Thread by @pec_exeter, What are the ecological consequences of gamebird release? Review by me and [...]

What are the ecological consequences of gamebird release?

Review by me and Rufus Sage @Gameandwildlife
http://publications.naturalengland.org.uk/publication/5078605686374400

We scoured the published, grey and unpublished literature to document the ecological impacts of gamebird release

What did we find?

(Thread)

It's a Rapid Evidence Assessment, so didn't set out to make specific recommendations. Policy makers may use this evidence for future decisions

Joint funded @NaturalEngland & @BASCNews

Neither org had input to Review content other than stipulate remit (exclude ethic/econ/social)

We scoured >3000 papers via formal searches and informal approaches to researchers in the field and sifted them for relevance to release & shooting of pheasant, RL partridge and mallard in the UK

Papers = 58 highly relevant; 60 moderately relevant; 101 weakly relevant

We also made FOI requests on release data from the APHA Poultry Register and extracted data about advertising commercial game shoots. This provided new information about release locations and levels

Gamebird release & management is long-established & deeply integrated in English countryside, occurring at an ever-increasing scale & over large areas

Its ecological effects are complex, complicated & wide-reaching. Evidence should be considered in framework accounting for this

The released birds have DIRECT EFFECTS

These are usually considered ecologically -ve: disturbing soil/plants, eating other wildlife, altering soil and water nutrients, spreading disease.

Some effects are ambiguous – carcasses may support popns of generalist preds or rare spp

DIRECT EFFECTS generally spatially confined around release pens, but may be long-lasting

Some effects may be at broader scale – e.g. carcasses supporting preds, or disease spread

Effects

as birds die/shot over the year

-ve effects usually greater at high density releases

The management of released birds has ASSOCIATED EFFECTS

Some of these are ecologically +ve: land management, habitat creation, legal pred control. Others are ambiguous – supp feeding may help overwrinter birds & rodent pests. Some are -ve – disturbance or shooting non-quarry spp

ASSOCIATED EFFECTS are dependent on game manager motivation and may extend over large areas of countryside

Relationship with, and dependence on, release sizes is unclear

What would game managers do in absence of releasing & shooting? It's unclear, but suggested

habitat care

The birds & their management exert INDIRECT EFFECTS on wildlife & habitats

E.g. managed woods support more bird & inverts
E.g. Gamebirds eating inverts may deprive non-game spp of chick food

This is likely contingent on scale, location & extent of releases and locally variable

Calculating NET +ve or -ve values for these is difficult but critical

E.g. Does creation of 10 acres of woodland & inverts in it, motivated by release, outweigh reduction in invert popns by gamebird predation in 1 acre of woodland release pen?

Requires considering whole web

Assessing the evidence overall, we found surprisingly little work in this area given the potential effects, & many gaps in our knowledge. Currently, there appear to be conspicuous ecological +ves AND -ves to gamebird release but collapsing these to single NET effect is difficult