Pheasant release in Great Britain: long-term and large-scale changes in the survival of a managed bird

Abstract

The release of artificially reared pheasants is a widespread practice in Great Britain, used to increase the number of birds available for hunting. We examined the spatial and temporal patterns of release and shooting between 1960 and 2014 using data from a self-selected sample of 1195 sites. We examined changes in the efficiency of release, the contribution of birds that were not released that year to the numbers shot, and the form of these relationships through time. An annual estimate of the efficiency by which releasing increased the numbers shot was 50% over the period 1960-1990 declining rapidly to 35% by 2005 and reducing more slowly thereafter. There was no obvious regional pattern to this relationship. It has been hypothesised that the efficiency of releasing is lower on sites that release higher densities of pheasants; this study does not support this hypothesis. Annual variation in the density of birds shot in the absence of releasing was closely correlated with a measure of annual gamebird chick survival. After this date, the relationship was no longer significant, consistent with a decline in wild pheasant stocks and coinciding with the declines in other farmland birds. We highlight increased fox abundance, genetic and behavioural changes arising from the rearing process, and increased shooting in late winter as possible causes for the observed decline in releasing efficiency. We consider the general increase in rearing, habitat changes, increased disease or losses to protected predators as unlikely to have been important causes of the changes in releasing efficiency. Pheasant releasing results in increased numbers for shooting, but has not prevented the wide-scale decline of wild pheasant numbers.

Associations between gamebird releases and generalist predators

“…A more recent estimate based on the National Gamebag Census (Aebischer, ) puts the figure for non‐native gamebird releases at 50 million birds (Roos et al, ). Fewer than half of the released birds are shot (Bicknell et al, ; Madden et al, ) and the gap between numbers released and numbers shot is increasing, leading to a surplus of over 20 million pheasants in 2005 (Larkman et al, ; Robertson et al, ). These surplus birds are predated or scavenged before or during the shooting season (36% in a large study in southern England; Sage et al, ), or survive to be predated in the breeding season, or to breed (Sage et al, ).…”

“…When large quantities of birds are released, these are likely to dominate naturalized populations numerically, therefore, free‐roaming gamebird densities will be higher near release sites because gamebirds are sedentary and management is designed to retain birds (Madden, Hall, & Whiteside, ; Robertson, Woodburn, & Hill, ). In the case of introduced species, this is particularly marked, as free‐roaming populations are ultimately descended from captive stock (Robertson et al, ). Gamebird abundance can be positively associated with predator numbers (Beja et al, ; Valkama et al, ), although evidence is limited (e.g.…”

Why do many pheasants released in the UK die, and how can we best reduce their natural mortality?

“…Interpretations of such data vary and exact numbers are disputed. Regardless, there is a general pattern of increased release numbers over the past 50 years, with around nine times as many pheasants released in 2011 compared to 1961 when monitoring began (Robertson et al 2017). Consequently, they now comprise around 23% of the mass of the UK bird breeding population (Eaton et al 2012) and hence constitute a potentially influential component of the British ecosystem (Mustin et al 2018, Roos et al 2018.…”

“…The numbers of birds being shot have not increased to the same extent. Currently, there is no legal requirement to record the numbers of birds being reared or shot, but crude bag counts commonly put return ratios at 35-40% of the total number of birds released (Robertson et al 2017). When considering only pheasants released at one site and shot on the same estate (confirmed by including only tagged birds), return rates are lower with 28.3% of 20,950 pheasants at six sites over 3 years (Turner 2007) and 20.4% of 26,502 pheasants at eight (different) sites over 6 years (Madden, unpublished data from shoots releasing > 600 birds).…”

Shooting pheasants for sport: What does the death of Cecil tell us?

“…The sport's Code of Good Shooting Practice (Anon, ) prescribes that wounded birds should be rapidly and humanely despatched (and also that shooting should not occur where wounded birds cannot be retrieved). The proportion of released pheasants that are shot has declined from around 50% to 35% over the period 1960–1990 (Robertson et al, ), raising the question as to the fate of the birds that evade the guns (a question which is not relevant for either wild or put and take (‘canned’) lion trophy hunting). High levels of predation (see also Sage et al, ), linked to genetic and behavioural changes, were suggested as a plausible explanation for this.…”