope ratios of red kites and sparrowhawks yet there was evidence of separation between the two species. There was also evidence of overlap with the isotope signature for coal and for Pb shot but the isotope signatures in the bird livers were distinct from that of petrol Pb. The Pb isotope pattern observed in the red kites and sparrowhawks in the current study may reflect the fact that liver Pb concentrations were low in the small sample of birds that were analysed and may have been a result of exposure to low-level, diffuse contamination

PBMS archive holdings: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability contaminant monitoring and surveillance work on avian predators. By monitoring sentinel vertebrate species, the PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. As part of its chemical monitoring studies the PBMS receives and carries out post-mortem examinations on approximately 300 birds or prey each year. A range of tissues are taken from the carcasses. Around 100 addled and deserted eggs from various species are also submitted to the PBMS. The eggs are cracked open and the contents collected. The shells are retained for two years prior to being donated to the National Museums Scotland for cataloguing and archiving. The main purpose for collecting tissues and egg contents is for use in annual monitoring of pollutant concentrations by the PBMS. However, not all samples are used each year for chemical analyses and, even when samples are used, typically only a sub-sample is analysed. Samples that are not analysed or for which only a sub-sample is analysed are retained in the PBMS archive. Overall, the number of samples in the PBMS archive is approaching 50,000 tissue and egg content samples. The material in the archive is used for research studies investigating chemical fate and behaviour, to trial new monitoring, and for a wide range of other studies, some of which are unrelated to pollutants. The purpose of this short report is to summarise the main holdings in the PBMS archive. This is done for the seven species for which we currently or used to obtain relatively large numbers of carcasses. We also draw attention to holdings of a small number of other species which may be of priority conservation concern. The information is broken down by type of sample that is held, the decade in which it was collected, and provenance as to whether samples were from England and Wales, or Scotland. In addition to information on numbers of samples from carcasses, we provide a description on the holdings for the number of egg contents for various species, again broken down by decade and provenance

Anticoagulant rodenticides in predatory birds 2012: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability contaminant monitoring and surveillance work on avian predators. By monitoring sentinel vertebrate species, the PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Anticoagulant rodenticides, and in particular second generation anticoagulant rodenticides (SGARs), can be toxic to all mammals and birds. Predators that feed upon rodents are particularly likely to be exposed to these compounds. The PBMS, together with other studies, has shown that there is widespread exposure to SGARs of a diverse range of predators in Britain and that some mortalities occur as a result. This report describes the PBMS monitoring for SGARs in barn owls (Tyto alba) found dead in 2012, summarises long term trends in exposure in this species, and compares the relative prevalence of SGARs in barn owls in England and Scotland. We also report the results of an initial investigation into SGAR contamination in 42 sparrowhawks (Accipiter nisus) found dead between 2010 and 2012. Sparrowhawks normally feed on birds and the aim of this investigation was to assess the potential importance of avian foodwebs in exposure of predators to SGARs. SGARs were detected in 87% of the 63 barn owls that were collected in 2012. The most prevalent compounds were difenacoum, bromadiolone and brodifacoum. The majority of the residues were low (< 0.1 µg/g wet weight). One owl was diagnosed as likely to have been poisoned by SGARs. Most of the sparrowhawk livers that were analysed had detectable liver SGAR concentrations, again mainly difenacoum, bromadiolone and brodifacoum (79%, 55% and 64% of birds, respectively). The proportion of sparrowhawks with detectable residues of one or more SGAR (93%) did not differ significantly from that for barn owls (86%) collected over the same time 2010-12 time period. Co-occurrence of multiple residues in the liver was common in barn owls and sparrowhawks (70% and 74% of birds respectively). Sparrowhawks had significantly lower liver sum SGAR concentrations than barn owls in those birds that had detectable residues. SGARs have been monitored in barn owls since 1983. 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 (<0.025 µg/g wet weight), which are now detectable, are not included in the time trend analysis. Overall, the proportion of both adult and juvenile barn owls with detectable liver concentrations of one or more SGAR has increased significantly over the course of monitoring. The proportion of barn owls with detectable SGAR residues over the period 1990-2012 was two-fold higher in England than in Scotland but residue magnitude did not differ between birds from the two areas

