Biology subjects

Sage, R. B.

Publications and source records attributed to Sage, R. B..

3 recordsLinked to original sources

bioRxiv2026

Effects of gamebird release on the non-gamebird dietary diversity and composition of red foxes (Vulpes vulpes) in Southern England

The red fox, Vulpes vulpes, is abundant in England and can exert limiting effects on their avian and mammalian prey. Large-scale gamebird releases in the UK may be sustaining high predator numbers, leading to greater predation on other prey species, especially once gamebird stocks are depleted. However, little is known how gamebird release affects the broader diet of the red fox. Here we used DNA metabarcoding to assess the diet of foxes from 18 agricultural estates in Southern England, 10 of which released large numbers of gamebirds (red-legged partridges - Alectoris rufus, and common pheasants - Phasianus colchicus) and 8 which did not. Scats were collected over one year, allowing for seasonal investigation of the foxes' diet. We investigated the vertebrate species consumed and compared the non-gamebird dietary diversity and composition between release and non-release estates and across seasons. The field vole (Microtus agrestis) was found to be the most frequently predated species overall. Brown hares and field voles were detected more on release sites, while bank voles and dog faeces were detected more on non-release sites. We found little evidence that foxes predate ground nesting birds or other species of concern. The dietary diversity was significantly lower on estates that released gamebirds, and this difference was most notable during the post-shoot, spring months (February to April). On both estate types, diversity was highest in the summer months. The altered predatory behaviour due to gamebird release is likely to affect the populations of the non-game prey of the red fox and this should be considered when designing policies regarding gamebird management and biodiversity conservation. Alternative predation combined with predator control may be reducing predation pressure on non-game prey where gamebirds are released, but high fox density elsewhere likely results in higher predation pressure on a wide range of species.

ecology↗

bioRxiv2026

The effect of atmospheric pollution caused by pheasant Phasianus colchicus releases on the epiphytic flora on trees in sensitive woodlands

The release and management of pheasants (Phasianus colchicus) in the UK for recreational shooting exerts a range of effects on the ecosystem into which they are released. We studied possible effect of nutrient deposition on epiphytic tree flora at 20 pheasant release sites distributed through England (18) and Wales (2) during winter and spring 2023/24. Sites were all Ancient Semi-natural Woodlands (ASNWs) and had substantial (600-8000 pheasants) in a single release pen. We measured N-sensitive and N-tolerant indicator bryophyte and lichen species on tree trunks near to the pen and then in plots along a transect 100m, 250m, 500m and 1km+ away from the pen. To achieve a gradient of pheasant use, the transects were located in the opposite direction to the game managed / shooting area. We recorded 1.9 times more coverage of N-tolerant lichens and bryophytes combined on selected tree species at the pen-edge compared to the control plots. The relationship showed a decline from the pen edge to 250m away but then stabilised. We also detected higher levels of coverage of N-sensitive tree flora at 100m and 250 m compared to the penedge plot. These measures were also higher at these mid distances compared to the 500m and 1000m plots. We suggest far plots were nearer wood edges and were affected by ambient inputs of aerial N from farmland and other external sources. The overall interpretation is that concentrations of pheasants in and around release pens for several months from late summer until early winter in ASNWs does affect the balance of N-sensitive and tolerant tree flora up to potentially 250m and this is a consideration when locating release pens in and near to sensitive woods.

ecology↗

bioRxiv2026

The dispersal of released pheasants and the risk of their intrusion into English protected areas

Large-scale annual releases of pheasants Phasianus colchicus and their subsequent management for recreational shooting create various ecological impacts in the UK. While effects at release sites are fairly well understood, dispersing birds may influence areas farther away. If they enter ecologically important but sensitive protected areas (PAs), any negative impacts could be especially harmful. Using tracking data, from 766 birds across 10 sites, we estimated survival and dispersal of released pheasants and applied these patterns to gamebird release records near English PAs to gauge intrusion risk. Of 2,885 registered release sites, just over half lay within 2 km of a PA. A large number of shoots release relatively few birds while a small number release many birds. Thus, numbers expected to enter a particular PA likely depend both on the size of releases and proximity to the PA. We estimate that, at a national level, a maximum of between 525,000 and 784,000 pheasants might be found within PAs very soon after release, representing around 1.7% of all the pheasants released annually. This number declines over the months after release until in February, we estimate that there are between 131,000 and 196,000 pheasants (0.4% of the total release) might be found within PAs. The critical metric by which ecological damage might occur is their density within PAs. Mean densities soon after release averaged 12.0 birds/ha in PAs within 250 m of release sites. This density declined markedly both in time (as birds died) and space (as they moved further from the pen as potential areas increased). By November, densities in PAs 500-1000m from release sites peaked at 0.5 birds/ha, falling to 0.16 birds/ha in February. These estimated densities are around two orders of magnitude lower than those known to cause strong, lasting impacts within release pens. The results are subject to assumptions about movement behaviour, game management and bias in registration. Despite these constraints, considerable local variation exists, with a minority of high-volume release sites very near PAs posing the greatest potential ecological risk.

ecology↗