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(Stephen Crouch, pers. comm.). The possibility was therefore
suggested that some of the birds purchased in England may
have been sourced from Scotland, where ducks can be legally
shot using lead ammunition if in terrestrial environments22. To
reduce this possibility those suppliers identified in the Defra-
funded compliance study as sourcing birds from Scotland were
not approached, and ducks were not purchased from the one
supplier contacted within this study who said his ducks were
sourced from Scotland.
Given the above discussion on efforts made to identify
provenance of birds and appreciating the number of ducks
both shot and purchased in England, it seems unreasonable to
unduly suspect that the information provided by game dealers
concerning the ducks in the present study (and that of the
Defra-funded study (Cromie et al. 2010) whose methods were
replicated here), is anything other than honest.
While 100 per cent proof of provenance is not available, the
weight of the evidence provided by the game dealers points
towards the ducks being shot in England.
Sample size and species
The previous English game dealer surveys (Cromie et al. 2002,
2010) indicated that ~70% of purchased ducks were shot with
lead.With an assumption that compliancewould have improved
since then an a priori power analysis to give a 95% confidence
of detecting birds shot with lead indicated at least 30 ducks
needed to be tested. Suspecting that this sample size may
attract criticism, a larger sample size of 100 birds containing
shot, purchased from across England, was aimed for.
As the majority of ducks sold are ‘oven-ready’ with feathers,
head, wings, legs and viscera removed, shot are sometimes no
longer present in carcases. Thus, knowing the proportion of
birds likely to be carrying shot at purchase (77% from Cromie
et al. 2010) a sample size of at least ~15 were purchased per
region to ensure ~12 birds would be carrying shot and in total
shot from some 100 birds could be analysed. These ~15 birds
were purchased from between three to six game dealers per
Government Office region.
As supplied mallards may be disproportionately shot by inland
duck shooters, significant efforts weremade to purchasewigeon
and teal as these may represent the coastal or other wildfowlers
to a greater extent – accepting that both species use inland
waters too.
RADIOGRAPHY AND POST MORTEM ANALYSIS
Radiography
To quickly eliminate birds without shot and to aid recovery of
shot by pathologists, all carcases were subjected to X-raying to
reveal the embedded radio-dense pellets.
Post mortem examination
Free-living wildfowl may contain embedded shot which proved
non-lethal from previous exposure to shooting (e.g. Noer and
Madsen 1996, Hicklin and Barrow 2004, Newth et al. 2011, Holm
and Madsen 2013). The provenance of such embedded shot is
impossible to obtain so it was important to ensure that only shot
that had most recently entered the bird at time of death were
analysed.
Pellets were determined to be ‘recent’23 and ‘non-recent’
depending on the post mortem examination findings.
Shot were judged to be ‘recent’when they were:
1. found at the site of fractured bones (ensuring that these are
fractures that occurred at the time of death and not those
caused thereafter) or within the bones themselves;
2. present within vital organs such as heart and lungs;
3. present within large areas of haemorrhage and bruising
showing that they entered the bird at, or very shortly before,
the time of death and the birdwould have been unable to fly
far with the damage inflicted;
4. present at the end of shot tracks containing feathers that
had not been ‘walled off’ by the body in any way showing
that they had recently occurred;
5. found at the back of the bird (or opposite side of entry)
having been tracked through the rest of the body including
vital organs.
22The law in Wales is analogous to that of England however in Scotland there are restrictions on use of lead over all wetlands and as mallards are predominantly birds
of wetlands, if the law is adhered to in Scotland, one would expect the majority of ducks shot there to be shot with non-lead ammunition.
23The word ‘recent’was decided on during the Defra-funded compliance study (Cromie et al. 2010) and means entered bird at or shortly before time of death. The word
‘lethal’could be used instead (accepting that not all shot entering the duck’s body are necessarily lethal if they do not cause significant injury e.g. a shot breaking a
wing bone is not in itself lethal although it results in the death of the bird).
Ruth Cromie, Julia Newth, Jonathan Reeves, Michelle O’Brien, Katie Beckmann & Martin Brown