Anticoagulant rodenticides in sparrowhawks: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Second generation anticoagulant rodenticides (SGARs) can be toxic to all mammals and birds. The PBMS together with other studies have shown that in Britain, there is widespread exposure to SGARs in a diverse range of predators of small mammals. Defra’s Wildlife Incident Monitoring Scheme (WIIS) and the PBMS have shown that some mortalities result from this exposure. The main transfer pathway for SGARs has been thought to be most likely via target and non-target rodents that eat SGAR bait. However, recent studies, including a preliminary analysis by the PBMS on sparrowhawks, Accipiter nisus, have suggested that that SGAR transfer through avian transfer pathways may also be important. The aims of the current study were to build on our earlier results by analysing a further 52 sparrowhawks for liver SGAR residues, and using the combined dataset to (i) assess overall levels of exposure in sparrowhawks from across Britain and (ii) determine if age and sex affect the magnitude of liver SGARs residues. A final aim was to compare exposure (assessed from liver residues) in sparrowhawks with that of the barn owl Tyto alba, a predator that takes predominantly small mammals We found one or more SGARs in the livers of 89% of the 94 sparrowhawks we analysed; all birds were collected by the PBMS between 2010 and 2013. A high proportion of these residues were relatively low and none were associated with haemorrhaging unconnected with physical trauma. The proportion of birds with detectable residues and the magnitude of those residues were significantly higher in adults than juveniles, but residues did not vary significantly between males and females. Comparison of liver SGAR residues in barn owls and sparrowhawks that had died over a similar time period indicated that, for both adults and juveniles, sparrowhawks were as likely to have detectable liver SGAR residues as barn owls but the magnitude of the residues was lower in sparrowhawks. Overall this study has demonstrated that food-chain transfer of SGARs can occur via a predominantly avian trophic pathway and lead to secondary exposure

Anticoagulant rodenticides in red kites (Milvus milvus) in Britain 2010 to 2015: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Second generation anticoagulant rodenticides (SGARs) can be toxic to all mammals and birds. The PBMS together with other studies have shown that in Britain, there is widespread exposure to SGARs in a diverse range of predators of small mammals, including red kites (Milvus milvus) which will scavenge dead rats, a target species for rodent control. Defra’s Wildlife Incident Monitoring Scheme (WIIS) and the PBMS have shown that some mortalities result from this secondary exposure. The aims of the current study were to build on our earlier results by analysing liver SGAR residues in a further 24 red kites that had been submitted to the Predatory Bird Monitoring Scheme between 2010 and 2015. We (i) assessed the scale and severity of exposure and, (ii) by combining the data with that from birds collected earlier (since 2006), we determined if age and sex affects the magnitude of liver SGARs residues accumulated in red kites. All of the 24 red kites contained detectable liver residues of one or more SGAR, and all but one bird (96%) contained residues of more than one SGAR. Difenacoum was detected most frequently (96% of birds) but bromadiolone and brodifacoum were both also detected in a large proportion of birds (83-88%). Most (approximately 75%) of the kites had sum SGAR livers concentrations >100 ng/g wet wt. and SGAR poisoning was likely to have been the cause of death in two birds. Relatively high liver SGAR residues were also detected in four other birds but they had external signs of trauma indicating they may have died from other causes. The monitoring of SGAR residues in red kites remains important contribution to our understanding of SGAR exposure in wildlife, particularly those issues related to scavenging species

