Table 1.

Interventions thought to improve the survival of released pheasants, along with causes of mortality that they are likely to ameliorate

Stage of intervention	Intervention	Likely effects	Evidence for increased survival/decrease mortality?	Presumed to reduce mortality due to:
				Predation	Disease	Starvation	Dispersal
Egg production	Use of eggs from wild birds; alter diet of laying hens	Reduces stress during rearing1; Improves learning ability3			✓	✓
Early life rearing	Rearing with surrogate parents	No effect on dispersal distance26
	Provision of elevated perches	Promotes roosting off the ground7,8; enhances morphology for perching7,8; improves spatial memory7; reduces stress7,8	Yes7	✓	✓		✓
	Provision of enriched rearing environment	Reduces stress2; improved flight muscle development6		✓	✓		✗ (improved flight may make dispersal easier)
	Anti-predator training (red-leg and Chukar partridge, but not tried for pheasants)	Improved vigilance	(Yes)	✓
	Provision of diverse diet including live prey	Increases foraging efficiency9; alters gut morphology9; assists transition to natural diet9,23	Yes9	✓		✓	✗ (may encourage dispersal to search for alternative food supplies)
	Vitamin E supplement	Reduces parasite load and oxidative stress in later life19			✓
Point of release	Reduced stocking density	Reduces risk of disease transfer13,14,15,16; decreases area outside release pen utilised by males25; decreases susceptibility to coronavirus19; reduced attractiveness of area to predators4,5		✓	✓		✓
	Moving feeder sites and release pens regularly	Reduces density of gapeworm eggs in local area21			✓
Post-release	Predator control	Reduces predator threat	Only at large scales 10,11	✓
	Supplementary feeding	Increases food availability; can reduce distance pheasant must travel from cover to forage12; maintains body condition23	No (females)22	✓	✗ (Concentrated feeding may increase disease transfer risk)	✓
	Anti-helminthic treatment (oral dosing or via feed)	Reduces worm load; reduced detectability on nest by predators15; increases chick production20	Yes15	✓	✓
	Aracicide treatment (necklaces)	Reduces tick load17,18; improves chance of acquiring harem (males)17; improves hatching rate (females)18	Yes (females)18	✓	✓
	Provision of suitable habitat	Reduces dispersal; avoid human disturbance/threats e.g. traffic24

¹(Santilli et al. 2004); ²(Hrabcakova et al. 2012); ³(Bagliacca et al. 2000); ⁴(Kenward et al. 1981); ⁵(Robertson 1988); ⁶(Robertson et al. 1993); ⁷(Whiteside et al. 2016); ⁸(Santilli and Bagliacca 2017); ⁹(Whiteside et al. 2015); ¹⁰(Frey et al. 2003); ¹¹(Trautman et al. 1974); ¹²(Hoodless et al. 2001); ¹³(Draycott and Parish 2000); ¹⁴(Draycott and Parish 2000); ¹⁵(Draycott et al. 2006); ¹⁶(Gethings et al. 2015b); ¹⁷(Hoodless et al. 2002); ¹⁸(Pennycott 2000); ¹⁹(Orledge et al. 2012b); ²⁰(Woodburn et al. 2002); ²¹(Gethings et al. 2015a); ²²(Hoodless et al. 1999); ²³(Draycott et al. 1998); ²⁴(Bagliacca et al. 2010); ²⁵(Turner 2007); ²⁶(Ferretti et al. 2012)