The potential for the use of population health indices in the Predatory Bird Monitoring Scheme: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Each bird that is submitted to the scheme is given a post-mortem examination during which approximately 60 macroscopic observations and measurements are made. The information gathered during this examination could potentially be used to monitor health status of the birds at the time of their death or at a particular stage of their development. In the current study, we focused on examining potential health indicators for the sparrowhawk, Accipiter nisus, as a candidate species partly because we have a long track record of collecting carcasses and eggs of this species, and so hold a substantial associated post-mortem (PM) observations and egg morphometric data sets. This species is sexually dimorphic, another reason for using it as a candidate species as it allowed us to investigate if the various health indices would need to be (and could be) defined separately by age class and sex. We were able to establish baseline “norms” in the form of Shewhart charts for indicators that could be broadly categorised as indicators of change in: (i) population demography because of altered recruitment, survival and mortality (measures were sex ratio, proportion of first-year birds, proportion deaths from starvation or disease, eggshell index); (ii) nutritional status (measures were body weight, fat score, condition index) and (iii) physiological stress (fluctuating asymmetry). The measurements necessary to calculate these indices are routinely captured by the PBMS through direct input into an Oracle database at the time of PM examination. We also explored the potential for annual monitoring of feather corticosterone as a simple effects biomarker for environmental stress, including environmental contaminants, but further work and resource would be needed to incorporate any such measure into annual health surveillance monitoring. We outline how the health indices described here could be reported in real-time and extended to other species to provide surveillance across different trophic strategists, and ecosystems. This report is intended to prompt debate about the type of population health indices that may be of use in assessing environmental health. It is not intended to be definitive in terms of which should be used

Mercury (Hg) concentrations in predatory bird livers and eggs as an indicator of changing environmental concentrations: a Predatory Bird Monitoring Scheme (PBMS) report

Concern over the potential health effects of mercury (Hg) has prompted an international agreement, the Minamata Convention on Mercury, that aims to control anthropogenic releases to the environment and reduce potential impacts on humans and wildlife. Monitoring is required to determine to what extent the convention is successful. The PBMS has monitored long-term trends in environmental Hg concentration using raptors and fish-eating birds as sentinels to track changes in exposure. Overall, PBMS monitoring of Hg in predatory birds provides an evidence base by which the impact of the Minamata Convention on environmental mercury concentrations in Britain can be assessed. The current study consisted of four main aims that would help rationalize and inform our long-term Hg monitoring. (i) Updating long-term data for liver Hg concentrations in sparrowhawks, (Accipiter nisus), a sentinel for exposure in lowland terrestrial habitats. (ii) Exploration of the use of alternative tissues for monitoring Hg in sparrowhawks. (iii) Comparison of trends in liver Hg residues in sparrowhawks and kestrels (Falco tinnunculus) to examine if trends in sparrowhawks, which feed on relatively mobile avian prey, reflect those in kestrels which mainly feed on small mammals that are more likely to reflect local contamination. (iv) Completion of work initiated last year to explore the potential for using Hg concentrations in the eggs of inland-feeding golden eagles (Aquila chrysaetos) as a sentinel to track changes in Hg bioavailability and uptake by biota in upland terrestrial systems. We measured liver Hg residues in sparrowhawks that had died in 2013 and 2014 to quantify current Hg exposure in lowland terrestrial habitats and to add to previously reported long-term data. Mercury residues in birds that died in 2013 and 2014 were largely consistent with those reported in recent previous years and were below those associated with mortalities. Three birds had residues higher than those associated with potential adverse effects on reproduction. Analysis of long-term data (1990-2014) indicated liver Hg residues in sparrowhawks vary with age and sex; concentrations are highest in adult males. Starvation also elevates liver Hg concentrations. Taking age and sex into account and using only data for non-starved birds, we investigated temporal trends and found that, although there has been between-year variation in liver Hg concentrations, there has been no consistent upward or downward trend. We used the long-term dataset to define “current baseline” liver Hg concentrations against which levels in future years, and consistent time trends, can be quantitatively and rapidly assessed. We found that total Hg concentrations in sparrowhawk liver, kidney and brain were closely related. We conclude it is possible to transfer our long-term monitoring of Hg in sparrowhawks (including retrospective calculation of “current baseline concentrations”) to analysis of kidney or brain. This would preserve [what are relatively small] sparrowhawk livers for other analyses. Comparison of historic trends in liver Hg in sparrowhawks and kestrels indicated that rates of decline during 1980-1998 were similar in the two species. This is consistent with the premise that sparrrowhawks are as likely as kestrels to be representative of changes in environmental exposure to (and associated bioaccumulation of) Hg in lowland terrestrial systems. The conclusion of our work on Hg concentrations in golden eagle eggs enabled us to quantify a “baseline concentration” for eggs laid by females feeding predominantly on terrestrial prey. We can use this to identify significant changes in future exposure and associated bioaccumulation and thereby use our measurements as sentinel of future change in Hg bioavailability in upland habitats in northern Britain

An exploration of concepts of community through a case study of UK university web production

The paper explores the inter-relation and differences between the concepts of occupational community, community of practice, online community and social network. It uses as a case study illustration the domain of UK university web site production and specifically a listserv for those involved in it. Different latent occupational communities are explored, and the potential for the listserv to help realize these as an active sense of community is considered. The listserv is not (for most participants) a tight knit community of practice, indeed it fails many criteria for an online community. It is perhaps best conceived as a loose knit network of practice, valued for information, implicit support and for the maintenance of weak ties. Through the analysis the case for using strict definitions of the theoretical concepts is made

Population health indices for barn owls: a Predatory Bird Monitoring Scheme (PBMS) report

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Each bird that is submitted to the scheme is given a post-mortem examination during which approximately 60 macroscopic observations and measurements are made. The information gathered during this examination could potentially be used to monitor health status of the birds at the time of their death or at a particular stage of their development. In a previous PBMS report, we focused on examining potential health indicators for the sparrowhawk, Accipiter nisus. We were able to establish baseline “norms” for indicators that could be broadly categorised as indicators of change in: (i) population demography because of altered recruitment, survival and mortality (measures were sex ratio, proportion of first-year birds, and proportion of deaths from starvation or disease); (ii) nutritional status (measures were body weight, fat score, condition index) and (iii) physiological stress (fluctuating asymmetry). In the current study we investigated whether these population health indices could be applied to barn owls, Tyto alba. With the exception of the fluctuating asymmetry (FA) metric, which did not comply with the assumptions of the methodology employed, we were able to establish baseline “norms” in the form of Shewhart charts in a format similar to those defined for the sparrowhawk. For the majority of health indices considered it was necessary to present results separately for males and females. There were no differences between age classes and so combined indices for adult and first-year birds were presented. The exception to this was the metric reporting the proportion of deaths from starvation or disease (putative cause of death) where age classes had to be separated. Although presentation of indices for age classes combined may reduce some of our ability to interpret any change in the indices it does facilitate annual reporting, as the necessity to combine multiple year’s data to satisfy statistical requirements may be less. This report has demonstrated that the proposed population health indices generally can be reported for barn owls in same way as proposed for sparrowhawks previously. However, some indices, for example fluctuating asymmetry, differ in their applicability to specific species. Therefore, data analyses similar to those carried out in the current report would be necessary if health index metrics were to be defined for other additional species

Anticoagulant rodenticides in red kites (Milvus milvus) in Britain in 2017 and 2018

Second generation anticoagulant rodenticides (SGARs) can be toxic to all mammals and birds. Various studies have shown that, in Britain, there is widespread exposure to SGARs in a diverse range of predatory mammals and birds, including red kites (Milvus milvus) which scavenge dead rats, a target species for rodent control. The Wildlife Incident Monitoring Scheme (WIIS) and the Predatory Bird Monitoring Scheme (PBMS) have shown that some mortalities result from this secondary exposure. In the present study, we analysed liver SGAR residues in 77 red kites that had been found dead in Britain in either 2017 or 2018. The carcasses were submitted to and necropsied by the Disease Risk Analysis and Health Surveillance (DRAHS) programme, the PBMS, the WIIS for England & Wales, the WIIS for Scotland and the Raptor Health Scotland study; the livers from the kites were subsequently analysed for SGAR residues. All the organisations are partners in the WILDCOMS network that promotes collaboration among surveillance schemes that monitor disease and contaminants in vertebrate wildlife. All of the 66 kites from England & Wales and 10 of the 11 red kites from Scotland had detectable liver residues of at least one SGAR. When considering the sample of kites as a whole, brodifacoum, difenacoum and bromadiolone were each detected in 73, 71 and 60 kites, respectively. Difethialone was found in 11 individuals while flocoumafen was detected in only one bird. Sum liver SGAR concentrations ranged between non-detected and 1218 ng/g wet wt. (arithmetic mean: 246 ng/g, median 154 ng/g). Post-mortem examinations indicated that 13 (16.8%) of red kites examined had internal haemorrhaging that was not associated with detectable trauma and had detectable liver SGAR concentrations. These birds had sum SGAR liver concentrations that ranged from 135 ng/g wet weight to 1218 ng/g wet weight. SGARs were considered a contributory cause of death in these cases. The stewardship scheme for anticoagulant rodenticides came fully into force in mid-2016 as re-registration of products for use in the UK was completed. A key aim is to reduce exposure of non-target wildlife to anticoagulant rodenticides but stewardship also aims to maintain efficacious rat control and so the number and density of AR-contaminated rats may remain unchanged. However, diligent searching, removal and safe disposal of poisoned rats, as promoted by stewardship, might be expected to reduce the availability of poisoned dead rats to red kites [and other scavengers] and thereby reduce the proportion of birds that are exposed and/or the magnitude of exposure. Concomitant with stewardship was a relaxation of the indoor use only restriction previously applied to brodifacoum, flocoumafen and difethialone, the three most acutely toxic SGARs. Any consequent increase in outdoor use of these three SGARs could increase the risk of secondary exposure in red kites. We therefore compared the data in the current report with that collected in 2015 and 2016 to determine if there was any evidence of a change in pattern or magnitude of exposure in red kites that might be connected to stewardship and/or change in usage restriction. The proportion of red kites exposed to SGARs in 2015 (90.6%), 2016 (89.6%) 2017 (96,4%) and 2018 (100%) was always 90% or more; the higher percentages in 2017 and 2018 were principally due to a greater proportion of birds from Scotland containing residues. Brodifacoum and difenacoum were the most prevalent compounds (89% of red kites across the four years for each compound) along with bromadiolone (75%). On average, there were residues of three different SGARs in each kite liver. There was no significant difference between years in liver sum (Σ) SGAR concentrations. We investigated if there was a change between years in the exposure of red kites to brodifacoum, flocoumafen and difethialone, the compounds for which indoor only usage restrictions were relaxed in 2016. To enable statistical analysis of data on residue prevalence, it was necessary to pool the data into two-year blocks. Data on presence/absence of detectable brodifacoum, flocoumafen or difethialone residues were therefore compared for 2015/16 (pre and year of implementation of change in usage restriction) and 2017/18 (post-change in usage restriction). The proportion of red kites with detectable residues was 82% (50 out of 61 red kites) in 2015/16 but significantly higher (95%; 73 out of 77 red kites) in 2017/18. However, there was also an increase [albeit not statistically significant] in the proportion of red kites with detectable liver difenacoum or bromadiolone residues (90% in 2015/16 vs. 97% in 2017/18). Therefore, these data may simply reflect an increase in the prevalence of exposure to SGARs generally rather than any effect of change in usage restriction. There was no difference between the four years in the summed magnitude of liver brodifacoum, difethialone and flocoumafen concentrations. The percentage of red kites examined that were diagnosed as birds in which SGARs were implicated as a contributory cause of death did not differ significantly between individual years nor show a significant trend across the years; the overall average across the four years was 22%. However, if data were pooled by pairs of years (2017/8 vs 2015/16), the proportion of red kites for which SGARs were implicated as a contributory cause of death was lower (18%) in 2017/18 than in 2015/16 (33%) for red kites from England & Wales. Our findings do not indicate that there has been any reduction in exposure in red kites to SGARs following implementation of stewardship, in terms of either the proportion of individuals exposed or the magnitude of residues detected. There is some evidence (depending upon the statistical approach used) that the proportion of red kites in which SGARs were implicated as a contributory mortality factor has decreased in more recent years. There was no clear evidence that relaxation of usage restrictions on brodifacoum, difethialone and flocoumafen has altered the pattern of residue accumulation in red kites to date